撃i i ̲ 3 蚤妻 賢哲季曇 苧 腎 門塁間毒 雷S Sy離 em S T的毒 軸岳 ngand 醐◎鮎 § 裏 mg紬葛 '晶 監om p崇母X脚or § d 昏i S 憲章 発撃等墨 等 ぎ発桑野鹿 奪 Sys骨em等 耳的重訂痛 貞門gand Mo e B e巨 岳 悶 g骨 0㌢讃 監¢獅 野営e xW即匡 d JohnD. St er man Mas s ac hus et t sI ns t i t ut eofTechnol ogy Sl oanSc hoolofMa nageme nt 幽腰 閲脱水 甘言 告 婁 Bos t on Bur rRi dge,l L Dubuque,l A Madi son, WINewYor k SanFr anci sco St .Loui s Bangk ok Bogot a Car acas Li sbon London Madr i d Mexi coCi t y Mi l an Ne wDel hiSeoulSi ngapor e Sydney T ai peiTor on t o Mc Gr a w‑ Hi l lHi ghe rEd uc at i o n ADL mS L O nO fTh eMc Gr a w‑ Hi l lCo mpa me s BUSI NESSDYNAMI CS SYs TE MSTHI NKI NGANDMoDE L I NGF ORACoMP L EXWoRLD Copyr i ght㊨2000byTheMc Gr a w‑ Hi l lCompa ni e s Jnc. Al lr i ght sr es e r ve d. Pr i nt e di nt heUni t e d St a t esofAme r i ca ・ Exc e pta spe r mi t t e dunde rt heUni t e dSt a t e sCopyr i ghtAc tof1 976, nopa r tof t hi spubl i c a t i onma yber e pr oduc e dordi s t r i but e di na nyf o r morbya nyme a ns , ors t or e di na da t a ba s eol‑r e t r i e va ls ys t e m, w it houtt hepr i orWr i t t e np er mi s s i onoft hepubl i s he r . Thi sbooki spnnt e dona c i d‑ f r e epa er p . 1 0QWV/ QWVO987 1 3 : 978‑ 0‑ 07‑ 2311 35‑ 8 I SBN‑ I SBN‑ 1 0: 0‑ 07‑ 231 1 3 5‑ 5 J e j f r e yJ.She l s t ad Publ i s he r : Se ni ors pons or l nge di t or : Sc ot tI s e nbe r g Ma r ke t i ngma na ge r : Zi naCr q f t Se ni o rpr o j e c tma na ge r :Gl ad ysTr ue Se ni orpr od uc t i ons upe r vi s or : Lor iKoe t t e r s Fr e e l a nc ede s i gnc oor di na t o r : Ma7 TL I .Chr i s t i ans on Fr e e l a nc ec ove rde s i gne r :TheVl ‑ s ual Cove ri ma ge' . ㊨Soni aDe l auna y / i&M Ser vi c e s , Ams t er damuat eGal l e r y , London / Ar t Re s ol uCe , NY Compos i t or :GAC/ I ndi ana pol i s Type f a c e:l l / 13Tl ' me sRoman Pr i nt e r :Quebec orPr i nt i ngBoo kGr ou pWer s ai l l e s Li br ar yo fCongr e s sCat log a ing‑ i n・ Publ i e at i onDat a St e r ma n, J ohn. Bus i nes sdyna mi cs:s ys t e mst hi nk i nga ndmode l i ngf b∫ac ompl e xwo r l d/J ohnD.St e r ma n. p・ c m・ I nc l udesbi bl i ogr a phi c a lr e f e r e nc esa ndi nde x・ 礼 l k. pa pe r ) I SBN0‑ 07‑ 2311 35‑ 5( i lI ndus t r i a lma na ge me nt ・ 2・Sys t e mt he or y. 3.Ma na ge me nti nf o r ma t i ons ys t e ms .I . Ti t l e. HD3 0. 2. S7835 2000 658. 4′ 038′ 01 1 ‑dc 21 99‑ 056030 ht t p: 〟www. mhhe. c om Fo rCi ndy ABOUTTHEAuTHOR J ohnD.St e r ma ni s∫ .Spe nc e rSt a ndi s hPr of es s orofMa na ge me nta tt heSl oa n Sc hoolofMa na ge me ntoft heMa s s a c hus e t t sI ns t i t ut eofTe c hnol ogya ndDi r e c t or ofMI T' sSys t e m Dyna mi c sGr oup.Hi sr es e a r c hc e nt e r sont hede ve l o pme ntof pr a c iCa t lme t hodsf ors ys t e mst hi nki nga nddyna mi cmode l i ngofc ompl e xs ys ‑ t e ms , Wi t ha ppl i c a t i onst oo r ga ni z a t i ona ll e a ml nga ndc ha nge, ope r a t i onsma na ge ‑ me nt , c or por a t es t r a t e gy , a ndno nl i ne a rd yna mi csi nawi der a ngeofs ys t e ms , f r om s uppl yc ha i nst os c i e nt i f i cr e vol ut i ons . Heha spl One e r e dt hede ve l o pme ntofma n‑ a ge me ntf li ghts i mul a t or sofc o r po r a t ea nde c onomi cs ys t e ms . The s ef li g hts i mul l a t o r sa r eus e di nr es e a r c ht ounde r s t a nda ndi mpr ovema na ge r i a lde c i s i onma ki ng i nc ompl e xdyna mi cs ys t e ms ; mo r ei mpo r t a nt l y, t he ya r enowwi de l yus e dbyc or ‑ por a t i onsa nduni ve r s i t i e sa r oundt hewo r l df o rt e a c hi ng, pr o bl e ms o l vi ng, a ndpol ‑ 1 C ydes i gn.Pr of es s orSt e r ma ndi s c ove r e ds ys t e m dyna mi c smode l i ngi nhi gh s c hool ,s t udi e di ta sa nunde r g r a dua t ea tDa r t mout hCol l e ge ,a ndr e c e i ve dhi sPhD f r omMI T・ Heha sbe e na wa r de dt heJ a yW For r e s t e rPr i z e, gl Ve nf o rt hebe s tpubl l i s he dwor ki nt hef i e l do fs ys t e mdyna mi c sove rt hepr i orf i veye a r s , a ndha sf our t i meswona wa r dsf ort e a c hi nge xc e l l e nc ef r omt hes t ude nt soft heSl oa nSc hool . Vl Ac c e l e r a t l nge c o no mi c , t e c hno l o g i c a l , s o c i a l , a nde nvi r o nme nt a lc ha ng ec ha l l e nge ma na g e r sa ndpo l i c yma ke r st ol e a r na t i nc r e a s i ngr a t e s , Whi l ea tt hes a met i met he c o mpl e xl t yOft hes ys t e msi nwhi c hwel i vei sg r o wl ng・ Ma nyo ft hepr o bl e mswe nowf a c ea r i s ea suna nt l C I Pa t e ds i d ee f f e c t sofo u rownpa s ta c t i ons . Al lt o oo f t e n t hepol i c i e swei mpl e me ntt os o l vei mpo r t a ntpr o bl e msf a i l ,ma ket hepr o bl e m wo r s e , orc r e a t ene wpr o bl e ms . Ef f e c t i ved e c i s i o nma ki nga ndl e a ni r ngl nawo r l dofg r owi ngdynami cc om‑ pl e xi yr t e qui r e sust obe c o mes ys t e mst hi n ke r s ‑t oe x pa ndt hebounda r i e so fo u r me nt a lmode l sa ndde ve l o pt oo l st ound e r s t a ndho wt hes t r uc t ur eo fc o mpl e xs ys ‑ t e msc r e a t e st h e i rbe ha vi o r . Thi sbooki nt r od uc e syo ut os ys t e md y na mi c smod e l i ngl brt hea na l ys i so fpo l ‑ l C ya nds t r a t e g y, wi t haf oc uso nb us i ne s sa ndpubl i cpol i c ya ppl i c a t i o ns ・ Sys t e m d yna mi c si sape r s pe c t i vea nds e to fc o nc e pt ua lt oo l st ha te na bl eust ounde r s t a nd t hes t r u c t u r ea ndd yna mi c so fc o mpl e xs ys t e ms . Sys t e mdy na mi c si sa l s oar l gO r‑ O usmo de l i ngme t hodt ha te na bl e sust obui l df o r ma lc o mput e rs i mu l a t i o nso fc o m‑ pl e xs ys t e msa ndus et he mt od e s i gnmo r ee fe c t i vepol i c i e sa ndo r ga ni z a t i o ns ・ To ge t he r ,t he s et ool sa l l owust oc r e a t ema na ge me ntf li g hts i mul a t or s ‑mi c r o‑ wo r l dswhe r es pa c ea ndt i mec a nb ec o mpr e s s e da nds l owe ds owec a ne x pe r i e nc e t h el o ng‑ t e r ms i d ee fe c t sofde c i s i o ns , s pe e dl e a r n l ng, de ve l o pourunde r s t a nd i ng o fc o mpl e xs ys t e ms , a ndd e s i gns t r uc t u r e sa nds t r a t e gl e Sf o rg r e a t e rs uc c e s s . Thef i e l do fs ys t e md yna ic m si st hr i vi ng. Ove rt hepa s td e c a de , ma nyt o pc o m‑ pa n i e s ,c o ns ul t i ngf i r ms ,a ndgov e r n me nt a lo r ga ni z a t i onsha veus e ds ys t e md y‑ na mi c st oa dd r e s sc r i t i c a li s s ue s .Mo r ei nnova t i veun i ve r s i t i e sa ndbus i ne s s s c hoo l sa r et e a c hi ngs ys t e m dyna mi c sa ndf i nd i nge nt hus i a s t i ca ndgr owl nge n‑ r o l l me nt s . Hun dr e dso fpr i ma r ya nds e c o nda r ys c hool s , f r omki nde r ga r t e nt ohi g h s c hoo l ,a r ei nt e g r a t l ngS ys t e mst hi n ki ng,s ys t e md yna mi c s ,a ndc o mput e rs i mul a ‑ t i o ni nt ot he i rc u r r i c ul a . Too l sa ndme t ho dsf o rs ys t e mdyna mi c smode l i ng, t hel i ‑ br a r yofs uc c e s s f ula ppl i c a t i o ns , a ndi ns i g ht si n t ot hee f f e c t i veus eo ft het oo l swi t h e xe c ut i ve sa ndo r ga ni z a t i o nsa r ea l le x pa nd i ngr a pi dl y ・ vi i vi i i P r e f a c e FEATURESAh 旧 にoNTENT Uni ve r s l t ya ndgr a dua t e l l e ve lt e xt s ,pa r t i c ul a r l yt hos ef oc us edonbus i ne s sa nd publ i cpol i c ya ppl i c a t i ons ,ha venotke ptpa c ewi t ht hegr owt hoft hef i e l d.Thi s booki sdes i gne dt opr ovi det hor oughc ove r a geoft hef i e l dofs ys t e mdyna mi cst o‑ da y, bye xa mi nl ng 。 Sys t e mst hi nki nga ndt hes ys t e mdyna mi c swor l dvi e w; ・ Tわol sf わrs ys t e mst hi nki ng, I nc l udi ngme t hodst oe l i c i ta ndma pt he s t r uc t ur eofc o mpl e xs ys t e msa ndr e l a t et hos es t r u c t ur e st o血e i rdyna mi cs ; ・ Tbol sf o rmode l i nga nds i mul a t i onofc ompl e xs ys t e ms ; 。 Pr oc e dur e sf ort e s t l nga ndi mpr ovl ngmode l s ; 。 Gui de l i nesf わrwor ki ngwi t hc l i e ntt e a msa nds uc c e s s f u li mpl e me nt a t i on。 Youwi l ll e a r na boutt hedyna mi csofco mpl e xs ys t e ms ,i nc l udi ngt hes t r uc t ur es t ha tc r e a t egr owt h,goa l ‑ s e e ki ngbe ha vi or ,os c i l l a t i ona ndi ns t a bi l i t y,S‑ s ha pe d gr owt h,ove r s hoo ta ndc ol l a ps e ,pa t hde pe nde nc e,a ndot he rnonl i ne a rdyna mi cs . Exa mpl e sa nda ppl i c a t i onsi nc l ude ・ Cor po r a t egr owt ha nds t a gna t i on, ・ Thedi f f us i o nofne wt e c hnol ogi e s , 。 Thedyna mi csofi nf e c t i ousdi s e a s es uc ha sHI V/ AI DS, ・ Bus i nes sc yc l e s , 。 Spe c ul a t i vebubbl e s , 。 Theus ea ndr e l i a bi l i t yoff or e c a s t s , 。 Thedes i gno fs uppl yc ha i nsi nbus i nes sa ndot he ror ga ni z a t i ons , 。 Se r vi c equa l i t yma na ge me nt , ・ Tr a ns por t a t i onpol i c ya ndt r a fi cc onges t i on, ・ Pr o j e c tma na ge me nta ndpr oduc tde ve l o pme nt , a ndma nyot he r s . Thegoa lofs ys t e mst hi nki nga nds ys t e mdyna mi c smode l i ngl St Oi mpr oveour unde r s t a ndi ngoft hewa ysi nwhi c ha nor ga ni z a t i on' spe r f or ma nc ei sr e l a t e dt oi t s i nt e r na ls t r uc t ur ea ndo pe r a t i ngpol i c i es ,i nc l udi ngt hos eofc us t ome r s ,c ompe t l ‑ t o r s ,a nds uppl i e r sa ndt he nt ous et ha tunde r s t a ndi ngt ode s i gnhi g hl e ve r a gepol i ‑ c i esf ors uc c e s s . Todos ot hi sbookut i l i z es 。 Pr oc e s sPoi nt st ha tpr ovi depr a c t i c a la dvi c ef ort hes uc c e s s ula f ppl i c a t i on oft het ool si nr e a lor ga ni z a t i ons . ・ Ca s es t udi e sofSys t e m Dynami c si nAc t i ont ha tpr es e nts uc c e s s f ul a ppl i c a t i onsr a ngi ngf r o mgl o ba lwa r mi nga ndt hewa rondr ugst o r e e ngl ne e r l ngt hes uppl yc ha i nofama j orc omput e rf i r m, ma r ke t i ng s t r a t e gyl nt hea ut omo bi l ei nd us t r y,a ndpr oc es si mpr ove me nti nt he pe t r oc he mi c a l si ndus t r y, Sys t e m dyna mi c si snotas pe c t a t ors por t .De ve l opl ngS ys t e mst hi nki nga ndmod‑ e l i ngs ki l l sr e qul r e St hea c t i vepa r t l C l pa t i onofyou, t her ea de r , vi a Pr e f a c e l X ・ Chal l e ng e s . Thec ha l l e nges , pl a c e dt hr oughoutt het e xt ,gl Veyo uPr a c t i c e wi t ht het ool sa ndt e c hni q ue spr es e nt e di nt hebooka ndwi l ls t i mul a t eyour or l gl na lt hi nki nga bouti mpor t a ntr e a lwo r l di s s ue s ・ Thec ha l l e ngesr a nge f r om s i mpl et houghte xpe r i me nt st of ul ‑ s c lemode a l i ngpr o j e c t s . l 。 Si m1 1 1 at i ons of t wa reandmode l s . Thea c c ompa nyi ngCD‑ ROM a ndwe b s i t e( ht t p: 〟www. mhhe. c om/ s t e r ma n)i nc l udea l lt hemode l sde ve l o pe di n t het e xta l ongwi t hs t a t e ‑ of ‑ t he ‑ a r ts i mul a t i ons of t wa r et or unt he m・ The r e a r es e ve r a le xc e l l e nts of t wa r epa c ka ge sdes i gne dt os uppo r ts ys t e m dyna mi c smode l i ng. The s ei nc l udei t hi nk, Powe r s i m, a ndVe ns i m. TheCD a ndwe bs i t ei nc l udet hemode l sf o rt het e xti na l lt hr e es of t wa r ef or ma t s . Thedi s ka l s oi nc l ude sf u l l yf u nc t i ona lve r s i onsoft hei t hi nk, Powe r s i m, a nd Ve ns i ms of t wa r es oyo uc a nr unt hemode l sus i nga nyOft he s epa c ka ge s wi t houtha vi ngt opur c ha s ea nya ddi t i o na ls of t wa r e・ ・ Addi t i ona l l y,t heI ns t r uc t or' sManuala ndi ns t r uc t o r ' ss e c t i onoft he we bs i t ei nc l udes ugge s t e ds ol ut i onsl brt hec ha l l e nges ,a ddi t i ona l a s s l gnme nt S ,Powe r poi ntf i l e swi t ht hedi a gr a msa ndf i gur esf r omt het e xt s ui t a bl ef ort r a ns pa r e nc i e s ,s ugge s t e dc our s es e que nc esa nds yl l a bi ,a nd ot he rma t e r i a l s . l NTENDEDAuDI ENCE Thebookc a nbeus e da sat e xti nc our s esons ys t e mst hi nki ng,s i mul a t i onmode l ‑ 1 ng,C Ompl e xl t y,S t r a t e gi ct hi nki ng,O pe r a t i ons ,a ndi nd us t r i a le ngl ne e r l ng,a mong ot he r s .I tc a nbeus e di nf u l lo rha l f ‑ s e mes t e rc our s es ,e xe c ut i vee duc a t i on,a nd s e l f ‑ s t udy.Thebooka l s os e r ve sa sar e f e r e nc ef orma na ge r s ,e ngl ne e r S ,C OnS ul ‑ t a nt s ,a ndot he r si nt e r e s t e di nde ve l o pl ngt he i rs ys t e mst hi nki ngs ki l l so rus l ngS yS ‑ t e mdyna mi csi nt he i ror ga ni z a t i ons 。 A NoTEON MATHEMATI CS S ys t e m dyna mi c si sgr ounde di nc ont r olt he or ya ndt hemode r nt he or yofnonl i n‑ e a rdyna mi cs . The r ei sa ne l e ga nta ndr i gor ousma he t ma t i c a lf ounda t i onf ort he t he or ya ndmo de l swede ve l o p. Sys t e mdyna mi csi sa l s ode s i gne dt obeapr a c t i c a l t oolt ha tpol i c yma ke r sc a nus et ohe l pt he ms ol vet hepr e s s l ngpr obl e mst he yc on‑ f r onti nt he i ro r ga ni z a t i ons . Mos tma na ge r sha venots t udi e dnonl i ne a rdi f f e r e nt i a l e qua t i onsore ve nc a l c ul us , o rha vef o r got t e ni ti ft he ydi d・ Tobeus e f ul , s ys t e mdy‑ na mi c smode l i ngmus tbea c c es s i bl et ot hewi des tr a ngeofs t ude nt sa ndpr a c t l C l ng ma na ge r swi t houtbe c o mi ngaVa gueS e tOfqua l i t a t i vet ool sa ndunr e l i a bl ege ne r ‑ a l i z a t i ons . Tha tt e ns i oni sc ompounde dbyt hedi ve r s l t yOfba c kgr oundswi t hi nt he c ommunl t yOfma na ge r s ,s t ude nt s ,a nds c hol a r si nt e r es t e di ns ys t e m dyna mi cs , ba c kgr oundsr a ngi ngf r om pe opl ewi t hnoma t he ma t i cse duc a t i onbe yondhi gh s c hoolt ot hos ewi t hdoc t or a t e si nphys i cs . X P r e f a c e j FYouDoN'THAVEA STRONG MATHEMATI CS BACKGROUND, FEAR No† sboo kpr e s e n t ss ys t e md yna ic m swi t hami n i mumo fma t he ma t i c a lf o r ma l i s m. Thi Theg oa li st od e ve l o pyo u ri nt ui t i ona ndc o nc e pt ua lu nd e r s t a ndi ng, wi t ho uts a c r i ‑ f i c i ngt her l gO rO ft hes c i e nt i f i cme t hod. Yo udono tne e dc a l c ul uso rdi f f e r e nt i a l e q ua t i onst oun de r s t a n d血ema t e r i a l . I nde e d, t hec o nc e pt sa r ep r e s e nt e dus l ngOnl y t e xt ,g r a phs ,a ndba s i ca l ge br a ・ Ma t he ma t i c a ld e t a i l sa ndr e f e r e nc e st omo r ea d‑ Va nc e dma t e r i a la r es e ta s i dei ns e pa r a t es e c t i o nsa ndf oo t no t e s . Hi g he rma t he ma t ‑ i c s , t ho ug hus e f u l , i sno ta si mpo r t a nta st hec r i t i c a lt hi nki ngs k i l l sd e ve l o pe dhe r e. f FYouHAVEA STRONG MATHEMATI CS BACKGROUND,FEAR No† Re a l i s t i ca ndus e f u lmode l sa r ea l mos ta l wa yso fs uc hc o mpl e x l t ya ndno nl i ne a r l t y t ha tt he r ea r enokn owna na l yt i cs ol ut i o ns , a ndma n yo ft hema t he ma t i c a lt o ol syo u ha ves t ud i e dha vel i mi t e da ppl i c a bi l i t y .Thi sboo kwi l lhe l pyouus eyours t r ong t e c hni c a lba c kg r o undt ode ve l o pyouri nt ui t i o na ndc o nc e pt ua lunde r s t a nd i ngof c o mpl e xl t ya nddy na mi c s . Mod e l i nghuma nbe ha v i o rd i fe r sf r ommo de l i ngphys ‑ i c a ls ys t e msi ne ng l ne e r l nga ndt hes c i e nc e s . Wec a nno tp ut ma na g e r su po nt hel a b be nc ha ndr une xpe r i me n t st ode t e r mi net he i rt r a ns f e rf unc t i o no rf r e q ue nc yr e ‑ s pons e . Webe l i e v ea l le l e c t r onsf ol l o wt hes a mel a wso fphys i c s , butwec a nnot a s s u mea l l pe o pl ebe ha v ei nt hes a mewa y. Be s i d e sas o l i dg r o u nd i ngl nt hema t he ‑ ma t i c sofd yna mi cs ys t e ms ,mode l i nghuma ns ys t e msr e q ul r e SuSt Ode ve l o po ur , knowl e dg eofps yc ho l o gy ,de c i s i onma ki ng,a ndo r ga ni z a t i ona lbe ha vi o r ・ Fi na l l y ma t he ma t i c a la na l ys t s ,Whi l ene c e s s a r y ,i sf a rf r o ms uf f i c i e ntf o rs uc c e s s f uls ys t e mst hi n k i nga ndmo de l i ng. Fo ryo urwo r kt oha vei mpa c ti nt her e a lwo r l dyo u mus tl e a r nho wt ode v e l o pa ndi mpl e me ntmo de l so fhu ma nbe ha vi o ri no r ga ni z a ‑ , pe r s o na l i t i e s , a ndpo l i t i c s . Th r ough‑ t i o ns , wi ha t l lt h e i ra mbi g ul t y , t i mepr e s s ue outt hebo o klha v es o ughtt oi l l us t r a t eho wt het e c hn i c a lt oo l sa ndma 血e ma t i c a l c o nc e pt syouma yha ves t udi e di nt hes c i e nc e so re ng l ne e r l ngC a nbea ppl i e dt ot he me s s ywo r l do ft hepo l i c yma ke r . ‑ r FEEDBACK Iwe l c o meyo urc o mme nt s , C r i t i c i s ms , a nds ugge s t i o ns . Sug ge s t i o nsf o ra dd i t i o na l e xa mp l es ,c a s e s ,t he o r y ,mo de l s ,f li g hts i mul a t o r s ,a nds oo n,t oma ket heboo k mor er e l e va nta ndus e f u lt oyoua r ee s pe c i a l l yi nvi t e d.Iwi l lu pda t et hewe bs i t e t oi nc o r po r a t eus e rf e e d ba c ka ndne wma t e r i a l s ・ Ema i lc o mme nt st o<Bus Dyn@ mi t . e du>. AcKNOWLEDGMENTS Thi swo r kbe ne f i t e di mme ns e l yf r o mt hea dvi c e , c r i t i c i s m, a nde nc o ur a ge me nto f ma nyc ol l e a gue s ,s t ude nt s ,a ndf r i e nds .Iowea ni mme a s ur a bl ede btt omyf i r s t , s ys t e mdy na mi c st e a c he r s , Da naMe a dows , De nni sMe a do ws ,a ndJ a yFo r r e s t e r f o rt he i ri nt e g r l t y ,hi g hs t a nda r ds ,a ndpa s s i o na t ec o mmi t me n t .I ' m pa r t i c ul a r l y i nde bt e dt ot hee xc e pt l O na ls t ude nt soft heMI TSl oa nSc hoo lofMa na g e me nt . The yc o ns t a nt l yc ha l l e ng emet oma ket hedi s c i pl i neo fs ys t e mdy na mi c sr e l e va nt , Pr e f a c e Xl us e f u l , a nde xc l t l ng; Iho pet he y' v el e a r ne da smuc h丘. ommea sI ' vel e a r n e df r om t he m.I na dd i t i o n,It ha n kmyc o l l e a gue sa tt heSl oa nSc hoola ndi nt hes ys t e m d yna mi c sc o mmu nl t ya r o undt hewo r l d, whohe l pe dbypr o vi d i ngda t aa n de xa m‑ pl e s , r e vi e wi ngt hed r a f t , t e s t l nge a r l yve r s i o nsi nt he i rc o ur s e s ,a ndi nc o unt l e s s o t he rwa ys ・Th i sg r o upi n c l ude s( buti snotl i mi t e dt o)t hef o l l owi ngf o l ksa nd i ns t i t ut i o ns : Ta r e kAbd e l ‑ Ha mi d( Na va lPos t g r a dua t eSc hool ) ;Da vi dAnde r s e n,Ge or ge Ri c ha r ds o n( SUNYAl ba ny) ; EdAnd e r s o n( Uni v . o fTe xa s ) ;Ca r l osAr i z a , Sha r on EI s ,Ke nCoo p e r ,J i m Lyne i s ,Ha nkTa yl o r( Pugh‑ Ro be r t sAs s oc i a t e s ) ;Ge o r ge Ba c kus( Po l i c yAs s e s s me n tCo r po r a t i on) ;Be ntBa k ke n( No r we g i a nDe f e ns eRe ‑ ) ;Ya ma nBa r l a s( Boga z i c iUni ve r s i t y,I s t a nb ul ) ;Mi c ha e l s e a r c hEs t a bl i s hme nt Be a n( Po we r s i mCo r p. ) ; Er i cBe i n hoc ke r , Da mo nBe ye r , And r e wDo ma n, Us ma n Gha ni ,Ma ur i c eGl uc ks ma n,Pa ulLa ngl e y,No r ma nMa r s ha l l( Mc Ki ns e ya nd l ,Va ne s s aCol e l l a ,Er ns tDi e hl ,St e veEp‑ Co mpa ny) ;La u r aBl a c k,J o hnCa r r ol pl ng e r ,Cha r l i eFi ne , Mi l aGe t ma ns ky ,Pa ul oGonc a l ve s , J a ne tCo ul dWi l ki ns o n, J i mHi ne s , Na nLux, Br a dMo r r i s o n, Ti mNuge n t , Ne l s o nRe pe nnl ng, EdRo be r t s , Sc o t tRoc ka r t ,Ge o r g eRo t h,EdSc he i n,Pe t e rSe ng e( MI T) ;Al l e na ndJ a ne Boo r s t e i n;St e v eCa va l e r i( Ce nt r a lCo nne c t i c utSt a t eUni v ・ ) ;Ge o f fCo yl e( Ro ya l Mi l i t a r yCo l l e g eo fSc i e nc e ,UK,r e t i r e d) ;Br i a nDa nge r f i e l d( Uni v.o fSa l f o r d) ; Pa lDa vi ds e n( Uni v .o fBe r ge n) ;J i m Doyl e ,Mi keRa dz i c ki ,Kha l i dSa e e d ( Wo r c e s t e rPo l yt e c hn i cl ns t i t ut e ) ;Bo bEbe r l e i n,To m Fi dda ma n,Da nGol d ne r , Da v i dPe t e r s o n, La ur aPe t e r s on( Ve nt a naSys t e ms ) ;Da vi dFo l e ya ndJ udyBe r k; And yFo r d( Wa s hi ng t o nSt a t eUni v. ) ;Da vi dFor d( Te xa sA&M Uni ve r s i t y) ; A,T. Ke a r n e y) ; Ri c hGo l d ba c h( Me t r oMa c hi neCo r p. ) ;Ch r i s ‑ Na t ha nFo r r e s t e r( t i a nHa x hol d t ,He a t he rHa z a r d( Cope nha ge nBus i ne s sSc hoo l ) ;J a c kHo me r ( Ho me rCons ul t i ng ) ;J o dyHo us e( Or e gonGr a d ua t eI ns t i t ut e ) ;Bi l ll s a a c s( Di a ‑ l ogos ) ;Sa ml s r a e l l t( Ar t hurAnde r s e n) ;Ni t i nJ og l e ka r( Bos t o nUn i v.Sc hool o fMa na ge me n t ) ;Dr e wJ o ne s( Sus t a i na bi l i t yI ns t i t ut e ) ;Chr i s t i a nKa mpma nn, Er i kMos e ki l d e( Te c hn i c a lUni v・o fDe nma r k) ;Da ni e lKi m,Vi r gi ni aWi l e y ( Pe ga s usCommuni c a t i o ns ) ;Cr a i gKi r kwood( Ar i z o naSt a t eUni v . ) ;El i z a be t h , Kr a hme rKe a t i ng( Nor t hwe s t e r nUni v . ) ;DonKl e i nmun t z( Uni v .o fI l l i no i s Ur ba na ‑ Cha mpa i g n) ; Da vi dKr e ut z e r( GKA, I nc. ) ; Ro be r t La n de l( Da r ° e nSc hool o fBusi ne s s , Un i v . o fⅥr g i ni a ) ; Da v i dLa ne( Lo ndo nSc hoolofEc o no mi c s ) ;Er i k La r s e n( Ci t yUn i ve r s i t y , Lo ndo n) ; Wi ns t o nJ . Le de t , Wi ns t o nP. Le de t( TheMa n‑ uf a c t uri ngGa me ,I nc. ) ;Ra l phLe vi ne( Mi c hi ga nSt a t eUn i v ・ ) ;Ang e l aLi pi ns ki ( Soc i et yf o rOr ga n i z a t i ona lLe a r ni ng) ;Ma r t i nGr o J 3 ma n n,Fr a nkMa i e r ,Pet e r Mi l l i ng ( Uni v . o fMa nn he i m,Ge r ma ny) ; Al iMa s ha ye khi( Sha r i fUni v.o fTec h‑ nol ogy,Te he r a n) ;Na t ha ni e lMa s s( Ge nCo r p) ;Pa ulMo n us( BP/ Amoc o ) ,J ohn Mo r e c ro f t ,An nva nAc ke r e ,Ki n Wa r r e n( Lo ndo nBus i ne s sSc hoo l ) ;Er l i ng Mo xnes( No r we g i a nSc ho olo fEc ono mi c sa n dBus i ne s sAd mi ni s t r a t i o n) ; Rog e l i o Ol i va(H a r va r dBus i n e s sSc ho ol ) ; Ma r kPa i c h( Co l o r a doCo l l e ge ) ; St e v ePe t e r s on, Ba r r yRi c hmo n d( Hi g hPe r f o r ma nc eS ys t e ms ) ; Gr e gPe t s c h( Co mpa qCo mput e r ) ; Ni c kPuda r( Ge n e r a lMo t o r s ) ;J a c kPug h,J u l i aPug h,Ro be r t aSpe nc e r( Sys t e m Wo r l dWi l dl i f eFundI n t e r na t i ona l ) ; Na nc y Dyna mi c sSoc i e t y) ,J Qr ge nRa nde r s( Ro be r t s( Le s l i eCo l l e ge ) ;J e nnyRud o l p h( Bos t onCo l l e ge ) ;J o r geRuf a t ‑ La t r e ( St r a t e go s ) ;An j a l iSa s t r y ,Ma r s ha l lva nAI s t yne( Uni ve r s i t yofMi c hi ga n) ;Bo b o n( Gl o ba lPr os pe c t us ,LLC) ;J o hn帆) ye r St e a r ns ;Sus a nSt e r ma n;J i m Thomps xi i Pr e f a c e ( Un i v . o fSo u t h e r nMa i ne ) ; Ly l eWa l l i s( De c i s i o, I nc . ) ; J i mWa t e r s( Wa t e r sBus i ‑ ne s sSys t e ms ) ; J a s o nWi t t e n be r g( Ha r va r dUn i v . ) ; Er i cWo l s t e nho l me( Le e °sBus i me s sSc hoo l , UK) ; Pa ve lZa mudi oRa mi r e z( Mo n i t o rCo mpa ny) ; t heCo pe nha ge n Bus i ne s sSc ho o l ,Thel nt e r na t i ona lNe t wo r ko fRe s o ur c el nf o r ma t i o nCe nt e r s ( a kat heBa l a t o nGr oup) ,Mc Ki ns e ya ndCo mpa ny ,t heNo r we gi a nSc hoolof Ma na g e me nt , Pugh‑ Ro be r t sAs s oc i a t e s ,t heSo c i e t yf o rOr ga ni z a t i ona lLe a r nl ng, t heTe c hni c a lUni v e r s i t yo fDe nma r k,a n d,o fc o u r s e ,t heMI TSl oa nSc hoolof Ma na g e me nt . Spe c i a lt ha nkst oHi ghPe r f わr ma nc eSys t e ms ,Po we r s i m,SA,a ndVe nt a na Sys t e ms ‑a ndt he i rgr e a tpe o pl e ‑f o rpr ov i d i ngt he i rs i mul a t i ons of t wa r ea nd t r a ns l a t i o nso ft hemode l sf o rt heCDa ndwe bs i t e . Th et e a ma t I r wi n Mc Gr a w‑ Hi l lde s e r v e ss pe c i a l me nt i o nf o rt he i re nt hus i a s m, pa t i e nc e , a nde d i t o r i a lhe l p, pa r ic t ul a r l ySc o t tI s e n be r g, Ca r o lRos e , J e f fShe l s t a d, a n dGl a d ysTr u e. Ca r al i a r be ra ndKe l l e yDo no va npr o vi de di mpo r t a nts e c r e t a r i a ls up por t . Ka t hySul l i va nwe ntbe yondt hec a l lo fdut yo nl i br a r yr e s e a r c h, da t ac ol l e c ‑ t i o n, e d i t o r i a lc ha nge s , a ndg r a phi c s , l . Fi na l l y ,t hel o vea nds u ppo r tofmyf a mi l yha vebe e nc o ns t a nta nde s s e nt i a Tha n ks , Ci nd y , Da vi d, a ndSa r a h. 一 Pr e f ae e v ii PARTI PERSPECTI VEANDPROCESS 1 1 Le ar n1 ngl nanda boutCompl e xSys t e ms 3 1 . 1 1 nt r o d uc t i o n 3 1 . 1 . 1 Pol i c yRe s i s t anc e ,t heLa wo fUni nt e nde dCons e que nc e s , andt heCount e r i nt ui t i v eBe havi oro fSoc i alS y s t e ms 5 1. 1 . 2 Caus e so fPol i c yRe s i s t anc e 1 0 l . 1 . 3 Fe e dbac k 1 2 1 . 1 . 4 Pr oc e s sPoi nt . ・TheMe ani ngo fFe e dbac k 1 4 CI l a l l e nge :Dyna mi c so fMul t i pl e ‑ Loo pSys t e ms 1 4 . 2 Le a r nl ngl saFe e d ba c kPr oc e s s 1 4 1 1 . 3 Ba r r i e r st oLe a ml ng 1 9 1. 3. 1 Dynami cCompl e xi y 21 t 1 . 3. 2 Li mi t e dI n f or mat i on 2 3 1 . 3. 3 Con f ou ndi ngV ar i abl e sandAmbi gui y 25 t 1 . 3. 4 Bounde dRat i onal i yandt t heMi s pe r c e pt i ons o fFe e db ac k 26 13. 5 Fl awe dCognl t i v eMa ps 28 1 . 3. 6 Er y me ou sI n f er e nc e saboutDynami c s 29 1 . 3. 7 Uns c i e nt l fi cRe as oni ng/Judgme nt alEr r or s andBi as e s 30 Cha l l e nge :Hypo t he s i sTe s t i ng 30 1. 3. 8 De f e ns i v eRout i ne sandI nt e r pe r s onalI mpe di me nt s t oLe ar nl ng 32 1. 3. 9 I mpl e me nt at i onFai l ur e 33 1 . 4 Re q ul r e me nt Sf o rSuc c e s s f u lLe a r nl ngi nCo mp l e xSys t e ms 33 1 . 4. 1 I mpr ov l ngt heLe ar mngPr oc e s s :Vi r t ue s o fT r l ' r t u alWor l ds 3 4 1 . 4. 2 Pi t f al l so fⅥr t ualT Y or l ds 35 1 . 4. 3 Wh ySi mul at i onI sEs s e nt i al 37 1 . 5 Su mma r y 3 9 xd l i i XJ V Cont e nt s 2 Sys t e mDyna ic m si nAe t i on 41 2・ 1 Appl i c a t i onsofSys t e mDy na mi c s 41 2. 2 Aut o mo bi l eLe a s i ngSt r a t e gy: Go neTo da y , He r eTomo r r ow 42 2. 2. 1 Dy na mi cHy pot he s i s 44 22. 2 El a bor at l n gt heMo de l 48 2. 2. 3 Pol i c yAnal y s i s 51 4 I mpac tandFol l ow‑ u p 5 4 2. 2. 2. 3 0nTi mea ndUnde rBudge t : TheDy na mi c s o fPr o j e c tMa na ge me nt 55 23. 1 TheCl ai m 56 2. 3. 2 I ni t i al Mode l De v e l o pme nt 5 7 23. 3 Dynami cHy pot he s i s 58 4 TheMo de l i n gPr oc e s s 61 2. 3. 2. 3. 5 Cont i nui ngI mpac t6 4 2. 4 Pl a y l ngt heMa i nt e na nc eGa me 66 2. 4. 1 Dynami cHy pot he s i s 6 7 2. 4. 2 TheI mpl e me nt at i o nChal l e nge 74 2. 4. 3 Re s ul t s 76 7 2. 4. 4 T r ans f e r r i ngt heLe ar ni n g:TheLi maEx pe r i e nc e 7 2, 5 Summa ry: Pr i nc i pl e sf orSuc c e s s f ulUs eo fSys t e mDyna mi c s 79 3 TheMode l i ngPr oc e s s 8 3 3. 1 ThePu r pos eo fMode l i ng: Ma na g e r sa sOr ga ni z a t i o nDe s i g ne r s 8 4 3. 2 Th eCl i e nta ndt heMode l e r8 4 3. 3 St e psoft heMode l i ngPr oc e s s 8 5 3. 4 Mo d e l i ngl sl t e r a t i ve 8 7 3. 5 0ve r v i e woft heMode l i ngPr oc e s s 8 9 3. 5. 1 Pr obl e mAr t i c ul at i o nITheI mpor t anc eo fPur po s e 89 2 For mul at i ngaDyn ami cHy pot he s i s 9 4 3. 5. 3. 5. 3 For mul at l n gaSi mul at i onMo de l1 02 4 T e s t l ng 1 03 3. 5. 3. 5. 5 Pol i c yDe s i gnan dEv al u at i on 1 03 3. 6 Su mma r y 1 0 4 4 St r uc t ur eandBe havi oro fDyna mi eSys も e ms 1 0 7 4. 1 Fu nda me nt a lMode sofDyna mi cBe ha v i o r 1 08 4. 1 . 1 Ex po ne nt i alGr owt h 1 08 i. 2 Go alSe e k i n g 1 1 1 4. 4. 1 . 3 0s c i l l at i on 1 1 4 4 Pr oc e s sPoi nt 1 1 6 4. 1 . Cha ll e nge:I de nt i f yi ngFe e dba c kSt r u c t u r e f r o mSys t e mBe ha vi o r 1 1 7 4. 2 I nt e r a c t i o nsoft heFunda me nt a lMo de s 1 1 8 4. 2. 1 S‑ Sh a pe dGr o wt h 1 1 8 4. 2. 2 S‑ Sh a pe dGT 1 0Wt hwi t hOv e r s hoot 1 21 Cha 土 l e nge:I de nt i f yi ngt heLi mi t st oGr owt h 1 21 42. 3 0v e r s hootandCol l a ps e 1 23 4. 3 0t he rMod e so fBe ha v i o r 1 27 4. 3. 1 St a s i s ,orEqui l i br i u m 1 27 X V Co n t e nt s 4. 4 4. 3. 2 Randomne s s 1 27 4. 3. 3 Chaos 1 29 Su mma r y 1 3 3 PARTI I TOOLSFORSYSTEMSTHI NKI NG 1 35 5 Cal l S a lLo o pDi a g r a ms 1 37 5. 1 Ca us a lDi a g r a mNo t a t i on 1 3 7 2 Gu i de l i ne sf o rCa us a lLoo pDi a g r a ms 1 41 5. 5. 2. 1 Caus at i onv e r s usCor r e l at i on 1 41 5. 2, 2 L abel i ngLi nkPol ar i y 1 t 42 Cha l l e ng e: As s i g ni ngLi nkPol a r i t i e s 1 43 5. 2. 3 De t e r mi ni ngLoo pPol ar i y 1 t 43 Cha l l e nge :I d e nt i f yi ngLi n ka ndLoo pPo l a r i t y 1 45 CI l a l l e nge :Empl oye eMot i va t i on 1 47 5. 2. 4 NameY ourLoo ps 1 48 5. 2. 5 I ndi c at eI mpor t antDe l aysi nCaus alL J i nk s 1 50 5. 2 . 6 V ar i abl eName s 1 52 5. 2. 7 Tl ' ps f orCaus alLoo pDi agr amLa you t 1 53 5. 2. 8 Choos et heRi ghtLe v e lo fAggr e gat i on 1 54 5. 2. 9 Don' tPut Al lt heLoo psi nt oOneLar geDi agr am 1 54 52. 1 0 Mak et heGoal so fNe gat i v eL J OO PSEx pl i c i t1 55 5. 2. 1 1 Di s t mgui s hbe t we e nAc t u al andPe r c e i v e dCondi t i ons 1 56 5. 3 Pr o c e s sPo i nt : De ve l o pl ngCa us a lDi a g r a ms f r o mI nt e r v i e wDa t a 1 5 7 Cha ll e nge :Pr o c e s sI mpr ove me nt 1 58 4 Co n c e pt ua l i z a t i o nCa s eSt ud y: Ma na g l ngYo u rWo r kl oa d 1 59 5. 5. 4. 1 Pr obl e mDe f i ni t i on 1 59 5. 4. 2 I de nt 的7 i ngKe yV ar i abl e s 1 60 5. 5 5・ 6 5・ 4・ 3 De v e l o pl : ngt heRe f e r e nc eMode 1 60 5. 4. 4 De v e l o pl ngt heCaus alDi agr ams 1 63 5. 4, 5 Li mi t at i onso ft heCaus alDi agr am 1 66 Cha l l e nge:Po l i c yAna l ys i swi t hCa us a lDi a g r a ms 1 68 Ad a mSmi t h' sl nvi s i bl eHa nda ndt he Fe e d ba c kSt r uc t u r eo fMa r ke t s 1 69 Cha l l e nge :TheOi lCr i s e soft he1 970S 1 72 Cha l l e nge :Spe c ul a t i veBubbl e s 1 73 Cha ll e nge :TheTho r oug hbr e dHo r s eMa r ke t1 7 4 5. 5. 1 Mar k e tFai l ur e , Adv er s eSe l e c t i on, andt heDe at hS pi r al 1 74 Cha ll e nge: TheMe di ga pDe a t hSpi r a l1 76 Ex p l a i ni ngPo l i c yRe s i s t a nc e: Tr a f f i cCo ng e s t i o n 1 7 7 5. 6. 1 Me nt al Mode l so ft heTr a j f i cPy 1 0bl e m 1 78 5. 6. 2 Compe ns at i ngFe e dbac k :TheRe s pons e t oDe c r e as e dConge s t i on 1 81 5. 63 TheMas sTr ans i tDe at hS pi r al 1 85 5. 6. 4 Pol i c yAnal ys i s :TheI mpac to fT e c hnol og y 1 88 5. 6. 5 Compe ns at i ngFe e dbac k:TheSour c e o fPol i c yRe s i s t anc e 1 89 XVl Con t e n t s Chal l e nge:I de nt i f yi ngt heFe e dba c kSt r uc t ur e ofPol i c yRes i s t a nc e 1 90 5・ 7 Summa r y 1 90 6 St oe ksandFl ows 1 91 6. 1 St oc ks ,Fl ows ,a ndAc c umul a t i on 1 91 6. 1 . 1 Di agr ammi n gNot at i onf o rSt oc k san dFl ows 1 92 6. 1 . 2 Mat he mat i c al Re pr e s e nt at i o no fSt oc k sandFl ows 1 93 6. 1 . 3 TheCo nt r i but i o no fSt oc k st oDyna mi c s 1 95 6・ 2 I de nt i f yi ngSt oc ksa ndFl ows 1 97 6. 2. 1 Uni t so fMe as ur ei nSt o c kan dFl owNe t wor k s 1 98 6. 2. 2 TheSna ps hotT e s t1 99 Chal l e nge:I de nt i f yi ngSt oc ksa ndFl ows 201 6. 2. 3 Cons e 7 Wat i o no fMat e r i ali n St oc kandFl o wNe t wor k s 201 6. 2. 4 St at e ‑ De t e r mi ne dS y s t e ms 2 02 6. 2. 5 Au xi l i af TV ar i abl e s 202 6. 2. 6 St o c k sChan geOnl yt hr ou ghThe i rRat e s 204 6. 2. 7 Co nt i nu ou sT l ' mean dI n s t a nt ane ou sFl ows 206 6. 2. 8 Co nt i nuou s l yDi v i s i bl ev e r s u sQu a nt i z e dFl ows 207 6. 2. 9 Whi c hMo de l i ngAp pr o ac hS hou l dY ouUs e? 208 6. 2. 1 0 Py 1 0C e S SPoi nt :Por t r a yi n gSt oc k sa ndFl o ws i nPr ac t i c e 2 09 6. 3 Ma ppi ngSt oc ksa ndFl ows 21 0 6. 3. 1 Whe nShoul dCau s al Lo o pDi a gr amsShow St o c kandFl owSt r u c t u r e? 21 0 Chal l e nge:Addi ngSt oc ka ndFl owSt uc r t ur e t oCa us a lDi a gr a ms 21 1 Cha1 1 e nge:Li nki ngSt oc ka ndFl owSt r uc t ur ewi t hFe e dba c k 21 2 6. 3. 2 Aggr e gat i o ni nSt oc kan dFl owMa ppl ng 21 3 Chal l e nge:Modi f yi ngSt oc ka ndFl owMa ps 21 3 Chal l e nge:Di s a ggr e ga t i on 21 4 6. 3. 3 Gui de l i ne s f orAggr e gat i o n 21 6 4 S ys t e mDy na mi c si nAc t i o n: 6. 3. Mo de l i n gLar ge ‑ Sc al eCo n s t r u c t i onPr o j e c t s 21 8 63. 5 Se t t i ngt heMo de l Bou ndaf T: " Chal l e ngl n gt heCl ou ds" 22 2 6. 3. 6 S ys t e mDy na mi c si nAc t i o n. ・ Au t o mo bi l eRe c yc l i n g 225 6. 4 Summa r y 229 7 Dynami c sofSt oe ksandFl ows 231 7. 1 Re l a t i ons hi pbe t we e nSt oc ksa ndFl ows 232 7. 1 . I St at i candDy nami cEqu i l i br i u m 23 2 7. 1 . 2 Cal c ul u swi t hout Mat he mat i c s 23 2 7. 1 . 3 Gr a phi c al I nt e gr at i o n 23 4 Chal l e nge:Gr a phi c a lI nt e g r a t i on 239 7. 1 . 4 Gr a phi c al DI Her e nt i at i o n 23 9 Chal l e nge:Gr a phi c lDi a f f e r e nt i a t i on 241 7・ 2 Sys t e mDyna mi c si nAc t i on: Gl oba lWa r ml ng 241 Con t e nt s xvi i 7・ 3 Sys t e mDy na mi c si nAc t i on: TheWa ro nDr ugs 2 50 7. 3 . 1 TheCoc ai neEpi de mi ca f t e r1 990 2 58 7・ 4 Summa r y 26 2 8 Cl os i ngt heLo op: Dynam ie sofSi mpl eSt r uc t ur e s 263 8. 1 Fi r s t ‑ Or d e rSys t e ms 263 8, 2 Pos i t i veFe e d ba c ka ndEx po ne nt i a lGr o wt h 26 4 8. 2. 1 Anal yt l ' cSol ut i onf ort heI / i ne arFi r s t ‑ 07 1 de rS y s t e m 265 8. 2. 2 Gr a phi c al Sol ut i ono ft heLi ne arFi r s t ‑ Or de r Po s i t i v eFe e db ac kS y s t e m 266 8. 2. 3 ThePo we ro fPos i t i v eFe e db ac k :Dou bl i n gT l ' me s 268 Cha ll e ng e:Pa pe rFo l di ng 2 68 8. 2. 4 Mi s pe r c e pt i o nso fEx po ne nt i alGr o wt h 26 9 8. 2 . 5 Pr oc e s sPoi nt /Ov e r c omi n gOv e r c o n f i de nc e 272 8. 3 Ne g a t i veFe e d ba c ka ndExpo ne nt i a lDe c a y 27 4 8. 3 . 1 T l ' meCo ns t ant sa ndHal f ‑ Li v e s 2 79 Cha l l e ng e . ・Goa l ‑ Se e ki ngBe ha vi or 281 8. 4 Mu l t i pl e ‑ Lo o pSys t e ms 28 2 8. 5 No n l i ne a rFi r s t ‑ Or de rSys t e ms : S‑ Sha pe dGr o wt h 28 5 Cha l l e nge :No nl i ne a rBi r t ha ndDe a t hRa t e s 28 6 8. 5 . 1 For mal De f i ni t i o no fLoo pDo mi n anc e 288 8. 5 . 2 Fi r s t 1 07 de rS ys t e msCannotOs c i l l at e 29 0 8. 6 Sum a r y 29 0 PARTI l l THEDYNAMI CSOFGROWTH 29 3 9 S・ Shape dGr owt h:Epi de ic m s , I nnovat i o nDi f f us i on,a ndt heGr owt hof Ne wPr od uc t s 295 9. 1 Mo d e l i ngS‑ Sha pe dGr owt h 29 6 9. 1 . 1 Lo gl S t i cGr owt h 296 9. 1 . 2 Anal yt i cSol ut i ono ft heLogi s t i cEqu at i o n 29 7 9. 1 . 3 0t he rCo mmonGr owt hMo de l s 29 9 9. 1 A T e s t i ngt heLogi s t i cMo de l 30 0 9. 2 Dy na mi c sofDi s e a s e: Mode l i ngEpi de mi c s 3 0 0 9. 2 . 1 ASi mpl eMode lo fI n f e c t i ou sDi s e as e 3 00 9. 2 . 2 Mo de l i n gAc ut eI n f e c t i on:TheS I RMod e l3 03 9. 2 . 3 Mo de l Be h av i or :TheT l ' ppl ngPoi nt 3 05 Cha l l e ng e:Ex pl or i ngt heSI RMod e l3 08 9. 2. 4 I mmu ni z at i onandt heEr adi c at i o no fSmal l po x 3 09 Cha l l e nge :TheEf f i c a c yofI m un i z a t i o nPr og r a ms 31 0 9. 2 . 5 He 7 1 dl mmu ni y 31 t 2 9. 2 . 6 Mo v i n gPa s tt heTl ' ppl n gPoi nt :Ma dCo wDi s e as e 31 4 Cha l1 e ng e:Ext e nd i ngt heSI RMod e l 31 6 9. 2 . 7 Mo de l i ngt heHW/ AI DSEpi de mi c 31 9 Cha l l e ng e:Mod e l i ngHI V/ AI DS 3 21 9. 3 I n n o va t i o nDi f f us i o na sI nf e c t i o n: Mo de l i ngNe wl de a sa ndNe wPr od uc t s 3 23 93. 1 TheLo gi s t i cMode lo fI nno v at i onDl #u s i o n: Ex ampl e s 3 25 xvi i i Co nt e nt s 9. 3. 2 Pr oc e s sPoi nt :Hi s t or i c al Fi t andMo de lV al i di y 328 t 9. 3. 3 TheBas sDl Hu s i o nMo de l 33 2 Chal l e nge:Pha s eSpa c eo ft heBa s sDi f f us i o nMod e l 333 9. 3. 4 Be hav i oro ft heBas sMo de l 33 4 Chal l e nge:Cr i t i qul ngt heBa s sDi f f us i onMo de l 33 4 Cha l l e nge:Ext e nd i ngt heBa s sMo d e l 33 5 9. 3. 5 Fa da ndFas hi o n: Mo de l i ngt heAba ndo n me nto fa nI nno v at i o n 33 9 Cha l l e nge:Mod e l i ngFa ds 3 41 9. 3. 6 Re pl ac e me ntPur c ha s e s 3 42 Cha l l e mge:Mod e l i ngt heLi f eCyc l eo fDu r a bl ePr od uc t s 3 45 9. 4 S umma r y 3 46 1 0 Pat hDe pe nde nc eandPos i t i veFe e dba e k 349 1 0, 1 Pa t hDe pe nde nc e 3 49 Cha l l e nge:I de nt i f yi ngPa t hDe pe nd e nc e 353 1 0. 2 ASi mpl eMo de lofPa t hDe pe nd e nc e : ThePo l yaPr oc e s s 3 54 1 0. 2. 1 Ge ne r al i z i n gt heMo de l :No nl i ne arPol yaPr oc e s s e s 3 57 1 0. 3 Pa t hDe pe nde nc ei nt heEc o no my: VHSve r s usBe t a ma x 359 Cha l l e nge:Fo r mul a t i ngaDyna mi cHy po t he s i s f o rt heVCRI nd us t r y 3 6 4 1 0. 4 Pos i t i veFe e d ba c k: TheEng i neo fCo r po r a t eGr owt h 3 6 4 1 0. 4. i Pr o duc t Awar e ne s s 3 65 1 0. 4. 2 Un i tDe v e l o pme ntCo s t s 3 6 7 0. 4. 3 Pr i c eandPr odu c t i o nCo s t3 68 1 1 0. 4. 4 Ne t wor kE j f e c t san dCompl e me nt af TGoo ds 3 70 1 0. 4. 5 Pr o duc tDI He r e nt i at i o n 3 71 1 0. 4. 6 Ne wPr oduc t De v e l o pme nt 3 73 0. 4. 7 Mar k e tPo we r 3 7 4 1 1 0. 4. 8 Me r ge r sandAc qul S i t i o ns 3 75 1 0. 4. 9 Wor k f or c eQu al i ya t ndLo y al y t 3 76 1 0. 4. 1 0 TheCos to fCa pi t al 3 78 1 0Al 1 TheRul e so ft heGame 38 0 1 0. 4. 1 2 Ambi t i o nandAs pi r at i o ns 38 0 1 0. 4. 1 3 Cr e at i ngS y ne r g yf orCor por at eGr owt h 38 2 1 0. 5 Pos i t i veFe e d ba c k, i nc r e a s i ngRe t u r ns , a ndEc ono mi cGr owt h 38 5 1 0. 6 Do e st heEc o no myLoc ki nt oI nf e r i o rTe c hnol og i e s ? 38 7 1 0. 7 Li mi t st oLoc kl n 38 9 1 0. 8 Mod e l i ngPa t hDe pe nde nc ea ndSt a nda r dsFo r ma t i o n 391 1 0. 8. 1 Mo de lSt r uc t ur e 3 9 2 1 0. 8. 2 Mo de lBe hav i or 3 96 1 0. 8. 3 Pol i c yI mpl i c at i o ns 402 Cha l l e nge:Pol i c yAna l ys I S 403 Cha ll e nge:Ext e ndi ngt heMo de l 40 4 1 0. 9 Summa r y 406 PARTI V TOOLSFORMODELI NGDYNAMI CSYSTEMS 407 l l De l a ys 409 1 1 . 1 De l a ys : Anl nt r od uc t i on 409 Co nt e nt s XI X Cha l l e ng e:Dur a t i ona ndDy na mi c sofDe l a ys 409 1 1 . 1 . 1 De f i ni n gDe l a y s 41 1 . 2 Ma t e r i a lDe l a ys : St r uc t ur ea ndBe ha vi o r 41 2 1 1 1 . 2. 1 What I st heAv e r ageLe n gt ho ft heDe l a y? 41 3 1 1 1 ・ 2・ 2 What l st heDi s t r i but i o no ft heOu t put ar o un dt heAv e r age De l a yT l ' me? 41 3 1 1 . 2. 3 Pi pe l i neDe l a y 41 5 . 2. 4 Fi r s t 1 07 de rMat e r i al De l a y 41 5 1 1 1 1 . 2. 5 Hi ghe r ‑ Or de rMat e r i alDe l a y s 41 7 1 1 . 2. 6 HowMu c hl si nt heDe l a y?Li t t l e' sLaw 421 Cha ll e ng e:Re s po ns eofMa t e r i a lDe l a yst o St e ps , Ra mps , a ndCyc l e s 425 1 1 . 3 I nf o r ma t i o nDe l a ys : St r uc t ur ea ndBe ha v i o r 426 1 1 . 3. 1 Mo de l i ngPe r c e pt i o ns : Ada pt l V eEx pe c t at i o nsa nd Ex pone nt i alSmoot hi ng 428 1 1 . 3. 2 Hi g he r ‑ Or de rI n f or mat i o nDe l a y s 432 1 1 . 4 Re s po ns et oVa r i a bl eDe l a yTi me s 43 4 Cha l l e ng e:Re s po ns eofDe l a yst oCha ng i ngDe l a yTi me s 43 5 1 1 . 4. 1 Nonl i ne arAd j u s t me ntT l ' me s : Mo de l i n gRat c he t E j f e c t s 43 6 1 1 ・ 5 Es t i ma t l ngt heDur a t i o na ndDi s t r i but i o no fDe l a ys 43 7 1 1 . 5. 1 Es t i mat i ngDe l a y sV V he nNu me r i c al Dat a Ar eAv ai l abl e 43 7 . 5. 2 Es t i mat l ngDe l a ysWhe nNu me r i c alDat a 1 1 Ar eNot Av ai l abl e 445 1 1 . 5. 3 Pr oc e s sPoi nt :1 砺‡ l kt heLi ne 4 49 1 1 . 6 Sys t e mDyna mi c si nAc t i o n: Fo r e c a s t l ngSe mi c o nd uc t o rDe ma nd 4 49 1 1 ・ 7 Ma t h e ma t i c sofDe l a ys : Koyc kLa gsa ndEr l a ngDi s t r i but i o ns 462 1 1 . 7. 1 Ge ne r alFor mul at i onf orDe l a y s 46 2 . 7. 2 Fi r s t ‑ OT l de rDe l a y 46 4 1 1 1 1 . 7. 3 Hi ghe r ‑ Or de rDe l a y s 46 5 . 7. 4 Re l at i ono fMat e r i alandI n f or mat i onDe l a y s 466 1 1 1 1 . 8 Su mma r y 466 1 2 Co f L owsa ndAg i ngCha i ns 469 1 2. 1 Ag i n gCha i ns 470 1 2. 1 . 1 Ge ne r alSt r u c t ur eo fAgi ngCh ai ns 47 0 1 2. 1 . 2 Exa mpl e :Po pul at i onandI n f r as t r u c t ur ei nUr ba n Dyna mi c s 472 1 2. 1 . 3 Exampl e :ThePo pul at i onPyr a mi dan dt h eDe mo gr a phi c Tr ans i t i on 474 1 . 4 Agi ngChai nsandPo pul at i o nl ne r t i a 48 0 1 2. 1 2. 1 . 5 S y s t e mDyn ami c si nAc t i o n: WT or l dPo pul at i onandEc o no mi cDe v e l o pme nt 481 1 2. 1 . 6 Cas eSt ud y/ Gr 1 0Wt handt heAgeSt r uc t ur eo fOr ga ni z at i ons 48 5 1 2. 1 . 7 Pr o mot i o nCh ai nsandt heLe ar nmgCu y ve 49 0 X X Cont e nt s 1 2. 1 . 8 Me nt or l ngandOn‑ The ‑ JobTr ai nl ng 493 CI l a l l e nge:TheI nt e r a c t i o nso fTr a i n i ngDe l a ysa ndGr owt h 495 1 2. 2 Cof lows : Mo de l i ngt heAt t r i b ut e sofaSt o c k 497 Cha ll e nge:Co lows 5 f 03 1 2. 2. 1 Co jl owswi t hNonc ons e r v e dFl ows 504 CI l a l l e nge:TheDy na mi c sofEx pe r i e nc ea ndLe a r nl ng 5 08 2. 2 I nt e gr at i ngCo j l owsandAgi ngChai ns 509 1 2. Cha l l e nge:Mo de l i ngDe s i g nWi nsi nt he Se mi c o nduc t o rl ndus t r y 51 1 1 2・ 3 Summa r y 51 1 13 Mo de l i ngDe c i s i onMa ki ng 51 3 1 3. 1 Pr i nc i pl e sf o rMo de l i ngDe c i s i o nMa ki ng 51 3 1 3. 1 . 1 De ci s i onsandDe c i s i onRul e s 51 4 1 3. 1 . 2 Fi v eFor mul at i onFundame nt al s 51 6 Cha ll e nge:Fi ndi ngFo r mul a t i o nFl a ws 520 1 3. 2 Fo r mul a t i ngRa t eEqua t i o ns 5 22 1 3. 2. 1 Fr ac t i onalI nc r e as eRat e 522 1 3. 2. 2 Fr ac t i onalDe c r e as eRat e 523 1 3. 2. 3 Ad j us t me ntt oaGoal 523 1 3. 2. 4 TheSt oc kManage me ntSt r uc t ur e: Rat e‑ Nor mal Rat e+Ad j u s t me nt s 524 1 3. 2. 5 Fl ow‑Re s our c e* Pr oduc t i v i y 524 t 1 3. 2. 6 Y‑ Yj ‑ *EHe c to fXIOnY*E He c to fX20nY*. .. *E He c t o fXnonY 525 1 3. 2. 7 Y‑ YS +E He c to fXIOnY+E j f e c to fX20nY+・ ・ . + E He c to fXn onY 527 Cha互 l e nge:Mul t i pl eNo nl i ne a rEfe c t s 5 29 1 3. 2. 8 Fu z z yMI NFu nc t i on 529 1 3. 2. 9 Fuz z yMAXFu nc t i o n 530 1 3 . 2. 1 0 Fl oat i ngGoal s 532 Chal l e nge:Fl o a t i ngGoa l s 533 Chal l e nge:Goa lFo r ma t i o nwi t hI nt e r na la ndExt e r na lI n put s 53 5 1 3. 2. ll Nonl i ne arWe i ght e dAv e r age 535 1 3. 2. 1 2 Mode l i ngSe ar c h:Hi l l ‑ Cl i mbi ngOpt i mi z at i on 537 Chai l e nge:Fi ndi ngt heOpt i ma lMi xo fCa pi t a la ndLa bo r5 43 1 3. 2. 1 3 Re s our c eAl l oc at i on 544 1 3. 3 Co mmo nPi t f a l l s 5 45 1 3. 3. 1 Al l0ut jl owsRe qui r eFi r s t ‑ Or de rCont r ol 545 Cha l l e nge:Pr e ve nt i ngNe ga t i veSt oc ks 5 47 1 3. 3. 2 Av oi dI F...T HEN...ELSEFor mul at i ons 547 1 3. 3. 3 Di s aggr e gat eNe tFl ows 547 1 3・ 4 Su mma r y 5 49 1 4 For mul at i ngNo nl i ne arRe l at i ons hi ps 551 1 4. 1 Ta bl eFunc t i ons 552 1 4. 1 . 1 S pe c l j yi ngT abl eFu nc t i ons 552 1 4. I . 2 Exampl e/Bui l di ngaNonl i ne arFunc t i on 552 Cont e nt s XXl 1 4. I . 3 Pr oc e s sPoi nt :T abl eFunc t i onsv e r s us Anal yt i cFu nc t i ons 562 1 4. 2 Ca s eSt udy: Cut t i ngCo r ne r sve r s usOve r t i me 563 Cha l l e nge :Fo m ul r a t i ngNo n l i ne a rFunc t i o ns 566 1 4. 2. 1 Wor ki ngOv e r t i me: TheE j f e c to fSc he dul ePr e s s ur eonT V or k we e k 567 1 4. 2. 2 Cut t i ngCor ne r s : TheEHe c to fSc he dul ePr e s s u誓onTi mepe rT as k 568 1 4. 3 Ca s eSt udy: Es t i ma t i ngNo nl i ne a rFunc t i o nsWi t hQua l i t a t i vea nd Nu me r i c a lDa t a 56 9 Chal l e nge :Re f i ni ngTa bl eFunc t i onswi t hQua l i t a t i veDa t a 5 69 4 Co mmo nPi t f a l l s 573 1 4. 1 4. 4. 1 Us i ngt heWr ongl n put 5 73 Cha l l e nge . ACr i t i qul ngNonl i ne a rFunc t i o ns 575 1 4. 4. 2 I mpr o pe rNor mal i z at i on 576 1 4. 4. 3 Av oi dHump‑ Sha pe dFunc t i ons 577 CI l a l l e nge:Fo r mul a t i ngt heEr r o rRa t e 58 3 Cha l l e nge :Te s t i ngt heFullMo de l 58 5 1 4. 5 El i c i t i ngMode lRe l a t i ons h i psl nt e r a c t i ve l y 58 5 1 4. 5. 1 Cas eSt ud y:Es t i mat i ngPr e c e de nc eRe l at i ons hi psi n Pr oduc tDe v e l o pme nt 58 7 1 4. 6 Su mma r y 595 1 5 Mode l ngHl i l ma nBe havi or:Bo unde dRa t i o na li t yo r Ra t i ona lExpe c t a t i o ns ? 597 1 5. 1 Hu ma nDe c i s i onMa k i ng: Bo und e dRa t i o na l i t yo r Ra t i o na lEx pe c t a t i o ns ? 5 98 1 5. 2 Co g ni t i veLi mi t a t i o ns 599 1 5. 3 hd i vi d ua la ndOr ga ni z a t i o na lRe s po ns e st o Bo und e dRa t i o na l i t y 6 01 1 53. 1 Habi t ,Rout i ne s ,andRul e so fThu mb 601 1 5. 3. 2 Managi ngAt t e nt i on 601 1 5. 3. 3 GoalFor mat i onandSat i s fi c i ng 601 1 53. 4 Pr obl e mDe c ompos i t i onandDe c e nt r al i z e d De c i s i onMak i ng 602 1 5. 4 Ⅰ nt e nde dRa t i ona l i t y 6 03 1 5. 4. 1 T e s t i ngf orI nt e nde dRat i onal i y:Par t t i al Mode lT e s t s 605 1 5. 5 Ca s eSt udy: Mode l i ngHi g h‑ Te c hGr o wt hFi r ms 6 05 1 5. 5. 1 Mode lSt r uc t ur e :Ov e nノ i e w 606 1 5. 5. 2 0r derFul fi l l me nt 607 1 5. 5. 3 Ca pac i yAc t qui s i t i on 609 Cha l l e nge:Hi l lCl i mbi ng 61 5 1 5. 5. 4 TheSal e sFor c e 61 5 1 5. 5. 5 TheMar k e t 61 9 1 5. 5. 6 Be hav i oro ft heFul lS ys t e m 621 Cha i l e nge:Pol i c yDe s i g ni nt heMa r ke tGr owt hMo de l 62 4 1 5. 6 Summa r y 629 x x j i Cont e nt s 1 6 For e c a s t sandFudgeFa c t o r s :Mode l i ngExpe c t at i onFor mat i on 6 31 1 6. 1 Mode l i ngEx pe c t a t i o nFo r ma t i o n 631 1 6. 1 . 1 Mo de l i n gGr o wt hEx pe c t at i o ns : TheT RENDFu nc t i o n 63 4 1 6. 1 . 2 Be h av i oro ft heT RENDFu nc t i o n 638 1 6. 2 Ca s eSt udy: Ene r g yCo ns u mpt l On 638 1 6. 3 Ca s eSt ud y: Co mmod i t yPr i c e s6 43 1 6. 4 Ca s eSt udy: I n la f t i o n 6 45 1 6. 5 I mpl i c a t i o nsf o rFo r e c a s tCo ns ume r s 655 Cbal l e nge :Ex t r a pol a t i o na ndSt a bi l i t y 656 1 6. 6 I ni t i a l i z a t i o na ndSt e a dySt a t eRe s po ns eo f t heTRENDFunc t i o n 6 58 1 6. 7 Su mma r y 6 6 0 PARTV I NSTABI LI TYANDOSCI LLATI ON 661 1 7 Suppl yCha insandt heOr i g i no fOs c i l l at i ons 66 3 1 7. 1 Su ppl yCha i nsi nBus i ne s sa ndBe yond 66 4 1 7. 1 . 1 0s c i l l at i o n , Ampl i f i c at i o n ,andPhas eL J a g 6 6 4 1 7. 2 TheSt oc kMa na g e me ntPr o bl e m 666 1 7. 2. 1 Man agl n gaSt oc k ISt r u c t ur e 668 1 7. 2. 2 St e ad ySt at eEr r or 6 71 1 7. 2. 3 Man agi n gaSt oc k IBe hav i or 6 72 Chal l e nge :Ex pl o r l ngAmpl i f i c a t i on 674 1 7. 3 TheSt oc kMa na g e me ntSt r u c t u r e 6 75 1 7. 3. 1 Be ha v i oro ft heSt oc kMana ge me ntSt r uc t ur e 68 0 Cha l l e nge;Ex pl o r i ngt heSt o c kMa na ge me n tSt r uc t ur e 68 3 1 7. 4 TheOr i g i no fOs c i l l a t i o ns 68 4 1 7. 4. 1 Mi s mana gl ngt heSu ppl yLi ne I me 68 4 TheBe e rDi s t r i bu t i o nGa 7. 4. 2 Wh yDoI V eI gnor et heSu ppl yLi ne? 69 5 1 1 7. 4. 3 Ca s eSt u d y:Bo o mandBu s ti nRe al Es t at eMar k e t s 6 98 Chal l e nge :Ex pa nd i ngt heRe a lEs t a t eMo de l7 07 1 7. 5 Summa r y 7 07 1 8 TheManuf ac t ur ingSuppl yChai n 709 1 8. 1 ThePo l i c ySt r uc t u r eo fl nve nt o r ya ndPr od uc t i o n 71 0 1 8. 1 . 1 07 de rFu l f i l l me nt 71 1 1 8. 1 . 2 Pr o duc t i on 71 3 1 8. 1 , 3 Pr o duc t i o nSt ar t s 71 4 1 8. 1 . 4 De mandFor e c a s t i n g 71 6 1 8. 1 . 5 Pr oc e s sPoi nt II ni t i al i z l n gaMo de li nEqui l i br i u m 71 6 Chal l e nge:Si mul t a ne o usI ni t i a lCo ndi t i ons 71 8 1 8. 1 . 6 Be ha v i oro ft hePr o du c t i o nMode l 72 0 1 8. 1 . 7 Enr i c hi ngt heMo de l : Addi ngOy de rBac k l o gs 7 23 1 8. 1 . 8 Be hav i oro ft heFi r mwi t hOy de rBac k l o gs 725 1 8. 1 . 9 Addi ngRawMat e r i al sl nv e nt oY y 725 1 8. 2 I nt e r a c t i o nsa mongSu ppl yCha i nPa r t ne r s 729 1 8. 2. I I nst abi l it ya n dT r u s ti nSu ppl yChai ns 735 x xi i i Co n t e nt s 2. 2 1 8. Fr omFunc t i onalSi l ost oI nt e gr at e dSu ppl yChai n Manage me nt 7 40 Cha ll e nge :Re e ngl ne e r l ngt heSu ppl yCha i n 7 41 1 8. 3 Sys t e mDyna mi c si nAc t i o n: Re e ng l ne e r l ngt heSuppl yCha i ni na Hi g h‑ Ve l oc i t yI nd us t r y 7 43 1 8. 3. 1 I ni t i alP7 1 0bl e mDe f i ni t i on 743 1 8. 3. 2 Re f e r e nc eModeandDynami cHy pot he s i s 746 1 8. 3. 3 Mode lFor mul at i on 749 1 8. 3 . 4 T e s t i ngt heMode l 749 1 8. 3. 5 Pol i c yAnal ys I S 751 1 8. 3. 6 I mpl e me nt at i on:Se que nt i alDe bot t l e ne c ki ng 753 1 8. 3. 7 Re s ul t s 755 1 8. 4 Summa r y 755 1 9 TheLabo rSuppl yCha ina ndt heOr i g i nofBus i ne s sCyc l e s 75 7 1 9. 1 TheLa borSuppl yCha i n 758 1 9. 1 . 1 St r uc t ur eo fLaborandHi r i ng 758 1 9. I . 2 Be havi oro ft heLaborSu ppl yChai n 760 1 9. 2 I nt e r a c t i onsofLa bo ra ndl nve nt o r yMa na ge me n t 76 4 Cha l l e nge:Me nt a lSi mul a t i o no f l nv e nt o r yMa na ge me ntwi t hLa bo r 76 6 1 9. 2. 1 I nv e nt o7 7‑T Y or k f or c eI nt e r ac t i ons :Be havi or 766 1 9. 2. 2 Pr oc e s sPoi nt :Ex pl ai nl ngMode lBe havi or 767 Cha l l e nge:Ex pl a i nl ngOs c i l l a t i o ns 76 7 2. 3 Unde r s t andi ngt heSour c e so fOs c i l l at i on 771 1 9. Cha l l e mge:Po l i c yDe s i g nt oEnha nc eSt a bi l i t y 773 2. 4 Addi ngOv e r t i me 774 1 9. 1 9. 2. 5 Re s pons et oFl e xi bl eWor k we e k s 776 Cha l l e nge:Re e ngl ne e r l ngaMa nuf a c t ur i ngFi r m f o rEnha nc e dSt a bi l i t y 778 1 9. 2. 6 TheCos t so fl ns t abi l i y 7 t 79 Cba l l e nge:TheCos t so fl ns t a bi l i t y 78 0 CI l a l l e nge: Addi ngTr a i ni nga ndEx pe r i e nc e 78 0 1 9. 3 I nv e nt o r y ‑Wo r kf o r c eI nt e r a c t i o nsa ndt heBus i ne s sCyc l e 78 2 1 9. 3. 1 I st heBu s i ne s sCyc l eDe ad? 785 1 9。 4 Summa r y 788 20 Thel nv is i bl eHandSo me t i me sSha ke s :Co mmodi t yCyc l e s 791 20・ 1 Commodi t yCyc l e s : Fr o mAi r c r a f tt oZi nc 792 2 0. 2 AGe ne r i cCo mmodi t yMa r ke tMod e 1 798 20. 2. 1 Pr oduc t i onandI nv e nt oT y 8 01 20. 2. 2 Ca paci y Ut t i l i z at i on 802 20. 2. 3 Py 1 0duc t i onCa pac i y 8 t 05 20. 2. 4 De s i r e dCa pac i y t 8 07 Cha l l e nge :I nt e nde dRa t i o na l i t yo ft heI n ve s t me ntPr o c e s s 81 0 20. 2. 5 De mand 81 1 20. 2. 6 ThePr i c e‑ Se t t i ngPr oc e s s 81 3 20. 3 App l i c a t i on: Cyc l e si nt hePul pa ndPa pe rl nd us t r y 8 24 Cl l a l l e nge :Se ns i t i vl t yt OUnc e r t a i nt yi nPa r a me t e r s 8 28 X X r V Co n t e n t s Cha l l e nge :Se ns i t i vl t yt OSt r uc t ur a lCha nge s 831 Cha l l e nge :I mpl e me nt l ngSt uc r t ur a lCha nge s I Mod e l i ngLi ve s t oc kMa r ke t s 8 36 Cha l l e nge :Po l i c yAna l ys I S 8 40 20. 4 Su mma r y 8 4l PARTVI MODELTESTI NG 843 21 7hl t handBe aut y: Va l i dat i ona ndMode lTe s t i ng 8 45 21 . 1 Va l i da t i o na ndVe r i f i c a t i o nAr eI mpos s i bl e 8 46 21 . 2 Que s t i onsMod e lUs e r sSho ul dAs k‑ButUs ua l l yDo nう ー8 51 21 . 3 Pr a g ma t i c sa ndPol i t i c sofMode lUs e 8 51 21 . 3. 1 T y pe so fDat a 8 53 21 . 3. 2 Doc u me nt at i o n 8 55 21 . 3. 3 Re pl i c abi l i y 8 t 5 5 21 ・ 3・ 4 Pr ot e c t i v ev e . r s u sRe j l e c t i v eMo de l i ng 8 58 21 . 4 Mo de l Te s t i ngi nPr a c t l C e 8 58 21 . 4. 1 Bou n d a7 TAde qu ac yT e s t s 8 61 21 A. 2 St r u c t u r eAs s e s s me ntT e s t s 8 63 21 . 4. 3 Di me n s i o nalCon s i s t e nc y 8 66 4 Par a me t e rAs s e s s me nt 8 66 21 . 4. 21 . 4. 5 Ext r e meCo n di t i o nT e s t s 8 69 Cha ll e nge :Ext r e meCo ndi t i o nTe s t s 8 71 21 . 4. 6 I nt e gr at i o nEr r orT e s t s 8 72 21 . 4. 7 Be ha v i orRe pr odu c t i o nT e s t s 8 74 21 . 4. 8 Be hav i orAno mal yT e s t s 88 0 21 . 4. 9 Fa mi l yMe mbe rT e s t s 881 21 . 4. 1 0 Su r pr i s eBe h av i orT e s t s 88 2 21 . 4. l l Se ns i t i v i yAnal t y s i s 883 21 . 4. 1 2 S y s t e mI mpr o v e me ntT e s t s 88 7 Cha l l e nge :Mo de lTe s t i ng 88 9 21 . 5 Summa r y 8 9 0 PARTVI I COMMENCEMENT 89 3 22 Chal l e nge sf o rt heFut ur e 8 95 22. 1 The o r y 8 95 22. 2 Te c hno l o gy 8 96 22. 3 I mpl e me nt a t i on 8 99 22. 4 Ed uc a t i on 9 0 0 22. 5 Appl i c a t i ons 901 Chal l e nge:Put t i ngSys t e mDyna mi c si nt oAc t i o n 9 01 APPENDI XA NUMERI CALI NTEGRATI ON 903 Chal l e ng e:Choos i ngaTi meSt e p 91 0 APPENDI XB NOI SE 91 3 Chal l e ng e:Ex pl o r l ngNo i s e 922 REFERENCES 9 25 I NDEX 947 Dyna mi c sofMu l t i pl e ‑ Loo pSys t e ms 1 4 Hy pot he s i sTe s t l ng 3 0 I d e n t i f y i ngFe e d ba c kSt r uc t ur ef r omSys t e mBe ha vi o r 1 1 7 I d e n t i f y i ngt heLi mi t st oGr owt h 1 22 As s i g ni ngLi nkPo l a r i t i e s 1 43 I d e n t i f yi ngLi nka ndLoo pPo l a r i t y 1 45 Emp l o ye eMo t i v a t i o n 1 47 Pr o c e s sl mpr ove me n t 1 58 Po l i c yAna l ys i swi t hCa us a lDi a g r a ms 1 68 TheOi lCr i s e so ft he1 970s 1 72 Spe c ul a t i veBub bl e s 1 73 TheTho r o ug hbr e dHo r s eMa r ke t 1 7 4 TheMe di ga pDe a t hSpi r a l 1 76 I d e n t i f y i ngt heFe e d ba c kSt r uc t u r eo fPo l i c yRe s i s t a nc e 1 9 0 I d e nt i f y i ngSt oc ksa ndFl o ws 2 01 Ad d i ngSt oc ka n dFl owSt mc t ur et oCa us a lDi a g r a ms 21 l Li n k i ngSt oc ka n dFl owSt r u c t ur ewi t hFe e d ba c k 21 2 Mod i f yi ngSt oc ka ndFl owMa ps 21 3 Di s a gg r e ga t i o n 21 4 Gr a p hi c a ll nt e g r a t i o n 239 Gr a p hi c a lDi fe r e nt i a t i on 2 4l Pa pe rFol d i ng 268 Goa l ‑ Se e ki ngBe ha vi o r 281 No nl i ne a rBi r t ha ndDe a t hRa t e s 28 6 Ex pl o r i ngt heSI RMode l3 08 TheEf f i c a c yofl mmuni z a t i o nPr og r a ms 31 0 Ext e ndi ngt heSI RMode 1 31 6 Mo d e l i ngHI V/ AI DS 321 Pha s eSpa c eoft heBa s sDi 軌l S i onMo de l 333 Cr i t i q ul ngt heBa s sDi 軌I S i o nMode l3 3 4 Ex t e ndi ngt heBa s sMode l 33 5 Mod e l i ngFa ds 3 41 X X V XXVl Li s to fCha l l e n ges Mode l i ngt heLi f eCyc l eo fDu r a bl ePr o duc t s 3 45 I de nt i f yi ngPa t hDe p e n d e n c e 3 53 Fo m ul a t l ngaDyna mi cHy po t he s i sf o rt heVCRI ndus t r y 36 4 Po l i c yAna l ys I S 403 Ex t e ndi ngt heMo de l 40 4 Dur a t i ona ndDyna mi c so fDe l a ys 409 Re s pons eofMa t e r i a lDe l a yst oSt e ps , Ra mps , a ndCyc l e s 425 Re s pons eofDe l a yst oCha ng i ngDe l a yTi me s 43 5 Thei nt e r a c t i o nso fTr a i ni n gDe l a ysa ndGr owt h 495 Cof lows 5 03 TheDyna mi c so fEx pe r i e n c ea ndLe a r nl ng 5 08 Mo de l i ngDe s i gnWi nsi nt heSe mi c o nduc t o rl nd us t r y 51 1 Fi nd i ngFo r mul a t i o nFl a ws 52 0 Mul t i pl eNo nl i ne a rEf f e c t s 529 Fl oa t i ngGoa l s 533 Goa lFo r ma t i o nwi t hl n t e ma la ndExt e r na ll nput s 53 5 Fi ndi ngt heOpt i ma lMi xo fCa pi t a la ndLa bo r5 43 Pr e ve nt l ngNe ga t i veSt oc ks 5 47 Fo r mul a t i ngNo nl i ne a rFunc t i o ns 566 Re f i ni ngTa bl eFunc t i o nswi h Qua t l i t a t i veDa t a 569 Cr i t i q ui ngNo nl i ne a rFunc t i o ns 5 75 Fo r mul a t i ngt heEr r o rRa t e 583 Te s t i ngt heFu l lMo de l 58 5 Hi l lCl i mbi ng 61 5 Pol i c yDe s i g ni nt heMa r ke tGr o wt hMode l6 24 Ext r a po l a t i o na ndSt a bi l i t y 656 Expl o r i ngAmpl i f i c a t i o n 6 7 4 Ex pl or i ngt heSt oc kMa na g e me ntSt r uc t ur e 683 Ex pa nd i ngt heRe a lEs t a t eMo de l 707 Si mul t a ne o usl ni t i a lCo ndi t i o ns 71 8 Re e ng l ne e r l ngt heSu ppl yCha i n 7 41 Me nt a lSi mul a t i onoHn ve nt o r yMa na ge me ntwi t hLa bo r 76 6 Expl a i ni ngOs c i l l a t i o ns 76 7 Pol i c yDe s i g nt oEnha n c eSt a bi l i t y 7 73 Re e ng l ne e r l ngaMa n uf a c t u r l ngFi r mf orEnha nc e dSt a bi l i t y 7 78 TheCos t sofl ns t a bi l i t y 78 0 Add i ngTr a i nl nga n dEx pe r i e nc e 78 0 I nt e nde dRa t i o na l i t yo ft hel n ve s t me ntPr o c e s s 81 0 Se ns i t i vl t yt OUnc e r t a i nt yi nPa r a me t e r s 8 28 Se ns i t i vl t yt OSt r uc t ur a lCha nge s 8 31 I mpl e me nt i ngSt r u c t u r a lCha nge s ‑Mode l i ngLi ve s t o c kMa r ke t s 8 3 6 Pol i c yAna l ys I S 8 40 Ext r e meCond i t i onTe s t s 8 71 Mode lTe s t i ng 88 9 Put t i ngSys t e mDy na mi c sI nt oAc t i o n 901 Choos l ngaTi meSt e p 91 0 Expl o r l ngNoi s e 92 2 ● ● i ̲ L e a ‑ , a . f i 呈 i l i g妄 言 1 A読 取da b和書 C⑲m 野畳 ex S ys 息 e m s Ex pe r i e nc ei sa ne x pe n s i v es c hool . ‑Be n j a mi nFr a n k l i n Ex pe r i e nc ei ss ome t hi n gyo uge t j u s ta f t e ry oune e di t . ‑An o l l y mO uS 1. 1 l NTRODUCT1 0N Theg r e a t e s tc o ns t a nto fmod e r nt i mesi sc ha nge. Ac c e l e r a t l ngC ha nge si nt e c h‑ nol ogy ,popul a t i o n,a nde c ono mi ca c t i vl t ya r et r a nS f o r ml ngO urwo r l d,f r o mt he pr os a i c ‑t hee f f e c tofi nf o r ma t i o nt e c hno l ogyo nt hewa yweus et het e l e pho ne ‑ t ot hepr of o und ‑t hee fe c to fg r e e n hous ega s e so nt heg l o ba lc l i ma t e . So meo ft he l t ,a nd c ha nge sa r ewo nd e r f ul ; o t he r sde f i l et h epl a ne t ,i mpove r i s ht hehuma ns pl r t hr e a t e no urs uⅣi va l . Al lc ha l l e nget r a di t i o na li ns t i t ut i ons , pr a c t i c e s ,a ndbe l i e f s . Mos ti mpor t a n t ,mos to ft hec ha ng e swenow s t r uggl et oc ompr e he nda r i s ea s c ons e que nc e s ,i l l t e nde da nduni nt e n de d,o fhuma nl t yl t S e l f . Al lt o oof t e n,we l 1 ‑ i nt e nt i o ne de fo r t st os o l vepr e s s l ngPr o bl e msl e a dt opol i c yr e s i s t anc e ,whe r eou r pol i c i e sa r ede l a ye d,di l ut e d,o rde f e a t e dbyt heunf o r e s e e nr e a c t i o nso fo t he r pe o pl eo rofna t ur e . Ma nyt l me SOu rbe s te fo r t st os ol veapr o bl e ma c t ua l l yma ke i two r s e. Thed i z z yl nge f f e c t so fa c c e l e r a t i ngC ha ngea r eno tne w.He n r yAda ms ,a pe r c e pt l VeO bs e r ve ro ft heg r e a tc ha nge swr o ughtbyt hei ndus t r i a lr e vo l ut i o n, 3 4 Pa r t I Pe r s p e c t i v ea n dP r o c e s s f or mul a t e dt heLa w ofAcce l e r a t i ont odes c r i bet hee xpone nt i a lgr owt hoft e ch nol ogy,pr oduc t i on,a ndpopul a t i ont ha tma det hel e ga c yofcol oni a lAme r i cahe : i nhe r i t e di r r e l e va nt ‑ Si nc e1 8 00, S c o r e so fne wf o r c e sha dbe e ndi s c ov e r e d; ol df o rc e sha dbe e nr a i s e d t ohi g h e rpowe r s日. ・Co mpl e x i t yha de xt e nde di t s e l fo ni mme ns eho r i z ons , a nda r i t hme t i c a l r a t l OSWe r eus e l e s sf o ra nya t t e mpta ta c c ur a c y . I fs c i e n c ewe r et ogoo ndo ubl i ngorq ua d r u pl i n gI t sC O mpl e xi t i e se ve r y l Oy e a r s , e v e nma t h e ma t i c ss houl ds oo ns uc c umb. Ana v e r a g emi ndha ds uc ‑ c umbe da lr e a dyi n1 85 0' , i tc o ul dnol o nge rund e r s t a ndt hep r o bl e mi n1 900. ( Ada ms1 91 8 , p p. 49 0, 496 ) Ada msbe l i e vedt her a di ca lc ha ngesi ns oc i e t yi nduce dbyt hes ef or c esH woul d r equl r eane ws oc i a lmi nd. "Wi t hunc ha r a c t e r i s t i c,a ndpe r ha psi r oni c,opt l mi s m heconc l ude d,H Thusf a r ,s i nc e50 r1 0t hous a ndye a r s ,t hemi ndha ds ucc es s f ul l y r e ac t ed,a ndnot hi ngyetpr ovedt ha ti twoul df a i lt or ea c t ‑ buti twoul dneed t oJ ump. " As t e a dys t r ea m ofphi l os ophe r s ,s c i e nt i s t s ,a ndma na ge me ntgur usha ves i nc e ec hoedAda ms ,l a me nt l ngt hea c cel e r a t i ona ndca l l i ngf ors i mi l a rl ea pst of unda‑ me nt l ne a wwa ysoft hi nki nga nda c t i ng. Ma nya dvoca t et hede ve l opme ntofs y s ‑ t e mst hi nk i n g ‑t heabi l i t yt os eet hewor l dasac ompl exs ys t e m,i nwhi c hwe unde r s t a ndt ha tH youca n' tj us tdoonet hi ngHa ndt ha t" e ve r yt hi ngl SC Onne C t edt o e ve r yt hi nge l s e. "I fpeopl eha dahol l s t i cwor l dvi e w,i ti sa r gue d,t he ywoul dt he n a c ti nc ons ona nc ewi t ht hel ong‑ t e r m bes ti nt e r es t soft hes ys t e ma sawhol e,i de n‑ t i f yt hehi ghl e ve r a gepol nt Si ns ys t e ms ,a nda voi dpol i c yr es i s t a nce・I ndee d,f or s ome, t hede ve l opme ntofs ys t e mst hi nki ngi sc r uc i a lf ort hes ur vi va lofhuma nl t y・1 Thec ha l l e ngef a c i ngusa lli show t omovef r om ge ne r a l i za t i onsa bouta cc el ‑ e r a t l ngl e a r nl nga nds ys t e mst hi nki ngt ot ool sa ndpr oces s est ha the l pusunde r ‑ s t a ndc ompl exi t y,de s i gnbet t e rope r a t i ngpol i c i es ,a ndgui decha ngei ns ys t e ms f r om t hes ma l l e s tbus i nes st ot hepl a ne tasawhol e. Howe ve r , l e a m1 nga boutc om‑ pl e xs ys t e mswhe nyoua l s ol i vei nt he mi sdi f f i c ul t ・ Wea r ea l lpas s e nge r sona n a i r c r a f twemus tnotonl yf lybutr edes i gni nf li ght . Sys t e m dyna mi csi samet hodt oe nha nc el ea r nl ngl nC Ompl e xs ys t e ms . J us tas a na i r l i neus esf li ghts i mul a t or st ohe l ppi l ot sl ea rn ,s ys t e m dyna mi csi s ,pa r t l y,a me t hodf ordeve l opl ngma nage me ntf li ghts i mul a t or s ,of t e nc omput e rs i mul a t i on model s ,t ohe l pusl ea r na boutdyna mi cc ompl e xi t y, unde r s t a ndt hes our c esofp 1 Cyr es i s t a nc e,a ndde s i gnmor ee fe c t i vepol i c i es . Butl ea r nl nga boutcompl exdyna mi cs ys t e msr e qul r eSmor et ha nt ec hni ca l t ool st oc r e a t ema t he ma t i ca lmodel s .Sys t e m dyna mi csi sf unda me nt a l l yi nt e r di s ‑ c i pl i na r y. Be ca us ewea r econc e r nedwi t ht hebe ha vi orofc ompl e xs ys t e ms ,s ys t e m , o ト 1 Th e r ear ema n ys c h o o l so fs y s t e mst h i n k i n g( f o rs u r v e y s ,s e eRi c h a r d s o n1 9 91a n dLane 1 9 9 4 ) . S o mee mp h a s i z eq u a l i t a t i v eme t h o d s ; o t h e r ss t r e s sf o ‑a l mo d e l i n g ・ Ass o u r c e so fme t h o d a n dme t a p h o rt h e yd r a wo nf i e l d sa sd i v e r s ea sa n t h r o p o l o g y , b i o l o g y , e n g l n e e r l n g , l i n g u i s t i c s , p s y ‑ c h o l o g y , p h y s i cs , a n dT a o i s ma n ds e e ka p p l i c a t i o n si nf i e l d ss t i l l mo r ed i v e r s e ・ Al la g r e e , h o we v e r , t h a t as y s t e msv i e wo ft h ewo r l di ss t i l l r a r e ・ J a yForr e s t e rd e v e l o p e ds y s t e md y n a mi c si nt h e1 9 5 0 s a t MI T. Ri c h a r d s o n( 1 9 91 )仕a c e st h eh i s t o r yo ft h ef i e l da n dr e l a t e ss y s t e md y n a mi c st oo t h e rs y s ‑ t e msa p p r o a c h e s . 5 Ch a p t e r1 Le a r n i n gl na n da b o u t Co mp l e xS y s t e ms d yna mi c si sgr o u nd e di nt het he o r yofnon l i ne a rd yna mi c sa ndf e e d ba c kc ont r ol d e ve l ope di nma t he ma t i c s , phys i c s , a nde ng l ne e r l ng. Be c a us ewea p pl yt he s et oo l s t ot hebe ha vi o rofhuma na swe l la sphys i c a la ndt e c hni c a ls ys t e ms ,s ys t e m d yna mi c sd r a wso nc o g nl t i vea nds oc i a lps yc hol og y , e c ono mi c s ,a ndo t he rs oc i a l s c i e n c e s . Be c a us ewebui l ds ys t e mdy na mi c smode l st os ol vei mpo r t a n tr e a l wo r l d pr o bl e ms ,wemus tl e a r nho wt owor ke fe c t i ve l ywi t hg r oupsofbus ypol i c y ma ke r sa ndhowt oc a t a l yz es us t a i ne dc ha ng ei no r ga ni z a t i o ns ・ Thi sc ha pt e rdi s c us s e st hes 女i l l sr e q ui r e dt ode ve l o pyo u rs ys t e mst hi nk i ngc a ‑ pa bi l i t i e s , ho wt oc r e a t ea ne fe c t i vel e a r ni ngPr oc e s si ndy na mi c a l l yc o mpl e xs ys t e ms ,a ndhow t ous es ys t e md yna mi c si no r ga ni z a t i onst oa dd r e s si mpor t a nt pr o bl e ms . If i r s tr e v i e wwha twekno wa bo utho wpe o pl el e rni a na nda bo utc o m‑ pl e xdyna mi cs ys t e ms .Suc hl e a r nl ngi sdi f f i c ul ta ndr a r ebe c a us eava r i e t yof s t r uc t ur a li mpe d i me n t st hwa r tt hef e e d ba c kpr o c e s s e sr e q ui r e df o rl e a r n l ngt OOC I c ur .Suc c e s s f u la pp r oa c he st ol e a r nl nga bo utc ompl e xdy na mi cs ys t e msr e q ul r e ( 1 )t ool st oe l i c i ta ndr e pr e s e ntt heme nt a lmo de l sweho l da bo utt hena t ur eo fd i f ‑ f i c ul tpr o bl e ms ; ( 2)f o r ma lmode l sa nds i mul a t i o nme ho t dst ot e s ta ndi mp r o veo ur me nt a lmode l s ,d e s i g nne wpo l i c i e s ,a ndpr a c t i c ene ws ki l l s ;a nd( 3)me t hodst o l s , i mpr oveg r o uppr o c e s s e s , a ndo ve r c o mede f e n‑ s ha r pe ns c i e nt i f i cr e a s o n l ngS k i l s i ver ou t i ne sf o ri nd i v i d ua l sa ndt e a ms 。 ‑ 1. 1L 下 Po! i cyResi st ance,t heLawoHJni n始t l ded eonsequemees,ame m的eeoumを eF 百 mを u盲 抽e Behav岳 oro菅Soei a日Syst ems Andi twi l l f al lou tasi nac o mpl i c at i ono fdi s e as e s ,t h atb ya ppl yi nga r e me d yt oo nes or e , youwi l l pr ov ok eanot he r ;andt h atwhi c hr e mo v e st he o nei l ls y mpt o mpr o du c e sot he r s‥. ‑Si rTho ma sMo r e Thebe s t ‑ l ai ds c he me so'mi c ean' me n /Ganga f ta‑ gl e y . ‑Ro be r tBur ns An yt hi ngt h atc a ngowr o n gwi l lgowr o ng. 一日 Mu r phyM t V ehav eme tt hee ne myan dhei su s 。 ‑Pogo Fr omThoma sMo r ei n1 51 6t oPo goi nt hemi d2 0t hc e nt ur yi tha sl o ngbe e na c k nowl e dge dt ha t pe o p l es e e k i ngt os o l veapr o bl e mof t e nma kei two r s e ・ Ou rpo l i ‑ c i e sma yc r e a t eu na n t i c I Pa t e ds i d ee fe c t s ・ Oura t t e mpt st os t a bi l i z et hes ys t e mma y d e s t a bi l i z ei t . Ou rd e c i s i o nsma ypr ov oker e a c t i o nsbyo t he r ss e e k i n gt or e s t o r et he ba l a nc eweups e t .Fo r r e s t e r( 1 971 a )c a l l ss uc hphe nome nat he… c ount e r i nt ui t i ve be ha vi o ro fs oc i a ls ys t e ms . HThe s eu ne xpe c t e dd yna mi c so f t e nl e a dt opol i c yr e ‑ s i s t a nc e ,t het e n d e nc yf o ri nt e r ve nt i o nst obede l a ye d,di l ut e d,o rde f e a t e dbyt he r e s po ns eo ft hes ys t e mt ot hei nt e r v e nt i o ni t s e l f( Me a dows1 98 2) ・ ‑ 6 P a r t IP e r s p e c t i v ea n dP r o c e s s FL GUR El・ l Pdi cyr ess t an c e : Roma ni a nbi r t h r at e s i ( aJ do a d oooLJJt2^ ¢ JSLuJ叩g) al t 2 t ]L J l J! g an PJ I U Thecr udebi r t h r at ei nRomani a showl ngt heef f ec t ofr es t r i c t i ngabor ‑ t i onbegl nnl ngl n 1 966 19661967196819691970197119711994 1994 1966 1971 D ght(1971) ri andW avld ;1971 S R ‑ ource: earb anSl ook1995 calY I' st /' at omani , , 100 1971 1994 101 areannual pp averages N ‑ e: ot . l Asa ne xa mpl e, c ons i de rt hebi r t hr a t ei nRoma ni ai nt hel a t e1 960S 。 Thec r ude bi r t hr a t e( bi r t hspe ryea rpe r1 000pe opl e )wa se xt r e me l yl ow‑a bout1 5pe r t hous a nd( Fi gur e1 ‑ 1 ) .Forva r i ousr e a s ons ,i nc l ud i ngna t i ona lpr i dea nde t hni c i de nt i t y ,t hel owbi r t hr a t ewa sc ons i de r e dt obeagr a vepr obl e m byt hegove r n‑ me nt , i nc l udi ngt hedi c t a t orNi c ol a uCe a us e s g u. TheCe a us e s g ur e gi mer e s ponde d byi mpos l ngpol i c i esdes i gne dt os t i mul a t et hebi r t hr a t e.Ⅰ mpor t a t i onofc onta c e pt i vede vi c e swa so ut l a we d; pr opa ga ndac a mpa l gnSe xt ol l i ngt hevi r t uesofl a r ge f a mi l i e sa ndt hepa t r i ot i c( ma t r i ot i cwoul dbemor ea c c ur a t e )dut yt oha vemor e c hi l dr e nwe r ei nt r oduc e d,a l ongwi t hs omemode s tt a xi nc e nt i vesf わrl a r ge rf a mi ‑ l i e s .Pe r ha psmos ti mpor t a nt ,a bor t i on‑f r e e l ya va i l a bl eonde ma nds i nc e1 957 t hr ought hes t a t ehea l t hc a r es ys t e m‑wa sba nne di nOc t obe r1 966( Da vi da nd Wr i ght1 971 ) . Ther e s ul twa si mme di a t ea nddr a ma t i c. Thebi r t hr a t er os es ha r pl yt one a r l y 40pe r1 000pe ryea r , r i va l i ngt hos eoft hef a s t es tgr owl ngna t i ons ・ Thepol i c ya p‑ pe a r e dt obeas e ns a t i ona ls uc c es s . Howe ve r , wi t hi nmont hst hebi r t hr a t ebe ga nt o f a l l .Byt hee ndof1 970,onl y4yea r sa f t e rt hepol i c ywa si mpl e me nt e d,t hebi r t h r a t eha ddr oppe dbe l ow20pe rt hous a nd,c l os et ot hel owl e ve l ss e e npr i ort Ot he i nt e r ve nt i on. Thought hepol i c yc ont i nue di nf or c e , t hebi r t hr a t ec ont i nue dt of a l l , r e a c hi ng1 6pe rt hous a ndby1 989 ‑a boutt hes a mel owr a t et ha tl e dt ot hei mpo s i t i onoft hepol i c y. Wha tha ppe ne d? Thes ys t e mr es ponde dt ot hei nt e r ve nt i oni nwa yst her e gl medi dnota nt i c i ‑ pa t e. Thepe o pl eofRoma ni af o undwa ysa r oundt hepol i c y. The ypr a c t i c e da l t e r na t i veme t hodsofbi r t hc ont r ol . The ys muggl e dc ont r a c e pt l Vepi l l sa ndde vi c e si n f r om ot he rc ount r i e s .De s pe r a t ewome ns oughta ndf oundba c k‑ a l l e ya bor t i ons . Ma nyoft he s ewe r euns a ni t a r yorbot c he d, l e a di ngt oane a rt r i pl i ngofde a t hsdue r ‑ ‑ ‑ Ch a p t e r1 Le a r n l n gl na n da b o u t Co mp l e xS y s t e ms 7 t oc ompl i ca t i onsofa bor t i onf r om 1 965t o1 967.Mos tho r r i bl y,t henumbe rof ne ona t a lde a t hsr os ebymor et ha n300%be t we e n1 966a nd1 967,a20%i nc r e a s e i nt hei nf a ntmo r t a l i t yr a t e( Da vi da ndWr i ght1 971 ) ・Ther es ul t :t hepol i c ywa s r e nde r e dc ompl e t e l yi ne f f e c t i vea lmos ti mme di a t e l ya f t e ri mpl e me nt a t i on. Butt heuna nt i c I Pa t e dc ons e que nc esdi dn' te ndwi t ht hef a i l ur eoft hepo pu‑ l a t i onpol i c y・ Th epe o pl eofRoma ni a ,a mongt hepoor e s ti nEu r o pe ,we r eha vi ng s ma l lf a mi l i esb e ca us et he yc oul dn' ta for dl a r ge rones .Chi l dc a r ewa suna va i 1 ‑ a bl ef ors ome. Ma nyot he r sl i ve dwi t ht he i re xt e nde df a mi l i esi ns ma ll ,c r owde d a pa r t me nt s ・J obswe r es c a r c e;i nc omewa sl ow・ Ma nype o pl ega vec hi l dr e n血e y c oul dn' ts uppor tt os t a t e ‑ unor r pha na ges . Thegove r nme nt ' spol i c ydi dn' tpr e ve nt t hepe opl eofRo ma ni af r omc ont r ol l i ngt he i rownf e r t i l i t y, buti tdi dbr e e di nt e ns e r es e nt me nta ga l nS tt hei nt r us i vepol i c i e soft her e gl me. I n1 989,whe nt heBe r l i n wa l lf e l la ndt het ot a l i t a r i a nr e gi mesOfEa s t e r nEur o pet o ppl e d, Roma ni awa st he onl yna t i onwhe r et heve l ve tr e vol ut i onwa svi ol e nt . Theha t e dCe a us es e ua ndhi s e qua l l yha t e dwi f ewe r es umma r i l ye xe c ut e dbyf i r i ngs qua d. The i rbl oodybodi e s we r el e 氏i nt hec o ur t ya r dof血epr e s i de nt i a lpa l a c ewhi l et hes c e newa sbr oa dca s t onna t i ona lt e l e v i s i on.Thel a wba nnl nga bor t i onwa st hef i r s tove r t ur ne dbyt he ne wgove r nme n t .Thebi r t hr a t e,a lr ea dyl ow,f e l lf ur t he r .Byt hemi d1 990S ,t he popul a t i ono fRo ma ni awa sa c t ua l l yde c l i ni nga sbi r t hsdr o ppe dbe l owde a t hs . Thec hi l dr e nofRoma ni as uf f e r e dt hemos tf r omt hepopul a t i onpol i c y. Dur ing t heye a r soft hepo pul a t i onpol i c yt hous a ndsofc hi l d r e nwe r epl a c e di nt hec a r eof s t a t eor pha na ge s ,whe r et he ywe r eke ptl i kea ni ma l si nc r i bs( c a ges ,r e a l l y)wi t h‑ outa t t e nt i ont obas i cne e ds ,muc hl e s st hel ove山a ta l lofusne e da ndde s e r ve. Foodwa ss os c a r c et ha tbl oodt r a ns f us i onswe r er out i ne l ygl Ve na Snut r i t i ona ls up‑ pl e me nt s ・Be c a us ene e dl e swe r eus e dr e pe a t e dl y ,a ne pi de mi cofAI DSs pr e a d r a pi dl ya mongt hec hi l dr e n・ Thes i dee fe c t soft hef a i l e dpopul a t i onpol i c yc a s ta s ha dowont heh e a l t ha ndha ppi nes sOfa ne nt i r ena t i on,as ha dows t r e t c hi ngove r ge ne r a t i ons . Pol i c yr e s i s t a nc ei snotl i mi t e dt odi c t a t or s . I tdoe s n' tr es pe c tna t i ona lbor de r s , pol i t i c a li de ol og y , o rhi s t or i c a le poc h・ Co ns i de rt heUSgove r nme nt ' sf i ghta ga l nS t i nf la t i oni nt hee a r l y1 970S . Fi gur el 1 2s howst heCons ume rPr ic eI nde x( CPI )f or t heUni t e dSt a t e sbe t we e n1 968a nd1 976. I nt hee a r l y1 970si nf la t i onha da c c e l e r ‑ a t e da ndt heNi x ona dmi ni s t r a t i onf e l ta c t i onha dt obet a ke n. Thoug haRe publ i ‑ c a n, Ni xonc hos et oi mpl e me ntwa gea ndpr l C eC O nt r OI s . Thepol i c ywa se x pe ns i ve: Ane wf e de r a lbu r ea uc r a c y,t heCounc i lonWa gea ndPr i c eSt a bi l i t y ,wa sc r e a t ed t oove r s e et hec o nt r ol sa nde nf or c ec ompl i a nc e.Wa gea ndpr l C ec ont r ol swer e ie v we dbyma nyi nNi xon' sownpa r ya t sve r gi ngOns oc i a l i s m,c os t l ngNi xon va l ua bl epol i t i c a lc a pi t a l . Atf i r s t , t hepol i c ys e e me dt owo r k, a l t houghi mpe r f ec t l y. Dur i ngs o‑ c a l l e dPha s eIoft hec ont r ol s , t her a t eofi nf la t i onf e l lbya boutha l f . The a dmi ni s t r a t i onde c i de dt hec ont r ol sc oul dber e l a xe d. I nPha s eI I , Pr e s i de ntFor d ( whoi nhe r i t e dt h epr ogr a mf r om Ni xon)l a unc he daj a wboni ngc a mpa i gn,com‑ pl e t ewi t hc a mpa l gn‑ S t yl ebut t onsl a be l e dH WI N! りf orH Whi pI nf la t i onNow! =・ Fe wobs e r ve r se x pe c t e dWI N. fbut t onst oha vea nye f f e c t ,a ndmos tf e l ti nf la ion t wo ldr u e t ur nt oi t sr a t epnort ot hes t a r tofc ont r ol s . I ns t e a d, i nna t i ona c t ua l l ya c‑ c e l e r a t e dunt i l , by1 9 75, t heCPIha dr e t ur ne dt ot het r a j e c t o r yl tWa sOnPr i o rt Ot he i mpos i t i onoft hepr i c eC Ont r OI s . Les st ha n4yea r sa f t e rt hei nt e r ve nt i ont he r ewas 8 Pa r t I Pe r s p e c t i v ea n dPr oc e s s FI GUREi‑ 2 Pol i c yr esi s t ancei nt hef i gh tagal ns ti nf l at i on i cel ndex( CPI )showi ngt heNi xon / For dwageandpr i ce TheUSConsumerPr c ont r ol s 0 5 ( ooL = e9 6 L ) 0 4 d d3 1968 1969 1970 1971 1972 1973 1974 1975 1976 nor es i dueofbe ne 臥 Ot he re xa mpl esofpol i c yr es i s t a nc eca nbef oundnea r l y e ve r yda yi nt hene ws pa pe r ・ Ta bl ei l ll i s t saf e w1 2 Ma c hi a ve l l i ,ake e nobs e r ve rofhuma ns ys t e ms ,di s c us s edpol i cyr es i s t a nc ea t l e ngt h,Obs e r vi ngi nt heDi s c our s e st ha t Whe napr obl e ma r i s e se i he t rf r omwi t h i nar e pu bl i co ro ut s i dei t , Onebr o ug ht a bo ute i t he rbyi nt e r na lo re xt e r na lr e a s o ns , O net ha tha sbe c o mes og r e a tt ha ti t be g i nst oma kee ve r yo nea f r a i d, t hes a f e s tpo l i c yl St Ode l a yd e a l i ngwi t hi tr a t he r t ha nt r yi ngt odoa wa ywi t hi t , be c a us et hos ewhot r yt odoa wa ywi t hi ta l mos t a l wa ysi nc r e a s ei t ss t r e ngt ha nda c c e l e r a t et heha r mwhi c ht he yf e a r e dmi gh tc o me f r o mi t . ( Ma c hi a ve l l i1 979, pp. 2 40 ‑2 41 ) . If i ndMa c hi a ve l l i ' svi e wt ooc yni ca lbutc a ns ympa t hi z ewi t hhi sf r us t r a t i oni nob‑ s e r vi nghi scl i e ntpr i nces( t heCEOsofRe na i s s a nc eI t a l y)t a kea ct i onst ha tonl y ma det he i rpr obl e mswor s e・ Amor er e le f c t i vevi e wi sofe r edbyt hel a t ebi ol ogl S t a ndes s a yi s tLe wi sThomas( 1 974,p. 90) : Whe nyo ua r ec o nf r o nt e dbya n yc o mpl e xs oc i a ls ys t e m, s uc ha sa nu r ba nc e n t e ro r aha ms t e r , wi ht t hi ngsa bou ti tt ha tyo u' r ed i s s a t i s f i e dwi ha t nda nxi o ust of i x, yo u c a nn ot j us ts t e pl na n ds e ta bo utf i xi ngwi t hmuc hho peo fhe l pi ng. Thi sr e a l i z a t i o n i so neo ft hes o r edi s c o ur a ge me n t so fo u rc e n t u r yI‑Yo uc a nno tme ddl ewi t ho ne pa r to fac o mpl e xs ys t e mf r omt heo ut s i d ewi t ho u tt hea l mos tc e r t a i nr i s ko fs e t t i ng o f fd i s a s t r o use ve nt st ha tyo uha dn' tc o u nt e do ni no he t r , r e mo t epa r t s . I fyo uwa n t t of i xs o me t hi ngyoua r ef i r s to bl i g e dt ounde r s t a nd... hewhol t es ys t e mH I n t e r ve nl ngl SaWa yOfc a us l ngt r o u bl e . 2 F u r t h e rr e a d i n g: J o h nMc Ph e e( 1 9 8 9 )o 恥r sawo n d e 血l d e s c r i p t i o no fp o l i c yr e s i s t a n c ei nt h e r e l a t i o n s h i po fp e o p l ewi t hn a t u r e . Mc Ph e eb il r l i a n t l yd e s c r i b e st h eu n a n t i c I P a t e ds i d ee f f e c t sa n d p o l i c yr e s i s t a n c ea r i s i n gf r o ma tt e mp t st od e f e a t t h r e ee l e me n t a lf o r c e so fn a t u r e : v o l c a n i s m, f l o o d , a n df i r e ・ Ed wa r dTe n n e r( 1 9 9 6 )a l s oi d e n if t i e sma n ye x a mp l e so fp o l i c yr e s i s t a n c e・ 9 Cha pt e r1 Le a r mngl na n da boutCompl e xSys t e ms TABLE l l l Exampl esofpol l cy r esi st ance " Us eofChe aperDr ugsPushesCos t sUp,NotDown,St udyFi nds:Li mi t i ng whati spr es cr i bed,asmanaged‑ car es ys t emsdo,hasuni nt endedef f ec tof i ncr easi ngc os t s,r esul t sshow"( Headl i nej nLA Tl ' mes,3/ 20/ 96,pl1,r eport‑ 1 ngUni v ,ofUt ahs t udyof1 3, 000pat i ent si nvar i ousHMOs) . " Washi ngt on' sbi gges tconser vat i onpr ogr am,whi chpay sf ar mer st ot ak e soj l ou tofcul t i vat i onf oradecadet ocombater osi onandhel pt heenvi r on men t ,i sawas t eofmoney, sos aysanews t udyoft he l l year ‑ Ol d pr ogr am ..・Forever yer odi ngacr eaf ar meri dl es,anot herf ar mer ‑or somet i mest hes ameone‑si mpJ ypl owsupnear 一 yasmuchaddi t i onal er osi on‑ pr one一 and..lE nt heGr eatPl ai ns, f ori ns t ance, f ar mer ssetasi de 1 7mi " i onac r es, ye tt het ot a一 cul t i vat edl anddr oppedbyonl y2m‖i onacr es" ( Busi nessWeek,3 / 1 8/ 96,p.6,r epor t i ngaUni v.ofMi nnesot as t udy) . Lowt arandni cot i necl gar et t esac t uaH yI ncr easei n t ak eofcar ci nogens,CO, et c.assmok er scompensat ef ort hel owni cot i necont en tbysmoki ngmor e cl gar et t eSPerday,byt aki ngl onger ,mor ef r equentdr ags, andbyhol di ngt he smok ei nt hei rl ungsl onger . Ant i l ockbr ak esandot heraut omot i vesaf et ydevi cescausesomepeopl et o dr i vemor ea ggr ess i veJ y ,Of f set t i ngsomeoft hei rbenef i t s, i nf or mat i ont echnol ogyhasnotenabl edt he" paper l es sOf f i ce" ‑papercon sumpt i onperc api t ai sup. Roadbui l di n gpr ogr amsdesi gnedt or educeconges t i onhavei ncr easedt r af f i c,del ays,andpol l ut i on. Despi t ewi de spr eadus eof一 abor ‑ savl ngaPPl l anCeS, Amer i canshave一 es s l ei sur et odayt han50year sago. TheUSgover nmen t ' swarondr ugs,f ocusl ngOni nt er dj c t i onandsuppl ydi s‑ r upt i on( par t i cul ar l ycocai nepr oduct i oni nSout hAmer i ca) ,wi t hacos ti nt he bHi ons,hashadonl yasmal li mpactoncocai necul t i vat i on,Pr oduc t i on,or smuggl l ng.Dr ugusei nAmer i caandel sewher er emai nshi ghr TheUSpol f C yOff i r esuppr essi onhasi ncr easedt hesi zeandsever i t yof f or es tf i r es.Rat hert hanf r equent ,sma"f i r es, f i r esuppr es si onr eadst ot he ac cumul at i onofdeadwoodandot herf uel sl eadi ngt ol ar ger ,hot t er ,and mor edanger ousf i r es,of t enconsum ngt heol des tandl ar ges tt r eeswhi ch pr evi ousl ysur vi vedsmal l erf i r esunhar med. Fl oodc ont r def f or t ssuchasl eveeanddam cons t r uc t i onhavel edt omor e sever ef l oodsb ypr event i ngt henat ur ar di ssi pat i onofexcesswat eri nf l ood pl ai ns. Thec os toff l ooddamagehasi ncr easedast hef l oodpl ai nswer ede‑ vel opedbyp eopl ewhobel i evedt heywer esaf e. l mposl ng200‑ mi l et er r i t or i a川mi t sandquot ast opr ot ec tf i shs t ock sdi d notpr eventt heco‖ apseoft heGeor gesBankf i sher yo什t hecoas tofNor t h Amer i ca1On c et hewor l d' sr i ches t ,byt hemi d1990sman yspeci eswer e commer ci al l yex t i nc t , t hef i sher ywasshutdown, t hef l eet swer ei dl ed, andt he‑ Oc al ec onomi eswer ei ndepr essi on. Der egul at i onoft heUSSavi ngsandLoani ndus t r y ,desi gnedt osavet he i n dus t r yf r on lf i nanc i al pr obl ems,J edt oawaveofspecuf at i onf o" owedby c oH apse,atac os tt ot axpayer si nt hehundr edsofbj J l i onsofdoH ar s. An t i bi ot i csha ves t i muJ at edt heevol ut i onofdr ug‑ r esi s t antpat hogens, i ncl udi ngvi r ul ents t r ai nsofTB,s t r ep,s t aph,andsexua" yt r ansmi t t ed di seases. ‑ l ‑ ‑ Pes t i ci desan dher bi ci deshaves t i mul at edt heevol ut i onofr esi s t antpest s andweeds,k i H edof fnat ur al pr edat or s,andac cumul at edupt hef oodchai n t opoJ SOnf i sh,bi r ds,andpossi bl yhumans. 10 P a r t I P e r s p e c t i v ea n dP r o c e s s Buthowc a nonec omet ounde r s t a ndt hewhol es ys t e m?Ho wdoe spol i c yr e s i s ‑ t a nc ea is r e ?Howc a nwel e a r nt oa vo i di t ,t of i ndt hehi g hl e ve r a gepo l i c i e st ha t c a npr od uc es us t a i na bl ebe ne f i t ? iI 1. 2 CausesofPoi i t CyRest ‑ St ance Onec a us eo fpol i c yr e s i s t a nc ei so urt e nd e nc yt oi nt e r p r e te x pe r i e nc ea sas e r i e so f e ve n t s , f o re xa mpl e ," i nve nt o r yl St o ohi g h, "o r" s a l e sf e l lt hi smont h. "Ac c o unt s o fwhod i dwha tt owhoma r et hemos tc o mmo nmod eofd i s c our s e , f r omt hema r o omt ot heboa r d r oo m,f r omhe a dl i ne st ohi s t o r yboo ks . Wea r et a ug htf r o ma n e a r l ya get ha te v e r ye ve ntha sac a us e , whi c hi nt u mi sa ne f f e c to fs omes t i l le r‑ a l i e rc a us e:" I nve nt o r yl St oohi g hbe c a us es a l e su ne x pe c t e d l yf e l l .Sa l e sf e l lbe c a us et hec o mpe t i t or sl o we r e dt he i rpr l C e.Thec ompe t i t o r sl owe r e dt he i rpr i c e be c a us e. ・・ "Suc he ve nt ‑ l e ve le x pl a na t i o nsc a nbee xt e nd e di nde f i ni t e l y , i na nu n‑ is t o t e l i a nc ha i no fc a us e sa nde fe c t s , u nt i lwea r ivea r ts omeFi r s tCa us e , b r o ke nAr o rmo r el i ke l y , l os ei nt e r e s ta l o ngt hewa y . Thee ve nt ‑ o r i e nt e dwo r l dv i e wl e a dst oa ne ve n Lo r i e nt e da ppr oa c ht opr o b l e m s o l v i ng・ Fi g ur e1 ‑ 3s howshowweo f t e nt r yt os o l vepr o bl e ms . Wea s s e s st hes t a t e o fa fa i r sa ndc o mpa r ei t t oo urgoa l s . Thega pbe t we e nt hes i t ua t i o nwede s i r ea nd t h es i t ua t i onwepe r c e i vede f i ne so urpr o bl e m・ Fo re xa mpl e , s uppos es a l e so fy o ur o r ga ni z a t i onwe r e$8 0mi l l i onl a s tq ua r t e r , bu tyo urs a l e sgoa lwa s$1 00mi l l i o n. Thepr o bl e mi st ha ts a l e sa r e2 0%l e s st ha nyo ude s i r e d. Yo ut he nc ons i de rva io r us o pt l O nSt Oc or r e c tt hepr o bl e m. Yo umi g htc utpr l C e St OS t i mul a t ede ma nda ndi n‑ c r e a s ema r ke ts ha r e ,r e pl a c et hev i c epr e s i d e ntofs a l eswi t hs omeo nemo r ea g‑ g r e s s i ve , o rt a keo t he ra c t i ons . Yo us e l e c tt heo pt l O nyo ude e mbe s ta ndi mpl e me nt i t ,l e a di ng( yo uho pe )t oabe t t e rr e s ul t .Yo umi g hto bs e r veyo urs a l e si nc r e a s e: p r o bl e ms ol ve d. Ors oi ts e e ms . , Thes ys t e mr e a c t st oyours ol ut i o n: Asyo urs a l e sr i s e , c o mpe t i t or sc utpnc e s a nds a l e sf a l la ga i n.Ye s t e r da y' ss ol ut i o nbe c o me st oda y' spr o bl e m. Wea r eno t p uppe tma s t e r si nf lue nc i ngaS ys t e mOutt he r e ‑wea r ee mbe dde di nt hes ys t e m. Thepu ppe tma s t e r ' smove me nt sr e s po ndt ot hepos i t i onoft hema r i one t t eo nt he s t r l ngS . The r ei sf e e d ba c k: Ther e s ul t so fo u ra c t i o nsde f i net hes i t ua t i onwef a c ei n t hef u t ur e .Thene ws i t ua t i o na l t e r so u ra s s e s s me ntoft hepr obl e ma ndt hede c i ‑ s i o nswet a ket o mor r ow( s e et het o po fFi g ur e1 ‑ 4) . Po l i c yr e s i s t a nc ea r i s e sbe c a us eweo f t e nd onotu nde r s t a ndt hef u l lr a ng eo f Fi g ur eト4) . Aso ura c t i o nsa l t e rt hes t a t eo ft he f e e d ba c kso pe r a t i ngi nt hes ys t e m( s ys t e m,O t he rpe opl er e a c tt or e s t o r et heba l a nc eweha veups e t ・Oura c t i o nsma y a l s ot r l gge rS i dee f f e c t s . i l ‑ ‑ FI GURE l 3 Ev en t 1 0r J l en t ed vi ewo ft h ewor l d l Goal s Zg i i si on → Pr obl em 一一一一」ト Deci . //P. I Si t uat i on Resul t s ll Cha pt e r1 Le a r n i ngl na nda boutCo mpl e xSys t e ms Wef r e que n t l yt lka a bouts i dee fe c t sa si ft he ywe r eaf e a t ur eofr e a l i t y . Nots o. I nr e a l i t y , t he r ea r enos i dee fe c t s , t he r ea r ej us te He c t s . Whe nwet a kea c t i on, he t r e a r eva r i ouse fe c t s .Thee f f e c t swet houg h tofi na dva nc e,orwe r ebe ne f i c i a l ,we c a l lt hema i n,ori nt e nde de f f e c t s .Thee fe c t swedi dn' ta nt l C I Pa t e,t hee fe c t s whi c hf e dba c kt ounde r c utourpol i c y , t hee fe c t swhi c hha me r dt hes ys t e m‑t hes e a r et heone swec l a i mt obes i dee f f e c t s , Si dee f f e c t sa r enotaf e a t ur eofr e a l i t ybut as i g nt ha touru n de r s t a ndi ngo ft hes ys t e mi sna r r owa ndf la we d. Una nt i c i pa t e ds i dee f f e c t sa r i s ebe c a us ewet ooof t e na c ta si fc a us ea nde fe c t we r ea l wa ysc l os e l yl i nke di nt i mea nds pa c e.Buti nc ompl e xs ys t e mss uc ha sa n ur ba nc e nt e roraha ms t e r( o rabus i ne s s ,s oc i e t y , o re c os ys t e m)c a us ea nde f f e c ta re of t e ndi s t a nti nt i mea nds pa c e. Na r r owmode lbounda ie r sof t e nl e a dt obe l i e f st ha t vi ol a t et hel a wso fphys i c s : i nt hem i d1 990sCa l i f o r ni aa ndt hea ut omobi l ei ndus ‑ t r yde ba t e dt hei n t r oduc t i onofs oI C a l l e dz e r oe mi s s i onve hi c l es( ZEVs )t or e duc e irpol a l ut i on.Tr ue,t heZEVs ‑e l e c t icc r a r s ‑woul dha venot a i l pi pe.Butt he powe rpl a n t sr e qui r e dt oma ket hee l e c t r l C l t yt Or unt he mdoge ne r a t epol l ut i on. I n r e li a y,Ca t l i f or n i awa spr omot l ngt hea do pt i onofDEVs ‑di s pl ac e de mi s s i onv hi c l e s ‑C a r swh os ewa s t e swoul dbl owdownwi ndt oot he rs t a t esora c c umul a t ei n nuc l e a rwa s t ed umpsout s i dei t sbor de r s . El e c t r i cc a r sma yt ur noutt obea ne nvi ‑ r onme nt a lboonc ompa r e dt oi nt e r na lc ombus t i on.Thet e c hnol ogyl Si mpr ovl ng r a pi dl y , a nda irpo l l ut i oni sama j orhe a l t hpr obl e mi nma nyc i t i es ・ Butnomodeof e ‑ FI GURE1 ‑ 4 Thef eedbackvi ew Envi r onment Ourd e ci s i on sal t erouren vi r onmen t ,l ea di n gt on e wdec i s i on s, Goa・ s ES de d c e t s Goal sof Ot her Agent s bu t al s ot r i gger l n gS i dee f f ec t s, del ay edr e ac t i on s, ch anges i ng o al san di n t eⅣen t i on sb yo t her s.Th e s ef e edb ac k smay l e adt ou n an t i c J P at edr esul t san di n e f f ec t i v ep o一 i ci es. 12 P a r tI P e r s p e c t i v ea n dP r o c e s s t r a ns por tore ne r gyc onve r s i onpr oc e s si sf r e eofe nvi r onme nt a li mpa c t ,a ndno l e gi s l a t ur ec a nr e ea p lt hes e c o ndl a woft he r modyna mi c s ・ 3 Toa voi dpol i c yr es i s t a nc ea ndf i ndhi ghl e ve r a gepol i c i esr e qul r eSuSt Oe x pa ndt hebo unda r i e sofourme nt a lmode l ss ot ha twebe c omea wa r eofa ndunde r ‑ s t a ndt hei mpl i c a t i onsoft hef e e dba c ksc r e a t e dbyt hede c i s i onswema ke・ Tha ti s , wemus tl e a r na boutt hes t r uc t ur ea nddyna mi c soft hei nc r e a s l ngl yc ompl e xs ys ‑ t e msi nwhi c hwea r ee mbe dde d. ‑ 1. 1. 3 Feedback Muc hoft hea r tofs ys t e m dyna mi csmode l i ngi sdi s c ove nnga ndr e pr e s e nt l ngt he f e e dba c kpr oc e s s e s ,whi c h,a l ongwi t hs t oc ka ndf l ows t uc r t ur e s , t i mede l a ys ,a nd non li ne a it r i es ,de t e r mi net hedyna mi c sofas ys t e m. Youmi h ti g ma gi net ha tt he r e i sa ni mme ns er a ngeofdi fe r e ntf e e dba c kpr oc es s esa ndot he rs t r uc t ur e st obe ma s t e r e dbe f or eonec a nunde r s t a ndt hedyna ic m sofc ompl e xs ys t e ms . I nf a c t , t he mos tc ompl e xbe ha vi or sus ua l l ya r i s ef r omt hei nt e r a c t i ons( f e e dba c ks )a mo ngt he c ompone nt soft hes ys t e m, notf r o mt hec o mpl e xi t yoft hec o mpone nt st he ms e l ve s ・ l ldyna A mi c sa r i s ef r om t hei nt e r a c t i onofj us tt wot ype soff e e d ba c kl oo ps , Pos i t i ve( ors e l f ‑ r e i nf o r c i ng)a ndne ga t i ve( ors e l f ‑ c or r e c t i ng)l oops( Fi g ur e1 1 5) ・ Pos i t i vel oopst e ndt or e i nf or c eora mpl i f ywha t e ve ri sha ppe nl ngi nt hes ys t e m: Themo r enuc l e a rwe a ponsNATOde pl oye ddur i ngt heCol dWa r , t hemo r et heSo vi e tUni onbui l t , l e a di ngNATOt obui l ds t i l lmor e. I faf i n l owe r si t spnc et oga l n ma r ke ts ha r e,i t sc ompe t i t o r sma yr e s pondi nki nd,f or c i ngt hef i r mt ol owe ri t s pnc es t i l lmor e. Thel a r ge rt hei ns t a l l e dba s eofMi c r os of ts of t wa rea ndl nt e lma c hi ne s , t hemor ea t t r a c t i vet he" Wi nt e l Ma r c hi t e c t ur ebe c a mea sde ve l o pe r ss ought t hel a r ges tma r ke tf o rt he i rs of t wa rea ndc us t ome r ss oughts ys t e msc ompa t i bl e wi t ht hemos ts of t wa r e;t hemo r eWi nt e lc omput e r ss ol d,t hel a r ge rt hei ns t a l l e d ba s e. Thes epos i t i vel oopsa r ea l lpr oc e s s est ha tge ne r a t et he i rowngr owt h,l e a d‑ 1 ngt Oa m Sr a c e s ,pnC eWa r s ,a ndt hephe nome na lgr owt hofMi c r os of ta ndl nt e l , r e s pe c t i ve l y. Ne ga t i vel oopsc ount e r a c ta ndoppos ec ha nge・ Thel es sni c ot i nei nac i ga r e t t e, t hemor es moke r smus tc ons umet oge tt hedos et he yne e d. Themor ea t t r a c t i vea ne i ghbor hoodorc i t y,t hegr e a t e rt hei nml gr a t i onf r om s ur r oundi nga r e a swi l lbe, i nc r e a s i ngune mpl oyme nt ,hous l ngPnC eS ,C r owdi ngi nt hes c hool s ,a ndt r a f f i c c onges t i onunt i li ti snomo r ea t t r a c t i vet ha not he rpl a c espe opl emi ghtl i ve・ The hi ghe rt hepnc eofac ommodi t y,t hel owe rt hede ma nda ndt hegr ea t e rt hepr o‑ duc t i on,l ea di ngt oi nve nt or ya c c umul a t i ona ndpr es s ur ef orl owe rpnc e st oe l i i‑ m na t et hee xc e s ss t oc k.Thel a r ge rt hema r ke ts ha r eofdomi na ntf i r ms ,t hemo r e l i ke l yi sgove r nme nta nt i t r us ta c t i ont ol i mi tt he i rmonopol ypower ・Thes el oo ps a l lde s c r i bepr oc es s est ha tt e ndt obes e l f ‑ 1 i ml t l ng, pr oc es s est ha ts e e kba l a nc ea nd e qui l i br i um. ‑ ‑ 3 Ev e ns c i e n t i s t ss u f f e rf r o mt h e s ep r o b l e ms ・ Io n c eh e a r dad i s t i n g u i s h e dp h y s i c i s t a r g u et h a t t he s o l u t i o nt ot h ee n e r g yp r o b l e mwa st ob u i l dh u n d r e d so fh u g eo fs h o r en u c l e rp a o we rs t a t i o n s , t ob e c o o l e db ys e a wa t e r . Th ewa n wa s t e wa t e rwo u l db ep u mp e db a c ki nt h eo c e a nwh e r e , h es a i d , " Th ewa s t eh e a t wo u l dd i s a p p e a r . "Ou t o fs i g h t , o u t o fmi n d ・ 1 3 Cha p t e r1 Le a r n i ngl na nda bo utCompl e xSys t e ms FI GURE 1 ‑ 5 Posi t i veandnegat i vef eedbackl oops Posi t i vef eedback:Posi t i veL oopsar esel f ‑ r ei nf or cmg. l nt hi scase,mor echi ck ensl aymor eeggs, whi chhat ch andaddt ot hechi ck enpopuF at j on,J eadi ngt os t i l l mor e eggs, andsoon・ ACaus alLoopDi agr am orCLD( chap‑ t er5)Capt ur est hef eedbackdependencyofchi ck ens andeggs.Thear r owsi ndi c at et hec ausalr el at i onshi ps. The+st gnsatt hear r owheadsi ndi cat e的at的eef f ec ti s posi t i vel yr el at edt ot hec ause:ani n cr easei nt he chi ck enpopuF at l L onc aus est henumberofeggsl ai deach dayt or i seabovewhati twoul dhavebeen( andvi ce ver sa: adecr easei nt hechi ck enpopuf at i oncausesegg l ayi ngt of aHbel owwhati twoul dhav ebeen) . Thel oopi s sel f ‑ r ei nf or cJ ng,henc et hel ooppol ar i t yi den t i f i erRJf t hi sL oopwer et heonJ yoneoper at i ng, t hechi ck enand eggpopul at i onwoul dbot hgr owexponent i aH y . Ofcour se,nor eal quant i t ycangr owf or ever . Ther emus t bel i ml l t St Ogr owt h. Thesel r f mi t Sar eCr eat edbynegat i ve f eedback. Negat i vef eedback:Negat i vel oopsar esel f ‑ c or r ect i ng. Theyc ount er ac tchange. Ast hechi ck enpopul at i on gr ows, var i ousnegat i vel oopswi "ac tt obal ancet he chi ck enpopul at i onwi t hi t scar r yl ngC apaci t y .OnecF as I si cf eedbacki sshownher e: Themor echi ck ens, t he mor er oadcr oss∫ ngst heyw川at t emp t .J ft her ei sany t r af f i c,mor er oadcr os sl ngSWi l Headt of ewerchi ck ens ( hencet henegat i ve‑pol ar i t yf ort hel i nkf r om r oad cr ossi ngst ochi ck ens) . Ani ncr easei nt hechi ck enpopul l at l r OnC ausesmor er i sk yr oadcr ossl ngs,whi cht hen br i ngt hechi ck enpopul at i onbackdo wn. TheBi nt he cen t erofal oopdenot esabal ancl ngf eedback.l ft he r oad‑ cr ossi ngl oopwast heonl yoneoper at i ng( saybe‑ causet hef ar mers el l sa‖t heヲggs) , t henumberof chi ck enswoul dgr aduaH ydecl l neun t i lnoner emai ned. AHsys t ems,nomat t erhowcompl ex,c onsi s tofnet ‑ wor k sofposi t i veandnegat i vef eedback s,anda" dynami csar i s ef r omt hei nt er ac t i ono ft hesel oops wi t honeanot her . r Eggs ・ り ナ ㌧ chi ckens ノ// Asyst em' sf eedbackst r uct ur e M gener at esi t sdynami cs St r uct ur e: 鯉 ・ 恵 、 ・ . /‑‑ ー、 、七了 chi ekens cr o R s o s ?n dgS 一、 ‑ ∫ 並 Behavi or: d Roa Cr ossi ngs Chi ckens Ti me / ■ 14 P a r tI P e r s p e c t i v ea n dP r o c e s s 1. i. 4 Pr ocessPoi nt :TheMeani ngofFeedback I nc ommonpa r l a nc et het e r m" f e e d ba c k"ha sc omet os e r veasae u phe mi s mf o r c r i t i c i z l ngOt he r s , a si n" t hebo s sga vemef e e dba c konmypr e s e n t a t i on・ "Thi sus e o ff e e dba c ki sno twha tweme a ni ns ys t e mdyna mi c s . Fur t he r , " pos i t i v ef e e d ba c k" doe snotme a n" pr a i s e "a nd" n e ga t i vef e e dba c k"d oe sno tme a n" c r i t i c i s m. "Pos i ‑ t i vef e e d ba c kd e not e sas e l f ‑ r e i nf o r c i ngp r oc e s s ,a ndne ga t i v ef e e d ba c kd e no t e sa s e l f ‑ c or r e c t l ngO ne . Ei t h e rt y peo fl oo pc a nbegoodo rba d,de pe ndi ngo nwhi c h wa yl ti so pe r a t l nga n dofc o ur s eo nyo urva l ue s ・ Re s e r vet het e r mspos i t i vea nd ne ga t i vef e e d ba c kf o rs e l f ‑ r e i nf o r c i nga nds e l f ‑ c o r r e c t i ngp r o c e s s e s , a nda vo i dde ‑ s c r i bi ngt hec r i t i c i s myo ugl VeO rr e c e i vet oo t he r sa sf T e e d ba c k. Te l l i ngs o me o ne you ro pl ni o nd oe sno tc o ns t i t u t ef e e d ba c kunl e s st he ya c to nyours ug ge s t i o nsa nd t husl e a dyo ut or e vi s ey o u rv i e w. Tho ug ht he r ea r eo n l yt wot y pe so ff e e d ba c kl oo p, mo de l sma ye a s i l yc o nt a i n t hous a ndsofl oo ps ,o fbo t ht y pe s ,c o u pl e dt oonea not he rwi t hmul t i pl et i mede ‑ l a ys , no nl i ne a r i t i e s , a nda c c umul a t i o ns . Thedyna mi c so fa l ls ys t e msa r i s ef r o mt he i nt e r a c t i o nsoft he s ene t wo r kso ff e e d ba c ks . I nt ui t i o nma ye na bl eust oi nf e rt he dyna mi c so fi s o l a t e dl oo pss uc ha st hos es howni nFi g ur eト5・ Butwhe nmul t i pl e l oo psi nt e r a c t , i ti sno ts oe a s yt od e t e mi r newha tt hed yna mi c swi l l be . Be f o r ec o n‑ t i nul ng,t r yt hec ha l l e ng es ho wni nFi gu r e1 ‑ 6. Whe ni nt ui t i onf a i l s ,Weus ua l l y t u仙 t oc o mput e rs i mu l a t i o nt ode d uc et hebe ha vi o ro fou rmode l s ・ Dymami eso菅Mu司 モ 岳 pB e‑ 』⑳opSys官 ems Wha ta r et hedy na mi c so ft hec hi c ke npo pul a t i o nwhe nbo t hl oo psa r es i mul t a ne ‑ ous l ya c t i ve( Fi g ur eL6 ) ?Ske t c hag r a phs howi ngt hebe ha vi o roft hec hi c ke n po pul a t i o no ve rt i me . As s umet hei ni t i a lc hi c ke npo pul a t i o ni ss ma l l( buti n c l ude s a tl e a s toner oos t e r ) . r Eggs 鯉 ・r chj ckens ・ りc r o R o ss q n d。S ・ 較 ㌧ノ/ / 架 ㌧ノ/ / / 1. 2 LEARNI NG J sA FEEDBACK PROCESS J us ta sdyna mi c sa r i s ef r o mf e e d ba c k, s ot ooa l ll e a r ni ngd e pe n dso nf e e d ba c k・ We ma kede c i s i o nst ha ta l t e rt her e lwo a r l d; wega t he ri nf o ma t i o nf e e d ba c ka bo ut t he r e a lwo r l d,a ndus i ngt hene wi nf o r ma t i onwer e vi s eo urunde r s t a nd i ngo ft he wo r l da ndt hede c i s i onswema ket obr i ngourpe r c e pt l O nO ft hes t a t eo ft hes ys t e m c l os e rt oo urgoa l s( Fi g u r e1 ‑ 7 ) . Thef e e dba c kl oo pi nFi g u r el 1 7a ppe a r si nma nygui s e st h r o ug ho u tt hes oc i a l s c i e nc e s .Ge o r geRi c ha r ds on( 1 991 ) ,i nhi shi s t o r yo ff e e d ba c kc o nc e p t si nt he s oc i a ls c i e nc e s ,s ho wshowbe g i nn l ngi nt he1 940sl e a di ngt hi n ke r si ne c o no mi c s , 15 Ch a p t e rl Le a r n i n gl na n da b o u t Co mp l e xS y s t e ms Ps yc hol og y,s oc i ol ogy,a nt hr opol ogy ,a ndot he rf i e l dsr e c ogni z e dt ha tt hec on‑ c e ptoff ee dba c kde ve l ope di nphys i csa nde ngl ne e r l nga ppl i e dnoton lyt os e r v0‑ , me c ha ni s msb utt ohuma nde c i s i onma ki nga nds oc i a ls e t t l ngSa SWe l l .By1 961 For r es t e r ,i nI n du s t r i alDy nami c s ,a s s e r t e dt ha ta l ldec i s i ons( i nc l udi ngl e a r ni ng) t a kepl a c ei nt hec ont e xtoff e e dba c kl oo ps ・ La t e r , t heps yc hol ogi s tPowe r s( 1 973, p. 351 )wr ot e: Fe e d b a c ki ss u c ha na l Lpe r v a s i v ea n df u n d a me n t a la s p e c to fb e ha v i o rt ha ti ti sa s i n v i s i bl ea st hea i rt ha tweb r e a t h e . qu i t el i t e r a l l yi ti sbe ha v i o r ‑Wekn o wn o t h i n g o fo u ro wnb e h a v i o rbu tt h ef e e d b a c ke fe c t so fo u ro wno u t p u t s . The s ef e e d ba c kt hi nke r sf ol l owe di nt hef oot s t e psofJ ohnDewe y , whor e c ogni z e d t hef e e d ba c kl oo pc ha r a c t e rofl e a r nl nga r oundt hebe gl nnl ngOft he20t hc e nt ur y whe nhedes c r i be dl ea rnl nga Sa ni t e r a t i vec yc l eofi nve nt i on,obs e r va t i on, r e le f c ‑ t i on,a nda c t i o n( Sc h6n1992) .Fe e dba c ka c c ount sofbe ha vi ora ndl e a r ni ngha ve nowpe r me a t e dmos toft hes oc i a la ndma na ge me nts c i e nc es .Lea r nl nga Sa ne x‑ pl i c i tf T e ed ba c kpr oc es sha se ve na ppe a r e di npr a c t i c a lma nage me ntt ool ss uc ha s Tot a lQua l i t yMa na ge me nt ,whe r et hes o‑ c a l l e dShe wha r t ‑De mi ngPDCAc yc l e ( Pl a n‑ Do‑ Che c k‑ Ac t )l i esa tt hehe a r toft hei mpr ove me ntpr oc es si nt hequa l i t y i mpr ove me ntl i t e r a t ur e( She wha r t1 939; Shi ba , Gr a ha m, a ndWa l de n1 993) . Thes i ng lef e e dba c kl oo ps howni nFi g ur el 1 7de s c r i best hemos tba s i ct ypeof l e a ml ng. Thel oo pI SaC l a s s i c a lne ga t i vef e e dba c kwhe r e byde c i s i onma ke r sc om pa r ei nf om a t i ona boutt hes t a t eoft her e a lwor l dt ova r i ousgoa l s ,pe r c e i vedi s ‑ c r e pa nc i esbe t we e ndes i r e da nda c t ua ls t a t es ,a ndt a kea c t i onst ha t( t he ybe l i e ve ) wi l lc a us et her e a lwor l dt omovet owa r dst hedes i r e ds t a t e.Eve ni ft hei ni t i a l c hoi c esoft hede c i s i onma ke r sdonotc l os et hega psbe t we e ndes i r e da nda c t ua l s t a t e s , 血es ys t e mmi ghte ve nt ua l l yr e a c ht hedes i r e ds t a t ea ss ubs e que ntde c i s i ons a r er e vi s e di nl i ghtoft hei nf o r ma t i onr e c e i ve d( s e eHoga r h1 t 981 ) . Whe nd r i vi ng, Ima yt ur nt hes t e e r l ngWhe e lt ool i t t l et obr i ng血eca rba c kt ot hec e nt e rofmy l a ne , buta svi s ua lf T e e dba c kr e ve a l st hee r r or , Ic ont i nuet ot um t hewhe e lunt i lt he c a rr e t ur nst ot hes t r a i ghta ndna r r ow. I ft hec ur r e ntpr i c ef o rpr oduc t sofmyf i m r i st ool owt oba l a nc eor de r swi t hpr od uc t i o n,de pl e t e di nve nt or i esa ndl ongde l i v‑ e r yde l a ysma yc a us emet ogr a dua l l yr a i s epr l C eunt i lldi s c ove rapr l C et ha tc l e a r s t. 4 t hema r ke ‑ FI GURE 1 ‑ 7 Lear mn gl Sa f eedb ac kpr oc es s. Feedb ac kf r omt h e r eal wor l dt ot he dec i s i onmak er i ncl u desaF l f or ms ofi n f or mat i on, bot hquan t i t at i ve andqu al i t at i ve, Rea一 Wor kl ヽ 了 Deci si ons L hf or m at i o n Feedbac k / 一一 / 4 De p e n d i n go nt h et i med e l a y sa n do t h e re l e me n t so fd y n a mi cc o mp l e x l t yi nt h es y s t e m, t h e s e ・ I t t a k e sb u t l i t t l ei c e , f o g , f a t i g u e , o ra lc o h o l t oc a u s ea na c c i d e n t , a n d e x a mp l e sma yn o t c o n v e r g e e q u i l i b r i u me l u d e sma n yi n d u s t r i e st h a t e x p e r i enc ec h r o n i cb u s i n e s sc y c l e s . 16 P a r tI P e r s p e c t i v ea n dP r o c e s s Thef e e d ba c kl o o ps ho wni nFi g ur e1 ‑ 7O bs c ur e sa ni mpor t a nta s pe c to ft he l e a m1 ngPr o c e s s . I nf o r ma t i o nf e e d ba c ka bo utt her e a lwo r l di sno tt heon lyi n put t oo urde c i s i ons . De c i s i o nsa r et her e s ul tofa ppl yi ngade c i s i onr ul eo rpol i c yt o i nf o r ma t i o na bo utt hewo r l da swepe r c e i vei t( s e eFo r r e s t e r1 961 ,1 9 92) . Thepol i ‑ c i e sa r et he ms e l ve sc ondi t i o ne dbyi ns t i t ut i ona ls t r uc t ur e s ,o r ga n i z a t i o na ls t r a t e ‑ gl e S ,a ndc ul t ur a lno r ms .The s e ,i nt ur n,a r egove r ne dbyourme nt a lmod e l s ( Fi g ur el 1 8 ) . Asl o nga st heme nt a lmo de l sr e ma i nunc ha ng e d,t hef e e d ba c kl oo p s howni nt hef i gur er e pr e s e n t swha tAr g yr i s( 1 98 5)c a l l ss i ngl e ‑ l oo pl e a r ni ng,a pr o c es swhe r e bywel e a r nt or e a c ho urc ur r e ntgoa l si nt hec o nt e x to fou re xi s t l ng me nt a lmo de l s .Si ng l e ‑ l oo pl e a ni ngdoe sno tr e s ul ti nd e e pc ha nget oo u rme nt a l mod e l s ‑O urunde r s t a ndi ngo ft hec a us a ls t r uc t ur eoft hes ys t e m, t hebo unda r ywe d r a wa r o undt hes ys t e m, t het i meho r i z o nwec o ns i de rr e l e va nt ‑n o ro urgoa l sa nd va l ue s . Si ngl e ‑ l oo pl e a in m gd oe sno ta l t e ro u rwo r l d vi e w・ Me n t a lmo de l sa r ewi d e l ydi s c us s e di nps yc ho l ogya ndphi l os o phy . Di f f e r e nt t he o r i s t sd e s c r i beme nt a lmo de l sa sc ol l e c t i onsofr out i ne so rs t a nda r do pe r a t l ng pr oc e d ur e s ,S c r i pt sf o rs e l e c t l ngpos s i bl ea c t i o ns ,c ognl t i vema psofad oma i n, t y‑ pol ogi esf o rc a t e go r i z l nge x pe r i e nc e,l og i c a ls t r uc t ur e sf o rt hei nt e r pr e t a t i o no f l a ng ua ge ,Ora t t r i but iO nsa bo uti nd i vi d ua l swee nc ount e ri nda i l yl i f e( Axe l r od 1 9 76; Bowe ra ndMo r r o w1 99 0;Che nga ndNi s be t t1 98 5; Do yl ea ndFo r d1 998; Ge nt ne ra ndSt e ve ns1 98 3; Ha l f o r d1 993; J o hns on‑ La i r d1 98 3; Sc ha n ka ndAbe l ‑ s o n1 9 77; Ve nni x1 9 90 ) . Thec o nc e ptoft heme nt a lmode lha sbe e nc e nt r a lt os ys ‑ t e m dyna mi c sf r om t hebe gi n ni ngo ft hef i e l d.Fo r r e s t e r( 1 9 61 )S t r e s s e st ha ta l l de c i s i o nsa r eba s e do nmo de l s ,us ua l l yme nt a lmode l s .I ns ys t e md yna mi c s ,t he t e r m" me nt a lmode l "i nc l ud e so u rbe l i e f sa bo utt hene t wo r ksofc a us e sa nde f f e c t s t ha tde s c r i beho was ys t e mo pe r a t e s , a l o ngwi t ht hebo unda r yoft hemod e l( whi c h va r i a bl e sa r ei nc l ude da ndwhi c ha r ee xc l ud e d)a ndt het i meho r i z o nwec o ns i de r r e l e va nt 10 urf r a ml ngO ra r t i c ul a t i o no fapr o bl e m・ , Mos tofusdono ta ppr e c i a t et heu bi qul t ya ndi nvi s i bi l i t yofme nt a lmode l s i ns t e a dbe l i e vl ngna i ve l yt ha to u rs e ns e sr e ve a lt hewo r l da si ti s . Ont hec o nt r a r y , FI GURE ・ 8 Si n g一 e‑ 一 oop l eaml ng: i n f or mat i on f eedb ac ki s i n t er pr e t edb y e xi s t i n gmen t al mode一 s. Real Wor 一 d l TheF e amng f eedb ac kop er at es i nt h ec on t e x tof exi s t i n gdec i s i on r u一 es, S t r a t egl e S, cul t ur e, an d i n s t i t u t i on swh i ch i nt ur nar eder i ve d f r omourmen t a一 model s. l n F e e d b a \ ー ̲ ̲ 一 一/ ヽ 了 f or mat i on ck c i s i on s De 丸、 St r a t egy, St r uc t ur e, Deci si onRul es Ment aIModel s ofReal Wor l d E 芦 璽 璽 ■ 璽 璽 巳 ⊆ i i Ch a p t e r1 Le a r n l n gl na n da b o u t Co mp l e xS y s t e ms 17 Ourwor l di sa c t i ve l yc ons t r u c t e d( mode l e d)byours e ns esa ndbr a i n.Fi gur e1 ‑ 9 S howsa ni ma gede ve l ope dbyps yc hol ogi s tGa e t a noKa ni z s a. Theva s tma J ont yof pe opl es e eabr i g htwhi t et r i a ngl er es t l ngOnt opOft hr e ec i r c l e sa ndas e c ondt r i ‑ a ngl ewi t hbl a c ke dge s . Thei l l us i oni se xt r e me l ypowe r ul( f t r yt ol ooka tt hef i g‑ ur ea nd" nots e e Ht het wot r i a ngl es ! ) .Re s e a r c hs howst ha tt hene ur a ls t r uc t ur e s r e s pons i bl ef ort hea bi l i t yt os e ei l l us or yc ont o ur ss uc ha st hewhi t et ia r ngl ee xi s t be t we e nt heopt l Cne r vea ndt hea r ea soft hebr inr a es pons i bl ef orpr oc e s s l ngVi s ua l i nf or ma t i on・ 5Ac t i vemode l i ngoc c ur swe l lbe f or es e ns or yi nf or ma t i onr e a c he st he a r e a soft hebr a i nr es pons i bl ef orc ons c i oust ho ught・ 6p owe r f ule vol ut i ona r ypr e s s ur e sa r er es po ns i bl e: Ours ur vi va lde pe ndss oc ompl e t e l yont hea bi l i t yt or a pi dl y i nt e r pr e toure nvi r onme ntt ha twe( a ndot he rs pe c i es )l onga goe vol ve ds t r uc t ur e s t obui l dt he s emode l sa ut oma t i c a l l y.Us ua l l ywea r ec ompl e t e l yuna wa r et he s e me nt a lmode l se ve ne xi s t .I ti sonl ywhe nac ons t r uc t i ons uc ha st heKa ni zs atri‑ a ngl er e ve a l st hei l l us i ont ha twebe c omea wa r eofourme nt a lmode l s . TheKa ni z s at r i a ngl ei l l us t r a t e st hene c es s l t yOfa c ivea t ndunc ons c i ousme nt a l mode l i ngorc o ns t r uc t i onof" r e a l i t y"a tt hel e ve lofvi s ua lpe r c e pt i on. Mode l i ngof hi ghe r ‑ l e ve lknowl e dgei sl i ke wi s euna voi da bl ea ndof t e nequa l l yunc ons c i ous . Fi gur e1 ‑ 1 0S ho wsame nt a lmode le l i c i t e ddur i ngame e t i ngbe t we e nmyc ol l e a gue Fr e dKof ma na ndat ea m 丘. om al a r gegl oba lc or por a t i on.Thec ompa nywo r ke d wi t ht heOr ga ni z a t i ona lLe a r nl ngCe nt e ra tMI Ti nt hee a r l y1 990st or e duc e t het ot a lc yc l et i mef ort he i rs uppl yc ha i n. Att ha tt i met hec yc l et i mewa s1 8 2da ys a ndt he ys oughtt oc uti ti nha l f . Thec ompa nyvi e we dr e duc t i onsi nc yc l et i mea s es s e nt i a lf orc o nt i nue dc ompe t i t i ve nes sa nde ve nc or por a t es ur vi va l .Wi t ht he ‑ FI GURE1 ‑ 9 Kani z s at r i angl e Doyous eet he br i gh twhi t e t r i angl el yl ngOn t opoft het hr ee dar kci r cl esanda secondt r i angl e? e nc e ,2 5 6,( 1 2J u n e1 99 2) , p p . 1 52 0 ‑1 521 . 5 S e esci 6 Ev e nmo r eo b v i o u s l y , o u ra b i l i t yt os e eat h r e e ‑ d i me n s i o n lwo a r l di st h er e s u l t o fe x t e n s i v e mo d e l i n gb yt hev i s u lp a r o c e s s l n gS y s t e m, S i n c et h er e t i n ai ma g e sap l a n a rp r o j e c t i o no ft hev is u a l f i e l d . 1 8 Fl GURE1 ‑ 10 Men t al model r e v ea一 e db y adi agr amo fa c omp an y ' s s uppl yc h ai n Th ef i 9ur eha s b eens i mpl i f i ed c omp ar edt ot h e ac t u al c h ar tt o pr o t ec tc omp an y ‑ c on f i den t i al i n f or ma t i onbu ti s dr a wnt os c a一 e. P a r tI P e r s p e c t i v ea n dP r o c e s s 1 8 2days; Cur r emtsuppl ychai nc ycl et i me, goal , 50% r educt i on Cu s t o me r Ma n u f a c t u r l n g Or d erF u 折目 me n t A c c e p t a n c e L e a dTi me L e a dTi me L e a dTi me ・ 7 5 2 2 8 5 s u ppo r tofs e ni o rma na ge me nt ,t he ya s s e mbl e dat e a mt oa d血e s st he s ei s s ue s . Att hef i r s tme e t i ngt het e a m pr e s e nt e dba c kgr o undi n f or ma t i on,i nc l udi ng Fi g ur e1 ‑ 1 0. Thef i g ur es howst hec u r r e ntc yc l et i medi vi de di nt ot h r e ei nt e r va l sa l onga l i ne:ma n uf a c t ur i ngl e a dt i me ,o r de rf ul f i l l me ntl e a dt i me,a ndc us t ome ra c c e p‑ 2da ys ,Oc c upl e Smo r e t a nc el e a dt i me .Or d e rf ul f i l l me nt ,whi c ht he nr e q ui r e d2 t ha nha l foft het ot a ll e ng t ho ft hel i ne , whi l et hema n uf a c t unngl e a dt i me, t he nr e q ui ing75da r ys( 70da ysduet os u ppl i e r s ) , r e c e i ve sa bo uton e ‑ f T o ur t ho ft hel e ngt h. Cus t ome ra c c e pt a nc e, t he nr e q ul r l ng8 5da ys ,oc c upl e SO nl ya bo utone ‑ e i g ht hof t het ot a ll e ng t h. Wha tt hef i g ur er e ve a l si st hepr o mi ne nc eo fo r d e rf ul f i l l me nto p‑ e r a t i onsi nt heme nt a lmode l soft hepe o pl eont het e a ma ndt hei ns i g ni f i c a nc ei n t he i rmi n dso fs up pl i e r sa ndc us t ome r s . I twi l lc omea snos u r pr is et ha tt heme m‑ be r soft het e a ma l lwo r ke di nf unc t i o nsc ont r i but i ngt oor de rf u l f i l l me nt . The r e wa sno tas l ng l epe r s o na tt heme e t l ngr e pr e S e nt l ngpr o c u r e me nt , no raS l ngl es up‑ pl i e rr e pr e s e nt a t i ve , no ra nyo nef r o ma c c o un t l ng, no raS l n gl ec us t o me r , Unt i lFr e d po i nt e do utt h i sdi s t o r t i o n, t heme mbe r soft heg r o upwe r ea su na wa r eo ft hei l l u‑ s o r yc ha r a c t e ro ft he i ri ma geo ft hes u ppl yl i nea sweno ma l l ya r eo ft hei l l us o r y c o nt ou r sou rbr a i nspr o j e c tO nt ot heda t at r a ns mi t t e dbyo uro pt l Cne r v e s . Thedi s t or t e dme nt a lmod e lo ft hes u ppl yc ha i ns i g ni f i c a nt l yc o ns t r a i ne dt hec ompa ny' s a bi l i t yt or e duc ec yc l et i me:Eve ni fo r de rf ul f i l l me ntc o ul dbea c c ompl i s he di n‑ l . s t a nt l yt heo r ga n i z a t i o nwo ul df a l lwe l ls ho r tofi t sgoa Thet ypeo fr e f r a ml ngS t i mul a t e dbyFr e d' si nt e r ve nt i on, de no t e ddoubl e ‑ l oo p l e ar ni n gbyAr g y r i s( 1 98 5) ,i si l l us t r a t e di nFi gu r el 1 1 1 . He r ei n f o r ma t i o nf e e d‑ ba c ka bo utt her e a lwo r l dno to nl ya l t e r sourde c i s i onswi t hi nt h ec o nt e xto fe xi s 1 ngf r a me sa ndde c i s i onr ul e sbuta l s of ee dsba c kt oa l t e ro u rme nt a lmode l s . As o urme nt a lmo de l sc ha ngewec ha nget hes t r uc t ur eo fo urs ys t e ms , C r e a t i ngdi fe r ‑ e ntd e c i s i o nr ul e sa ndne ws t r a t e gi e s . Thes a mei nf o ma r t i on, pr oc e s s e da ndi nt e r ‑ pr e t e dbyadi fe r e ntde c i s i onr ul e ,no wyi e l dsad i f f e r e n tde c i s i on. Al t e r l ngt he s t mc t u r eofo u rs ys t e mst he na l t e r st he i rpa t t e mso fbe ha v i o r ・ Thede ve l o pme nto f s ys t e mst hi nk i ngi sado ubl e ‑ l oo pl e a r ni ngpr oc e s si nwhi c hwer e pl a c ear e d uc ‑ t i o ni s t , na r r o w, s ho r t ‑ r u n, s t a t i cvi e woft hewo r l dwi t haho l i s t i c , br oa d, l ong‑ t e r m, mi cvi e wa ndt he nr e d e s i g nou rpol i c i e sa ndi ns t i t ut i o nsa c c o r di ngl y. d yna ‑ ‑ ト 1 9 Ch a p t e r1 Le a r n l n gl na n da b o u t Co mp l e xS y s t e ms FI GURE1‑ ll Doubl e‑ l oop l ear nl ng Feedbackf r omt he r eal wor l dcanal so st i mul at echanges i nment almodel s. Suchl ear nl ng i nvol vesnew under s t andi ng orr ef r aml ngOf asi t uat i onand l eadst onewgoal s andnewdeci si on r ul es,notj us t newdeci si ons. 1. 3 Rea一 Wor l d 了 ci s i on s De ヽ h f o r m a t i o n F e d b c k 一 一 一 / i \ L 丸‑‑ St r at egy,St r uct ur e, Deci si onRul es GE J Ment aIModel s ofRealWor E d 璽 璽 寧『璽璽5i BARRl ERSTO LEARNI NG Forl ea r nl ngt OOcc ure a c hl i nki nt het wof e edbac kl oopss howni nFi gur el 1 11 mus twor ke fe c t i ve l ya ndwemus tbea bl et ocycl ea r oundt hel oopsqui c kl y r el a t i vet ot her a t ea twhi c hc ha ngesi nt her ea lwor l dr e nde re xi s t i ngknowl e dge obs ol e t e.Ye ti nt her ea lwor l d,pa r t i c ul a r l yt hewor l dofs oc i a la c t i on,t hes ef e e d‑ ba c ksof t e ndonotope r a t ewe l l .Mor et ha nt woa ndaha l fc ent ur i ese l a ps e df r om hef t i r s te xpe r i me nt ss howi ngt ha tl e monJ ul C ecoul dpr e ve nta ndc ur es c ur vyunt i l c i t r usus ewa sma nda t edi nt heBr i t i s hme r c ha ntma r i ne( Ta bl el 1 2) .Lea r ni ngi n t hi scas ewast e 汀i bl ys l ow,des pi t et hee nor mousi mpor t a nceoft hepr obl e ma nd TABLE l l 2 Teachi ngscur v y dogsnewt r i ck s ‑ r ot al del ay i nl ear nr ng: 264year s・ Pr i ort ot he1 600S,scur v y( vi t ami nCdef i ci enc y)wast hegr eat es tk 川erof seaf ar er s ‑mor et hanbat t l edeat hs,s t or ms,acci dent s,anda"ot her s combI ' ned. 1601:Lanc as t erc onduc t sacont r ol l edexper i mentdur i nganEas tl ndi a Companyvoyage: Thecr ewononeshi pr ecei ved3t sp.ofl emonj ul cedai l y; t hecr ewont hr ee ot hershi psdi dnot . Resul t s: Att heCapeofGoodHopel 10outof278s ai l or shaddi ed,mos t f r om scur v y . Thecr ewr ecei vl ngl emonJ ul Cer emai nedl ar gel yheal t hy. 1747:Dr , JamesLi ndconduc t sacont r o" edexper i menti nwhi chs cur v y pat i en t swer et r eat edwi t havar i et yofel i xi r s. Thoser ecel Vl ngCi t r uswer e cur edi naf ewdays;noneoft heot hert r eat ment swor k ed. 1795: TheBr i t i shRoyalNavybegmsusl ngCi t r usonar egul arbasi s.Scur v y wJ Pedout . 1865: TheBr i t i shBoar dofTr ademandat esci t r ususe.Scur vywi pedou ti n t hemer chan tmar i ne. Sour ce:Mo s t e l l e r ( 1 981 ) . 20 Pa r tI P e r s p e c t i v ea n dP r o c e s s t hedec i s i vee vi de nc es uppl i edbycont r ol l ede xpe r i me nt st hr oughoutt heyea r s . Youma yr e pl yt ha tt oda ywea r emuc hs ma r t e ra ndl ea r nf a s t e r ・Per ha ps . Ye tt he r a t eofc or por a t ea ndor ga ni za t i ona lf ai l ur er e ma i nshi gh( f o rexa mpl e,ove rone‑ t hi r doft heFor t une500l a r ges ti ndus t r i a lf i n si n1 970ha ddi s a ppea r e dby1 983 l deGe us1 997] ) . Toda yt her a t eofc ha ngei nours ys t e msi smuc hf as t e r ,a ndt hei r compl e xi t yl Smuc hgr ea t er .Thede l a ysi nl ea r ni ngf orma nypr es s l ngpr obl e ms r e ma i nwoe f ul l yl ong.I nmos ts et t l ngSWel a c kt hea bi l i t yt or unexpe r i me nt s , a ndt hede l a ysbe t wee ni nt e r ve nt i onsa ndout comesa r emuchl onger .Ast he r a t eofc ha ngea c c e l e r a t est hr oughouts oci e t y,l ea ml ngr e ma i nss l ow,une ve n,a nd i na de qua t e. Fi gur el 1 1 2s howst hema i nwa ysi nwhi c hea c hl i nki nt hel ea i ngf m ee dba c ks ca nf a i l . Thes ei nc l udedyna mi cc ompl e xi t y,I mpe r f e c ti nf or mat i ona boutt hes t a t e oft her ea lwor l d,conf oundi nga nda mbi guousva ia r bl e s , Poors c i e nt i f i cr eas onl ng s ki l l s ,de f e ns i ver out i nes ,a ndot he rba r r i e r st oe fec t i vegr ouppr oc es s es ,i mpl e一 me nt a t i onf a i l ur e,a ndt heml S Pe r C e Pt l OnSOff e e dba c kt ha thi nde roura bi l i t yt oun‑ de r s t a ndt hes t r uc t ur ea nddyna mi csofc ompl e xs ys t e ms . Fl GURE1‑ 12 I mpedi ment s t ol ear ni ng Rea一Wor 一 d Un k n o wns t r u c t u r e Dy n a mi cc o mp l e x i t y Ti med e l a y s l n a b i l i t yt oc o n d u c t c o n t r o l l e d e x p e r l me n t S Deci si ons l mp l e me n t a t i o nf a i l u r e Ga mep l a y l n g I n c o n s I S t e n C y Pe r f o r ma n c ei sg o a l l nf or mat i onFeedback oSe l e c t i v ep e r c e p t l 0 n .Mi s s i n gf e e d b a c k .De l a y oBi a s , d i s t o r t i o n , e r r o r oAmb i g u i t y St r at egy,St r uct ur e, Deci si onRu首 es Ment alModel s Mi s p e r c e p t i o n so f f e e d b a c k Un s c i e n t l f i cr e a s o n l n g J u d g me n t a l b i a s e s De f e n s i v er o u t i n e s 'l n a b l Myt oi n f e r d y n a mi c s f r o mme n t a l mo d e l s Ch a p t e r1 Le a mn gl na n da b o u t Co mp l e xS y s t e ms 21 1 . 3. 1 Dy n a mi cComp一 e x i t y Muc hoft hel i t e r a t ur ei nps yc hol ogy,e c onomi cs ,a ndot he rf i e l dss ugges t sl e a r nl l ngPr oc e e dsvi at hes i mpl ene ga t i vef e e dba c kl oo psde s c r i be di nFi g ur eI l l l ・ I m‑ pl i c i t l y,t hel oo psa r es e e na ss wi f t ,l i nea r ,ne ga t i vef e e dba c kst ha tpr oduc es t a bl e c onve r ge nc et oa ne qui l i br i umoro pt l ma lout c ome, j us ta Si mme di a t evi s ua lf e e d‑ ba c ka l l owsyo ut of i l lagl a s sofwa t e rwi t houts pi l l i ng・ Ther e a lwor l di snots o s i mpl e.Fr om t hebe gi nnl ng,S ys t e m dyna mi cse mpha s i z e dt hemul t i l oo p,mul t i ‑ s t a t e,nonl i ne a rc ha r a c t e roft hef T e e dba c ks ys t e msi nwhi c hwel i ve( For r es t e r 1 961 ) . Thede c i s i onsofa nyonea ge ntf or mbutoneofma nyf T e e d ba c kl oopst ha t ope r a t ei na nyg l Ve nS ys t e m. Thes el oopsr e a c tt ot hede c i s i onma ke r ' Sa c t i onsi n wa ysbot ha nt l C l pa t e da nduna nt l C l pa t e d; t he r ema ybepos i t i vea swe l la sne ga t i ve f e e dba c kl oops ,a ndt he s el oopswi l lc ont a i nma nys t oc ks( s t a t eva r i a bl e s )a nd ma nynonl i ne a it r i es . Na t ur a la ndhuma ns ys t e msha vehi ghl e ve l sofd ynami cc om‑ pl e xi y.Ta t bl e1 ‑ 3S howss omeoft hec ha r a c t e r i s t i csofs ys t e mst ha tgi ver i s et o dyna mi cc ompl e xl t y. Mos tpe opl et hi nkofc ompl e xl t yl nt e r msOft henumbe rofc ompone nt si na s ys t e m ort hen umbe rofc ombi na t i onsonemus tc ons i de ri nma ki ngade c i s i on・ Thepr obl e mo fo pt l ma l l ys c he dul i nga na i r l i ne' Sf li ght sa ndc r e wsi shi ghl yc om‑ pl e x,butt hec ompl e xi t yl i esi nf i ndi ngt hebe s ts ol ut i ono utofa na s t r o nomi c a l numbe rofpos s i bi l i t i e s .Suc hne e dl e ‑ i n‑a ‑ ha ys t a c kpr o bl e msha vehi ghl e ve l sof c ombi nat or i alc o mpl e xi t y( a l s ok n owna sde t ai lc ompl e xi t y) . Dynami cc ompl e x‑ 1 t y , l nC Ont r a S t , C a na r i s ee ve ni ns i mpl es ys t e mswi t hl owc ombi na t or i a lc ompl e x‑ i t y. TheBe e rDi s t r i but i onGa me( St e ma n1 989 b, c ha p.1 7・ 4)p r ovi de sa ne xa mpl e: Compl e xa ndd ys f unc t io na lbe ha vi ora is r e sf r omave r ys i mpl es ys t e mwhos er ul e s c a nbee xpl a i ne di n1 5mi nut e s . Dyna mi cc ompl e xi t ya r i s e sf r omt hei nt e r a c t i o ns a mongt hea ge n t sove rt i me. Ti mede l a ysbe t we e nt a k i ngade c i s i o na ndi t se fe c t sont hes t a t eoft hes ys t e m rec a ommona ndpa r t i c ul a r l yt r oubl es ome. Mos tobvi o us l y , de l a ysr e duc et henum‑ be roft i me son ec a nc yc l ea r oundt hel e a r nl ngl oop,s l owl ngt hea bi l i t yt oa c c u‑ mul a t ee xpe r i e nc e, t e s thypot hes es ,a ndi mpr ove・Sc hne i de r ma n( 1 988)e s t i ma t e d t hei mpr ove me ntha l fl i f e ‑t het i mer e qui r e dt oc utde f e c t si nha l f ‑i nawi de r a ngeofma nuf a c t ur ingf i r ms . Hef oundi mpr ove me ntha l fl i vesa ss ho r tasaf e w mont hsf orpr oc e s s e swi t hs hor tde l a ys ,f ore xa mpl er e duc i ngope r a t o re r r ori na j obs hop, whi l ec ompl e xpr oc e s s eswi t hl ongt l mede l a yss uc ha spr oduc tde ve l o p一 me れtha di mpr o ve me ntha l fl i ve sofs e ve r a lye a r sormo r e・ 7 Dyna mi cc ompl e xi t ynotOnl ys l o wst hel e a r nl ngl oo p;i ta l s or e duc est he l e a ml ngga i ne do ne a c hc yc l e .I nma n yc a s e sc ont r ol l e de xpe r i me nt sa r epr ohi bi ‑ t i ve l yc os t l yo rune t hi c a l . Mor eo洗e n, i t i ss i mpl yi mpos s i bl et oc on血c tc ont r ol l e d e xpe r i me nt s .Co mpl e xs ys t e msa r ei nd i s e qui l i br i um a nde vol ve・ Ma nya c t i ons yi e l di r r ever s i bl ec ons e q ue nces.Thepa s tc a nnotbec ompa r e dwell t oc ur r e ntc i r ‑ c ums t a nce.Thee xi s t e nc eofmul t i pl ei nt e r a c t i ngf e e d ba c ksme a n s it i sdi f f i c ul tt o hol dot heras pe c t soft hes ys t em con s t a ntt oi s ol a t et hee f f e c tof theva r i a bl eof i nt e r es t .M anyva r i a bl esc ha ngesi mul t a ne ous l y,c onf oundi ngt he i nt e r pr e t a t i on 7 st e man,Re p e n n i n g , a n dKo f ma n(1997)s h o wh o wt h e s ed i f f e r e n t i a l i mp r ov e me n t r a t e sl e dt o d i fi c u l t ya t al e a d i n gs e mi c o n d u c t o rma n u f a c t u r e r ・ 22 r tI Pe r s pe c t i v ea ndPr oc e s s Pa TABLE1 ‑ 3 Dynami c compl exi t y Dynam i ccom p一 exi t yar i sesbecausesyst emsar e S,overa Dynami c:Her acr i t ussai d," Al li schange. "Whatappear st obeunchangl ngl l ongert i mehor i zon,Seent ovar y .Changei ns ys t emsoccur satmanyt i mescaJ es, andt hesedi f f er entscal essomet i mesi nt er ac t . As t arevol vesoverbi l l j onsofyear sas i tbumsi t shydr ogenf uel , t hencanexpl odeasasuper novai nseconds.Bul lmar k et s cangoonf oryear s,t hencr ashi namat t erofhour s. Ti ght l ycoupl ed:Theac t or si nt hes ys t em i nt er ac ts t r ongl ywi t honeanot herand wi t ht henat ur al wor l d.Ever y t hi ngl Sconnec t edt oever y t hi ngel se. Asaf amous bumpers t i ck erf r om t he1960spr ocl ai med," Youc an' tdoj us tonet hi ng. " Gover nedbyf eedback:Becauseoft het i ghtcoupI H l gSamongact or s,Ourac t i ons f eedbackont hems el ves.Ourdeci si onsal t ert hes t at eoft hewor l d, Causl ngChanges i nnat ur eandt r i ggenngot her st oac t , t hu sgl vl ngu set OanewSi t uat i onwhi cht hen i n f l uencesournextdeci si ons.Dynami csar i sef r omt hesef eedback s. Nonl i near :Ef f ec ti sr ar el ypr opor t i onal t oc ause,andwhathappensl ocal l yl naS ys t em ( neart hecur r entoper at i ngpoi n t )of t endoesnotappl yi ndi s t antr egi ons( ot her st at esoft hes ys t em) .Nonl i near i t yof t enar i sesf r omt hebasi cphysi c sofsyst ems:ln‑ su f f i ci enti nven t or ymaycaus eyout oboos tpr oduc t i on,butpr oduct i oncanneverf al l bel owzer onomat t erhow muchexces si n vent or yyouhave.NonH near i t yal soar i s es asmul t j pl ef ac t or si nt er acti ndeci si onmak i ng:Pr essur ef r om t hebos sf orgr eat er achi evementi ncr easesyourmot i vat i onandef f or t ‑ upt ot hepoi ntwher eyouper ‑ cei vet hegoaHobei mpossi bl e.Fr us t r at i ont hendomi nat esmot i vat i onandyougl Ve uporgetanewbos s. Hi st or y‑ dependent :Taki ngoner oadof t enpr ecl udest aki ngot her sanddet er mi nes wher eyouendup( pat hdependence) .Man yac t i onsar ei r r ever si bl e: Youcan' tun‑ scr ambl eanegg( t hesecondl awoft her modynami c s) .St ock sandf l ows( accumu‑ l at i ons)andl ongt i medel aysof t enmeandoi ngandundoi nghavef undament al l y di f f er entt i mec onst ant s:Dur i ngt he50year soft heCor dWarar msr acet henucl ear nat i onsgener at edmor et han250t onsofweapons‑ gr adepl ut oni um ( 2 3 9 pu) . Thehal f l i f eof2 3 9 Pui sabout24, 000year s. Sel f ‑ or gand Zl ng:Thedynami csofs ys t emsar i sespont aneousl yf r omt hei ri nt er nal s t r uc t ur e.Of t en,smal l ,r andom per t ur bat i onsar eampl i f i edandmol dedbyt hef eed‑ backs t r uc t ur e,gener at i ngpat t emsi nspaceandt i meandcr eat i ngpat hdependence. Thepat t er nofs t r i pesonazebr a, t her hy t hmi ccont r ac t i onofyourhear t ,t heper si s ‑ t entc ycl esi nt her eal es t at emar k et ,ands t r uc t ur essuchasseashel l sandmar k et s al l emer gespont aneous一 yf r om t hef eedback samongt heagent sandel ement soft he s ys t em. Adapt i ve:Thecapabi l i t i esanddeci si onr ul esoft heagent si ncompl exs ys t ems changeovert i me.Evol ut i on一 eadst ose一 ec t i onandpr ol i f er at i onofsomeagen t swhi l e ot her sbec omeex t i nc t . Adapt at i onal sooccur saspeopl er eam f r om exper i ence,esI peci aJ I yast heyr eam newwayst oachi evet hei rgoal si nt hef aceofobs t acl es.Lear n‑ 1 ngI Snotal waysbenef i ci al ,however . Count er j nt ui t i ve:l ncompl exs ys t emscauseandef f ec tar edi s t anti nt i meandspace whH ewet endt ol ookf orcausesneart heevent sweseekt oexpl ai n.Ourat t ent i onI S dr awnt ot hes ympt omsofdi f f i cul t yr at hert hant heunder F yngcause.Hi ghl ever age po一 i ci esar eof t ennotobvi ous. Pol i cyr esi st ant :Thecompl exi t yoft hes ys t emsi nwhi chwear eembeddedover ‑ wheJ msourabi l i t yt ounder s t andt hem. Ther esul t :Manyseeml ngl yobvi oussol ut i ons t opr obl emsf ai r oract ual l ywor s ent hesi t uat i on. Char act er i 2 : edbyt r ade・ of f s:Ti medel aysi nf eedbackchanne一 smeant hel ong‑ r un r esponseofas ys t em t oani nt er ven t i oni sof t endi f f er entf r om i t sshor t ‑ r unr espons e. Hi ghl ever agepo一 i ci esof t encausewor se‑ bef or e‑ bet t erbehavi or ,whi l el owl ever age pol i ci esof t engener at et r ansi t or yI mpr ovementbef or et hepr obl em gr owswor se. ‑ Ch a p t e r1 Le a ml n gl na n da b o u t Co mp l e xS y s t e ms 23 ofs ys t e mbe ha vi ora ndr e duc i ngt hee f f e c t i ve ne s sofe a c hc yc l ea r oundt hel e a n‑ r 1 ngl oo p. De l a ysa l s oc r e a t ei ns t a bi l i t yi ndyna mi cs ys t e ms .Addi ngt i mede l a yst o 8s ys ‑ ne ga t i vef e e dba c kl oopsi nc r e a s e st het e nde nc yf ort hes ys t e mt oos c i l l a t e・ t e msf r om d r i v i ngaca r ,t odr i nki nga l c ohol ,t or a i s l nghogs ,t oc ons t r uc t i onof of f i c ebui l di ngsa l li nvol vet i mede l a ysbe t we e nt hei ni t i a t i onofacont r ola c t i on ( a c c e l e r a t i ng / br a ki ng,de c i di ngt o" ha vea not he r , Hc hoos i ngt obr e e dmor ehogs , de ve l o pi ngane wbui l di ng)a ndi t se fe c t sont hes t a t eoft hes ys t e m. Asar e s ul t , de c i s i onma ke r sof t e nc ont i nuet oi nt e r ve net oc or r e c ta ppa r e ntdi s c r e pa nc i es be t we e nt hede s i r e da nda c t ua ls t a t eoft hes ys t e me ve na f t e rs ufi c i e ntc or r e c t i ve a c t i onsha vebe e nt a ke nt or es t or et hes ys t e mt oe qui l i br i um.Ther e s ul ti sove r ‑ s hoota ndos c i l l a io t n: s t o p‑ a nd‑ got r a f f i c , dr unke nne s s , c ommodi t yc yc l e s , a ndr e a l 4) .Os c i l l a t i ona ndi ns t a bi l i t yr e duc e e s t a t eboom‑ a nd‑ bus tc yc l es( S e ec ha pt e r1 7. oura bi l i t yt oc ont r olf orc onf oundi ngva r i a bl esa nddi s c e m ca us ea nde f f e c t ,f ur ‑ t he rs l owl ngt her a t eofl e a ml ng. 1. 3. 2 LI L mi t edl nf or mat i on Wee xpe r i e nc et her e a lwor l dt hr oughf i l t e r s . Noonek n Owst hec ur r e nts a l e sr a t e oft he i rc ompa n y , t hec ur r e ntr a t eofpr oduc t i on, o rt het r ueva l ueoft heor de rba c k l oga ta nygl Ve nt i me. i ns t e a dwer e c e i vee s t i ma t e soft he s eda t aba s e dons a mpl e d, a ve r a ge d,a ndde l a ye dmea s ur e me nt s . Thea c tofme a s ur e me nti nt r od uc esdi s t or ‑ t i ons , de l a ys , bi a s es , e r r or s , a ndot he ri mpe r f e c t i o ns , s omek n own, ot he r sunknown a ndunknowa bl e. l l , me a s ur e me nti sa na c tofs e l e c t i on. Ours e ns e sa ndi nf om a t i ons ys ‑ Abovea t e mss e l e c tbutat i nyf r a c t i onofpos s i bl ee xpe r i e nc e. Someoft hes e l e c t i oni sha r d wi r e d( wec a nnots e ei nt hei nf r a r e dorhe a rul t r a s ound) .Somer es ul t sf r om our ownde c i s i o ns . Wede f i negr os sdome s t i cpr oduc t( GDP)s ot ha te xt r a c t i onofnon‑ r e ne wa bl er es o ur c esc ount sa spr oduc t i onr a t he rt ha nde pl e t i onofna t ur a lc a pl t a l s t oc ksa nds ot ha tme di c a lc a r ea ndf u ne r a le xpe ns esc a us e dbypol l ut i on‑ i nduc e d di s e a s ea ddt ot heGDPwhi l et hepr oduc t i onoft hepol l ut i o ni t s e l fdoe snotr e duc e i t .Be c a us et hepr l C eSOfmos tgoodsi noure c onomi cs ys t e m donoti nc l udet he c os t sofr es o ur c ede pl e t i onore nvi r onme nt a lde gr a da t i on,t he s ee xt e r na l i t i e sr e ‑ c e i vel i t t l ewe i g hti nde c i s i onma ki ng( s e eCobba ndDa l y1 989f b∫t ho ught f uldi s ‑ c us s i onofa l t e r na t i veme a s ur esofe c onomi cwe l f a r e ) . Ofc our s e,t hei nf or ma t i ons ys t e msgove r nl ngt hef e e dba c kwer e c e i vec a n c ha ngea swel e a r n.The ya r epa r toft hef e e d ba c ks t r uc t ur eofo urs ys t e ms ・ Thr o ughourme nt a lmode l swede f i nec ons t uc r t ss uc ha sGDPors c i e nt i f i cr e ‑ s e a r c h,c r ea t eme t r i csf ort hes ei de a s ,a ndde s i gni nf or ma t i ons ys t e mst oe va l ua t e a ndr e po r tt he m.The s et he nc ondi t i ont hepe r c e pt l OnSWef or m・Cha ngesi nour me nt a lmode l sa r ec ons t r a i ne dbywha twepr e vi ous l yc hos et ode f i ne,me a s ur e, ‑ ‑ 8 T e c h n i c a l l y , n e g a t i v el o o p swi t hn ot i med e l a y sa re f i r s t 1 0 r d e r ; t h ee i g e n v a l u eo ft h el i n e a iZ r e d s y s t e mc a no n l yb er e a l a n do s c i l l a t i o ni si mp o s s i b l e . Ad d i n gd e l a y s( s t a t ev a r i a b l e s )a l l o wst h e e l g e n V lu a e st ob e c o mec o mp l e xc o n j u g a t e s , y i e l d i n go s c i l l a t o r ys o l u t i o n s ・ Wh e t h e rt h eo s c i l l a t i o n s i n e a r i z e ds y s t e ma r ed a mp e dore x p a n d i n gd e p e n d so nt h ep a r a met e r s ・ All e l s ee q u a l , t h e o ft h el mo r ep h a s el a gl naC O n t r O l l o o p , t h el e s ss t a b l et h es y s t e mwi l l b e . 24 Pa r t I P e r s p e c t i v ea n dP r o c e s s a nda t t e ndt o.Se e i ngi sbe l i e vi ngandbe l i e vi ngl SS e e l ng・ The yf e e dba c konone a not he r . I naf a mouse xpe r i me nt , Br une ra ndPos t ma n( 1 949)s howe dpl a yi ngc a r dst o pe opl eus l ngat a C hi s t os c opet oc ont r ole xpos ur et i met ot hes t i mul i .Mos tc oul d i de nt i f yt hec a r dsr a pi dl ya nda c c ur a t e l y.The ya l s oi nc l udeds omea noma l ous c a r ds , s uc ha sabl a c kt hr e eofhe a r t sorar e dt e nofs pa des . Pe opl et ookona ve r a ge f ourt i me sa sl ongt oj udget hea noma l ousc a r ds IMa nymi s i de nt i f i e dt he m ( e. g. ,t he ys a i dt hr e eofs pa desort hr e eofhe a r t swhe ns hownabl a c kt hr e eof l l ,e ve nwi t hve r yl onge x pos ur e he a r t s ) .Somec oul dnoti de nt i f yt hec a r da ta ime t s ,a ndgr e wa nxi ousa ndc o nf us e d.Onl yas ma l lmi nor i t yC O r r e C t l yi de nt i f i e d t hec a r ds I Br une ra ndPos t ma nc o nc l ude d," Pe r c e pt ua lor ga ni z a t i oni spowe r f ul l y de t e r mi ne dbye xpe c t a t i onsbui l tuponpa s tc omme r c ewi t ht hee nvi r onme nt 。 " He nr iBe r gs onputi tmor es uc c i nc t l y:H Thee yes e esonl ywha tt hemi ndi spr e ‑ pa r e dt oc ompr e he nd. " Thes e l f ‑ r e i nf o r c i ngf e e d ba c kbe t we e ne xpe c t a t i onsa ndpe r c e pt l OnSha sbe e n r e pe a t e dl yde mons t r a t e di nawi deva r i e t yofe xpe r i me nt a ls t udi e s( s e ePl ous1 993 f ore xc e l l e ntdi s c us s i on) ・So me t i mest hepos i t i vef e e dba c ka s s i s t sl e a r ni ngby s ha r pe nl ngOura bi l i t yt ope r c e i vef e a t ur e soft hee nvi r onme nt ,a swhe na ne xpe r i ‑ e nc e dna t ur a l i s ti de nt i f i esabi r di nadi s t a ntbus hwhe r et henovi c ebi r de rs e e sonl y at a ngl e dt hi c ke t .Of t e n,howe ve r ,t hemut ua lf e e dba c kofe xpe c t a t i onsa ndpe r ‑ c e pt l Onl i mi t sl e a r ni ngbybl i ndi ngust ot hea noma l i est ha tmi ghtc ha l l e ngeour me nt a lmode l s . Thoma sKuhn( 1 9 70)c i t e dt heBr une r ‑Pos t ma ns t udyt oa r guet ha t as c i e nt i f i cpa r a di gm s uppr e s s e st hepe r c e pt i onOfda t ai nc ons i s t e ntwi t ht hepa r a ‑ di gm,ma ki ngi tha r df o rs c i e nt i s t st ope r c e i vea noma l i e st ha tmi ghtl e a dt os c i e n‑ 9 t i f i cr e vol ut i on. Asoneofma nye xa mpl es ,t hehi s t or yofoz onede pl e t i onbyc hl or of luor o‑ c a r bons( CFCs )S howst hemut ua lde pe nde nc eofe xpe c t a t i ona ndpe r c e pt i oni sno l a bor a t or ya r t i f a c tbutaphe nome nonwi t hpot e nt i a l l ygr a vec ons e que nc esf or huma nl t y. Thef i r s ts c i e nt i f i cpa pe r sde s c r i bi ngt hea bi l i t yofCFCst ode s t r oya t mos ‑ phe r i cozonewe r epubl i s he di n1 974( Mol i naa ndRowl a nd1 974;St ol a r s kia nd Ci c e r one1 974) .Ye tmuc hoft hes c i e nt i f i cc ommuni t yr e ma i ne ds ke pt ic a l ,a nd de s pi t eaba nonCFCsa sa e r os o lpr o pe l l a nt s , lo g ba lpr o duc t i ono fCFCsr e ma i ne d ne a ri t sa l lt i mehi gh.I twa snotunt i l1 985t ha te vi de nc eofade e poz onehol ei n t heAnt a r c t i cwa spubl i s he d( Fa r ma n,Ga r di ne r ,a ndSha nkl i n1 985) . Asde s c r i be d byMe a dows , Me a dows ,a ndRa n°e r s( 1 992, pp.1 51 ‑1 52) : Then e wsr e v e r be r a t e da r o u n dt h es c i e n t i f i cwo r l d. Sc i e n t i s t sa t[ NASA]‥. s c r a m‑ b l e dt oc he c kr e a d i n gso na t mo s p h e r i co z o n ema d ebyt h eNi mb us7s a t e l l i t e , me a ‑ S u r e me n t st ha tha db e e nt a k e nr o u t i n e l ys i nc e1 9 78 . Ni mb us7ha dn e v e ri n d i c a t e d a no z o neho l e . 9 s t e r ma n( 1 9 8 5 a ) d e v e l o p e daf o r ma lmo d e l o fKu h n ' St he o r y , wh i c hs h o we dt h a t t h ep o s i t i v e f e e d b a c kb e t we e ne x p e c t a t i o n sa n dp e r c e p t 1 0 n SS u p p r e s s e dt h er e c o g n l t i o no fa n o ma l i e sa ndt h e e me r g e n c eo fn e wp a r a d i g ms . S t e r ma na n dWi t t e n b e r g( 1 9 9 9 )e x t e n d e dt h emo d e l t os i mu l a t e t h ec o mp e t i t i o na mo n gr i v a l t h e o r i e s . Ch a p t e r1 Le a r I l l n gl na n da b o u t Co mp l e xS y s t e ms 25 Ch e c k i ngba c k, NASAs c i e n t i s t sf o u n dt ha tt h e i rc o mp u t e r sha dbe e npr 0 ‑ g r a mme dt or e j e c tVe r yl o wo z o n er e a d i n g so nt h ea s s u mp t 1 0 nt ha ts u c hl o w r e a d i n g smus t i n di c a t ei ns t r u me n te r r o r ・ TheNASAs c i e nt i s t s ' be l i e ft ha tl owoz oner e a di ngsmus tbee r r one ousl e dt he m t ode s i gname a s ur e me nts ys t e mt ha tma dei ti mpos s i bl et ode t e c tl owr e a di ngst ha t mi g htha ves hownt he i rbe l i e ft obewr ong. Fo r t una t e l y, NASAha ds a ve d血eo ng‑ i na l , unf i l t e r e dda t aa ndl a t e rc onf i r me dt ha toz onec onc e nt r a t i onsha di nde e dbe e n f a l l i ngs i nc et hel a unc hofNi mbus7. Be c a us eNASAc r e a t e dame a s ur e me nts ys ‑ t e mi mmunet odi s conf i r ma t i ont hedi s c ove r yoft heoz onehol ea ndr es ul t i ng g l oba la gr e e me nt st oc ea s eCFCpr oduc t i onwe r ede l a ye dbyasmuc ha s7ye a r s . Thos e7ye a r sc oul dbes i gni f i c a nt : oz onel e ve l si nAnt a r c t i c adr oppe dt ol e s st ha n o ne ‑ t hi r dofnor ma li n1 993,a ndc ur r e ntmode l ss howt ha te ve nwi t hf ul lc ompl i ‑ a nc ewi t ht heba n( t he r ei sat h r i vi ngbl a c kma r ke ti nCFCs ) , a t mos phe r i cc hl or i ne wi l lnotbe gi nt of a l lunt i lt hef i r s tde c a deoft he21 s tc e nt ur y, a ndt he nonl ys l owl y・ Da t ac ol l e c t e dne a rTor ont oi nt hee a r l y1 990ss howe da5% i nc r eas ei nc a nc e r ‑ c a us i ngUVBu l t r a vi ol e tr a di a t i ona tgr o undl e ve l , i ndi c a t l ngt ha toz onede pl e t i on a l r e a dya fe c t st hehe a vi l ypopul a t e da nda gr l C ul t ur a l l yvi t a lnor t he m he mi s phe r e ( Cul o t t aa ndKo s hl a nd1 993) . The血i nni ngoft heoz onel a ye ri sagl oba lphe nom‑ e non, not j us taPr obl e mf orpe ng ui ns . 1 . 3. 3 Conf oundi ngVar i abl esandAmbi gui t y Tol e a n wemus tus et hel i mi t e da ndi mpe r f e c ti nf or ma t i ona va i l a bl et oust oun‑ de r s t a ndt hee fe c t sofourownde c i s i ons ,S owec a na d j us tourde c i s i onst oa l i gn t hes t a t eoft hes ys t e m wi t hourgoa l s( s i ng l e ‑ l oopl e a ni ng)a nds owec a nr e vi s e ourme nt a lmod e l sa ndr e des i gnt hes ys t e mi t s e l f( doubl e ‑ l oo pl e a mi ng) . Ye tmuc h o ft hei nf or ma t i onwer e c e i vei sa mbi guous . Ambi gui t ya is r esbe c a us ec ha ngesi n t hes t a t eoft hes ys t e mr es ul t i ngf r om ourownde c i s i onsa r ec onf ounde dwi t hs i 一 mul t a ne ousc ha nge si nahos tofot he rva r i a bl e s ・Thenumbe rofva r i a bl e st ha t ig m hta fe c tt hes ys t e mva s t l yove r whe l mst heda t aa va i l a bl et or ul eo uta l t e ma t i ve t heo r i esa ndc omp et l ngl nt e r Pr e t a t i ons ・ Thi si de nt i f i c a t i onpr obl e m pl a guesbot h qua l i t a ivea t ndqua nt i t a t i vea ppr oa c he s . I nt heq ua l i t a t i ver e lm,a a mbi gui t ya is r e s f r omt hea bi l i t yofl a ngua get os uppor tmul t i pl eme a nl ngS ・ I nt heope nl ngS Ol i l o‑ quyofRi c hay dI l l ,t hehump‑ ba c ke dRi c ha r dl a me nt shi sde f om l t y: Andt he r e f o r e , s i n c eIc a n n o t p r o v eal o v e r , Toe n t e r t a i nt h e s ef a i rwe 1 1 1 S P O k e nd a ys Ia md e t e r in m とdt op r o v eav i l l in a An dha t et hei d l epl e a s u r e so ft h e s ed a ys ・ , i , 28 ‑31 ) ( i Doe sRi c ha r dc e l e br a t ehi sf r e ec hoi c et obee vi lorr es i gnhi ms e l ft oapr e des t i ne d f a t e?Di dSha ke s pe a r ei nt e ndt hedoubl eme a ni ng?Ri c h,a mbi guoust e xt s ,Wi t h mul t i pl el a ye r sofme a nl ngOf t e nma kef orbe a ut i f ula ndpr of ounda r t ,a l ongwi t h e mpl oyme ntf わrl i t e r a r yc r i t i cs , buta l s oma kei tha r dt oknowt hemi ndsofot he r s , r ul eoutc ompe t i nghypot hes e s ,a nde va lua t et hei mpa c tofourpa s ta c t i onss owe c a nde c i dehowt oa c ti nt hef u t ur e. 26 Pa r t IP e r s p e c t i v ea n dP r o c e s s I nt hequa nt i t a t i ver e a l m,e ngl ne e r Sa nde c onome t ic r i a nsha vel ongs t ugg r le d wi t ht hepr obl e m ofuni q ue l yi de nt i f yi ngt hes t uc r t ur ea ndpa r a me t e r sofas ys t e m f r om i t so bs e r ve dbe ha vi o r . El e ga nta nds ophi s t i ca t e dt he or ye xi s t st ode l i mi tt he c ondi t i onsi nwhi c honec a ni de nt i f yas ys t e mf r om i t sbe ha vi ora l one・ I npr a c t i c e t heda t aa r et oos c a r c ea ndt hepl a us i bl ea l t e ma t i ves pe c i f i c a t i onsa ret oonume r ‑ ousf ors t a t i s t i c a lme t hodst odi s c r i mi na t ea mongc ompe t l ngt he or i e s .Thes a me l l , a ndconc l us i onsba s e don da t aof t e ns uppo r twi l dl ydi ve r ge ntmode l se qua ll ywe s uc hmode l sa r enotr obus t . AsLe a ne r( 1 983)puti ti na na r t i c l ee nt i t l e dH Le t ' s Ta ket hè Con' OutofEc onome t r i c s M: I no r d e rt od r a wi n f e r e n c e sf r o md a t aa sd e s c ibe r dbye c o n o me t ict r e x t s , 1 ti sn e c e s S a r yt oma k ewh i ms i c a la s s u mpt l O nS. ‥Th eha pha z a r dwa ywei n d i v i d u a l l ya n d c ol l e c t i v e l ys t u d yt hef r a g i l i t yo fi n f e r e n c e sl e a ve smos to fusu nc o n v i n c e dt ha ta n y i nf e r e n c ei sbe l i e va bl e . 1 0 ‑ 1・ 3L 4 BoundedRat i ol l a! 嘩 andt he脚i sper c甲 t i ons ofFeedback Dyna mi cc ompl e xi t ya ndl i mi t e di nf om a t i onr e duc et hepot e nt i a lf orl e a ml nga nd pe r f or ma nc ebyl i mi t i ngO urknowl e dgeoft her e a lwor l d・Buthowwi s e l ydowe us et hek n owl e dgewedoha ve?Dowepr oc es st hei nf o‑ a t i onwedoge ti nt he bes twa ya ndma ket hebes tde c i s i onswec a n?Unf or t una t e l y ,t hea ns we ri sno. Huma nsa r enotonl yr a t i ona lbe i ngs ,C ool l ywe i ghi ngt hepos s i bi l i t i e sa nd j udgi ngt hepr oba bi l i t i e s .Emot i ons ,r e le f x,unc ons c i ousmot i va t i ons ,a ndot he r nonr a t i ona lo ri r r a t i ona lf a c t or sa l lpl a yal a r ger ol ei nourj udgme nt sa ndbe ha vi or . Bute ve nwhe nwef i ndt het i met or e le f c ta ndde l i be r a t ewec a nnotbe ha vei na ma‑ f ul l yr a t i ona lma nne r( t ha ti s , ma ket hebe s tde c i s i onspos s i bl eg ive nt hei nf o r t i ona va i l a bl et ous ) . Asma r ve l ousa st hehuma nmi ndi s , t hec o mpl e xi t yoft her e a l wor l ddwa rf sourc ognl t l VeC a pa bi l i t i es .He r be r tSi monha sbe s ta r t i c ul a t e dt he l i mi t sonhuma nde c i s i on‑ ma ki nga bi l i t yi nhi sf a mous" pr i nc i pl eofbounde dr a ‑ "f orwhi c hhewont heNobe lMe mor ia lPr iz ei ne c onomi c si n1 979: t i ona l i t y, Thec a pa c l t yO ft h eh u ma nm in df o rf o r mu l a t i n ga n ds o l v i n gc o mpl e xp r o b l e msi s v e r ys ma l lc o mpa r e dwi t ht h es i z eo ft h ep r o b l e mwh os es o l u t i o ni sr e q u i r e df o ro b‑ j e C t i v e l yr a t i o n a l be ha v i o ri nt h er e a l wo r l do re ve nf わrar e a s o n a b l ea p p r o x i ma t i o n t os u c ho b j e c t i ver a t i o na l i t y . ( S i mo n1 9 5 7, p.1 98 ) Fa c e dwi ht t heove r whe l i ngc m ompl e xi t yoft her e a lwor l d, t i mepr e s s ur e, a ndl i m‑ i t e dc ognl t l VeC a pa bi l i ie t s ,Wea r ef or c e dt of a l lba c konr ot epr oc e dur es ,ha bi t s , r ul esoft humb,a nds i mpl eme nt a lmode l st oma kede c i s i ons .Tho ughwes ome ‑ t i mess t ivet r oma ket hebe s tde c i s i onswec a n,boundedr a t i ona l i t yme a nsweof ‑ t e ns ys t e ma t i c a l l yf a l ls hor t , l i it m i ngo ura bi l i t yt ol ea nf r r om e xpe ie r nc e. h i W l ebounde dr a t i o na l i ya t fe c t sa l lde c i s i onc ont e xt s , i ti spa r t i c ul a r l ya c ut e i ndyna mi cs ys t e ms ・ i nde e d, e xpe r i me nt a ls t udi e ss howt ha tpe o pl edoqul t epoo r l y m Ia mn o t a r g u i n gt h a t e c o n o me t ic r ss h o u l db ea b a n d o n e d , d e s p i t ei t sd i f f i c u l t i e s ・ Ont h ec o n t r a r y , Wi s eu s eo fn u me r i c a l d a t aa n ds t a t i s t i c a l e s t i ma t i o ni sc e n t r a l t og o o ds y s t e md y n a mi c sp r a c ‑ t i c e , a n dmo r ee f f o r ts h o u l db ed e v o t e dt ot h eu s eo ft h e s et o o l si ns i mu l a t i o nmo d e l d e v e l o p me n t 21. a n dt e s t i n g , S e ec h a p. ‑ Ch a p t e r1 Le a r n i n gl na n da b o u t Co mp l e xS y s t e ms 27 i ns ys t e mswi t he ve nmode s tl e ve l sofdyna mi cc ompl e xi t y( Ta bl e1 ‑ 4) .Thes e s t udi esl e dmet os ugge s tt ha tt heobs e r ve ddys f unc t i oni ndyna mi c a l l yc ompl e x s e t t i ngsa r i s esf r om mi s pe r c e pt i onso ff e e db ac k ・Theme nt a lmode l spe opl eus e t ogui det he i rde c i s i onsa r edyna mi c a l l yde f i c i e nt ・Asdi s c us s e da bove,pe o pl e ge ne r a l l ya dopta ne ve nt ‑ ba s e d,ope n‑ l oo pvi e w ofc a us a l i t y,I gnor ef e e dba c k pr oc e s s es ,f a i lt oa ppr e c i a t et i mede l a ysbe t we e na c t i ona ndr e s pons ea ndi nt he r e por t i ngOfi nf o ma r t i on, donotunde r s t a nds t oc ksa ndf lowsa nda r ei ns e ns i ivet t o nonl i ne ri a t i est ha tma ya l t e rt hes t r e ngt hsofdi f f e r e ntf e e dba c kl oopsa sas ys t e m e vol ves . Subs e que nte xpe r i me nt ss howt ha tt heg r ea t e rt hedyna mi cc ompl e xl t yOft he e nvi r onme ntt hewor s epe opl edor e l at i v et opot e nt i al .Fur t he r ,t hee xpe r i me nt s s howt heml S Pe r C e Pt l OnSOff e e d ba c ka rer obus tt oe xpe ie r nc e, f i na nc i a li nc e nt i ve s , e xpe r i e nc e,a ndt hepr e s e nc eofma r ke ti ns t i t ut i ons( s e e,e. g. ,Di e hla ndSt e r ma n 1 993;Pa i c ha ndSt e ma r n1 993;Ka mpma nna ndSt e ma r n1 998) . Ther obus t ne s soft heml S Pe r C e Pt l OnSOff e e dba c ka ndt hepoorpe r f or ma nc e t he yc a us ea r ed uet ot woba s i ca ndr e l a t e dde f i c i e nc i e si nourme nt a lmode l . Fi r s t , ourc ognl t l Vema psOft heca us lS a t r uc t ur eofs ys t e msa r evas t l ys i mpl i f i e dc om pa r e dt ot hec ompl e xi t yoft hes ys t e mst he ms e l ves . Se c ond, Wea r euna bl et oi nf e r c or r e c t l yt hedy na ic m sofa llbutt hes i mpl e s tc a us a lma ps . Bot ha red i r e c tc ons e ‑ que nc e sofbound edr a t i ona l i t y , t ha ti s , t hema nyl i mi t a t i onsofa t t e nt i on, me mor y , r e c a l l ,i nf om a t i o npr oc es s l ngC a pa bi l i t y,a ndt i met ha tc ons t r a i nhuma nde c i s i on ma ki ng. ‑ TABLE l ・ 4 Mi sper c ept i ons off eedback havebeen documen t ed i nmany exper i men t af s t udi es. l nasi mpl epr oduc t i on ‑di s t r i bu t i ons y s t em( t heBeerDi s t r i bu t i onGame) , peopl e, f r omhi ghs chool s t uden t st oCEOs,gener at ec os t l yf l u c t uat i ons ( busi nes sc y cl es ) . Aver agec os t swer emor et han1 0t i mesgr eat ert han opt i mal ( St er man1 989b) . Sub j ec t sr es ponsi bl ef orc api t al i n ves t men ti nasi mpl emul t i pI I er ‑ ac c el er at or model oft hee conomygener at el ar geampl i t udec ycl esevent houghc on‑ sumerdeman di sc ons t an t . Aver agec os t swer emor et han30t i mesgr eat er t h anopt i mal ( St er man1 989a) l Sub j ec t smanagl ngaf i r mi nas i mul at edc onsumerpr odu c tmar k etgener at e t hebooman dbus t ,pr l C eWar , ands hak e‑ ou tchar ac t er i s t i co fi ndus t r i esf r om vi deogamest och ai ns aws( Pai chandSt er man1 993) . Par t i ci pan t si nexper i men t al as s etmar k et sr epeat edl ybi dpr l C eSWe"abo ve v al ue,onl yt os eet hempl ummetwhena" gr eat erf ool "c ann o f undamen t al l ongerbef oun dt obu y . Thes es pecul at i vebubb一 esdonotdi s app earwh en t hepar t i ci pan t sar ei n ves t men tpr of es si onal s, whenmonet ar yl nC en t i vesar e pr ovi ded, or whensh or t ‑ s eH i n gi saE I owed( Smi t h,Suchanek, andWi " i ams 1 988) . F naf or es tf i r esi mul at i on,man ypeopf eaI I owt hei rheadquar t er st obur n downdespi t et hei rbes te什or t st opu tou tt hef i r e( Br ehmer1 989) . l namedi c al s et t i ng, Sub j ec t spl ayl ngt her o一 eofdoc t or sor dermor et es t s whi l et he( si mul at ed)pat i en t ssi ck enanddi e( KI ei nmunt zandThomas 1 987) . 28 P a r tI P e r s p e c t i v ea n dP r o c e s s 1. 3. 5 F長 awedCogni t i veMaps Ca us a la t t ibu r t i o nsa r eac e nt r a lf e a t ur eofme n t a lmo de l s . Wea l lc r e a t ea ndupda t e c ognl t l Vema psOfc a us a lc onne c t i onsa monge nt i t i e sa nda c t o r s ,f r om t hepr oI s a i c ‑i fIt o uc haf la meIwi l l bebu r ne d ‑t ot heg r a nd ‑t hel a r g e rt hegove r n me nt de f i c i t , t hehi gh e ri n t e r e s tr a t e swi l lbe .St udi e sofc og nl t l Vema psS howt ha tf e w i nc o r po r a t ea nyf e e d ba c kl oo ps .Ax e l r od( 1 9 76)f o un dvi r t ua l l ynof e e d ba c k pr oc e s s e si ns t ud i e soft hec og nl t l Vema psO fpo l i t i c a ll e a d e r s ; r a t he r , pe o pl et e nde d t of o r mul a t ei nt ui t i v ed e c i s i ont r e e sr e l a t i ngpos s i bl ea c t i onst opr o ba bl ec o ns e ‑ que nc e s ‑a ne v e nトl e ve lr e pr e s e nt a t i o n・Ha l l( 1 976)r e po r t ss i mi l a ro pe nl l oo p me nt a lma psi nas t ud yoft hepubl i s hi ngi ndus t r y . D6 ne r r( 1 98 0,1 99 6)f o undt ha t pe o pl et e ndt ot hi n ki ns l ng l es t r a ndc a us a ls e r i e sa ndha ddi fi c ul t yi ns ys t e mswi t h , s i dee f f e c t sa ndmul t i pl ec a us a lpa t hwa ys( muc hl e s sf e e d ba c kl oops ) .Si mi l a r l y e x pe r i me n t si nc a us a la t t ibut r i o ns howpe o pl et e ndt oa s s umee a c he fe c t ha sas i n gl ec a us ea ndo f t e nc e a s et he i rs e a r c hf o re xpl a na t i onswhe nt hef i r s ts uf f i c i e nt c a us ei sf ou nd( s e et hed i s c us s i oni nPi o us1 993 ) . Thehe u r i s t i c sweus et oj udg ec a us a l r e l a t i onsl e a ds ys t e ma t i c a l l yt oc og nl t l Ve ma pst ha ti g no r ef e e d ba c ks , mul t i pl ei n t e r c o nne c t i o ns , n on li ne a r i t i e s , t i med e l a ys , a ndt heo t he re l e me nt sofdy na i cc m o mpl e xi t y . Thec a us a lf i e l do rme nt a lmode lof t hes t a geo nwhi c ht hea c t i o noc c ur si sc r uc i a li nf r a ml ngPe O Pl e' sj udgme nt so f c a us a t i o n( Ei nho r na ndHoga r t h1 986) . Wi t hi nac a us a lf i e l d, pe o pl eus eva io r us c ue st oc a us a l i yi t n c l ud i ngt e mpo r a la nds pa t i lp a r o xi ml t yO fc a us ea nde fe c t , t e m‑ po r a lpr e c e de nc eo fc a us e s ,c ova r i a t i on,a nds i mi l a r i t yo fc a us ea nde fe c t . The s e he ur i s t i c sl e a dt odi f f i c ul t yl nc o mpl e xs ys t e mswhe r ec a us ea nde f f e c ta r eof t e n di s t a nti nt i mea nds pa c e ,whe r ea c t i o nsha vemul t i pl ee fe c t s ,a ndwhe r et hede ‑ l a ye da ndd i s t a n tc o ns e q ue nc e sa r edi fe r e n tf r oma ndl e s ss a l i e n tt ha npr oxi ma t e e fe c t s( o rs i mpl yu nknown) .Themu lt i pl ef e e d ba c ksi nc o mpl e xs ys t e msc a us e ma nyva ia r bl e st obec o r r e l a t e dwi t ho nea no t he r , c o nf o u nd i ngt het a s ko fj udgi ng c a us e・ Howe v e r , pe o pl ea r epoo rj udg e so fc o r r e l a t i on・ Ex pe ime r nt ss howpe opl e c a ng e ne r a l l yde t e c tl i ne a r , pos i t i vec o r r e l a t i onsa mo ngva r i a bl e si ft he ya r egl Ve n e no ug ht ia r l sa n di ft heo ut c omef e e d ba c ki sa c c u r a t ee noug h. Howe ve r ,Weha ve or , nonl i ne a r l t y , a ndne ga t i vec o r r e l a ‑ g r e a tdi f f i c ul t yi nt hep r e s e nc eofr a ndo me r r t i ons , of t e nne ve rdi s c ov e r i ngt het uer r e l a t i ons hi p( Br e h me r1 98 0) . Af u nda me n t a lpr lnC i pl eofs ys t e m dyna mi c ss t a t e st ha tt hes t r uc t ur eo ft he r ,pe opl eha veas t r o ngt e nde nc yt oa t ‑ s ys t e m gl Ve Sr i s et oi t sbe ha vi or . Howe ve t r i but et hebe ha v i o ro fo t he r st od i s pos i t i o na lr a t he rt ha ns i t ua t i o na lf a c t or s , t ha ti s , t oc ha r a c t e ra nde s pe c i a l l yc ha r a c t e rf l a wsr a t he rt ha nt hes ys t e mi nwhi c ht he s e hepe r s onr a t he rt ha nt hes ys t e mi ss o pe o pl ea r ea c t l ng. Thet e nde nc yt obl a met s t r o ngps yc ho l ogi s t sc a l li tt he" unda f me n t a la t t r i but i o ne r r o r "( Ros s1 977) .I n c ompl e xs ys t e msd i fe r e ntpe o pl epl a c e di nt hes a mes t r uc t ur et e ndt obe ha vei n ort ope r s on a l i t ywel os es i ghtofhowt he s i mi l a rwa ys . Whe nwea t t r i bu t ebe ha v i s t uc r t ur eoft hes ys t e ms ha pe do urc hoi c e s . Thea t t ibut r i o nofb e ha vi ort oi ndi vi d‑ ua l sa nds pe c i a lc i r c ums t a nc e sr a t he rt ha ns ys t e ms t r uc t ur edi ve r t soura t t e nt i on e des i gnl ngt hes ys t e mo rgove r nl ngPOl i c y f r omt hehi g hl e ve r a gepoi n t sWhe r er c a nha ves i g ni f i c a nt , s us t a i ne d, be ne f i c i a le fe c t sonpe r f o r ma nc e( Fo r r e s t e r1 969, c ha p. 6; Me a d ows1 98 2) . Whe nwea t t r i but ebe ha vi ort ope o pl er a t he rt ha ns ys t e m s t r uc t ur et hef わc usofma na g e me ntbe c omess c a pe goa t l nga ndbl a mer a t he rt ha n ‑ Ch a p t e r1 Le a ml n gl na n da b o u t Co mp l e xS y s t e ms 29 t hedes i gnofo r ga ni z a t i onsi nwhi c hor di na r ype opl ec a na c hi e vee xt r a or di na r y l l r es ul t s . 1. 3. 6 Er r oneoushf er encesaboutDynami cs Eve ni fourc og nl t l Vema psOfc a us a ls t r uc t ur ewe r epe r f e c t ,l e a r nl ng,es pe c i a l l y doubl e ‑ l oo pl ea r nl ng,woul ds t i l lbedi f f i c ul t ・Tous eame nt a lmode lt ode s i gna ne ws t r a t e gyoror ga ni z a t i onwemus tma kei nf e r e nc e sa boutt hec ons e que nc esof de c i s i onr u l e st ha tha vene ve rbe e nt r i e da ndf orwhi c hweha venoda t a. Tbdos o r eq ui r esi nt ui t i ves ol ut i onofhi g h‑ or de rnonl i ne a rdi fe r e nt i le a qua t i ons ,at a s kf a r e xc e e di nghuma nc ogni t i vec a pa bi l i t i e si na l lbutt hes i mpl e s ts ys t e ms( Fo r r e s t e r 1 971 a;Si mon1 98 2) .I nma nye xpe r i me nt a ls t udi e s ,i nc l udi ngDi e hla ndSt e ma n ( 1 995)a ndSt e r ma n( 1 989a ) ,t hepa r t i c i pa nt swe r egi ve nc ompl e t eknowl e dgeof a l ls t r uc t ur a lr e l a t i ons hi psa ndpa r a me t e r s , longw a it hpe r f e c t , c ompr e he ns i ve , a nd i mme di a t eknowl e dgeofa l lva r i a bl es ・Fur t he r ,t hes ys t e mswe r es i mpl ee nough t ha tt henumbe rofva r i a bl e st oc ons i de rwa ss ma l l . Ye tpe r f bm a nc ewa spoo ra nd l e a r nl ngWa sS l o wI Poorpe r f or ma nc ei nt he s et a s ksi sduet oouri na bi l i t yt oma ke r e a s ona bl ei nf e r e nc e sa boutt hedyna mi c soft hes ys t e m de s pl t ePe r f e c ta ndc om‑ pl e t eknowl e dgeo ft hes ys t e ms t r uc t ur e. Pe o pl eca nnots i mul a t eme nt a l l ye ve nt hes i mpl e s tpos s i bl ef e e d ba c ks ys t e m, t hef i r s t ‑ or de rl i n e a rpos i t i vef e e dba c kl oo p・ 1 2suc hpos i t i vef e e dba c kpr oc e s s esa r e c ommonpl a c e,f r o mt hec ompoundi ngofi nt e r es tt ot hegr owt hofpopul a t i ons . Wa ge na a ra ndSa ga r i a( 1 975)a ndWa ge na a ra ndTi mme r s( 1 978,1 979)s howe d t ha tpe opl es i gni f i ca nt l yunde r e s t i ma t ee xpone nt i lg a r owt h, t e ndi ngt oe xt r a pol a t e l i ne a r l yr a t he rt ha ne xpone nt i a l l y. Us i ngmo r eda t apol nt SO rg r a phi ngt heda t adi d nothe l p,a ndma t he ma t i c a lt r a i nl ngdi dnoti mpr ovepe r f or ma nc e. Bounde dr a t i o na l i t ys i mul t a ne o us l yc ons t r a i nst hec ompl e xl t yOfourc ognl t l Ve ma psa ndo ura b i l i t yt ous et he mt oa nt l C l pa t et hes ys t e m dyna mi c s . Me nt a lmod‑ e l si nwhi c ht hewor l di ss e e na sas e que nc eofe ve nt sa ndi nwhi c hf e e dba c k, non‑ l i ne a r l t y,t i mede l a ys ,a nd mul t i pl ec ons e que nc esa r el a c ki ng l e a dt opoor pe r f o r ma nc ewhe nt he s ee l e me nt sofdyna mi cc ompl e xi t ya repr e s e nt . Dys f unc t i on t r uc t ur eof i nc ompl e xs ys t e msc a na ri s ef r omt heml S Pe r C e Pt l OnOft hef e e d ba c ks t hee nvi r onme nt ・ Butr i c hme nt a lmode l st ha tca pt ur et he s es o ur c e sofc ompl e xi t y c a nnotbeus e dr e l i a bl yt ounde r s t a ndt hedyna mi cs IDys f unc t i o ni nc ompl e xs ys ‑ t e msc a na r i s ef r om f a ul t yme nt ls a i mul a t i on‑t heml S Pe r C e Pt 1 0nOff e e dba c k d ynami c s .Thes et wodi fe r e ntboundsonr a t i onal i t ymus tbot hbeove r c omef o r e f f T e c t i vel e a ni r ngt OOC C ur ・ Pe r f e c tme nt a lmode l swi t houtas i mul a t i onc a pa bi l i t y yi e l dl i t t l ei ns i g ht ;ac a l c ul usf orr e l i a bl ei nf e r e nc esa boutdyna mi csyi e l dss ys ‑ t e ma t i c a l l ye r r on e ousr es ul t swhe r ̲ I a ppl i e dt os i mpl i s t i cmode l s . l l Re p e n n i n ga n dS t e r ma n(1999)s h o wh o wt h ef u n d a me n t a l a t t ib r u t i o n? r r o ra r o s ei na ma j o rma n u f a c t u r i n gO r g a n i z a t i o n , hwa t rt i n gt h e i re f f o r t st oi mp r o v eo p e r a t i o n sa n dp r o d u c t d e v e l o p me n t ・ Sr e p r e s e n t e db yt h ed i fe r e n t i a l e q u a t i o nd x / d t‑g xa n d 1 2 Th ef i r s t 1 0 r d e r l i n e a rp o s i t i v el o o pI y i e l d sp u r ee x p o n e n t i a l g r o wt h , x‑x 。 e x p ( g t ) ; s e ec h a p . 8. 3 0 Pa r t IP e r s p e c t i v ea n dP r o c e s s 1. 3, 7 Unsci ent i f i cReasonhg: Judgment a=≡ r r or sandBi ases Tol e a r ne f f e c t i ve l yl nawor l dofdyna mi cc ompl e xl t ya ndi mpe r f e c ti nf or ma t i on pe o pl emus tde ve l opwha tDa vi sa ndHoga r t h( 1 992)c a l lH i ns i ghts ki l l s " ‑t he s ki l l st ha the l ppe opl el e a n whe nf e e dba c ki sa mbi guous : t i v ea n ddi s c i pl i ne dt a s kgo v ‑ l T] h ei n t e r p r e t a t i o no ff e e d b a c k. . . n e e dst ob ea nac e r n e db yt h er i g o r o usr ul e so fs c i e n t i f i ci n f e r e n c e . Be l i e f smu s tbea c t i ve l yc ha l ‑ l e n g e db ys e e ki n gpos s i b l ed i s c o nf i r ml n ge v i d e n c ea n da s k i n gwh e t he ra l t e na r t i v e b e l i e f sc o u l dn o ta c c o un tf o rt hef a c t s( e mp h a s i si no r i g i na l ) . Unf or t una t e l y , pe opl ea repoori nt ui t i ves c i e nt i s t s , ge ne r a l l yf a i l i ngt or e a s oni na c ‑ c o r da nc ewi t ht hepr l nC i pl e sofs c i e nt i f i cme t hod. Fo re xa mpl e , pe opl edonotge n‑ e r a t es uf f i c i e nta l t e r na t i vee xpl a na t i onsorc ons i de re noughr i va lhypot hes es . Pe opl ege ne r a l l ydonota de qua t e l yc ont r olf orc onf o undi ngva r i a bl eswhe nt he y e xpl or eanove le nvi r onme nt .Pe opl e' sj udgme nt sa r es t r ongl ya fe c t e dbyt he f r a mei nwhi c ht hei nf or ma t i oni spr e s e nt e d, e ve nwhe nt heob j e c t i vei nf or ma t i on i sunc ha nge d.Pe opl es ufe rf r om ove r c onf i de nc ei nt he i rj udgme nt s( unde r ‑ es t i ma t i ngunc e r t a i nt y) ,wi s hf ult hi nki ng( a s s es s i ngdes i r e dout c omesa smor e l i ke l yt ha nundes i r e dout c omes ) , a ndt hei l l us i onofc o nt r ol( be l i e vi ngonec a npr e ‑ di c tori nf lue nc et heout c omeofr a ndom e ve nt s ) .Pe o pl evi ol a t ebas i cr ul e sof pr oba bi l i t y,donotunde r s t a ndba s i cs t a t i s t i c a lc o nc e pt ss uc hasr e gr es s i ont ot he me a n,a nddonotupda t ebe l i e f sa c c or di ngt oBa ye s ' r ul e. Me mor yi sdi s t or t e dby hi nds i ght ,t hea va i l a bi l i t ya nds a l i e nc eofe xa mpl e s ,a ndt hedes i r a bi l i t yofout ‑ c ome s . Ands oon.Hoga r t h( 1 98 7)di s c us s e s30di f f e r e ntbi as esa nde r r or sdoc u‑ me nt e di nde c i s i on一 ma ki ngr e s ea r c ha ndpr ovi de sagoodgui det ot hel i t e r a t ur e ( s e ea l s oKa hne ma n,Sl ovi c, a ndTve r s ky1 98 2) . Ther es e a r c hc onvi nc i ngl ys hows t ha ts c i e nt i s t sa ndpr of e s s i ona l s ,notonl y" or di na r y"pe o pl e ,s uf f e rf r om ma nyof t he s ej udgme nt a lbi a s es . Amo ngt hef a i l ur esofs c i e nt i f i cr e a s oni ngmos ti ni ic m a lt ol ea r ni ngi st het e n‑ on‑ de nc yt os e e ke vi de nc ec ons i s t e ntwi t hc ur r e ntbe l i e f sr a t he rt ha npot e nt i a ldi s c f i r ma t i on( Ei nhom a ndHoga r t h1 978・ , Kl a yma na ndHa1 98 7) . I naf a mouss e r i e s ofe xpe r i me nt s , Wa s ona ndc ol l e a gue spr es e nt e dpe o pl et a s ksoft hes or ts howni n 3・ 1 3Be f or ec ont i nul ng, t r yt hec ha l l e nges howni nt hef i gur e・ Fi gur e1 1 1 Hypot hesi sTest i ng Yo ua r es hownt he s ef ourca r ds . Ea c hc a r dha sal e t t e rono nes i dea ndanumbe ron Wha ti st hes ma l l e s tnumbe rofc a r dsyo us houl dt ur nove rt ot e s tt her ul e t heo t he r . t ha tc a r dswi t hvowe l sonones i deha vee ve nnumbe r sont her e ve r s e?Whi c ha r e t he y? E ] ㊦E ] E] 1 3 Th es u mma r yo f t h eWa s o nt e s t i sd r a wnf r o mP l o u s(1993, c h a p . 20) . 31 Ch a p t e r1 Le a r n l n gl na n da b o u t Co mp l e xS y s t e ms I noneve r s i onyo ua r es hownones i deoff ourc a r ds , e a c hwi t hal e t t e ronone s i dea ndanumbe ron血eot he r ,s a yE, K, 4, a nd7. Youa r et ol dt ha ti rac a r dha sa vowe loni t ,t he ni tha sa ne ve nnumbe ront heot he rs i de . Youmus tt he ni de nt i f y t . t hes ma l l e s ts e to fc a r dst ot ur nove rt os e ei ft hepr opos e dr ul ei sc o r r e c Wa s ona ndJ o hns on‑ La i r d( 1 972)f oundt ha tt heva s tma j or i t yofs ub j e c t ss e ‑ l e c t e dEo rEa nd4a s仙ea ns we r s . Les st ha n4% ga vet hec o r r e c ta ns we r : Ea nd7. fp,t he nq.Fa l s i f i c a t i onr e qui r e so bs e r va t i onof Ther ul eha st hel og i c lf a o r ml pandnot ‑ q.Theonl yc a r ds howi ngpi st heEc a r d,s oi tmus tbee xa mi ne d( t he ba c kof山eEc a r dmus tbea ne ve nnumbe rf ort her ul et ohol d) .Theonl yc a r d ‑ qi st he7,s oi tt oomus tbee xa mi ne d. TheKa nd4c a r dsa r ei r r e l e ‑ s howi ngnot va nt .Ye tpe opl ec ons i s t e nt l yc hoos et hec a r ds howl ngq,aC hoi c et ha tc a nonl y pr ovi deda t ac ons i s t e ntwi t ht het he or y ,butc a nnott e s ti t ;i ft heba c koft he4i sa c ons ona nt , youha vel e a ne dnot hi ng,s i nc et her ul ei ss i l e nta boutt henumbe r sa s ‑ s oc i a t e dwi t hc o ns ona nt s . Expe r i me nt ss howt het e nde nc yt os e e kc onf i r ma t i oni s C , ma t he ma t i c s , a nds t a t i s t i cs . Se a r c hs t r a t e gl eS r obus ti nt hef a c eo ft r a i nl ngi nl ogl t ha tf oc usonl yo nc onf i ma r t i onofc ur r e ntbe l i e f ss l owt hege ne r a t i ona ndr e c ogn1 ‑ t i onofa noma li e st ha tmi ghtl e a dt ol e a nl r ng, Pa r t i c ul a r l ydo ubl e l l oo pl e ml a ng. Somea r guet ha twhi l epe o pl ee r ri na ppl yi ngt hepr l nC i pl e sofl ogl C,a tl e a s t pe o pl ea r er a t i on a l i nt hes e ns et ha tt he ya ppr e c i a t et hede s i r a bi l i t yofs c i e nt i f i ce xI pl a na t i on.Unf o r t una t e l y , t hes i t ua t i oni sf a rwor s e. Ther a t i o na l ,s c i e nt i f i cwo rd vi e wi sar e c e ntde ve l o pme nti nhuma nhi s t or ya ndr e ma i nsr a r e.Ma nype opl e pl a c et he i rf a i t hi nwha tDos t oye vs ky' sGr a ndl nqul S i t orc a l l e d" Ⅰ 血‑ a c l e, mys t e r y, a nda ut hor i y, t =f o re xa mpl e,a s t r ol ogy, ESP,UFOs ,c r e a t i oni s m,c ons pl r a C yt he o r i esofhi s t or y ,c ha nne l i ngofpas tl i ves ,c ul tl e a de r spr omi s i ngAr ma ge ddon,a nd El vュ ss i ght i ngs . Thepe r s i s t e nc eofs uc hs upe r s t i t i ousbe l i e f sde pe ndspa r t l yon血e bi ast owa r dsc on f i r mi nge vi de nc e.Wa deBoggs ,f o r me rBos t onRe dSoxba t t i ng c ha mpi on,a t eC h i c ke ne ve r yda yf orye a r sbe c a us eheonc eha dapa r t i c ul a r l ygood da ya tt hepl a t ea f t e radi nne rofl e monc hi c ke n( Sha ughne s s y1 987) . Dur i ng血i s t i meBoggswonf i veba t t i ngc ha mpi ons hi ps , pr ovl ngt hewi s dom oft he" c hi c ke n t he o r y. HCons i de rt hec ont i nue dpopul a r i t yofa s t r ol ogy,ps yc hi cs ,a nde c onomi c f or e ca s t e r s ,whopubl i c i z et he i rs uc c e s s esa nds uppr e s st he i r( mor enume r ous ) f a i l u r e s . Re me mbe rt ha tt he40t hpr es i de ntoft heUni t e dSt a t e sa ndf i r s tl a dyma n‑ a ge da fa i r so fs t a t eo nt heba s i sofa s t r ol ogy( Robi ns on1 988 ) ・ Andi two r ke d: He wa sr e e l e c t e di nal a nds l i de. Suc hl una c ya s i de , t he r ea r ede e pe ra ndmor edi s t ur bi ngr e a s onsf ort hepr e va ‑ l e nc eoft hes el e a r nl ngf a i l ur e sa ndt hes upe r s t i t i onst he ye ng e nde r ・ Huma nbe i ngs a r emor et ha nc o gnl t l Vei nf o r ma t i onpr oc es s or s .Weha veade e pne e df ore mo‑ t i ona la nds pl r l t ua ls us t e na nc e. Butf r om Cope r ni c a nhe l i oc e nt r i s mt hr oughe vol u‑ t i on, r e l a t i vl t y , qu a nt u mme c ha ni c s , a ndG6de l i a nunc e r t a i nt y , s c i e nc eha ss t r i ppe d a wa ya nc i e nta ndc omf or t i ngbe l i e f spl a c i nghuma nl t ya tt hec e nt e rofar a t i ona l uni ve r s ede s i gne df o rusbyas upr e mea ut hor i t y.Forma nype opl es c i e nt i f i c t houghtl e a dsnott oe nl i ght e nme nta nde mpowe r me ntbutt oe xi s t e nt i a la ngs ta nd t hea bs ur di t yofhuma ni ns l gni f i ca nc ei na ni nc ompr e he ns i bl yva s tuni ve r s e・ Ot he r sbe l i e ves c i e nc ea ndt e c hnol ogywe r et hes hoc kt r oopsf ort het r i umphof ma t e r i a l i s ma ndi ns t ume r nt a l i s m ove rt hes a c r e da nds pi r i t ua l . The s ea nt i s c i e nt i f i c r e a c t i onsa repowe r f ulf o r c e s . I nma nywa yst he ya r ei mpor t a ntt r ut hs ・ The yha ve l e dt oma nyoft hemos tp r of oundwor ksofa r ta ndl i t e r a t ur e ・ Butt he yc a na l s ol e a d t omi ndl e s sne w‑ a g eps yc hoba bbl e. l ‑ ‑ 32 P a r t iP e r s p e c t i v ea n dP r o c e s s Ther e a de rs houl dnotc onc l udef r omt hi sdi s c us s i ont ha tIa mana i vede f e nde r ofs c i e nc ea si ti spr a c t i c e dnora na pol ogi s tf ort her e a la ndc ont i nul ngda ma ge donet ot hee nvi r onme nta ndt oourc ul t ur a l , mor a l ,a nds pi r i t ua ll i vesi nt hena me ofr a t i ona l i t ya ndpr ogr es s .Ont hec ont r a r y ,Iha ves t r es s e dt her es e a r c hs howi ng t ha ts c i e nt i s t sa r eof t e na spr onet ot hej udgme nt a le 汀O r Sa ndbi as e sdi s c us s e d a bovea sl a ype opl e. I ti spr e c i s e l ybe c a us es c i e nt i s t sa r es ub j e c tt ot hes a mec og‑ ni t i vel i mi t a t i onsa ndmor a lf a i l ur esa so t he r st ha twee xpe r i e nc ea bomi na t i ons s uc ha st heUSgove mme ntf unde dr e s e a r c hi nwhi c hpl ut oni um wa sl n j e C t e di nt o l lpa t i e nt s ,a ndi nwhi c hr a di oa c t i vec a l c i um wa sf e dt or e t a r de dc hi l ‑ s e r i ous l yi dr e n,a l lwi t houtt he i rk n owl e dgeorc ons e nt( Ma nn1 994) ・ Ac e nt r a lpr i nc i pl eof s ys t e m dyna mi csi st oe xa mi nei s s ue s血. om mul t i pl epe r s pe c t i ves ;t oe xpa ndt he bo unda ie r sofourme nt a lmode l st oc o ns i de rt hel o ng‑ t e r mc ons e que nc e sa nd" s i de e f f e c t s "ofoura c t i ons , i nc l udi ngt he i re nvi r onme nt a l , c ul t ur a l ,a ndmo r a li mpl i c a ‑ t i ons( Me a dows , Ri c ha r ds on,a ndBr u c kma nn1 982) . 1. 3. 8 Def ensi veRout i nesandht er per sonai E mpedi ment s† oLear ni ng Le a ni ngbygr oups , whe t he rs ys t e md yna mi c si sus e do rnot , c a nbet hwa r t e de ve n i fpa r t l C I Pa nt Sr e c ei vee xc e l l e nti nf o ma t i onf e e d ba c ka ndr e as onwe l la si ndi vi d u‑ a l s . Wer e l yonourme nt a lmode l st oi nt e r pr e tt hel a ngua gea nda c t sofot he r s , c on‑ s t r uc tmea ni ng,a ndi nf e rmot i ves . Ho we ve r ,a sFor r e s t e r( 1 971 )a r gue s , Th eme n t a lmo d e li sf u z z y . I ti si n c o mp l e t e . I ti si mp r e c i s e l ys t a t e d・ Fu r t h e r mo r e , wi t hi no nei n d i v i d u a l , ame n t a l mo d e l c ha n g e swi t ht i mea n de v e nd u r i n gt h ef lo w o fas l n g l ec o n ve r s a t i o n. Theh u ma nmi n da s s e mbl e saf e wr e l a t i o n s hi pst of i t t h e c o n t e x to fad i s c us s i o n. st A hes u b j e c ts h i f t ss od o e st h emo d e l・ ・ ・l E] a c hpa r t i c i ‑ p a n ti nac o n v e r s a t i o ne mpl o ysad i f f e r e n tme n t a lmo d e lt oi n t e r p r e tt hes u b j e c t ・ Fu n da me n t a la s s umpt i o nsd i f f e rb u ta r en e v e rb r o u g h ti n t ot heo pe n. Ar gyr i s( 1 985) ,Ar gyr i sa ndSc h6n( 1 978 ) ,J a ni s( 1 982) ,Sc he i n( 1 969,1 985, 1 98 7) ,a ndot he r sdoc ume ntt hede f e ns i ver o ut i ne sa ndc ul t ur a la s s umpt i onspe o‑ pl er e l yon,of t e nunknowl ngl y,t oi nt e r a c twi t ha ndi nt e r pr e tt he i re xpe r i e nc eof ot he r s . Weus ede f e ns i ver out i ne st os a vef a c e , a s s e r tdomi na nc eove rot he r s , ma ke unt e s t e di nf e r e nc ess e e ml i kef a c t s ,a nda dvoc a t eourpos i t i onswhi l ea ppe a r l ngt O t r i but i onsa boutt heda t awer e c e i ve・ bene ut r a l . Wema kec onf li c t l ng,unS t a t e da t Wef a i lt odi s t i ngui s hbe t we e nt hes e ns e ‑ da t aofe xpe r i e nc ea ndt hea t t r i but i o nsa nd ge ne r a l i z a t i onswer ea di l yf or mf r om t he m・Wea voi dpubl i c l yt es t l ngOurhy‑ l l ,de f e ns i vebe ha vi or pot he s e sa ndbe l i e f sa nda voi dt hr e a t e nl ngl S S ueS ・ Abovea i nvol ve sc ove r l nguPt hede f e ns i ve nes sa ndma kl ngt he s ei s s uesundi s c us s a bl e, e ve nwhe na l lpa r t i e sa r ea wa r et he ye xi s t . De f e ns i ver out i nesa r es ubt l e. The yof t e na r r i vec l oa ke di na ppa r e ntc onc e r n a ndr e s pe c tf orot he r s .Cons i de rt hes t r a t e gyc a l l e dH e a s l ng‑ 1 n: H I fy o ua r ea bo u tt oc r i t i c i z es o me o newhomi g h t be c o med e f e ns i v ea n dyo uwa n t h i mt os e et hepo l n tWi t ho u tu nd u er e s i s t a n c e , d on o ts t a t et h ec r i t i c i s mo p e n l y; l n‑ l y , hewi l lf i g u r eo u twh a t s t e a d, a s kq u e s t i o nss uc ht h a ti fhea ns we r st h e mc o r r e c t y o ua r en o ts a yi n g( Ar g y r i s , Pu t n a m, a n dSmi t h1 98 5, p・ 8 3 ) ・ Ch a p t e r1 Le a r l l l n gl na n da b o u t Co mp l e xS y s t e ms 33 Bute a s l ng‑ i no f t e n Cr e a t e st h ev e r yd e f e ns i v e n e s st ha ti ti si n t e n d e dt oa v o i d, b e c a us et her e c I Pl e n t t y p l C a l l yu n d e r s t a n d st ha tt hea c t o ri se a s l n g‑ i nJn d e e d , e a s l n g ‑ 1 nC a nbes u c c e s s f u l o n l yi ft her e c l p l e n t un d e r s t a n dst ha th ei ss u p p o s e dt oa ns we r仇eq u e s t i o nsi na pa r t i c u l a rwa y , a n dt h i se n t il a st heun d e r s t a nd i n gt h a tt h ea c t o ri sne ga t i v e l ye va lu‑ m, a n d a t i n gt h er e c i p i e n ta n da c t i n ga si ft hi swe r en o t t h ec a s e( Ar g y r i s , Pu t n a S mi t h1 98 5 , p. 8 5 ) . De f e ns i vebe ha v i o r ,i nwhi c ht hees pous e dt he o iesweofe r rt oot he r sdi f f e rf r om o urt he o ie r si nus e , pr e ve nt sl e a i ngbyhi m di ngi mpo r t a nti nf o r ma t i onf r omot he r s , a voi di ngpubl i ct es t l ngOfi mpor t a nthypot hes e s ,a ndt a c i t l yc ommuni ca t l ngt ha t wea renotope nt oha vi ngourme nt a lmode l sc ha l l e nge d, De f e ns i ver out i nesof t e n yi e l dgr oupt hi nk( J a ni s1 982) , whe r eme mbe r sofagr oupmut ua l l yr e i nf or c et he i r c ur r e ntbe l i e f s ,s u ppr es sdi s s e nt ,a nds e a lt he ms e l vesoff r omt hos ewi h di t fe r e nt vi e wso rpos s i bl edi s c onf i r ml nge Vi de nc e・ De f e ns i ver out i nese ns ur et ha tt heme n‑ t a lmode l soft e a m me mbe r sr e ma i ni l lf om e d,a mbi guous ,a ndhi dde n.Thus l e a r ni ngbyg r ou psc a ns ufe re ve nbe yondt hei mpe di me nt st oi ndi vi dua ll e ml a ng. 1. 3. 9 h pl ement at i onFai l ur e l nt her e l wor a l dde c i s i onsa r eof t e ni mpl e me nt e di mpe r f e c t l y,f ur t he rhi nde ing r l e a ml ng. Eve ni fat e a ma gr e e dont hepr ope rc o ur s eofa c t i on, t hei mpl e me nt a t i on oft he s ede c i s i onsc a nbede l a ye da nddi s t o r t e da st hea c t ua lo r ga ni z a t i onr es ponds . Loc a li nc e nt i ve s ,a s ymme t r i ci n丘) r ma t i on,a ndpr i va t ea ge nda sca nl e a dt oga me pl a yl ngbya ge n t st hr oughoutas ys t e m.Obvi o us l yi mpl e me nt a t i onf a i l ur e sca n hur tt heo r ga ni z a t i on. I mpe r f e c ti mpl e me nt a t i onc a nde f e a tt hel e a ml ngPr oc es sa S we l l ,be c a us et h ema na ge me ntt e a me va lua t i ngt heout c omesoft he i rde c i s i ons ma ynotknowt hewa ysi nwhi c ht hede c i s i onst he yt houghtt he ywe r ei mpl e me nt ‑ 1 ngWe r edi s t o r t e d. Fi na l l y,i nt her ea lwor l dofi r r e ve r s i bl ea c t i onsa ndhi ghs t a kest hene e dt o ma i nt a i npe r f or ma nc eof t e nove r r i de st hene e dt ol e a r nbys uppr es s i ngne wS t r a t e ‑ gi e sf o rf e a rt he ywoul dc a us epr es e ntha m e r ve nt hought he ymi ghtyi e l dgr e a ti n‑ s i ghta ndpr e ve n tf u t ur eha m. lh 4 REQUJ REMENTSFORSuccESSFULLEARNMG 弓 N CoMPLEXSYsTEMS Wef a c egr a vei mpe di me nt st ol e ml a ngl nC OmPl e xs ys t e msl i keana t i on,f i r m,o r f a mi l y・ Eve r yl i n ki nt hef e e dba c kl oopsbywhi c hwem ig htt e a mc a nbewe a ke ne d orc utbyava ie r t yofs t u rc t ur e s . Someoft hes ea r ephys i ca lori ns it t ut i ona lf e a t ur es oft hee nvi r onme nt 一也ee l e me nt sofdyna mi cc ompl e xi t y仙a tr e duc eoppor t uni ‑ t i e sf o rc ont r ol l e de x pe ime r nt a t i on,pr e ve ntusf r om l e a ni r ngt hec ons e que nc e sof oura c t i ons ,a ndd i s t o r tt heout c omef e e dba c kwedor e c e i ve.Somea r ec ons e‑ que nc e sofourc ul t ur e ,gr ouppr oc es s ,a ndi nqul r yS 女i l l s .St i l lot he r sa r ef u nda 一 me nt a lboundso nhuma nc ognl t l On,pa r t i c ul a r l y血epoorqua l i t yofourme nt a l ma psa ndouri na bi l i t yt oma kec or r e c ti nf e r e nc e sa boutt hedyna mi csofc ompl e x nonl i ne a rs ys t e ms . 34 P a r t I P e r s p e c t i v ea n dP r oc e s s 1. 4. 1 h pr ovi ngt heLear ni ngPT OCer ' S: Vi r t uesofVi r t ua一Wor 一 ds Wha tt he na r et her e qul r e me nt Sf o rs uc c e s s f u ll e a r nl ngl nC Ompl e xs ys t e ms ?I fwe a r et oc r e a t eus e f ulpr ot oc ol sa ndt ool sf orl e a r nl nge fe c t i vel yi nawor l dofdy‑ na mi cc ompl e xl t yWemus ta t t e ndt oa l loft hei mpe di me nt st ol e a r nl ng・Fi gur e 1 ‑ 1 4S howshowt hel e a r ni ngf e e d ba c kswoul dope r a t ewhe na l lt hei mpe di me nt s t ol ea ml nga r ea ddr es s e d. Thedi a gr a mf e a t ur e sane wf e e dba c kl oo pc r e a t e dbyt he us eofv i r t u alwor l ds . Vi r t ua lwo r l ds( t het e m i r sSc h6n' S[ 1 983] )a r ef om a lmod‑ e l s ,s i mul a t i ons , or" mi c r owo r l ds M( Pa pe r t1 980) , i nwhi c hde c i s i onma ke r sc a nr e ‑ f r e s hde c i s i on‑ ma ki ngs k i l l S , c onduc te x pe r i me nt s , a ndpl a y. The yc a nbephys i c a l mode l s ,r ol epl a ys ,orc omput e rs i mul a t i ons . I ns ys t e mswi t hs i gni f i c a ntdyna mi c c ompl e xi t y , C omput e rs i mul a t i onwi l lt ypi c a l l ybene e de d( 仇Ol l ght he r ea r eno t a bl e e xc e pt i ons ,s uc ha st heBe e rDi s t r i but i onGa me( St e ‑a n1 989b)a ndt heMa i nt e 一 れa nc eGa mede s c r i be di ns e c t i on2. 4,a l ongwi t hr ol e ‑ pl a y / c omput e rhybr i dss uc h FI GURE1‑ 14 1 deal i zedl eaml ng Pr OC eS S Ef f ec t i v el ear nE n g i n vol ves c on t i nu ou s e xper i ment at i on i nbot ht h evi r t u af wor l dandr ea一 wor l d.Feedbac k f r ombo t hi n f or ms t hedev e一 opmen t ofmen t al model s , f or mal mode一 s ,and t hedes i gnof exper i men t sf or t henex ti t er at i on. Rea一 Wor 一 d Un k n o wns t r u c t u r e D y n a mi cc o mp l e x i t y e l a y s Ti med l n a b l l i t yt oc o n d u c t c o n t r o l l e d e x p e r i me n t s Vi r t ual Wor 一 d Kn o wns t r u c t u r e Va r i a b l el e v e l o f c o mp l e x i t y Co n t r o ‖ e de x p e r i me n t s Deci si ons Re a l Wo r l d: Vi r t u a 日 Wo r l d: l mp l e me n t a t i o n P e r f e c t i mp l e me n t a t i o n f a i l u r e Co n s i s t e n t i n c e n t i v e s Ga mep l a y l n g Co n s i s t e n t a p p 一 i c a t i o n o f d e c i s i o nr u l e s I n c o n s i s t e n c y P e r f o r ma n c el S L e a r n l n gC a nb eg o a l 9 0 a l Si r at egy,St r uct ur e, Deci si onRul es Si mu l a t 1 0 nu s e dt oi n f e r d y n a ml C SO fme n t a l mo d e 一 sc o r r e c t l y I nf or mat i onFeedback Re a l Wo r 一 d: Vi r t u a d Wo r l d: Se l e c t i v ep e r c e p t i o n , Co mp l e t e a c c u r a t e , Mi s s i n gf e e d b a c k i mme d i a t e De 一 a y k f e e d b a c On , e r r o r B i a s , d l S t O r t I Amb i g u i t y Ment alModel s Ma p p i n gO He e d b a c ks t r u c t u r e Di s c i p l i n e da p p l l C a t i o no f s c i e n t l f l Cr e a s o n i n g Di s c u s s a b i l i t yo f g r o u p p r o c e s s , d e f e n s i v eb e h a v i o r 35 Cha p t e r1 Le a r nl ngl na n da bou tCompl e xSys t e ms a sFi s hBa n ks , Lt d・ ( Me a dows , Fi dda ma n, a ndSha n no n1 993) ・ Ma nyoft het o ol s o fs ys t e md yna mi c sa r ede s i gn e dt ohe l pyo ud e ve l o pus e f ul , r e l i a bl e , a nde f f e c t i v e mod e l st os e r vea svi r t ua lwo r l dst oa i dl e a r nl nga ndpo l i c yde s i gn. Ⅵr 山a lwor l dsha ves e v e r a lv i r t ue s . Fi r s t ,t he ypr ovi del ow‑ c os tl a bo r a t o r i e s f o rl e a r nl ng. Th evi r t ua lwo r l da l l o wst i mea nds pa c et obec ompr e s s e do rdi l a t e d. Ac t i o nsc a nber e pe a t e du nde rt hes a meo rd i f f e r e ntc ond i t i ons .Onec a ns t o pt he a c t i o nt or e le f c t . De c i s i o nst ha ta r eda nge r o us , i nf e a s i bl e ,O rune t hi c a li nt her e a l s ys t e mc a nbet a ke ni nt hevi r t ua lwo r l d. Thusc o n t r o l l e de xpe r i me nt a t i o nbe c o me s pos s i bl e ,a ndt h et i med e l a ysi nt hel e a r nl ngl oo pt h r o ught her e a lwo r l da r ed r a ‑ ma t i c a l l yr e d uc e d. I nt her e a lwo r l dt hei r r e ve r s i bi l i t yo fma nya c io t nsa ndt hene e d t oma i n t inhi a g hpe r f o ma r nc eo f t e no ve r r i d et hegoa lo fl e a i ngbypr m e ve n t l nge x pe ime r nt swi t hun t r i e dpos s i bi l i t i e s( " I fi ta i n' tbr o ke, do n' tf i x t) . I nt hev i r t wo r l dyouc a nt r ys t r a t e gi e st ha tyo us us pe c twi l ll e a dt opo orpe r f o r ma nc eo re v e n ( s i mul a t e d)c a t a s t r ophe・ Of t e np us hi ngas ys t e mi nt oe xt r e mec ondi t i onsr e v e a l s mo r ea bouti t ss t r uc t ur ea ndd yna mi c st ha ni nc r e me nt la a d j us t me nt st os uc c e s s f u l s t r a t e g l e S .Vi r t u a lwo r l dsa r et heonl ypr a c t i c a lwa yt oe x pe r i e nc ec a t a s t r o phe i na d va nc eoft her e a lt hi ng.Thusag r e a tde a lo ft het i mepi l o t ss pe ndi nf li g ht s i mul a t o r si sde vot e dt oe xt r e mec o nd i t i onss uc ha se ngi nef a i l ur eo re xpl os i v e d e c o mpr e s s i on. o pl eEx p7 1 e S S Vi r t ua lwo r l dsp r o vi d ehi g h‑ qua l i t yo ut c o mef e e dba c k. I nt hePe Manage me ntFl i ghtSi mul at or( St e r ma n1 988 a ) , f o re xa mpl e ,a nds i mi l a rs ys t e m dy na mi c ss i mul a t i o ns ,pl a ye r sr e c e i vepe r f e c t , i mme di a t e ,und i s t o r t e d,a ndc o m‑ pl e t eout c omef e e d ba c k. I na na f t e moo nonec a nga i nye a r sOfs i mul a t e de x pe r i e n c e . Thed e g r e eo fr a nd o mva r i a t i oni nt hev i r t ua lwo r l dc a nbec o nt r ol l e d. Vi r t ua l wo r l dsof f e rt hel e ne a rg r e a t e rc o nt r olo ve rs t r a t e gy , l e a dt omo r ec ons i s t e ntde c i ‑ s i o nma ki ng, a ndde t e ri mpl e me nt a t i o nf a i l u r ea ndga mepl a y l ng. I nc ont r a s tt ot he r e a lwo r l d, whi c h, l i keabl a c kbox, ha sapo o r l yr e s o l ve ds t uc r t ur e , vi r t ua lwo r l ds c a nbeo pe nbox e swhos ea s s u mpt l O nSa r ef ul l ykno wna ndc a ne v e nbemod i f i e d by血el e a r I l e r . Ⅵr t ua lwor l dsf orl e a ml nga ndt r a i nl nga r eC OmmOn pl a c ei nt hemi l i t a r y ,l n pi l o tt r a i nl ng, 1 npowe rpl a nto pe r a t i ons , a ndi nma nyot he rr e a lt i met a s kswhe r e e xt e c hni c a ls ys t e ms . Vi r t ua lwo r l dsa r ea l s o hu ma no pe r a t o r si nt e r a c twi t hc o mpl c t ur ea nde ngl ne e nngt ha tl e ndt he ms e l ve s c o mmo ni npr o f e s s i o nss uc ha sa r c hi t e 98 3 ) .Theus eofvi r t ua lwo r l dsi nma n‑ t ot heus eofph ys i c a lmode l s( Sc h6 n1 a ge r i a l t a s ks , wh e r et hes i mul a t i o nc o mpr e s s e si nt omi n ut e so rho ur sd yna mi c se x‑ e n ta ndl e s swi de l ya do pt e d・ Ye tt he s e t e ndi ngove rye a r so rde c a de s , i smo r er e c a r ep r e c i s e l yt h es e t t l n g SWh e r ed y n a mi cc o mp l e x l t yl Smostprobl e ma t i c,whe r e t h el e a in m gf e e d b a c k s d e s c i r b e da b o v ea r el e a s t e fe c t i ve , a ndwhe r et hes t a ke sa r e ‑ i " u a l ‑ h i g h e s t . 1. 4. 2 Pi t t al l sofVi r t ualWor l ds Vi r t ua lwo r l dsa r ee fe c t i vewhe nt he ye nga gepe o pl ei nwha tDe we yc a l l e d" r e ‑ ne c t i vet houg ht "a ndwha tSc h6 n( 1 992)c a l l s" r e le f c t i vec onve r s a t i o nwi t ht he s i t ua t i on. "Thou g hs i mul a t i o nmo de l sa ndvi r t ua lwor l dsma ybene c e s s a r yf o r e fe c t i vel e a ml ngi ndy na mi c ll a yc o mpl e xs ys t e ms , t he ya r enots uf f i c i e n tt oo ve r ‑ l s ,a ndg r ou p c o met hef la wsi nou rme nt a lmod e l s ,s c i e nt i f i cr e a s onl ngS ki l pr O C e S S e S ・ 36 P a r tI P e r s p e c t i v ea n dP r oc e s s Obvi ous l y, whi l et hev i r 山a lwor l de na bl e sc on t r ol l e de x pe r i me nt a t i o n, i tdoe s notr e qul r et hel e a r ne rt oa ppl yt hep r l nC i pl e sofs c i e nt i f i cme t ho d. Ma nypa r t i c i ‑ pa n t si ns ys t e mdy na mi c spr o j e c t sl a c kt r a i nl ngl ns c i e nt if i cme t ho da n da wa r e ne s s o ft hepi t f a l l si nt hed e s i gna ndi nt e r pr e t a t i o no fe x pe r i me nt s . Ac o mmo nl yob‑ s e r v e dbe ha vi o ra mongmo d e l e r sa ndi nwo r ks ho psus i ngma na g e me n tf li g hts i m‑ ul a t o r si st hevi d e oga mes y nd r o mei nwhi c hpe opl epl a yt o omuc ha ndt hi nkt oo l i t t l e. Pe o pl eof t e ndono tt a ket i met or e le f c to nt heou t c o meofas i mu l a t i o n, i de n‑ t i f ydi s c r e pa nc i e sbe t we e nt heo ut c ome sa ndt he i re x pe c t a t i o ns ,f o r mul a t ehy‑ pot he s e st oe x pl a i nt hed i s c r e pa nc i e s , a ndt he nde vi s ee xpe r i me n t st odi s c r i mi na t e a mo ngt hec o mpe t l nga l t e ma t i ve s . Efe c t i vel e a m1 ngus i ngS ys t e md y na mi c swi l l o f t e nr e qul r et r a i n i ngf o rpa r t l C I Pa nt Si ns c i e nt i f i cme t ho d. Pr ot o c o l sf o rt heus eo f r e ,s uc ha ske e pi ng s i mul a t i o nss ho ul dbes t r uc t u r e dt oe nc o ur a gepr o pe rpr oc e du l a bo r a t o r yno t e bo o ks , e x pl i c i t l yf o r mul a t i ngh ypo t he s e sa ndpr e s e nt l ngt he mt ot he gr ou p,a nds oo n. De f e ns i ver o ut ine sa ndg r ou pt hi n kc a no pe r a t ei nt hel e a ml ngl a bo r a t o r yJ us t a si nt her e a lo r ga ni z a t i o n. I nd e e d, pr ot oc o l sf o re fe c t i vel e a r nl ngl nV i r t ua lwo r l ds s uc ha spubl i ct e s t i ngO fhy pot he s e s ,a c c o unt a bi l i t y ,a ndc o mpa r i s o no fd i fe r e nt s t r a t e gl eSC a nbehi g hl yt h r e a t e nl ng,i nduc i ngde f e ns i ver e a c t i o nst ha tp r e v e nt l e a i ng( m I s a a c sa ndSe nge1 992 ) . Theus eofs ys t e md yna ic m st os t i mul a t el e a r n‑ 1 ngl nO r ga ni z a t i o nso f t e nr e q ul r e Sme mbe r soft hec l i e ntt e a mt os pe ndt i mea d‑ d r e s s l ngt he i ro wnde f e ns i vebe ha v i o r .Ma na ge r suna c c us t o me dt odi s c i pl i ne d s c i e nt i f i cr e a s o ni nga nda no pe n, t us r t i nge nvi r onme ntwi t hl e rn a i nga Si t sgo lWi a l l ha vet obui l dt he s eba s i cs ki l l sbe f or eas ys t e md yna mi c smode l 10 ri nd e e d,a ny mode l ‑c a np r o veus e f ul . De ve l o pl ngt he s es ki l l st a ke se f f o r ta n dpr a c t i c e . St i l l ,s e t t l ngSWi t hh i g hd yna i cc m ompl e xl t yC a nga r bl et her e le f c t i vec o nve r ‑ s a t i o nbe t we e nt hel e a r ne ra ndt hes i t ua t i on. Lo ngt l med e l a ys , C a us e sa nde fe c t s t ha ta r ed i s t a nti nt i mea nds pa c e ,a n dt hec onf o und i nge fe c t so fmul t i pl eno li n n‑ e a rf e e dba c ksc a ns l o wl e a ml nge v e nf o rpe o pl ewi t hgo odi ns i ghta ndg r o up pr oc e s ss k i l l s .Le a r n l ngl nVi r t ua lwor l dsc a nbea c c e l e r a t e dwhe nt hemod e l i ng pr oc e s sa l s ohe l pspe o pl el e a nho wt or e pr e s e ntc o mpl e xf e e d ba c ks t r uc t ur e sa nd und e r s t a ndt he i ri mpl i c a t i onsr a t he rt ha ns i mpl ypr e s e nt l ngt her e s ul t so fa na na l y‑ s i s . Tol e a ni ndyna mi c a l l yc ompl e xs ys t e mspa r t l C I Pa nt Smus tha v ec o nf i d e nc e t ha tt hemod e li sa na ppr o pna t er e pr e s e nt a t i onoft h epr obl e mt he yc a r ea bo ut 。 The ymus tbe l i e vei tmi mi c st her e l e va ntpa r t soft her e a lwor l dwe l le no ug ht ha t t hel e s s onse me r g i ngf r o mt hev i r t ua lwo r l da p pl yt ot her e a lo ne . Tode v e l o ps uc h c onf i de nc et hevi r t ua lwo r l dmus tbea no pe nboxwhos ea s s umpt i o nsC a nbei n‑ s pe c t e d, C r i t i c i z e d, a ndc ha ng e d. Tbl e a n, p∬t l C l pa nt Smus tbe c o memod e l e r s , no t me r e l ypl a ye r si nas i mul a t i o nga me . I npr a c t i c e ,e f f e c t i v el e a r ni ngf r o m mode l soc c ur sbe s t ,a ndpe r ha pso nl y , whe nt hede c i s i o nma ke r spa r t l C l pa t ea c t i ve l yi nt hede v e l o pme nto ft hemod e l . Mod e l i nghe r ei nc l ud e st hee l i c i t a t i o noft hepa r t i c l pa nt S ' e xi s t l ngme n t a lmod e l s , i nc l ud i nga r t i c u l a t i ngt h ei s s ue s( pr o bl e ms t r u c t ur i ng) , s e l e c t i ngt hemod e lbo und‑ a r ya ndt i meho r i z o n,a ndma ppl ngt hec a us a ls t r uc t ur eoft her e l e va nts ys t e m. Al o ngwi t ht e c hni q ue sde ve l o pe di ns ys t e m dyna mi c s , ma nyt o ol sa ndp r o t o c ol s f org r o upmode l ‑ bui l di nga r eno wa va i l a bl e ,i nc l udi ngc a us a ll oo pd i a g r a ms , pol i c ys t r uc t ur edi a g r a ms ,i nt e r a c t i vec omput e rma ppl ng,a ndva r i o usp r o bl e m s t r uc t ur i nga nds o 氏s ys t e msme t ho ds( s e e, e. g. , Che c kl a nd1 981 ; Ede n, J o ne sa nd Cha pt e r1 Le a ml ngl na nda boutCompl e xSys t e ms 37 Si ms1 983;La n e1 9 9 4;Mo r e c r of t1 98 2;Mor e c r o f ta ndSt e r ma n1 99 4;Re a ga n‑ Ci r i nc i onee ta l ・1 991 ;Ri c hmo nd 1 98 7,1 993;Ros e nhe a d1 98 9;Se ng ea nd St e r ma n1 992; a ndWo l s t e n hol me1 9 90) . 1, 4, 3 WhySj muZ at i ont sEssent はI El i c i t i nga ndma ppi ngt hepa r t i c I Pa n t S ' me n t a lmode l s , whi l ene c e s s a r y , i sf a rf r o m s uf f i c i e nt . Asd i s c us s e da bo ve , t het e mpo r a la nds pa t i a lbo unda r i e sofo u rme nt a l , mode l st e ndt ob et oona r r o w. The ya r ed yna mi c a l l yd e f i c i e nt , o mi t t i ngf e e d ba c ks t i mede l a ys , a c c umul a t i o ns , a ndno nl i ne a r i t i e s . Theg r e a tv i r t ueo fma nyp r o t o c o l s a ndt ool sf o re l i c i t a t i o ni st he i ra bi l i t yt oi mpr o veo urmode l sbye nc o ur a gl ngPe o‑ pl et oi de nt i f yt h ee l e me nt so fdy na mi cc o mpl e xl t yno r ma l l ya bs e ntf r o mme n t a l mode l s .Howe v e r ,mos tpr o bl e ms t r uc t ur l ngme t hodsyi e l dq ua l i t a t i vemo de l s s howi ngc a us a l r e l a t i o ns hi psbu to mi t t l ngt hepa r a me t e r s , f unc t i o na lf o r ms , e xt e r na li n put s ,a ndi ni t i a lc o nd i t i o nsne e de dt of ul l ys pe c i f ya ndt e s tt hemod e l .Re ‑ ga r d l e s so ft hef o r moft hemo d e lo rt e c hni q u eus e d, t her e s ul to ft hee l i c i t a t i o na nd ma ppi ngpr o c e s si sne ve rmo r et ha nas e to fc a us a la t t r i but i ons , i ni t i a lhy po t he s e s a bo utt hes t r uc t u r eo fas ys t e m, whi c hmus tt he nbet e s t e d. Si mul a t i o ni st heo nl ypr a c t i c a lwa yt ot e s tt he s emode l s ・ Thec o mpl e x l t yOf ou rme nt a lmod e l sva s t l ye xc e e dso u rc a pa c i t yt Ounde r s t a ndt he i ri mpl i c a t i o ns . T y pi c lc a onc e pt ua l mode l ss uc ha st het y peo fc a us a ldi a g r a ms howni nFi g u r el 1 6 a r et ool a r gea ndc o mpl e xt os i mu l a t eme nt a l l y . Wi t ho uts i mul a t i on, e ve nt hebe s t c o nc e pt ua lmod e l sc a no nl ybet e s t e da ndi mpr ove dbyr e l yi ngo nt hel e a r n l ng f T e e d ba c kt hr oug ht her e a lwo r l d. Asweha ves e e n, t hi sf e e dba c ki sve r ys l o wa nd of t e nr e nde r e di ne fe c t i vebyd yna mi cc o mpl e xl t y ,t i mede l a ys ,i na d e q ua t ea nd a mbi guousf e e d ba c k,poo rr e a s o ni ngS ki l l s ,de f e ns i ver e a c t i ons ,a ndt hec os t sof e x pe r i me nt a t i o n. I nt he s ec i r c ums t a nc e ss i mul a t i o nbe c ome st heo nl yr e l i a bl ewa y t ot e s thypo t he s e sa nde va l ua t et hel i ke l ye fe c t sofpol i c i e s . So mes c ho l a r sa r g uet ha tf o r ma lmod e l i ngc a na tbe s tpr o vi deq ua nt i t a t i ve pr e c i s i o nwi t hi npr e e xi s t l ngP r o bl e mde f i ni t i o nsbutc a nno tl e a dt of u nda me nt a l l y ne wc o nc e pt i ons( f o rva r i o usvi e wss e eDr e y f usa ndDr e yf us1 98 6a ndt hed i s c us I s i c ‑ ni nLa ne1 9 9 4) .Ont hec o nt r a r y ,f o r ma li z i ngqua l i t a t i vemode l sa ndt e s t i ng t he mv i as i mul a t i ono f t e nl e a dst or a di c a lc ha nge si nt hewa yweun de r s t a n dr e a レ 1 t y.Si mul a t i ons pe e dsa nds t r e ngt he nst hel e a r ni ngf e e dba c ks .Di s c r e pa nc i e s be t we e nf o r ma la ndme nt a lmode l ss t i mul a t ei mpr o ve me nt si nbo t h,i nc l udi ng c ha nge si nba s i ca s s u mpt l O nSS uc ha smo de l bo unda r y , t i meho r i z on, a ndd yna mi c hy po t he s e s( s e eFo r r e s t e r1 98 5a ndHo me r1 996f o rphi l os o phya nde xa mpl e s ) ・ her l gO r O uSt e S t l nge na bl e dby Wi t houtt hed i s c i pl i nea ndc o ns t r a i nti mpos e dbyt l st obed r i ve nbyi d e ol o g yo r s i mul a t i o n, i tbe c ome sa l lt o oe a s yf わrme nt a lmode un c o ns c i o usbi a s . l e rt oo mi ti mpo r t a nta s pe c t so f So mea r g uet ha tf o r ma l i z a t i o nf o r c e st hemode t hepr obl e mt op r e s e r vet r a c t a bi l i t ya nde na bl et he o r e mst obepr o ve do rt oo mi t The s ea r ei nde e dda nge r s . Thel i t ‑ s o f tva r i a bl e sf T o rwhi c hnon u me r i c a lda t ae x i s t . l si nwhi c he l e ga n tt he o r e msa r e e r a t ur eoft hes o c i a ls c i e nc e si sr e pl e t ewi t hmode i c i t ydo mi na t e sut i l i t y ,a ndwhe r e de r i ve df r omq ue s t i o na bl ea x i o ms , whe r es i mpl va r i a bl e sknownt obei mpo r t a n ta r eI g no r e dbe c a us eda t at oe s t i ma t epa r a me t e r s a r euna va i l a bl e.Sys t e m dy na mi c swa sde s i gne ds pe c i f i c a l l yt oove r c o met he s e ‑ 38 P a r t IP e r s p e c t i v ea n dP r o c e s s l i mi t a t i onsa ndf r om t hebe gi nnl ngS t r es s e dt hede ve l o pme ntofus e f ulmode l s ; mode l sunc o ns t r a i ne dbyt hede ma ndsofa na l yt i ct r a c t a bi l i t y , ba s e donr e a l i s t i ca s ‑ o r , gr ounde di nf i e l ds t udyofde c i s i onma ki ng,a nd s umpt i onsa bo uthuma nbe ha vi ut i l i z l ngt hef ul l r a ngeofa va i l a bl eda t a , notonl ynume r i c a lda t a , t os pe c i f ya nde s t i ma t er e l a t i ons hi ps( s e eFo r r es t e r1 961 ,1 98 7) ・ Somepe o pl edon' tbe l i e vet ha tmode l sofhuma nbe ha vi orc a nbede ve l o pe d. Si mul a io t nsofna t ur a la ndt e c hni c a ls ys t e mss uc ha st hec l i ma t eora noi lr e f i ne r y ‑ unde r s t oodl a wsofphys i cs ,but ,i ti sa r gue d,t he r ea r enoc om‑ a r eba s e donwel pa r a bl yr e l i a bl el a wsofhuma nbe ha vi or . Thi svi e wove r e s t i ma t e sourunde r s t a nd‑ 1 ngOfna t ur ea ndunde r e s t i ma t est her e gul a r i t i e si nhuma nde c i s i onma ki ng. As , H Anyt hi ngt ha te xi s t si spos s i bl e・ MYouwi l ls e ema ny Ke nne t hBoul di ngpol nt SOut e xa mpl e sofmode l sofhuma ns ys t e mst hr oughoutt hi sbook( s e ea l s ot hemode l s i nLe vi nea ndFi t z ge r a l d1 992; Robe r t s1 978; La ngl e ye ta l ・1 98 7; St e ma n1 985a; Home r1 985;a ndma nyoft hemode l sc i t e di nSa s t r ya ndSt e ma n1 993) . I si tpos s i bl et ol e a r ne fe c t i ve l yi nc ompl e xs e t t i ngsWi t ho uts i mul a t i on?Ca n t heus eofpr o bl e ms t r uc t ur l ngme t hods ,e l i c i t a t i ont e c hni ques ,a ndot he rqua l i t a ‑ t i ves ys t e msme t hodsove r c omet hei mpe di me nt st ol e a r ni ng?I fi nt ui t i oni sde ve l ‑ ope dhi ghl ye no ugh,i fs ys t e mst hi nki ngl Si nc or por a t e di npr e c ol l e gee duca t i on e a r l ye nough,o ri fwea r et a ughthow t or e c ognl Z eaS e tOfH s ys t e ma r c he t ype s H ( Se nge1 990) ,wi l lwebea bl et oi mpr oveouri nt ui t i ona boutc ompl e xdyna mi cs e nought or e nde rs i mul a t i onunne c e s s a r y? Thea ns we ri sc l e a r l yno. I ti st r uet ha ts ys t e mst hi nki ngt e c hni ques , i nc l udi ng s ys t e m dyna mi c sa ndqua l i t a t i veme t hodss uc ha ss of ts ys t e msa na l ys i s ,C a ne n‑ ha nc eouri nt ui t i ona boutc ompl e xs i t ua t i ons , J us ta ss t udyi ngphys i csca ni mpr ove o uri nt ui t i ona boutt hena t ur a lwor l d. 1 4AsWol s t e nhol me( 1 990)a r gue s , qua l i t a t i ve s ys t e mst ool ss houl dbema dewi de l ya va i l a bl es ot ha tt hos ewi t hl i mi t edma t he一 ma t i c a lba c kgr o undc a nbe ne f i tf r om t he m.Ia m as t r onga dvoc a t ef ort hei nt r o‑ duc t i onofs ys t e m dyna mi c sa ndr e l a t e dme t hodsa ta l ll e ve l soft hee duca t i ona l s ys t e m. Ye te ve ni fwea l lbe ga ns e r i o uss t udyofphys i csi nki nde r ga r t e na ndc on‑ t i nue di tt hr oughaPh. D. ,i ti sl udi c r oust os ugges tt ha twec oul dpr e di c tt het r a c k ofahur r i c a neorunde r s t a ndbyi nt ui t i ona l onewha tha ppe nswhe nt woga l a xi es c ol l i de.Ma nyhuma ns ys t e msa r ea tl e a s ta sc ompl e x・Eve ni fc hi l dr e nl e a r nt o t hi nki ns ys t e mst e r ms ‑ agoa llbe l i e vei svi t a l l yI mpor t a nt ‑i twi l ls t i l lbene c ‑ es s a r yt ode ve l o pf or ma lmode l s ,s ol ve dbys i mul a t i on,t ol e a r na bouts uc hs ys ‑ t e ms . ‑ l Mos ti mpo r t a nt , whe ne xpe r i me nt a t i oni nr e a ls ys t e msi si nf e a s i bl e, s i mul a t i on fhow be c omest hema i n,a ndpe r ha pst heonl y,wa yyouc a ndi s co ve rf oryoursel sr ot el e a r nl ngba s e dont heaut ho r i t yof c ompl e xs ys t e mswor k. Thea l t e r nativei t het ea c he ra ndt e xt book, ame t hodtha tdul l sc r e a t i vl t ya nds t unt st hedevel opme nt oft hes c i e nt i f i cr e a s onl ngS ki l l sneede dt ol e a r na boutc o mpl e xi t y. ed e d . Wh e na s k e dt h eq u e s t i o nH I fap e ni s 1 4 s u c hk n o wl e d g eo f b a s i cp h y s i c si sd e s p e r a t e l yn e d r o p p e do nt h emo o n , wi l l i t( a ) no a t a wa y ; ( b )f l o a t wh e r ei t i s ; ( C )f a l l t ot h es u r f a c eo ft h e mo o n ? H48o u t o f168S t u d e n t si np h y s i c sc o u r s e sa t i o waS t a t eUn i v e r s l t yg a v ei n c o r r e c t a n s we r s ・ T y p i c a l s t u d e n t e x p l a n a t i o n swe r e" Th eg r a v l t yO ft h emo o nc a nb es idt a ob en e li g g i b l e "a n d" Th e , mo o n ' sav a c u u m, t h e r ei sn oe x t e na r l f o r c eo nt hep e n・ Th e r e f o r ei t il w l lo f a t wh e r ei t i s . "( Pa r t e e p e r s o n a l c o mmu n i c a t i o n ,1 992) . Ch a p t e r1 Le a r n i n gl na n da b o u t Co mp l e xS y s t e ms 39 Thei mpl i c a t i onsf ort hi sbooka r ec l e a r .Sys t e m dyna mi csi snotas pe c t a t or s por t :Thr ougho utt hebookIha vet r i e dt oe nc our a get hea c t i vepa r t i c l pa t i onof you,t her e a de r ・ Youwi l lf i ndCha l l e ngesi nea c hc ha pt e r ‑exa mpl e sf oryout o c ons i de ra ndwo r kt hr oughyour s e l f ,s uc ha st hec hi c ke na nde ggc a us a ll oo pdi a ‑ gr a mi nFi gur e1 ‑ 6a ndt heWas onca r dpuz z l ei nFi gur eト1 3.Someoft hes ea r e f ol l owe dbyas ugge s t e dr e s pons e. Ot he r sa r enot . Asyouwo r kt hr o ught hebook, e xt e ndt hee xa mpl es . Bui l dt hemode l s ・ Expe r i me ntwi t ht he m. Appl yyours ki l l s t one wpr obl e msa ndne wi s s ue s ・ And,mos tofa l l , ha vef un・15 1. 5 SuMMARY Compl e xdyna mi cs ys t e mspr es e ntmul t i pl eba r r i e r st ol e a r nl ng. Thec ha l l e ngeof be t t e r l ngt hewa ywel e a na boutt he s es ys t e msi si t s e l fac l a s s i cs ys t e mspr obl e m. Sys t e m dyna mi c si sapowe r f ulme t hodt oga l nus e f uli ns i ghti nt os i t ua t i onsof dyna mi cc ompl e xl t ya ndpol i c yr e s i s t a nc e.I ti si nc r ea s l ngl yus e dt odes i gnmor e s uc c e s s f ulpol i c i e si nc ompa ni esa ndpubl i cpol i c ys e t t l ngS .Howe ve r ,noone me t hodi sapa na c ea .Ove r c oml ngt heba r r i e r st ol e a r nl ngr e qul r e SaS ynt hes i sof ma ny me t hodsa nd d i s c i pl i ne s ,f r om ma t he ma t i c sa nd c omput e rs c i e nc et o ps yc hol ogya ndor ga ni z a t i o na lt he o r y. The or e t i c a ls t udi esmus tbei n t e gr a t e dwi 仙 f i e l dwor k・I nt e r ve nt i onsi nr ea lo r ga ni z a ionsmus t tbes ub j e c t e dt or i gor ous f ol l ow‑ upr e s e a r c h. Thef i e l dofs ys t e mdyna mi c si si t s e l fdyna mi c. Re c e nta d va nc e si ni nt e r a c t i ve mode l i ng,t ool sf orr e pr e s e nt a t i onoff e e dba c ks t r uc t ur e,a nds i mul a t i ons of t wa r e ma kei tpos s i bl ef o ra nyonet oe nga gei nt hemode l i ngpr oc es s . Cor po r a t i ons , uni t ve r s i t i es ,a nds c hool sa r ee xpe r i me nt l ngVl gOr OuS l y・ Thel i br a r yofs uc c es s f u ll n‑ t e r ve nt i onsa ndi ns i g ht f ulr e s e a r c hi sgr owl ng. Muc hf u r t he rwo r ki sne e de dt ot es t t heut i l i t yoft het ool sa ndpr ot oc ol s , e va l ua t et he i ri mpa c toni ndi vi dua la ndor ga ‑ ni z a t i ona ll e a r ni ng,a ndde ve l ope fe c t i vewa yst ot r a i not he r st ous et he m. Ne ve r be f br eha vet hec ha l l e nge sofouri nc r e a s i ngl ydyna mi cwor l dbe e nmor eda unt l ng. Ne ve rbe f or eha vet heo ppor t ni u t i esbe e ngr e a t e r . I t ' sa ne xc l t l ngt i met Obel e a r n‑ 1 ngl na nda bo utc ompl e xs ys t e ms . 1 5 Th ea c c o mp a n y i n gCD‑ ROMa n dwe b s l t e( h t t p : / / www. mh h e . c o I 〟s t e r ma n ) i n c l u d et h emo d e l s d e v e l o p e di nt h et e x t a n ds i mu l a t i o ns o f t wa r ey o uc a nu s et or u na nde x t e n dt h e m. Sぎ § 書 e ‑ 三 ? ̲ ‑ 呈互 き き 一 語員 i 3 ̲ t i 主 だ §言 訳Ae 喜 i L l 呈 呈 l S y s t e md y n ami c s ]i san a ppr o ac ht hats houl d he l pi ni mpor t antt o p‑ man age me n tpr obl e ms...Thes ol u t i o nst os mal lpr o bl e msyi e l ds mal l r e way ds .Vef To f t e nt hemos ti mpor t ant p7 1 0bl e msar ebu tl i t t l emor edl Mi c ul tt o ha ndl et h ant h eu ni mpor t ant . Man yl pe o pl e ]pr e de t e r mi neme di o c r er e s ul t sb y s e t t i n gi ni t i a l go al st ool ow.Theat t i t u demu s tbeoneo fe nt e r pr i s ede s i gn.The e x pe c t a t i o ns houl dbef orma j ori mpr ov e me nt...Theat t i t u d et hatt hegoali s t oe x pl ai nb e hav i o7 3Whi c hi sf ai r l yc o mmo ni nac a de mi cc i r c l e s ,i snot s u j f i c i e nt .T h ego als houl dbet of t ' ndma na ge me nt pol i c i e sa n dor gani z at i onal s t r u c t ur e st h atl e a dt ogr e at e rs u c c e s s . ‑J a yW. F o r r e s t e r( I n d u s t r i a l Dy n a mi c s ,1 961 , p. 449) . Thi sc ha pt e rpr e s e nt st hr e ec a s es t udi e soft hes uc c e s s f ula ppl i ca t i onofs ys t e mdy‑ na mi cst os o l vei mpor t a ntr e a lwor l dpr o bl e ms . Thec a s ess pa nar a ngeofi ndus ‑ t r i e sa ndi s s ue s . The yi l l us t r a t edi f f e r e ntc ont e xt sf ort heus eofs ys t e m dyna mi cs a nddi f f e r e ntmo d e l i ngpr oc e s s e s , f r oml a r ge , da t ai nt e ns i vemode l st os ma l lmod‑ e l s ,1 nt e r a C t i vema na ge me ntf li ghts i mul a t or s ,a ndr ol e ‑ pl a yl ngga me s . Thec a s e s i l l us t r a t ehows ys t e mdyna mi csc a nbeus e dt ohe l ps ol vehi gh‑ s t a ke spr obl e msi n r e a lt i me. Thec a s esi l l us t r a t e血epr l nC i pl esdi s c us s e di nc ha pt e r1a ndpr e vi e w ma nyoft het ool sa ndme t hodsdi s c us s e di ns ubs e que ntc ha pt e r s . 2. 1 AppLI CAT! ONSOFSysTEM DYNAMI CS S ys t e mdyna mi c sha sbe e na ppl i e dt oi s s ue sr a ngi ngf r omc or por a t es t r a t e gyt ot he dyna mi c sofdi a b e t es ,f r om t hec ol dwa ra r msr a c ebe t we e nt heUSa ndUSSRt o t hec omba tbe t we e nHI Va ndt hehuma ni mmunes ys t e m. Sys t e mdyna mi csca nbe 41 42 Pa r t I P e r s p e c t iv ea n dP r oc e s s a ppl i e dt oa nydyna mi cs ys t e m,wi t ha nyt i mea nds pa t i a ls ca l e.I nt hewor l dof bus i ne s sa ndpubl i cpol i c y,s ys t e m dyna mi c sha sbee na ppl i edt oi ndus t r i e sf r om a i r c r a f tt oz i nca ndi s s ue sf r omAI DSt owe l f a r er e f or m. l De ve l opl nga ni ns i ght f ulmode li sdi f f i c ul te nough;us l ngmode l i ngt ohe l p c ha ngeor ga ni z a t i onsa ndi mpl e me ntne wpol i c i e si se ve nha r de r . Thegr e a t e s tpo‑ t e nt i a lf o ri mpr ove me ntc omeswhe nt hemode l i ngpr oc es sc ha ngesde e pl yhe l d me nt a lmode l s .Ye tt hemor ef unda me nt a lt heme nt a lmode lyouc ha l l e nge,t he mor ede f e ns i vet hec l i e ntma ybe. Tor e s ol vet hedi l e mmat hec l i e nt smus tdi s c ove r t hei ns i ght sf o rt he ms e l ve sbya c t i vepa r t i c l pa t i oni nt hemode l i ngpr oc e s s . Thi sc ha pt e rpr es e nt st hr e ec a s es t udi esi l l us t r a t l ngt hepr oc es s .Ea c ha d‑ d r e s s e da ni mpor t a ntr e a lwor l di s s ue. Ea c hi nvol ve dadi fe r e ntc ont e xta ndt he r e ‑ f o r eus e dadi fe r e nta ppr oa c h・ Ye te a c ha l s os uc c e e de di ni nvol vi ngt hec l i e nt sa s pa r t ne r si nt hemode l i ngpr oc e s s , i nc ha ngl ngl ong‑ es t a bl i s he dme nt a lmode l s , a nd i nge ne r a t l ngS i gni f i c a ntbe ne f i t . 2. 2 AuTOMOBI LELEASI NG STRATEGY: , GoNEToDAY i lEREToMORROW2 I nt he1 990sane w wa yt obuyc a r se me r ge di nt heUni t e dSt a t es ‑t heus e dc a r s upe r s t or e. Na t i ona lc ha i nsl i keCa r Ma xa ndAut oNa t i o nofe r e dal a r ges e l e c t i on ofc l e a n,l owmi l e a gel a t emode lc a r swi t hwa r r a nt i e s , r oa ds i dea s s i s t a nc epl a ns , a ndot he ra me ni t i e st r a di t i ona l l ya va i l a bl eo nl yt one wc a rbuye r s . Supe r s t o r es a l e s gr e wf r om not hi ngi n1 992t omo r et ha n$1 3bi l l i oni n1 998.I nt e r ne tc a rve ndo r s be ga nt os pr l ngupa SWe l l . Ma nya na l ys t sbe l i e ve dt hec ombi na t i onofs upe r s t o r e s a ndi nt e r ne ts a l e she r a l de dar e vol ut i o ni nt her e t a i la ut oma r ke t . I n1 995S omes e ni orma na ge r sa tGe ne r a lMot o r swe r ec onc e r ne da bo utt he i mpa c toft hes upe r s t o r e sonne wc a rs a l e s ・ Woul dt he yc uti nt oGM' sc or ema r ke t ? Woul dt he yf or c epr l C eSdown?Howc oul dGM r e s pond?RonZa r e l l a ,t he nvi c e pr e s i de nta ndgr oupe xe c ut i vef o rNo r t hAme r i c a nve hi c l es a l es ,s e r vi c e ,a ndma r ke t i ng( VSSM)a ndl a t e rpr omot e dt opr e s i de ntofGM' sNor t hAme r i c a nr e gi on, ne e de dawa yt oe xa mi net he s ei s s ue s . The r ewa sl i t t l er es e a r c hont heus e dc a rma r ke ta va i l a bl et ohe l p.Forma ny de c a de st hene wa ndus e dc a rma r ke t swe r eonl yl oos e l yc oupl e dbe c a us epe o pl e t e nde dt okee pt he i rc a r sal ongt l me. Ma r ke tr e s ea r c hi nt hee a r l y1 990ss howe d ne wc a rbuye r swe r eke e pl ngt he i rca r sa na ve r a geofmor et ha n6yea r s ・ Thebul k ofus e dc a r sof f e r e df ors a l ewe r e40rmo r eye a r sol da ndwe r epoo rs ubs t i t ut e sf or ne wc a r s .Thepr e va i l i ngme nt a lmode li nt hea ut oi ndus t r y,I nc l udi ngGM,wa s ‑ l Ri c h a r d s o n( 1 9 9 6 ) , Ro b e r t s( 1 9 7 8 ) , a n dMo r e c r o f t a n dS t e r ma n( 1 9 9 4 ) , a mo n go t h e r s , p r o v i d e e x a mp l e so ft h ea p p l i c a t i o no fs y s t e md y n a mi c st oi mp o r t a n t p r o b l e msi nawi d er a n g eo fi n d u s t r i e s a n dp u b l i cp o l i c yi s s T e s ・ Mo s e k i l d e( 1 9 9 6 )d e s c r i b e sa p p l i c a t i o n si np h y s i c sa n db i o l o g y ・ F o r d ( 1 9 9 9 ) d e s c r i b e se n v l r O n me n t a l a p p l i c a t i o n s . 2 Th i sc a s ei sb a s e do nt h ewo r ko ft h eGe n e r a l Mo t o r sS t r a t e g yS u p p o r t Ce n t e r ,l e db yNI C k P u d a r . Ⅰ ' mg r a t e f u l t oNi c ka n dGMf o r p e r mi s s i o nt op r e s e n t t h ec a s ea n dt oNi c ka n dMa r kP a i c h f o rh e l pl ni t sp r e p a r a t i o n . Ch a p t e r2 S y s t emD y n a mi c si nAc t i o n 43 t ha ta ut oc ompa ni eswe r ei nt hebus i ne s sofs e l l i ngne wc a r s ;t heve hi c l e spe o pl e t r a de di nwe r eo l da nde f f e c t i ve l ydi s a ppe a r e di nt oas e pa r a t es ys t e m, t heus e dc a r "t hee xe c ut i vedi r e c t orof ma r ke t .H The r ea r er e a l l yt woma r ke t s 一me wa ndus e d, s a l esope r a t i onsa tFo r dt ol dTheWal lSt 7 1 e e tJ our nali n1 994( 3J une, p. Bl ) . Za r e l l ac on t a c t e dVi nc eBa r a bba ,t he nge ne r a lma na ge rofc or por a t es t r a t e gy a ndknowl e dgede ve l opme nti nt heVSSM o r ga ni z a t i on,a nddes c r i be dhi sc on c e ms . Ba r a bba , f o r me rhe a doft heUSCe ns usBur e a u, a l s ohe a de dupt heDe c i s i on Suppor tCe nt e r( DSC)a nda s ke dNi c kPuda r , t he nas e ni orbus i nes sa na l ys ti nt he DSC, t owor ko nt hes upe r s t or ei s s ue. TheDSCi sa ni nt e r na lgr oupGM f o r me dt o he l pbus i ne s suni t sa ndpr o j e c tt e a mst hr oughoutt hec ompa nyde ve l opa ndi mpl e ‑ me nts t r a t e gy.TheDSCus esava r i e t yofa na l yt i c a lt ool s ,i nc l udi ngs ys t e m dy‑ na mi c s .Mor et ha ns i mpl yagr oupofa na l yt i c a lmode l e r s ,t heDSCde ve l o pe da s o phi s t i c a t e da p pr oa c h, t hedi a l oguede c i s i onpr oc es s , des i gnedt obui l dc ons e ns us t ha tl e a dst oa c t i on, notme r e l ya na l ys i sa ndr e por t s ・ Ba r a bbaa ndPuda r( 1 996)de ‑ s c r i bet hedi a l og uede c i s i onpr oc es sa s ‑ ri e so fs t r u c t u r e dd i a l ad i s c i pl i n e dd e c i s i o nma k i ngp r o c e s swh i c hi n v o l v e sas e l o g u e sb e t we e nt wog r o u psr e s po ns i bl el brr e a c h i ngad e c i s i o na n di mpl e me n t l n g t h er e s u l t i n ga c t i o np l a n・ Thef i r s tg r o u p( De c i s i o nRe v i e wBo a r d )c o ns i s t so ft h e d e c i s i o n‑ ma k e r s , wh og e n e r a l l yr e p r e s e n td i f f e r e n tf u n c t i o ns . h a W tt h e yha v ei n c o mmo ni st h ea ut ho r i t yt oa l l o c a t er e s o u r c e s : p e o p l e , c a pl t a l , ma t e r i a l s , t l me , a n d e q u i pme n t. . . Thes e c o ndg r o u p( Co r eTe a m) , c o ns i s t so fH. t h os ewi t has t a kei n t h ei mpl e me nt a t i o n. Thed i a l o g u ebe t we e n血et wog r o u ps , wh i c hi n vo l v e ss ha r i nga ndl e a r n l n gf o r bo t h, t a ke spl a c ei nf o u rs e q u e n t i a ls t a g e s :1 )f r a mi n gt h ep r o bl e m; 2 )d e v e l o p i n g a l t e r n a t i v e s ; 3 )c o n d u c t i ngt h ea na l ys i s ; a n d4)e s t a b l i s h i ngc o n ne c t i o n・ Ea c ho f t h e s ef o u rs t e p si sc o mpl e t e db yt heCo r eTe a ma n ds u p po r t e db yf a c i l i t a t o r s e q u l p pe dwi t hd e c i s i o na n a l y t i ct o o l s ・ Att h ee n do fe a c hp ha s e , t h e yha v ead i a ‑ l og u es e s s i o nwi t ht h eDe c i s i o nRe v i e wBoa r dwhe r et he yJ O l n t l yr e vi e wt he p r o g r e s s ・ I na na t mos p he r eo fi nq u i r y・ ‑S e n i o rl e a d e r s h i pc o nv e r s e swi t hac r o s s ‑ f un c t i o na lt ea mo fma na g e r so nat o pi cO fmu t ua ls t r a t e g l Ci mp o r t a n c e ・ Puda rt ol dZa r e l l ahewoul dne e dt oc ommi tt oas e ve r a lhourme e t i nge a c hwe e k f o ramon血 H t obes ur ewea r ewor ki ngont her i g htpr obl e m. "Whi l eZa r e l l a ' s s c he d ul ewa se xt r e me l yt i ghtheof f e r e dt ome e twi t hBa r a bbaa ndPuda rt he ne xtda y. Puda r ,wor k i ngwi t hMa r kPa i c h, a ne xt e r na ls ys t e m dyna mi c sc ons ul t a nta nd pr of e s s o rofe c o nomi c sa tCol or a doCol l e ge , Da r r e nPos toft heDSC,a ndTomPa ‑ t e r s on( a not he rc ons ul t a ntt ot heDSC)s c r a mbl e dt ode ve l o pa ni ni t i a lmode loft he i s s ue. Tha ta f t e r noont he yde ve l ope das i mpl edi a g r a mr e pr e s e nt i ngt hes t oc ksa nd lowsofc f a r st hr ought henew a ndus e dma r ke t sa nds omeoft hef e e dba c kst ha t mi ghtc oupl et h e m.The yde l i be r a t e l yke pti tve r ys i mpl e,bot ht obes ur et he y c o ul dc ompl e t ei ti nt i mea nds ot he yc oul de xpl a i ni tc l e a r l y・ Tha tni ghtPuda rde ve l ope das i mpl e ,wo r ki ngs i mul a t i onmode loft hei nt e r ‑ a c t i onsbe t we e nt hene wa ndus e dma r ke t s .Themode li nc l ude ds e c t or sf or ne wa ndus e dc a r s( di vi de di nt oGM a ndnon‑ GM ve hi c l es )a ndt r a c ke dve hi c l es f r om pr oduc t i ont hr oughi ni t i a ls a l eorl e a s e,t r a de ‑ i n,t heus e dc a rma r ke t ,a nd, 44 Pa r t I P e r s p e c t i v ea n dP r o c e s s ul t i ma t e l y,S c r a ppl ng. I ta l s ot r a c ke dt hef l o wso fc us t o me r smo vl ngI n t oa ndo ut oft hema r ke ta ndi n c l ude das i mpl ec o ns ume rc ho i c emo de lf ort hene w/ us e dpur ‑ c ha s ede c i s i on. Puda rus e dda t aa tha nda ndhi sj udgme n tt oes t i ma t epa r a me t e r s . Fi gur e21 l s howsas i mpl i f i e dd i a gr a m oft hei ni t i a lmo de l .Thes t r uc t ur ei n bl a c kc a pt ur e st hepr e va i l i ngme n t a lmo de lf oc us e do nt hen e wc a rma r ke t . Thel e f t s i det r a c kst hes t o c ksa ndf l o wso fve hi c l e s .St a r t i nga tt het op,t hei nve nt o r yof uns o l dne wc a r si si n c r e a s e dbypr od uc t i o na ndd r a i ne dbyne wc a rs a l e s . Ne wc a r s a l e sa ddt ot hes t oc ko fl a t emode lc a r so nt her oa d・ Pe o pl es e l lo rt r a dei nt he i rc a r a ndbuyane wo newi t haf r e q ue nc yde f ne i dbyt hea ve r a g et r a d e ‑ i nt i me・ a rma r ke t . Fi gur e2‑ 1a l s os howst hema i nf e e dba c kso pe r a t i ngi nt henewc Ma n uf a c t ur e r sa ndde a l e r spa yc l os ea t t e nt i o nt ot hes t o c ko fne wc a r s Jn ve nt o r y c ove r a g eo fa bou t45d a ysp r o vi de sago odba l a nc ebe t we e nt hes e l e c t i o na va i l a bl e onde a l e rl ot sa ndc a r r yi ngc os t s .Lo wc ove r a gehu r t ss a l e sbe c a us ec a r sa r e n' t a va i l a bl e; hi ghi n ve n t o r i e ss l a s hd e a l e ra nda ut o ma k e rpr of i t sa sc a r r y i ngc os t sba l l l oo n. I fi nve nt o r yc o ve r a ger i s e sa boveno r ma l , c a r ma ke r sc utpr od uc t i on,whi c h he l psr e d uc ei nve nt o r i e sba c kt ono r ma l . Ther e s po ns eofpr od uc t i o nt oi nv e n t o r i e s f o r mst hene ga t i ve( ba l a nc i ng )Pr od uc t i onCo nt r o lf e e d ba c kl oo p, B1 . Howe ve r , a ut o ma ke r sa r er e l uc t a n tt oc u tp r od uc t i o na ndi na nyc a s e , i tt a ke st i me . Thed e l a y i na d j us t i ngPr od uc t i o nme a nsi nve nt o r i e st e ndt of luc t ua t ea r o undd e s i r e dl e ve l s a sde ma ndva r i e s . Thes e c o ndma i nr e s po ns et oe xc e s si nve n t o r i e si sl o we rpr l C e S . Whe ni nve n‑ t o r yc ove r a gei shi g h,de a l e r sa r emo r ewi l l i ngt oc utt he i rma r gi nsa ndma nu‑ f a c t ur e r sof f e ri nc e nt i ve ss uc ha sc a s h‑ ba c ka ndl ow a nn ua lpe r c e nt a ger a t e s ( APRs )Onl oa nsf i na n c e dt hr o ug ht he i rc r e di td i vi s i o ns . Lowe rpr i c e sma kene w c a r smo r ea t t r a c t i ver e l a t i vet ot hec a r spe opl ea l r e a dyo wn. Pe o pl et r a dei nt he i r ol dc a r ss oone r , boos t i ngne wc a rs a l e sunt i li nve nt o r i e sf a l lba c kt ono r ma l( t he ne ga t i vePr i c i ngl oo p, B2) . 2. 2月 Dynami cHypo帥es妄 s Cha l l e ng i ngt hec o nve nt i o na lwi s d o m, t het e a me x pa nd e dt hes t o c ka ndf lows t r uc ‑ t ur et oi nc l udel a t emod e lus e dc a r s . Ⅰ ns t e a dofdi s a ppe a r l ng,t r a de ‑ i nsa ddt oi n‑ ve nt o r i e sofl a t emode lus e dc a r sO nde a l e rl ot sora va i l a bl ef o ra uc t i on.Whe n t he s ec a r sa r epu r c ha s e d, t he yr e e nt e rt hes t oc ko fl a t emode lc a r so nt her oa d. The s umo ft hec a r so nt her oa da ndc a r so nde a l e rl o t si st het o t a ls t o c ko fl a t emod e l ve hi c l e s( s ho wnbyt hel a r g er e c t a ng l ei nFi g u r e2‑ 1 ) ; t he s ec a r sg r a d ua l l ya gei n t o t hepo pul a t i o nofo l d e rc a r sa nda r ee ve nt ua l l ys c r a ppe d. Th emo d e lus e da n" a g i ng c ha i n"t oke e pt r a c ko ft hec a r sont her oa da ndi nus e dc a ri nve nt o r i e sbyトye a r c o ho r t s .Thea gi ngc ha i n( c ha pt e r1 2)a l l owe dt het e a mt oe xa mi nehow t he numbe rof1 ‑ , 2‑ , a nd3 ‑ ye a r ‑ ol dc a r so nt her oa da ndf o rs a l ec ha ng e di nr e s po ns e t os a l e s . Thes t oc ka ndnowpe r s pe c t i vemo t i va t e dt hemode l i ngt e a mt oa s kwhe r et he s upe r s t o r e sgo tt hel a r gei nve nt o r i e sofa t t r a c t i vel a t emo de lc a r st he yr e q ui r e d. Pa r toft hea ns we rwa st hegr owl ngq ua l i t yo fne wc a r s ・St i mul a t e dbyt hehi g h a r l yt heJ a pa ne s ei mpor t s ,a l lma nuf a c t ur e r sha d qua l i t yoff o r e i g nc a r s ,pa r t i c ul Cha pt e r2 Sys t e mDy na mi c si nAc t i on 4 5 Fd GURE2 ・ l Asi mpF emodeloHheaut omobi l emar ket Rect angl esr epr esentst ocksofcar s;pI PeSandval vesr epr esentf l owsbet ween cat egor i es( chapt er6) . Ar r owsandpol ar i t i es( +or‑)i ndi cat ecausali nf l uences: Ani ncr easei nNew Carhvent or yl eadst oani ncr easei nI nvent or yCover age( anda decr ease一 eadst oadecr ease) ;ani ncr ease( decr ease)i nI nvent or yCover agecauses Pew CarPr i cest odecr ease( i ncr ease) ;Seechapt er5・Gr ayst r uct ur ewasnotcapt ur ed F nt hepr eval l l ngi ndust r yment almodeli nwhi chnew andusedcarmar ket sdonot i nt er act . 4 6 Pa r t iP e r s p e c t i v ea n dP r o c e s s i nve s t e di nma j o rqua l i t ypr ogr a ms . Thought he r ewa ss t i l lr oo mf o ri mpr ove me nt , byt he1 990St hequa l i t ya nddur a bi l i t yofne wc a r swa ss i gni f i ca nt l yhi ghe rt ha ni n t he1 980S . Butqua l i t yl mpr OVe me nta l onec oul dnote xpl a i nt her i s eoft hes upe r s t or es . Byt het i memos tc a r sa r et r a de di nt he ya r et oool dt oc ompe t ea ga l nS tne wC a r s a nda r euns ui t a bl ef ort hes upe r s t or es . Qua l i t yi mpr ove me nt smi ghte ve nl e ngt he n het t r a de ‑ i nc yc l et i me , r e duc i ngt hes uppl yofl a t emode lus e dc a r s . Thea ns we rwa sl e a s l ng. I nt hee a r l y1 990sl e a s l ngWa st hehotne wma r ke t i ng t ooli nt hea ut omo bi l ei ndus t r y. Le a s i ngOf f e r e dwha ts e e me dt obeas ur e ‑ f i r ewa y t oboos ts a l es , Ri s i ngqua l i t yme a ntt hema r ke tva l ueof2‑ ,3‑ ,a nd4‑ ye a r01 dc a r s wa smuc hhi g he rr e l a t i vet one wc a r st ha ni nt hepa s t . Thehi ghe rt her es i dua lva l ue a tt hee ndofal e a s e , t hel owe rt hel e a s epa yme nt s . Le a s e sa l s og l VeC us t ome r st he opt i ont Obuyt hec a rwhe nt hel ea s ee xpl r eSa tt hes pe c i f i e dr es i dua lva l ue,t r a ns ‑ f e r r i ngt her i s koff luc t ua t i onsi nt hema r ke tva l ueofus e dve hi c l esf r om t hec us ‑ t ome rt ot hec a r ma ke r . Mos ti mpo r t a ntt ot hema nuf a c t ur e r s , t y pi c a ll e a s et e r msa r e 2t o4ye a r s ,S t i mul a t i ngs a l e sbyc ut t l ngt het r a de ‑ i nc yc l et i me・ Le a s i ngI nc r ea s e d f r om4. 1 %ofa l lne wc a rs a l esi n1 990t omor et ha n22%i n1 99 7. Fr omt hepe r s pe c t i veoft hepr e va i l i ngme nt a lmode l , l e a s i ngWa saboon. Fi r s t , i ts t i mul a t e ds a l e s . Whe ne ve ri nve nt or i esr i s ec a r ma ke r sc oul di nc r e a s ei nc e nt i ves f orl e a s i ngt hr oughl e a s es ubve nt i on.Subve nt i onl owe r sl e a s epa yme nt sbya s I s umi nghi ghe rr e s i dua l s ,l owe ri nt e r es tr a t es ,Orl owe ri ni t i a lca pl t a l i z a t i on;t ypi c a l l yc a r ma ke r swo ul dr a i s er e s i dua lva l u esa bovegui de bookva l uesf orus e dc a r s ・ Lowe rl e a s epa yme nt sboos tt hea t t r a c t i ve nes sofne wc a r sa ndi nduc es omepe o pl e t ot r a det he i rc ur r e ntc a rf orane wl ea s e dve hi c l e( f or mi ngt heba l a nc i ngLea s e l nc e nt i vel oo pB3i nFi gur e2‑ 1 ) .Se c ond,t hes hor t e rt hea ve r a gel e a s et e r m,t he s hor t e rt het r a de ‑ i nt i mea ndt heg r e a t e rt hes a l es( t heba l a nc i ngLe a s eTe r ml oop B4) . I fa l lne wc a rbuye r ss wi t c he dt ol e a s eswi t ha na ve r a get e r m of3ye a r s ,t he t r a de ‑ i nc yc l et i mewo ul dbec uti nha l fa ndne wc ar s a l e swo ul ddoubl e ‑al le l s e e qual . Themode l i ngt e a mqui c kl yc ha l l e nge dt hea s s umpt l Ont ha ta l le l s ewa se qua l ・ Whi l ea6‑ ye a rol dc a rュ sapoors ubs t i t ut ef orane wc a r , a1 ‑t o3‑ yea r ‑ ol dc a rwi t h l owmi l e a gemi ghtbea t t r a c t i vet oma nype opl e. Ast heg r owl ngVOl umeofl e a s es e xpi r e dt heus e dc a rma r ke tc oul dbef loode dwi t hhi g h‑ qua l i t ynea r l yne wc a r s ・ Us e dc a rpr l C e Smi ghtpl umme t . Somepe opl ewhomi g htha vet r a de dt he i rc ur r e nt c a r sf orne wone so pti ns t ea df orofl l e a s eve hi c l e s ,r a i s i ngt hea ve r a get r a de ‑ i n t i mea ndr e t ur ni ngmo r el a t emode lus e dc a r st ot hes t o c kofc a r sont her oa d( t he ba l a nc i ngUs e dCa rMa r ke tl oop,B5) .Le a s i nga l s os ho r t e nst hea ve r a get r a de ‑ i n c yc l et i me,r a i s l ngt hea ve r a gequa l i t yofus e dc a r sf o rs a l e・ Mor epe opl eoptf or of f l l e a s eve hi c l e si ns t e a dofbuyi ngne w. Thea ve r a get r a de ‑ i nt i mef ort hepopuh t i ona sawho l er i s e s , f o r mi ngt heba l a nc i ngUs e dCa rQua l i t yl oo p, B6・ Eve nmor e i nt e r e s t l ng, t heus e dma r ke tc oul df e e dba c kt oa f f e c tt hef r a c t i onofc us t ome r swho c hoos et obuyt he i rc a rwhe nt he i rl e a s ee xpl r eS ・ I f , a tl e a s ee nd, us e dc a rpr l C e Sa r e hi ghe rt ha nt her e s i d ua lva l uewr i t t e ni nt ot hel ea s e, t hec us t ome rc a npur c ha s et he ca rbe l owma r ke tva l ue. Thec us t ome rr e t e nt i onf r a c t i onwoul dr i s e. I f ,howe ve r , us e dc a rpr i c e sdr o ppe dbe l owr es i dua lva l ue s , t her e t e nt i onf r a c t i onwoul df a l la s mo r ec us t ome r st ur ne dt he i rc a r sba c kt ot hel es s or . Thei nve nt or yofl a t emode l ‑ Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n 47 Ca r swoul dr i s ea ndus edca rpr l C eSWOul ddr ops t i l lmor e,i navi ci ousc yc l e,t he pos i t i ve( s e l f ‑ r e i nf or c i ng)Pur c ha s eOpt i onl oop, Rl . 3 Howe ve r ,t hef T e edba c kss howni ngr a yope r a t ewi t hal ongde l a y( r oughl y e qua lt ot hea ve r a gel e as et e r m)a ndwe r epoor l yunde r s t oodi nt hei ndus t r y. Lea s ‑ ‑ r un.Una wa r eoft hes t r uc t ur es howni ngr a yl n 1 ngS t i mul a t ess a l esi nt hes hot Fi gur e2‑ 1,t hee xpe r i e nceoft heea r l y1 990St a ughtca r ma ke r st ha tl eas i ng wor k s ‑a ndt he ydi ve r t e ds t i l lmor ema r ket i ngdol l a r st os ubve nt i ona nds hor t e r t e r ms . r I ni t i a lr es ul t ss ugges t e d,howe ve r ,t ha tl eas l ngWOul de ve nt ua l l yc r ea t eagl ut ofhi gh‑ qua l i t ynea r l yne w ca r s ,de pr es s l ngl a t emode lus edc a rpr l C eS .Ne w ca r s a l e swoul ds uf f e ra smor ec ons ume r sopt e df orc hea pof f ‑ l eas eve hi c l es . Theca r ‑ ma ke r s 'c r edi tc ompa ni es( Ge ne r a lMot or sAcce pt a nc eCor por a t i on[ GMAC] , For dCr edi tCor por a t i on,a ndChr ys l erCr edi tCor por a t i on)woul df a c el os s esas ma r ke tva l uesf e l ls hor toft her es i dua lva l uet he yha dbookeda ndasf e we rc on‑ s ume r sexe r c i s edt he i ropt l Ont Obuy, t ur nl ngt heca rba c kt ot hel es s or si ns t ea d. Thef ol l owl ngda yPuda ra ndhi st ea m pr es ent edt hes er es ul t st oZa r e l l a,i n‑ c l udi ngt hes t r uc t ur eoft hei ni t i a lmode la nds i mul a t i onss howl ngt hepr obl e msa g一 gr es s i vel eas l ngCOul dc a us e.Bys hor t e nl ngt r a de‑ i nc ycl et i mest hr oughl eas l ng a ndne e ts a l es ,C a r ma ke r swe r ec r ea t i ngagl utofhi gh‑ qua l i t yus e dc a r sa ta t t r a c t i vepr l CeS .Su pe r s t or eswe r es i mpl yt hema r ketr es pons et ot heoppor t unl t yt he ma nuf a c t ur e r st he ms e l vesha dc r e a t e d. ‑ Us e dca rs upe r s t or eswe r eonl yt hes ympt om ofade e pe rpr obl e m‑ t hel e as i ng pol i c i esoft heca ma ke r s . Lea s l ngI nc r eas eds a l esi nt hes hor tr unbuts e ti nmot i on f ee dba c kst ha tca us e ds a l est os l umpwhe nt hel eas e dve hi c l esr e e nt e r e dt hema r ‑ ke t ・I nt heol dda ys ,peopl eke ptt he i rca r sl onge nought ha tt r a de‑ i nse fe c t i ve l y di s a ppea r e df r om c onc e r n.Buti nawor l dofs hor t ‑ t e r ml ea s es ,ne wca r sa r egone t oda y,he r et omo r r ow. Ther ea l i z a t i ont ha ts upe r s t or eswe r ea ne ndogenouscons e quenc eoft heca r ma ke r s 'Owna c t i onsdr a ma t i ca l l yr ede f i nedt hef ocusoft hewor k.I ni ia t lmodel a na l ys i ss ugge s t edGM s houl dde ‑ e mphas i zel eas l ng,e xa c t l yc ount e rt oi ndus t r y t r e nds . ‑ Thes eefe ct sma ys ee m obvi ous( es pe ci a l l ynow t ha tyouha ver ea dt hede‑ s c r i pt i onoft hemodela bove) ,a nda ut oi ndus t r yexe c ut i vesdi dknow t hats ome ofl l eas eca r swoul dr e e nt e rt hema r ket .Howeve r ,mos tdi s count e dt hepos s i bi l i t y ofa nypr obl ems .I n1 994,US AT odayquot edaGe ne r a lMot or sl e as i nge xe c ut i ve whos a i d,H Thede ma ndf orca r sc omi ngOf fl ea s esi st r i pl et hes uppl y.Lea s e‑ e nd ca r sha vè notc r ea t e dabot t l e nec ki nt hei ndu s t r y' H( 2Novembe r ) . ADe t r oi t ‑ a r ea 3 Th ePu r c h a s eOp t i o nl o o pl Sp a r t i a l l yo f f s e t b e c a u s ec u s t o me r st u r n l n gt h e i rc a r sb a c kt o l e s s o r sp u r c h a s ea n o t h e rv e h i c l e . I fl e a s ec u s t o me r su s e dt h e i rp u r c h a s eo p t l O nt Oma k eap u r ea r b i ‑ t r a g ep l a ywh e nu s e dc a rp r l C e Sf e l l b e l o wr e s i d u a l v a l u e sb yt u r n l n gt h e i rc a r si na n di mme d i a t e l y b u y i n gi d e n t i c a l o n e sa t t h el o we rma r ke t p r l Ce , t h e nt h en e t e fe c t o fc h a n g e si nt h er et e n t i o nf r a c ‑ t i o nwo u l db ez e r o . Ho wev er , s o mec u s t o me r st u r n l n gt h e i rc rsb a a c kt ol e s s o r swi l l b u yan e wc a r o rd i f f e r e n t u s e dc ar , p o s s i b l yf r o mac o mp e t i t o r ・ Onn e tal o we rr e t e n t i o nf r a c t i o nf o rag l V e nma k e a n dmo d e l wi l l t e n dt op u s hp r i c e sf o rt h a t c a rd o wns t i l l more , t r l g g e r l n ge v e nl o we rr e t e n t i o n・ Th e s ee fe c t swe r ec a p t u r e di nt h ef u l l mo d e l b u tf o rc l a r l t ya r en o tS h o wni nFi g ur e21 1 A 48 P a r t I P e r s p e c t i v ea n dP r o c e s s Ca di l l a cde a l e rd i s mi s s e da nyl i nka gebe t we e nt hene wa ndus edma r ke t sf orhi gh‑ e ndc a r s , s c of f i ng, " You' l lne ve rge tal uxur ybuye rt ot a keac a rwi t h30, 000mi l es oni t "( TheWal lSt y l e e t Jour nal ,3J une1 994) . I nt hes a mea r t i c l e,TheJour nalwe nt ont onot et ha tFo r d' Se xe c ut i vedi r e c t orofs a l e so pe r a t i ons a r g ue st ha tt h ei n d us t r yh a sh a dac h r o n i cs ho r t a g eo fg o o dt wo ‑ ye a r ‑ o l dc a r st o Th i s[ s ho r t ‑ t e r ml e a s i ng ]b r i ngst hec a r sba c ka t j us t t her i g h tt i me , wh e n s e l l‥ .H r , t h eus e d‑ c a rma r k e ti sa t l e a s t t wi c ea sbi g d e ma n di sh i g he s t , Hh es a ys ・ Mo r e o ve a st h en e wI C a rma r k e ta n dc a ne a s i l ya bs o r bt hep r o j e c t e dv o l u me s . Th eu n d e r l y i n gs t r e n g t hi nus e d ‑ C a rd e ma n dwi l ls a f e l ya bs o r bt h evo l u meo f us e dv e h i c l e sc o ml n gO f fl e a s e , wi t ho utc a n n i ba l i z l n gn e w‑ C a rS a l e s , Hp r e d i c t s. . . [ a n ]a u t os e c u r i t i e sa n a l ys ta tSa l o mo nBr os . The r ea ppe a r e dt obea mpl ee vi de nc et os uppo r tt he s evi e ws ・ Us e dc a rs a l e sgr e w f r om 37. 5mi l l i oni n1 990t onea r l y42mi l l i oni n1 995whi l e1 995ne wc a rs a l es we r ea bout1 5mi l l i on,ar i s eofonl ya boutami l l i onve hi c l es / yea rs i nc e1 990. Us e dc a rpr l C e Sr os emor et ha n6%/ yea rbe t we e n1 990a nd1 995, muc hf a s t e rt ha n i nf la t i on. Wi t hr i s l ngus e dc a rpr l C e S , mor ea ndmo r epe o pl eopt e dt oke e pt he i rve ‑ hi c l ewhe nt he i rl e a s ee xpi r e d・Ma nyi nt hei ndus t r y ,l nC l udi ngGM,a r gue dt ha t s t r ongde ma nda ndr i s i ngus e dc a rva l uesJ us t i f i e de ve nhi ghe rr es i dua lva l ue s ,a 1 ‑ l owl ngl owe rl e a s epa yme nt sa ndboos t l ngne wC a rS a l e ss t i l lmor e. Whi l et hei ni t i a lr e s ul t swe r ei nt r l gul ng, mor ewo r kwa sne e de dbe f o r ec r e di ‑ bl epol i c yr e c omme nda t i onsc oul dbema de,muc hl e s sa nya c t i ont a ke n.Eve ni f l ea s i ngWa sade vi l ' sba r ga l n,e ve r yC a r ma ke rf e l ts t r ongpr es s ur et oma t c ht he t e r msa ndpr i c esofi t sc ompe t i t or s .Onc ea l lma j orma nuf a c t ur e r swe r eofe r i ng s ho r tl e a s et e r mswi t ha gg r e s s i ves ubve nt i on, uni l a t e r a l l yba c k i nga wa yf r oml e a s l ngmi ghtr i s kt oomuc hma r ke ts ha r e. Za r e l l aa s ke dt het e a mt oc ont i nuet hemod‑ e l i ngt oa dd r e s st hes eques t i ons . TheDSCf or me dade c i s i onr e vi e wboa r d, c ha i r e d byZa r e l l aa ndBa r a bba,t oove r s e et hepr o j e c ta ndt hemode l i ngt e a mt he nbe ga n t or e f i net hemode la ndga t he rt heda t ane e de dt oc a l i br a t ei t ・ The yha d20da ys . l 2. 2, 2 E】 ' ‑ l bor a軸 gt hen i l odL ng Themode l i ngt e a mi nt e r vi e we dpe opl et l l r Oug h outt heo r ga ni z a t i o nt ounde r s t a nd t hei s s ue sa ndga t he rda t a・ Thr ought heme e t l ngSOft hec o r ea ndmode l i ngt e a ms t he yope ne dupt hemode lt oc r i t i ca lr e vi e wa ndpr e s e nt e di nt e r i mr es ul t sf or di s c us s i on. Onea r e af ori mpr ove me ntwa st het r ea t me ntoft hec o mpe t i t i ona nds e gme n‑ t a t i onoft hema r ke ti nt odi fe r e ntve hi c l et ype s . Somea r gue df o re x pl i c i tt r e a t me nt ofe ve r yma j o rma nuf a c t ur e ra ndma r ke ts e gme nt ・Br a ndl oya l t yl Si mpor t a nt : Pe o pl ewhoboughtGM c a r sl a s tt i mea r emor el i ke l yt obuya not he rGM c a rt ha n non‑ GM owne r s . The ya l s oa r gue dt ha tGM c us t ome r swe r edi f f e r e ntf r omFo r dor Hondac us t o me r sa ndt ha tma r ke t sf orl uxur yc a r s , f a mi l ys e da ns ,s por tut i l i t yve ‑ hi c l es , a nds oonwe r ea l ldi fe r e nt . Thet e a mc ount e r e dt ha tt heda t ar e qui r e me nt s f ors uc hade t a i l e dmode lwoul dbee nor mousa ndwoul dde l a yde ve l opme ntofa us e f ulmode l . The ypr e f e r r e da ni t e r a t i vea ppr oa c h, wi t hmor el i mi t e ddi s a ggr e ga ‑ t i on;i fs e ns i t i vl t ya na l ys i ss howe dt ha tf u r t he rs e gme nt a t i o nwa sne e de dt he y c oul dt he nr e vi s et hemode lt oi nc l udemor ede t a i l . Thet e a ma g r e e dt os e pa r a t et he 4 9 Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n ma r ke ti nt oGM a ndnon‑ GM ve hi c l esbutt or e pr e s e ntonl yas i ngl ea ggr ega t e ve hi c l et ype. Anot he ri mpor t a nta r e aofdi s c us s i onwa sd i s a ggr e ga t i onoft hec us t ome rba s e. Pa r a l l e lt ot hef low ofc a r sbe t we e nt he" ont her oa d"a nd" f ors a l e "s t oc ksa r e s t oc ksa ndf lowso fd r i ve r s .Eve r yca rt r a de di nmove sac us t ome rf r om " ont he r oa dHt oH i nt h ema r ke t ; "e ve r yne w orus e dc a rs ol dput sadr i ve ront her oa d a ga i n. Cha nge si nt her e l a t i vea t t r a c t i ve nes sofne wa ndus e dc a r ss hi f tt hepr opo r ‑ t i onofdr i ve r si nt hema r ke topt l ngf orane wc a r .Thec hoi c ebe t we e nne wa nd us e dve hi c l e sa l s ode pe ndsont he i rpa s tbe ha vi or .Thec ha nc eac us t ome rwi l l l e a s e, buyne w,o rbuyus e dde pe ndsonwhe t he rheors hel ea s e d,boughtne w,or boughtus e dl a s tt i me. Someme mbe r soft heor ga ni z a t i onpo l nt e do utt ha tt hec om‑ pa ny,t hr oughe xt e ns i vema r ke tr e s e a r c h,a l r e a dykne wal ota boutc ons ume rbe ‑ ha vi ori nt hen e wc a rma r ke t .The yi ns i s t e dt ha tt hedyna mi cmode li nco r por a t e t he s eda t as ot h eDSCc oul ds pe a kwi t honevoi c ea nda voi dt hene e dt or e c onc i l e c onf li c t i ngmo de l s . Toa ddr e s st hebr a ndl oya l t ya ndc ons ume rbe ha vi o ri s s ue st hemode l i ngt e a m di s a ggr e ga t e dt hec us t ome rba s ei nt os e ve r a lc a t e gor i e s :t hos ewhol e a s e dane w c a r , pur c ha s e dane wc a r , Orpu r c ha s e dus e dc a r sofva r i ousa ge s . Fi gur e2 ‑ 2S hows as i mpl i f i e dr e p r e s e nt a t i onoft her es ul t i ngt r a ns i t i onma t r i x・ Ea c he nt r yi nt hema ‑ t r i xi st hepr o ba bi l i t yt ha tbuye r sc omi ngf r omapa r t i c ul a rc a t e go r ys howni nar ow wi l l ,whe nt he yne xtt r a dei n, movet ot hec a t e gor i ess howni nt hec ol umns . The a c t ua lma t r i xha dt wi c ea sma nyca t e gor i esa si ti nc l ude dpr oba bi l i t i esf ore a c h pur c ha s eopt l O nf わrbot hGM a ndnon‑ GM ve hi c l es . Thet r a ns i t i o npr oba bi l i t i esi nt hema t r i xwe r enotc ons t a ntbutc ha nge da s t hepr l C e SO fne wa ndus e dc a r sc ha nge d. Lowe rpa yme nt sonGM l e a s e si nc r e a s e FI GURE2 ‑ 2 Thema t r i xshows t hepr obabi l i t y =)t h atcu s‑ p( t omer si neach c at egor yshown , on i nr owi wHl t r ade‑ i n,move t ot h ec at egor y . i nc ol umnJ Thet r an si t i on pr obabi l i t i esi n t hef ul H mode一 ar evar i abl ean d depen donr el a t i ve pr l C eS. Thef ul l mat r i xdi s aggr e‑ gat esGMand non ‑ GMvehi cl es. FRoM= TO= 武 芸D G 誓言g t 0. 焉,a : o y 挙 7 b : :t JS t N e wCa r N e w ( i , j ) p 1 ‑ Y r 一 〇】 d 2 ‑ Y r 一 〇l d 3 ‑ Y r 一 〇l d 4 ‑ Yト OF d C U ∪ P a s u 「 e r c L d h e C a s s a e e r Ad a p t e df r o mGM De c I S 1 0 nSu p p o r t Ce n t e r d i a g r a m・ Us e dwi t h Sour ce: p e r ml S S i o n . 50 P a r t I P e r s p e c t i v ea n dP r o c e s s t hep r o po r t i ono pt l ngf o raGM l e a s e ,whi l el owe rus e dc a rpr l C e Si nc r e a s et he s ha r eo fpe o pl ebuyi ngus e dc a r sa tt hee x pe ns eo fne wpur c ha s e sa ndl e a s e s . The r e s po ns et os uc hc ha ng e sdi f f e r e df o re a c hc a t e g o r yo fc us t ome r . v‑ Thed i s a gg r e ga t i o no ft hemo de lwa snota c c o mpl i s he di no nes t e pbuti ns e e r a li t e r a t i ons ・ Ate a c hs t a gemode l i ngt e a mme mbe r sma des ur et he yunde r s t o od t hes t r uc t u r ea ndbe ha vi o ro ft hemod e la ndpr e s e nt e di tt oZa r e l l aa ndhi st e a mf o r c omme nta ndr e vi e w. Ea c hi t e r a t i ont he yi nc o r po r a t e dt hec r i t i c i s msa nds ugge s ‑ t i o nst he yr e c e i ve d.Eve nwi t ht hel i mi t e dd i s a gg r e ga t i o noft hemode lt heda t a c ha l l e nge swe r ef o r mi da bl e・ Gi ve nt he2 0‑ da yde a dl i ne , t het e a mha dt ous eda t a a l r e a dya va i l a bl ei nva ri o uspa r t soft heo r ga n i z a t i o n. Thema r ke t r e s e a r c hda t af o r ne wc a r swe r ee xc e l l e nt .Da t ao nl e a s l ng,ar e l a t i ve l yne w phe nome no n,we r e s ke t c hy・Andc o ns i s t e ntwi t ht hepr e va i l i ngme nt a lmode lt ha tdown pl a ye dt he us e dc a rma r ke t ,t he r ewa sa l mos tnor e s e a r c hde s c r i bi nghowpe opl et r a de dof f ne wa ndl a t emode lus e dve hi c l e s . The yd r e wont hebe s tda t as o ur c e sa va i l a bl e a ndus e dj udg me nta ndq ua l i t a t i veda t awhe r en ume r i c a lda t awe r enota va i l a bl e . Att hee ndo ft he2 0da yst het e a mme ta ga l nWi t hZa r e l l aa ndhi st e a mJns t e a d o fpr e s e nt l ngt hemod e la ndr e s ul t s ,t he yc o nf i g ur e dt hemode la sa ni nt e r a c t i ve ma na ge me ntf li g hts i mul a t o r ・ A" da s h boa r d"c o nt a i ne ddi a l sa ndga uge sr e po r t l ng s t a nda r da c c o unt i ngi nf o r ma t i ons uc ha si nve nt o r yl e ve l s ,s a l e svol ume s , pr i c e s , ma r ke ts ha r e ,a ndpr o f i t a bi l i t y .Pl a ye r ss e tp r od uc t i ont a r ge t s ,i nc e nt i ve s ,l e a s e t e ms , a nds oo n. Byc l i c ki ngabut t o no nt hes c r e e npl a ye r sc o ul dge ta d di t i o na l i n‑ l . f o r ma t i oni nc l udi ngt hes t r uc t ur ea nda s s umpt l O nSO ft hemode Bypl a yi ngt hega mei ns t e a do fl i s t e n l ngt Oapr e s e nt a t i o n, Za r e l l aa ndhi st e a m , e xpl o r e dt hed yna mi c sofl e a s i ngf o rt he ms e l v e s . The yc o ul dt r yv a r i o uss t r a t e g i e s f r o ma g g r e s s i ves u bve nt i o no fl e a s e st opul l i ngo uto ft hel e a s ema r ke ta l t og e t he r , a nds e et hei mpa c to ns a l e sa ndpr of i t si nt hes ho r tr u na ndt hel o ngr un. The yd i s I c o ve r e dt ha tt hef u l li mpa c tofl e a s l ngd e c i s i o nst oo kupt 05ye a r st opl a yo ut . Whi l el e a s l ngdi dpr o vi deal i f tt os a l e si nt hes ho r tr u n,i tof t e nc a us e dpr o bl e ms whe nt heo f f ‑ l e a s ec a r sr e t ur ne dt ot hema r ke t . Af t e r20da yst hemod e l i ngp r oc e s sr e ve a l e dt hec ha l l e nge sl e a s i ngPOS e df T o r t hec o mpa nya ndi nd i c a t e dpr e l i mi na r ypol i c yr e c omme nda t i o ns . Howe ve r , be f o r e oa de ne dt o a nyc ons e ns usf わra c t i onc oul dbede ve l o pe d, t hep r o c e s sha dt obebr i n c l ud eo t he rke yde c i s i o nma ke r st hr o ug ho u t No r t hAme r i c a nOpe r a t i ons( NAO) . Themode l i ngt e a mbe ga nt owo r kwi t ht heLe a s i ngSt r a t e gyl mpl e me nt a t i o n Te a m, at a s kf o r c ei nc l ud i ngpe o pl ef r o mma r ke t i ng, f i na nc e ,a ndo t he rf unc t i o ns . dn' tt hi n ka The i rma nda t ewa st oboos tma r ke ts ha r ea ndpr of i t a bi l i t y・The ydi mode lwa sne c e s s a r y ,di d n' tt r us tt hemo de l i nga ppr oa c h,a ndo ppos e dt hei ni t i a l l ,t hi spos i ‑ r e c o mme nda t i ons .Vi e we dt h r o ug ht hel e nso ft he i rme nt a lmode t i onwa se nt i r e l yr a t i o na l ・Thes uc c e s so fl e a s l nga nds t r e ng t hoft heus e dc a r ma r ke tpr o vi de da mpl ee v i de nc et ha tc o mpe t i t i vel e a s l ngWa se s s e nt i a lt oGM' s S t r a t e g y ・ r s t a ndi ng Wo r k i ngwi t hyo u rc r i t i c si sof t e nt hebe s twa yt oi mpr oveyo urunde o fc o mpl e xi s s ue s . Ove rt hene x tf e wmo n t hst hemode l i ngt e a mr e f i ne dt hemode l s t r uc t ur e ,i mpr ove dt heda t aa ndc a l i br a t i on,a ndt e s t e dt hemode love rawi de ht opr e s e nt r a ngeofc o ndi t i o ns . The yme twi t ht hel e a s l ngt e a ma bo uto nc eamont i n t e r i mr e s ul t sa ndl i s t e nt oc r l t l qu e S . 51 Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n 2. 2. 3 P ol i c yAn al y si s Ast he i rc onf i de nc ei nt hef or mul a t i onsa ndc a l i br a t i o noft hemode lgr e w, t het e a m t ur ne dt opol i c ya na l ys i s . Pol i c yl e ve r si nc l udel e a s et e r msa nds ubve nt i onl e ve l s , a l ongwi h pur t c ha s ei nc e nt i ves ,f le e ts a l es ,a ndva r i ousde c i s i onr ul esf orpr oduc ‑ t i on. Thei mpa c tofe a c hpol i c yc ombi na t i onde pe nde dont hepol i c i esoft hec om‑ pe t i t or sa nd ahos tofma r ke tunc e r t a i nt i es ,f r om c ha ngesi nt hee c onomy, de mogr a phi c s ,gas ol i nepr i c es ,a ndi nt e r es tr a t est oc ha nge si nt heuni tc os t sof e a c hc a r ma ke r , C a rqua l i t y,a ndbr a ndl oya l t y. Thec ombi na ionofpol t i c i esa ndma r ke ts c e na r i osde f i neapol i c yma t r i x. The t e a m us e dt hemode lt of i ndt heo pt i ma ll ea s epol i c i e sf ore a c hc e l li nt hema t r i x. Fi gur e21 3S howsas a mpl ei l l us t r a t i ngt hene tpr e s e ntva l ueofGM pr of i t sa sa f unc t i onofl e a s i ngpol i c y( nol e a s i ngvs 12‑ ,3‑ ,o r4‑ ye a rt e r ms )f ore a c hc ombi ‑ na t i onofc ompe t i t orl e a s et e r msa nde c onomi cgr owt hs c e na r i o( s t a bl e,boom,or r e c e s s i on) . Thepol i c ya na lys i sS howe dt ha tt he r ewa snogol ngba c k: Pr of i t swi t houtl e a s l l ngWe r ec ons i s t e nt l yne ga t i ve, r e le f c t i ngt hea t t r a c t i ve ne s sofl e a s i ngt Oc ons ume r s a ndt hepr l S One r ' sdi l e mmat ha tuni l a t e r a l l ys t oppl ngl e a s i ngWhi l ec ompe t i t or s c ont i nue dt oofe ri tdr a ma t i ca l l yr e duc e dGM s a l e s ・ Thea na l ys i sa l s os howe dt ha tGM' spr of i t swe r ec ons i s t e nt l yhi ghe rwi t h4‑ yea rl e a s et e r ms .Four ‑ ye a rt e r mswe r es upe r i orove rawi der a ngeofcompe t i t or s t r a t e gl e Sa ndun c e r t a i nt i es . Longe rt e r msha vet woma i nbe ne f i c i a le f f e c t s IFi r s t , t houghs hor t e rt e r msdos hor t e nt het r a de ‑ i nc yc l e, t her e s ul t i nggl utofne a r l yne w c a r sde pr e s s e sus e dpr i c e ss omuc ht ha tt hes ubs t i t ut i onofus e df o rne wpur c ha s es 1 , t heUs e dCa rMa r ke t , Us e dCa rQua l ‑ o f f s e t st he i rbe n e f i t . I nt e r msofFi gur e2‑ 1 t y, a ndPur c ha s eOpt i onl oo psove r whe l mt hebe ne f i to ft heLe a s eTe r ma ndLe a s e I GURE2 ‑ 3 Po l i cya n a l ysI S F 2y ear 3year ! uo ssa3Ot j 3! ∈ OuO3山 al qCt S ! J l eua3S 0 Thepol l C ymat r i x sh owst he si mul a t ednet pr es en tv al ue ( NPV)o fGM pr of i t sasa f un c t i onofGM' s l easl ngPOl l C y ( nol easi ngor21t O 4‑ y eart er ms )f or eachc ombi nat i on ofec on omi c s c enar i oand compe t i t or s t r a t egy ・ Compet i t orLeaseTer m Sour ce' Ad a p t e df r o mGM DSCd i a g r a m. Us e dwi t hp e r mi s s i o n ・ 4year 52 I P e r s p e c t i v ea n dP r o c e s s Pa r t I nc e nt i vel oops . Four ‑ ye a rt e r msme a nt hec a r sc oml ngOf fl e as ea r el es sa t t r a c t i ve s ubs t i t ut e sf orne wc a r s , whi l es t i l ls pe e di ngt het r a de ‑ i nc yc l es ome wha t . Thes e c ondbe ne f i tofl onge rt e r msi samo r es ubt l e ,di s e qui l i br i um e f f e c t . By i nc r e a s l ngt hes ubs t i t ut a bi l i t ybe t we e nne wa ndne a r l yne wus e dc a r s ,s ho r t ‑ t e r m l e a s esi nc r e as e dt hevul ne r a bi l i t yofea r nl ngSt Oi ndus t r ydownt ur ns .Ra t he rt ha n s howl ngC Ompl e xdi a gr a mss uc ha sFi gur e2‑ 1t oe xpl a i nwhy,Puda rde ve l ope d Fi gur e2‑ 4,s howi ngt hes t oc kofl a t emode lve hi c l esa saba t ht ub. Theba t ht ubdi ‑ a gr a m us e sas i mpl eme t a phort oi l l us t r a t et hedyna mi c sofl ea s l ng. Thes t oc kof ne wa ndne w‑ C a rs ubs t i t ut e si si nc r e a s e dbypr oduc t i ona ndt hef lOwofl a t emode l us e dc a r sc omi ngof fl ea s e( a ndoutofr e nt a lca rf leet s ) .Sa l e sdr a i nt het ub. Dur i ngr e c e s s i ons ,a ut os a l esd r o p. Thewa t e rl e ve li nt het ubr i s es . Ca ma ke r s c omeunde rpr es s ur et oc utpr l C e Sa nds ubs i d i z el e a s e st odr a i nc a r soutoft het ub f a s t e ra nda l s oc utpr oduc t i ont os t o pt hei nf low. Howe ve r , t hef lowofne wc a rs ub‑ s t i t ut e si nt ot hema r ke tf r ome xpl r l ngl e a s e sc a nnotbet ur ne dof f . Whe nar e c e s s i on hi t s ,l e a s e ss ol ddur i ngt hepr e c e di ngboom c ont i nuet oe xpl r e,boos t i ngt hel e ve l i nt het ub・ Lowe rus e dc a rpr l C e Sa ndc o nc e r nsove rf ut ur ei ncomel e a dmo r epe o‑ pl et ot ur nt he i rof トl ea s ec a r sba c kt ot hel es s orr a t he rt ha ne xe r c I S l ngt he i ro pt l On t obuy・Thel a r ge rt hes ha r eofne wc a r ss ol dt hr oughl ea s l ng,t hel a r ge rt heun‑ s t o ppa bl ef lowofr e t ur ni ngVe hi c l e s . Pr i c e sa r ef o r c e ddowne ve nf a r t he r , a ndp duc t i onc ut smus tbee ve nde e pe r ,s l gni f i c a nt l ye r odi ngpr of i t s . Thet e a m us e dt heba t ht ubdi a g r a mi npr es e nt a t i onst os e ni orma na ge r s t hr o ughoutt hef i r m,i nc l udi nga l lbr a ndma na ge r s .Ofc our s et hef or ma la na l ys i s , mode ls t r uc t ur e, a ndot he rde t a i l swe r epr e s e nt e d, butt heba t ht ubpr ovi de dapow‑ e r f ulme t a phort ocommuni c a t ea ni mpo r t a ntdyna mi ci ns i ghta ndhe l pe di nt he di fi c ul tpr oc es sofc ha ngi ngme nt a lmode l s . r FI GURE2‑ 4 Bat h t ub di agr amt o i H us t r at e t hei mpac t oHeasl ng o ‑ Whydoshor t ・ t er ml easesmakeusmor evul ner abl e dur i nganeconomi cdownt ur n? Pr oduc t i on Ne wCarSubs t i t ut es .Wheni n dus t r ydemandf aH s,t hef l owofr et ur ni ngl easecar sc annotbes t opp ed ‑Pr i c esofu sedcar sw川bedr i v endown; ‑Newcart r an sac t i onpnc eswi Hb ef or ceddown; ‑Somer et ur ni ngJ es s eeswi l lop tf orcheapu sedcar s. ●Pr i c edoesnotal t ert h esuppl yofnewc ars ubs t i t u t es Sour cerGM D e c i s I O nSu p p o r t Ce n t e r . Us e dwl t hp e r ml S S i o n . Ch a p t e r 2 S y s t e mDy n a mi c si nAc t i o n 53 Puda ra ndh i st e a m ma det woma i nr e c o mme nda t i o nst oZa r e l l aa ndot he r s e n i o rma na g e r si nNAO・ Fi r s t ,GM s ho ul ds hi f ti nc e nt ive st of a vo rl o nge rl e a s e s a ndmovet hemi xo ft hel e a s l ngpo r t f o l i ot owa r dahi g he ra ve r a get e r m.Se c ond, t he yr e c o mme n de dt ha ta l lpr o pos a l sf o rne wp r l C l nga ndma r ke t i ngpr og r m sf a o r 一 ma l l yi nc l ud ea na l ys i so ft he i ri mpa c to nt heus e dc a rma r ke ta ndi t sf e e d ba c kt o t hene wc a rma r ke t . The yr e c o mme nde dt hema r ke tr e s e a r c ho r ga ni z a t i onc r e a t e n e wc l i n i c st oa s s e s sne w/ us e d / l e a s ec o ns ume rc ho i c ebe ha v i o rs ot ha tup‑ t o‑ da t e da t awo ul dbea va i l a bl eona nongol ngba s i s .The ya l s os uppo r t e dc ha ngl ngt he i n c e n t i ve sa ndme t r i c sf o rma na ge r so ft hec a rg r o upst oi nc l udet hepr o f i to rl os s GMACr e a l i z e da sar e s ul to fl e a s l ng, Ma n ybr a ndma na ge r sa ndbr a nda na l ys t swe r ei ni t i a l l yo p pos e dt ot he s er e c ‑ o mme nda t i o ns ・ The ya r gue dt ha tc o ns ume r sha dbe e nc o nd i t i o ne dt opr e f e rs ho r t ‑ t e r ml e a s e s ・Co mpe t i t i onwa si nt e ns ea ndGM' sma r ke ts ha r eha dbe e ns l i ppl ng. a r ,wa sa ggr e s s i ve l ypus hi ng2‑ ye a rl e a s e swi t hs i g ni f i c a nts u b‑ Fo r d,i npa r t i c u l v e nt i o n;unl e s sGM r e s po nde di nki nd,t he ya r g ue d,ma r ke ts ha r ewo ul ds ufe r mo r e ・ Gi ve nt het r e me ndo uspr e s s ur et he yf a c e dt os t a yc o mpe t i t i ve , t he ywe r eno t wi l l i ngt os a c r i f i c ema r ke ts ha r ea ndpr o f i t st o da yt oa vo i dt hepos s i bi l i t yt ha tl e a s l l ngmi gh tl e a dt opr o bl e msi naf e wye rs a . Br a ndma na g e r sa ndt hes a l e so r ga ni z a ‑ t i o nputs t r ongpr e s s ur eont hes e ni o rma na g e me nto fNAOt oi nc r e a s er e s i dua l l e ve l s ・ The ypo i nt e dt os t r ongus e dc a rde ma nda ndr i s i ngus e dc a rpr i c e st OJ uS t i f y i nc r e a s e dr e s i d ua l s . The ya l s oa r g ue dt ha ts u bve nt i o nl e ve l ss ho ul dbei nc r e a s e d e ve nf u r t he ra bo vet hehi g he rr e s i dua l st he ywe r er e c o mme nd i ng・ Fi na l l y , t he ya r 一 g ue df o rade c r e a s ei nt hef r a c t i o nofo f f ‑ l e a s eve hi c l e sGM pr e di c t e di two ul d ha v et ot a keba c ka tl e a s ee nd. Thec os t so fs u bve nt i ona rede f e r r e dbe c a us et he y a r eo nl yr e a l i z e dwhe nc a r sc o meo f fl e a s e . Ac c o unt l ngr u l e sr e qul r eC a r ma ke r st o s e ta s i d er e s e r v e st oc ove rt hee xpe c t e dc os to fs ubve nt i o n; t he s er e s e r ve sr e d uc e c u r r e n tpe r i ode a r nl ngS ・ Thea mo unts e ta s i d ei nr e s e r ve sd e pe ndso nt hef r a c t i o n o fc a r st he ye x p e c tt ober e t ur ne d. I fc us t o me r se xe r c i s et he i ro pt l Ont Obuywhe n he t i rl e a s ee x pl r e St he nGMACne ve rha st opa yt hed i f f e r e nc ebe t we e nt hes ub‑ ve nt e dr e s i d ua la ndma r ke tva l ue. Ma n ybr a ndma na g e r sbe l i e ve dt ha tt hes t r ong us e dc a rma r k e t me a ntr e s e r ve swe r et oohi g ha ndc o ul ds a f e l ybec u t , a l l owi ngt he c a rd i v i s i o nst os howhi g he rc ur r e ntpe r i odpr o f i t swhi l ei nc r e a s i ngma r ke ts ha r e. The ys uppo r t e dt he i rc a s ewi t hs pr e a ds he e t si nwhi c hr e c e n tt r e ndst owa r dhi g he r us e dc a rpr l C e Sa ndhi ghe rc us t o me rr e t e nt i o no fo f f ‑ l e a s eve hi c l e swe r ea s s ume d t oc o nt i nue ,t ha ti s ,i nwhi c ha l lf e e d ba c ksbe t we e nt hene wa ndus e dma r ke t s we r ec ut . Thed y na mi cmod e l , i nc o nt r a s t , s ugg e s t e dt ha t us e dc a rpr l C e SWO ul ds oo nde ‑ c l i nea st hel a r g evol umeofl e a s e da ndf le e tve hi c l e ss o l di nt hel a s tf e wye a r s r e e n t e r e dt hema r ke t . Thet e a mヲ sa na l ys i ss ug ge s t e ds o meo ft hes ur gei nus e dc a r pr l C e SWa sat e mpor a r ybl i pge ne r a t e dbyt heus e dc a rs upe r s t o r e sa st he ybo ug ht he a vi l yt os t o c kt he i rl o t s . Whe nt ha tpe r i odo fi nve nt o r ybui l di nge nde d, us e dc a r s a l e swo ul ds l u mpwhi l et hef lOw ofc a r sc omi ngOf fl e a s ec ont i nue d.Asus e d pr l C e Sf e l lbe l owt hec ont r a c t e dr e s i d ua l s ,mo r ec us t o me r swo ul dt e r mi na t et he i r l e a s e se a r l ya ndf e we rwo ul de xe r c i s et he i ro pt i o nt Obu y , de c r e a s l ngt her e t e nt i o n f r a c t i o na ndboo s t i ngt hes u ppl yo fl a t emod e l us e dc a r ss t i l l mo r e . GM woul dha ve t ot a keas i g n i f i c a n tc ha r gea ga l nS te a r nl ngSf o rr e s i d ua l r e c o nc i l i a t i on, a ndne wc a r s a l e swou l ds uf f e ra sc us t ome r so pt e df o rl a t emo de lo fl l e a s eve hi c l e s . 5 4 P a r t I P e r s p e c t i v ea n dP r o c e s s Se ni orma na ge r sa tNAOde c i de dt of oc uson36‑t o48‑ mont ht e r msa nde l i m‑ i na t e d2‑ ye a rl ea s es . The ya l s oc hos enott oi nc r e a s er e s i dua lva l uesa ndmove dt o f ul la c c r ua lofr es i dua lr i s ki nc a l c ul a t i ngr e s e r ve s . The s ede ci s i onsma des ubve n‑ t i onmuc hmo r ee xpe ns i vet obr a ndma na ge r sa ndr a i s e dl e a s epa yme nt s . 2 . 2. 4 ぎ mp a c ta n dF oH ow・ up I n1 997af loodofof f ‑ l e a s eve hi c l esi nunda t e dt hema r ke t ・ Us edc a rpr l C eSf e l ls i g‑ ni f i c a nt l y( Fi gur e21 5) . Theda t as howt hea ggr ega t ef ora l lus e dca r s ; t hed r o pf or l a t emode lve hi c l eswa smuc hs t e e pe ra ndwa smos ts e ve r ei nt hes e gme nt si n whi c hl e a s i ngha dg r ownmos tr a pi dl y. Aspr l C eSf e l l ,f e we rc us t ome r sopt e dt oke e pt he i rc a r s . TheCons ume rBa nkl l ngAs s oc i a t i o nr e po r t e dt ha tt hef r a c t i ono fve hi c l esf r ome xpl r l ngf ul l ‑ t e r ml e a s e s r e t ur ne dt ol es s o r sJ umpe df r om29%i n1 997t o39%i n1 998・ Aboutt hr e e ‑ qua r t e r s ofa l lof f ‑ l e a s eve hi c l e sr e t ume dt ol e s s o r si nc ur r e dl os s e s ; t hea ve r a gel os si n1 998 wa s$1 8 78pe rve hi c l e ,220%mor et ha nt hea ve r a gef or1 993. GM' se a r l ya c t i onhe l pe di ta voi dt he s el os s es ,whi l eot he rca r ma ke r sf ound t he ms e l vesf a c i nghuger e c o nc i l i a t i onc ha r ge s . Pr of i t sa tFor dCr e di tCo r po r a t i on f e l l$41 0mi l l i oni n1 997C ompa r e dt 01 996,a28% dr o p,l a r ge l yduet ol os s eson of f l l e a s eve hi c l es . AtGMAC,ne ti nc omef r om a ut omot i vef i na nc l ngo pe r a t i ons f e l lonl y$36mi l l i on, l es st ha n4%, a ndove r a l lGMACpr of i t sr os emor et ha n6%. I n1 997s e ve r a lca r ma ke r s , i nc l udi ngFor da ndNi s s a nUSA, a t t e mpt e dt opr op upwhol es a l epr i c esf o rt he i rc a r sbypa yi ngde a l e r st oke e pof トl e a s ec a r si ns t e a d ofr e t ur ni ngt he mt ot hema nuf a c t ur e rf o rs a l ea ta uc t i on. For dpa i dde a l e r s$700t o $6000( de pe ndi ngont hemode l )f o re a c h21 ye a rOl dof f l l e a s eve hi c l et hede a l e r a gr e e dt oke e p,di ppi ngI nt oi t sr e s i dua lr es e r vesf ort hef i r s tt i met odos o. Thi s pol i c yr educ e dt henumbe rof2‑ ye a r ‑ ol dc a r ss ol da ta uc t i on,butofc o ur s e ,s i nc e r e t e nt i onoft hes ec a r sa dde dt ode a l e ri nve nt or i es , t henumbe roft hes ec a r sde a l e r s boughta ta uc t i onf e l lbyt hes a mea mo unt ,S owhol e s a l epr i c esc ont i nue dt os l i de. I n1 998GECa pi t a ld r oppe di t spa r t ne r s hi pwi t hChr ys l e rt of i na nc el e a s e sbe ‑ c a us e ,a sAut omot i v eNe ws( 24Augus t , p.1 )r e po r t e d, 0 0 4 3 ■ ︼l l lll L= 寸?N 9 00 6 L 0 2 l ll J ndexsh owst h e usedc arandt r uc k componen toft he USCon sumer Pr i c eI nde x, seas onaH y ad j us t ed. 0 5 ト i 5 FI GURE2‑ Us edcarpr l CeS, 1989‑1 999 1988 1990 1992 1994 1996 So u r c e : USBu r e a uo f L a b o r S t a t i s t i c s , s e r i e sCUSRO O O SE T AO 2 . 1998 2000 Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n 5 5 GECa p i t a l Au t oFi n a n c i a lSe r v i c e sg o t b u r n e do nr e s i d ua l ‑ v a l u el o s s e si n1 9 9 7. Mu c ho ft ha t wa sd u et oo f f ‑ l e a s ep r o d u c t sf r o mCh r ys l e r. . . GECa p i t a lc i t e d r e s i d ua ll os s e sa so ner e a s o nf o rt h ed e c l i n ei no pe r a t i ngP r o f i t sf o rCo ns u me r Se r v i c e s , t heGEu n i tt ha ti n c l ud e sAu t oFi n a n c i a lSe r v i c e s . Pr o f i t sf e l lf r o m $1 . 3bi l l i o ni n1 9 9 6t o$ 5 63mi l l i o n[ i n1 9 9 7 ] . I n1 998ne ti nc omea tFor dCr e di tr os e$53mi l l i onove rt hede pr es s e dl e ve lof 1 997butr e ma i ne d25% be l owt hene tf or1 996・ 4GMAC' sne tona ut of i na nc l ng r os e$74mi l l i o nove r1 997,ar i s eof4% ove r1 996,a ndt ot a lGMACpr of i tf o r 1 998r os e$1 81mi l l i onove r1 996,aga i nof1 5%.I n1 998Fo r da ndot he rc a r ma ke r sbe l a t e d l yf ol l owe dGM' Sl e a da ndbe ga nt omovea wa yf r om s hor t ‑ t e r m l e a s l ng. Si nc e1 996t hel e as l ngmode lha sbe e nupda t e ds e ve r a lt i mes ,di s a ggr e ga t e d f ur t he rt os e pa r a t et hec a ra ndl i ghtt r uc ks e gme nt s ,a ndus edt oe xa mi nei s s ues s uc ha ss a l e so ff l e e tve hi c l e s .Themode li snow us e dona nongol ngba s i sby NAO' sPor t f ol i oPr ic l ngTe a m,t hegr oupr e s pons i bl ef orr e vi e wa nda ppr ova lof a l lpr l C l nga ndi I I C e nt i vepr ogr a msi nNor t hAme r i c a・ Puda r , nowDi r e c t oroft heDSC( r e na me dt heSt r a t e gySuppor tCe nt e r[ SSC] ) , r e por t st ha tt heSSC c ont i nue st oa ppl ys ys t e m dyna mi cs ,i nc ombi na t i onwi t h ot he ra na l yt i cme t hods ,t oawi der a ngeofi s s ue s ,f r om ne got i a t i ngJ Ol ntVe nt ur e s wl t hf o r e i gngo ve r nme nt st odes i gni ngbus i ne s spl a nsf orne wpr oduc t s ,s e r vi c e s , a ndbus i ne s sun i t s . ‑ 2. 3 0 NTl MEAN【 )uNDEF 3BL 旧GET: THEDYNAMI CSOFPROJECTMANAGEMENT5 I n1 970,I nga l1 sShi pbui l di ngofPa s c a goul a , Mi s s i s s I PPl ,wonama j orC Ont r a C tt O bui l daf le e tof30ne wdes t r oye r sf ort heUSNa vy・Combi ne dwi t hi t s1 969c on‑ a na mphi bi ousa s s a ul t / a i r c r a f tc a r r i e r ) , I nga l l sf oundi t s e l fi nt he t r a c tfr9LHAs( ha ppypos i t i onofl a ndi ngt wooft hel a r ge s ts hi pbui l di ngpr ogr a msi nt hewor l d a ndl ooke df or wa r dt ohe a l t hys a l e sa ndpr of i t sf orye a r st oc ome.Byt hemi d1 1 970S , howe ve r , I nga l l swa si nde e pt r o ubl e, f a c i ngc os tove r r unspr o j e c t e dt oe xI c e e d$500mi l l i on. Wi t ha nnua ls a l e si nt hemi d‑ 1 970sof$500‑800mi l l i on,t he ove r r unt hr e a t e ne dt os i nkl nga l l s ,a ndi t spa r e ntLi t t onl ndus t r i e s ,a l t oge 血e r . Ad‑ j us t e df ori nf la t i ont heove r unwoul r de xc e e d$1 . 5bi l l i oni n1 999dol l a r s . Bot hc ont r a c t swe r ea wa r de da st o t a lpa c ka gepr oc ur e me nt pr o j e c t sWi t haf i r m f i xe d‑ pr i c ec ont r a c ts t uc r t ur ei nwhi c hI nga l l s" wa spr ovi de donl ywi t ht hepe r f o r ‑ ma nc es pe c i f i c a t i ons ,a ndwa st he r e a f t e rs ol e l yr e s pons i bl ef ora l ls ys t e m de s i gn, de t a i l e d des i gn,ma t e r i a l spr oc ur e me nt ,pl a nnl ng,t eS t l ng,a nd c ons t r uc t i onH ( Coo pe r1 980, p. 22) 。 Bot hpr ogr a msi nvol ve di nnova t i vea ndt e c hni c a l l ys ophi s t i c a t e dne wdes i gns ・ TheDDc l a s smul t i mi s s i ondes t r oye r swe r et wi c ea sl a r gea se a r l i e r" t i nc a ns . "The o 4 Ex c l u d i n go n e ‑ t i mei n c o mef r o ma s s e t s a l e s ・ 5 Th i ss e c t i o ni s b a s e do nCo o p e r( 1 9 8 0 )a n dp e r s o n a l c o mmu n i c a t i o nwi t hKe nCo o p e r l s n ‑ i t t o nI n d u s t ie r sa n d ( p r e s i d e n t , P u g h ‑ Ro b e r t s ss A o c i a t e s ) , Ri c hGo l d b a c h( f o r me r l ywi t hI n g a l c u r r e n t l yp r e s i d e n t , Me t r oMa c h i n eCo r p o r a t i o n ) , a n dma n yo t h e r sa t P u g h ‑ Ro b e r t s As s o c i a t e s . Ⅰ ' mg r a t e f u l f o rt h e i rh e l p . 56 P a r t ∫P e r s p e c t i v ea n dP r o c e s s LHAwa sa l s oa ne nt i r e l yn e wde s i g n. Mor et ha n2 0S t o r i e sh i gha ndt h r e ef o ot ba l l f i e l dsl o ng, e a c hLHAc a r r i e sac o mpl e me ntof2 000ba t t l e ‑ r e a d yMa r i ne sa nd200 C o mba tve hi c l e st ha tc a nbed e pl oye dbyl a ndi ngc r a f ta nds e ve r a ldoz e nhe l i ‑ c o pt e r s . TheDDa ndLHAc o nt r a c t sr e q ui r e dama s s i vemo bi l i z a t i ono fl nga l l s ' r e ‑ s o ur c e s .Al r e a dyo neo ft hel a r ge s ts hi pya r dsi nt hewo r l d,I nga l l sdou bl e di t s wo r kf or c et omo r et ha n20, 000.Dur i ngt hi st i met he r ewe r es ho r t a g e so fs o me s ki l l e dt r a de sa ndc r i t i c a lma t e r i a l s . I nga l l sa l s oha dt oc r e a t ene wo r ga ni z a t i ona l s t r u c t u r e st oma na g et het wopr og r a ms . La r ge ‑ s c a l epr qJ e c t sa r ea mo ngt hemos ti mpo r t a nta ndc o ns i s t e n t l ymi s ma n a g e de nd e a vo r si nmo d e r ns oc i e t y. La rge ‑ s c a l epr o j e c t si nc l u d et hede s i g na ndc o n‑ s t r uc t i o no fc i v i lwo r ksa ndi nf r a s t r uc t u r e( e. g. , br i dge s , t unne l s , po we rpl a nt s , a nd t e l e c o mmuni c a t i onsne t wo r ks ) , mi l i t a r ys ys t e ms( e . g"a i r c r a f t , s hi ps , a ndwe a po ns s ys t e ms ) ,a ndne wpr od uc t si ne ve r yi ndus t r y( e. g"s o f t wa r e ,a ut omo bi l e s ,s e mi ‑ c o nd uc t o rc h i pde s i g n, a ndwa f e rf a bc o ns t r uc t i o n) . Pr o j e c t sofa l lt y pe sr o ut i ne l ye xpe r i e nc ec os to ve r r uns ,d e l a ys ,a ndq ua l i t y pr o bl e ms . Coo pe ra ndMul l e n( 1 9 93)e xa mi ne das a mpl eo fl a r g ec i v i l i a na ndmi l ‑ i t a r ypr o j e c t s( a ve r a g i ng1 3 0, 000pe r s o n‑ ho ur so fpl a n ne dwo r ko ve ra bo utaye a r f o rt hec i v i l i a npr o j e c t sa nd1 70, 0 00pe r s o n‑ ho ur sofpl a n ne dwo r ko ve rmo r et ha n 2ye a r sf o rt hemi l i t a r ypr o j e c t s ) . The yf o undc omme r c i a lpr o j e c t sc os t1 40%a nd t oo k1 90%a sl o nga so r i g i na l l ys c he d ul e d, whi l ede f e ns epr o j e c t sc os t31 0%oft he o r l g l na le s t i ma t e sa ndt oo k46 0%a sl o ngt oc o mpl e t e . De l a ys ,c os tove r r uns ,a ndq ua l i t ypr o bl e msi nc o mme r c i a lne wp r od uc tde ‑ ve l o pme ntc a nki l lac o mpa ny , pa r t i c ul a r l yi nhi g h‑ ve l oc l t yi ndus t r i e ss uc ha ss of t ‑ wa r ea ndhi g ht e c hno l o gy . Ov e r r unsa ndde l a ysi nc i v i lwo r ksa ndmi l i t a r yp r o j e c t s c a na fe c tt hee c onomi cvi t a l i t yofar e gi o na ndt hea bi l i t yofana t i o nt ode f e nd f ' . i t s e l ‑ 2. 3. 1 TheCl ai m TheNa vya ndI nga l l sdi s a gr e e ds ha r pl yove rt hec a us e soft hede l a ysa ndc os t ove 汀un.I nga l l sbe l i e ve dt hema j o r i t yO ft hec os tove r r unwa sc a us e dbyt hea c ‑ t i o nso ft heNa vy . Asi sc o mmo ni nl a r ge,l e ngt hypr qJ e c t s , t het e c hnol og l e Sa nd s ys t e mst obeus e di nt heDDa ndLHAs hi pswe r eno tma t ur ea tt het i met hec on‑ t r a c t swe r ea wa r de d. Te c hnol ogi e sf o rna vi ga t i on, i nt e l l i ge nc e ,c ommuni c a t i o ns , a ndwe a po nss ys t e ms ,f o re xa mpl e ,we r ea dva nc i ngr a pi dl y ,a ndt heNa vyna r a l l ys oug htt oi nc o r po r a t et hemos tu p‑ t o‑ da t es ys t e msi nt hes hi ps ・ Ri c hGol d‑ ba c h, t he nas e n i o rma na g e ra tl nga l l sa ndo neo ft heke ypa r t i c l pa nt Si nt hec l a i m, c o mme nt e dt ha t" I nga l l swa sc onvi nc e dt ha tt hegove r nme nti nt e r f e r e dwi t ht he de s l gnf ort heLHAf r o mt hes t a r tb ymi c r o‑ ma na gl ngt hede s i g npr o c e s s . "As hi g h‑ l e ve lde s i gn,de t a i l e dde s i gn,a nde ve nc ons t r uc t i onpr oc e e de d,I nga l l sr e ‑ c e i ve dma nyt ho us a ndso fde s i g nc ha nge s血・ o mt heNa v y.I nga l l sbe l i e ve dt ha t muc hoft heove r r unwa sc a us e dbyt hei mpos i t i o noft he s ed e s i g nc ha ng e s . Af t e r t heNa vyr e pe a t e dl yr e f us e dt oc ompe ns a t el nga l l sf o rt he s ec os t s , I nga l l sb r oug ht ac l a i ma ga i ns tt heNa v yt or e c ove rt he$500mi l l i o ni nl os s e si te x pe c t e d. Sui ngyo urc us t o me r si sa l wa yst r i c ky. ht hec a s eo fl nga l l si twa spa r t i c ul a r l y de l i c a t e.I nga l l sbr oug htt hec l a i me a r l y ,whi l et het wopr og r a mss t i l lha dma ny ye a r st or unJnga l l sha dt oc ont i n uet oma na get het wopr og r a msa ndma i nt a i na t u ‑ Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n 57 goodwor ki ngr e l a t i ons hi pwi t ht heNa vywhi l es i mul t a ne ous l ypur s ui ngt hec l a i m・ Fur t he r ,s i ncecomme r c i a ls hi pbui l di ngwasi ndecl i nei nt heUS,t heNa vywa s I nga l l s ' mos ti mpor t a ntc us t ome ra ndwoul dbef ort hei nde f i ni t ef ut ur e・ 6 TheNa vyc once dedt ha ti tha dge ne r a t e dt hedes i gnc hangesbuta r gue dt ha t t he i ri mpac twasl i mi t edt ot hedi r ec tcos tofr ei s s ul ngt hes pec i f i ca t i onsa ndr e ‑ wor ki ngt hea fe c t ede ngi ne e r i ngdr a wl ngS ・ Thet ot a lcos toft hes edi r e c ti mpa c t s wa sas ma l lf r a c t i onoft het ot a lc l a i mJnga l l sc ount e r e dt ha tades i gnc ha ngec oul d c r ea t emuc hl a r ge rcos t s ,f ore xa mpl e,bya l t e r l ngt hes equenceoft a s ksa ndr e qul r l ngove r t i mea nduns c he dul edhi r i ngt ha ti nt e r f e r edwi t hot he rphas esoft he wor k,di l ut ede xpe r i enc e,a ndr e duce dpr oduc t i vi t yeve ni nwor kphas esnotdi ‑ r e c t l ya fect edbyc ha ngeor de r s .I nga l l sbe l i eve ds uc hr i ppl ee f f ec t scoul dmul t i ‑ pl yt hedi r ec ti mpa c tofac ha ngenot i c ema nyt i mes ,l ea di ngt os l gni f i c a ntove r a l l H de l a ya nddi s r upt l On. " TheNa vycount e r edt ha tt hes uppos e dde l a ya nddi s nl pt l OnWe r ea c t ua l l yt he r es ul tofcont r a c t ormi s ma na ge me ntorde l i be r a t eunde r bi ddi ngt owi nt hec ont r a c t . Di s put esove rt hede l a ya nddi s r upt l OnCOmpOne ntOfpr i orcl a i mst hr oughoutt he de f ens ei ndus t r yof t endr a gge doutove rma nyyea r s ・ TheNa vyhadneve rpa i da s i gni f i ca ntdel a ya nddi s upt r i onC l a i m. ‑ 2. 3. 2 書 ni t i aEModelDeveJ opmenモ I nga l l ss pents e ve r a lyea r spur s ul ngt hec l a i m,butt r a di t i ona lpr o j e c tma na ge me nt t ool sdi dnotpr ovi deamea nst oqua nt i f yt her l PPl ee f f ect s .I nga l l st ur ne dt o s ys t e m dyna mi c st oqua nt i f yt hede l a ya nddi s uPt r l OnC r eat edbyNa vydes i gn c ha nges ・Themode l ,deve l ope dbyPugh‑Robe r t sAs s oc i a t esofCa mbr i dge, Ma s s a c hus e t t s ,s i mul a t e da l lpha s esoft heDD a ndLHApr o j ec t s ,f r om t hea wa r d oft hec ont r a c tt ot hedel i ve r yoft hel a s ts hi p,t he n5yea r si nt hef ut ur e. Themode lul t i ma t e l ycont a i nedma nyt hous a ndsofequa t i ons ,ave r yl a r ge mode li ndee d( es pe c i a l l ycons i de r i ngt hes t a t eofcomput e rt e c hnol ogya tt het i me) . I tbega n,howe ve r ,asamuc hs ma l l e rmode ldes i gnedt oi l l umi na t et hebas i cf ee d ba c kst ha tmi g htber es pons i bl ef orr i ppl ee fe ct s .Themodel i ngt ea m wor ked c l os e l ywi t hl nga l l s ' cl a i m ma na ge me ntor ga ni za t i on, i nc l udi ngma na ge r s丘・ om a l l ma j orPhas esofea c hpr ogr a ma ndke ya t t ome ys .Lea dmode l e rKe nCoope rde‑ s c r i be dt hepr oc e s st hi swa y( 1 980,pp.26‑ 27) : ‑ TheI nga l l sp r o j e c tt e a mg ui de da ndr e v i e we dt hede c i s i ono fwha te l e me n t s t oi nc l udei nt hemo de l , a ndwi t hwha tme a s ur e sa ndi nwha tde t a i lt oi nc l ude t he m...l D] o z e nso fi nd i vi d ua l si na l ls t a g e so fs hi pbui l di ng, f r o mwo r ke r s t hr oug hvi c ep r e s i de nt s , we r ei nt e r v i e we d. The yof f e r e dqua l i t a t i vea ndq ua nt i t a t i ve o bs e r va t i o nso ns hi pd e s i gna ndc o ns t r l ユ C t i o n. Ast hede s i g noft hemo de lbe ga nt o ge l , t henume r i c a lda t ar e q ulr e me nt SWe r eC l a r i f i e d;ama s s i veda t ac ol l e c t i one f ‑ f ot , l nC On C e r tWi t hot he re l e me n t so ft hec l a i m, wa sunde r t a ke n. The s eda t aa n d i nf わr ma t i o np r o vi de de no ug hma t e r i a lt oa s s e mbl eapr e l i mi na r yma t he ma t i c a l mode lo fas l n g l ewo r kpha s e . Thee qua ions t , pa r a me t e r s , a ndd e t a i l e do ut put we r er e vi e we dbyt hepr o j e c tt e a m, a nds e ve r a lmod e lmodi f i c a t i o nsma d e. r 6 Du ei np a r t t ot h ep r o b l e mse n c o u n t er e di nt h ep r o g r a m, t h en u mb e ro fLHA su t l i ma t e l y b u i l t wa sc u tt o5 ・ LHA5 , t h eUS SPe l e l i u , wa sc o mp l et e di nmi d1980, a swa st h el a s t DDc l a s s d e s t r o y e r , USSFl e t c h e r . 58 I P e r s p e c t i v ea n dP r o c e s s Pa r t 2. 3. 3 Dynami cHypot hesi s Af ul lde s c r l Pt 1 0 nOft hef e e d ba c ks t r uc t ur eoft hemode li sbe yondt hes c o peoft hi s di s c us s i on;t hi ss e c t i onpr ovi desonl yaf e wi l l us t r a t i onsoft het ypeofr i ppl ee f ‑ f e c t st hemode la ddr e s s e d. Fi gur e21 6s howsahi ghl ys i mpl i f i e ds t oc ka ndf low s t r uc t ur ef o rt hef low of wor kwi t hi nas l ngl epr q】 e c tpha s e. Thet a s ksc oul dbehi g h‑ l e ve ls ys t e msdes i gn t a s ks ,pr e pa r a t i onofde t a i l e de ngl ne e r l ngdr a wl ngS ,OrC OnS t uC r t i onofaves s e l . Ther e c t a ngl e sa ndva l vesr e pr es e ntt hes t oc ka ndf low s t r uc t ur eoft hes ys t e m1 7 Thes t oc ksr e pr e s e ntt hea c c umul a t i onsofwor ki ndi f f e r e ntc a t e gor i es ; t heva l ves r e pr e s e ntt hef lo woft a s kst hr o ught hes ys t e m. I ni t i a l l ya l lt a s ksa r ei nt hes t oc kof Wor kt obeDo ne. Compl e t i ngat a s kr e qul r e Sr es o ur c e sS uc ha sapr oduc t i vel a bor f or c ewi t ha ppr o pr l a t eS ki l l s ;t henumbe ra ndpr oduc ivi t t yOft hel a borf or c eva r y ove rt i mea spr o j e c tc o ndi t i onsc ha nge. Ta s ksc a nbedonec o r r e c t l yori nc or r e c t l y, de pe ndi ngont hequa l i t yoft hewor k.Ta s ksdonec or r e c t l ya ddt ot hes t oc kof Wor kRe a l l yDonewhi l et a s ksc ont a i nl nge r r or sOfva r i oust ypesa ddt ot hes t oc k ofUndi s c ove r e dRe wo r k. Wor kqua l i t yi sof t e nqul t el ow,a sne wI Pr Oduc tde ve l ‑ opme nta ndl a r ge ‑ s c a l epr o j e c t sus ua l l yI nvol vene wt e c hnol ogi e s ,ma t e r i a l s ,a nd s ys t e msa ndof t e ni nvol veuni quene wc i r c ums t a nc e s .Coo pe ra ndMul l e n( 1 993) FI GURE2‑ 6 St oc kandf 一 ow s t r uc t ur eo fa pr oj ec tPh ase Rec t ang一 es r epr es en tt he s t oc koft ask s, S t r ai gh tl i n esand val v esr epr es en t f l owsoft ask s bet ween c at egor i es ( chap t er6) . Qual i t yi st he f r ac t i onoft ask s donec or r ec t l y. Thedi agr am i s nl gni ysi mpl i f i ec i andomi t ss ever al t askc at egor i es andf l owsi ncl uded i nt hef u川model . P e o p l eP r o d u c t v i t yQ u a l i t y i Obs oJ es c enc e Ra t e S cs t omer Cha∩ ge s Sour ce: Ad a p t e df r o mad l a g r a mdevel opedb yP u g h ‑Ro b e r t sAs s o c i a t e s , Ca mb r i d g e ,MA . Us e dwi t h p e 「 ml S S i o n . l y , e a c hs t o c ki st h ei n t e g r a l o ft h ef lo wsi nl e s st h ef l o wso u t . S t o c k sa n df lo ws 7 Ma he t ma t i c a l a r ed i s c u s s e di nc h a p t e r s6a n d7. Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n 59 f oundt hea ve r a gef r a c t i onofwor kdonecor r ec t l yt hef i r s tt i mei nt he i rs a mpl et o be689 u orc omme r c i a lpr o j e c t sa ndj us t3 4% f orde f e ns epr o j ec t s . Uncove r l nge r r or st a kest i mea ndr es our c es . Of t e n,e r r or sa r eonl yde t e c t e dby adowns t r ea m phas e,a swhe nades i gnf la wi sdi s cove r e ddur i ngt hecons t uc r t i on phas e.Tas ksi nt hes t oc kofundi s cove r edr e wor ka r et he r e f or epe r c e i vedt obe compl e t ea nda r et r ea t e dasdonebyt heor ga ni za t i on・ Di s c over yofe r r or sbyqua l ‑ 1 t ya s s ur a nc e,t eS t l ng,Oradowns t r ea m pha s emovest hei mper f e c t l ydonet a s kst o t hes t oc kofKnownRe wor k. Coope ra ndMul l e n( 1 993)f ounda ve r a ger e wor kdi s I cove r yde l a ysofa bout9mont hsf orbot hci vi la ndmi l i t a r ypr o j ec t s ,aS i gni f i ca nt f r a c t i onofs c he dul e dpr o j e c tdur a t i on・ Cha ngesi nc us t ome rs pec i f i ca t i onsha vee fec t ss i mi l a rt ot hedi s cove r yof e r r or s .Spec i f i c a t i onc ha ngesma kes omewor kpr e vi ous l ydonec or r e c t l yobs ol e t e, movi ngt hos et as ksf r om t hes t oc kofWor kReal l yDonet ot hes t oc kofKnown Re wor k. Thea f f e ct edpha s emus tr e ca l lwor ki tpr e vi ous l yr e l eas e dt oot he rphas es a nduponwhi c ht hos edowns t r ea m pha s esha vebas edt he i rownwor k.Theor 一 ga ni z a t i onmus tt he ni nc r eas et her es our c esa nda t t ent i ondevot edt or e wor k,s l ow‑ 1 ngCOmpl e t i onofr e ma i nl ngbas e wor kt as ksa ndpot e nt i a l l ydi s r upt l ngt hee nt i r e t1 8 pr o j eC 0bvi ous l yc us t ome rc ha ngest ha tma kec ompl e t eddes i gnwor kobs ol e t ea r e cos t l ybe ca us et hea f f ec t e dt a s ksmus tber e wor ked;t hes ea r et hedi r e c ti mpa c t sof c ha ngest heNa vywa swi l l i ngt opa yf or . Butt hei ndi r e c te f f e c t sc a nbema nyt i mes l a r ge r .Fi gur e21 7S howsaf e w oft hef e edba c kst ha te xpl a i nhowt hei ndi r e c te f ‑ f e c t sofc us t ome rc ha ngescoul dbea mpl i f i ed. Asapr o j ec tf a l l sbe hi ndcont r a c t or sha veonl yaf e wc hoi ces ・ The yca nputt he exi s t i ngWOr kf o r c eonove r t i me,t husi nc r eas l ngt heef f ec t i venumbe rofpeopl e wor ki ngont hepr o j e c t . Thi snega t i veorba l a nc i ngf ee dba c ki st hei nt e ndedefe c t ofove r t i mea ndi ss howni nt hedi a gr a m bys ol i dl i nes .Howe ve r ,e xc es s i veore x‑ t e nde dove r t i mec a us esf a t i guea ndbur nout . Pr oduc t i vi t ya ndqua l i t yf a l l , r e duc i ng pr ogr es sa ndi nc r ea s l ngt hes t oc kofundi s cove r edr ewor k.Bur nouta l s ol e adst o a bs e nt ee i s ma nda t t r i t i onase mpl oye esr e ques tt r a ns f e r sorqui t , r e duc i ngt henum‑ be rofpeopl eont hepr o J e C t ・ Thes euni nt e nde de fe c t s ,s hownasdas he dl i nes ,f or m pos i t i ve( s el f ‑ r e i nf or c i ng)f e e dba c kst ha ta ctasvi ci ouscycl est ounde r c utt he pr ogr es s ‑ e a nc l nge f f e c tofove r t i me. Toa voi dt hes i dee f f e ct sofove r t i memor e pe opl eca n ehi r ed( a not he rba l a nc i ngl oop) .Butr a pi dhi r i ngdi l ut est hee xpe r i ‑ enc ebas eoft hee mpl oye es I I ft hepoolofqua l i f i edwor ke r si nt her e gl Oni ss ma l l r e l a t i vet oi r i ngne e ds ,a cc e l e r a t e dhi r i ngl owe r st hea ve r agequa l i t yofa va i l a bl e ca ndi da t es . Rec r ui t l ngS t a nda r dsof t ene r odes ova ca nc i esca nbef i l l e dqui c kl y・ A l l l i t ya nds l ow pr ogr es se ve na sma nag e一 t hes eefec t sl owe rpr oduc t i vl t ya nd qua me nts e e kst oboos thea dc ountands pee dpr ogr es s . n h b h 8 Mo s t l a r g emi l i t a r ya n dc i v i l i a np r o j e c t ss p e c i f yd e a d l i n e sf o rd e l i v e r y ・ Fa i l u r et ome e t t h e d e a d l i n el e a d st op e n lt a i e s , k n o wna sl i q u i d a t e dd a ma g e s( LDs ) , f o re v e r yd a yt h ep r o j e c t i sl a t e . , LDsc a nr a p i d l ymo u n t t oma n ymi l l i o n s ・ I nd i s p u t e ss u c ha sd i s c u s s e dh e r et h eLDsf o r mt h e p r l ma r yb a s i sf o rt h ec u s t o me r ' sc o u n t e r c l ima a g a l n S t hec t o n t r a c t o r ・ I ns e v e r a l c a s e sf o rwh i c h s y s t e md y n a mi c smo d e l sh a v eb e e nu s e dt h ed i f f e r e n c eb e t we e nt h ec o n t r a c t o rd e l a ya n dd i s r u p t 1 0 n c l a i ma n dt h ec u s t o m ' sc o u n t e r c l a i mwa ss e v e r a l b i l l i o nd o l l a r s . Ev e nwh e nLDsd on o t a p p l y , a s f o ri n ‑ h o us ec o mme r c i a l p r o d u c t d e v e l o p me n t p r o j e c t s ,e v e r yd a yt h ep r o j e c ti sl a t ee r o d e st h e c o mp e t i t i v e n e s so ft h ep r o d u c t a n dt h es a l e sa n dp r o f i t si t c a ng e n e r a t e ・ e r 60 P a r t IP e r s p e c t i v ea n dP r o c e s s FI GURE2‑ 7 Si dee f f ec t sofc or r ec t i v emeasur esl eadt ovi ci ou sc y cl es Asc us t omerchangesc aus eapr o j ec tt Of a"behi nd,managemen tc anacc el er at et he s chedul e,u s eov er t i me, andhi r emor epeopl e, f or ml n gnegat i vef eedback sdesi gned t ogett hepr o j e c tbackont r ack( S ol i dl i nes ) .However , eachoft hes enegat i vel oop st r i g‑ ger ssi deef f ec t st hatunder cu tt hei n t endedef f ec t s, f or mi ngvi ci ou sc y cl es( posi t i vef eed‑ back s,s ho wnb yt h edash edl i n es ) . Sour ce: Ad a p t e df r o mad l a g r a md e v e l o p e db yPu g h ‑Ro b e r t sAs s o c i a t e s , Ca mb n d g e , MA. Us e dwE t hp e r mI S S i o n . Asapr o j e c tf a l l sbe hi nds c he dul ema na ge me ntof t e npr es s ur ese mpl oye est o wor kha r de ra ndc ompr e s s e st hes c he dul ebyove r l a ppl nga c t i vi t i est ha ts ho ul dbe donei ns e que nc e. Appa r e ntpr oduc t i vl t yr l S eS , butt he r ea r ea l s ouna nt l C l pa t e ds i de e fe c t s . Sc he dul ec ompr e s s i onf or c e spe opl et odowor koutofs e que nc e, me a nl ng i mpor t a nti nf or ma t i onorma t e r i a l sf r om ups t r e a m pha s e sa r enota va i l a bl e・ De t a i l e ddes i gnma ys t a r tbe f or es ys t e m des i gni sma t ur ea nds t a bl e.Pr ot ot ype bui l dsma ybe gi nbe f o r ec ompone nts pe c i f i c a t i onsa rec ompl e t e1 9s c he dul ec om‑ pr es s i ona l s ol e a dst owo r ks i t ec onges t i on, bei tove r l oa de dCAD/ CAM f a c i l i t i e s i ne ngl ne e nngOraC r owde dc ons t r uc t i ons i t e. Ma na ge r sa nds upe r vi s or sf i ndt he i r 9 Ma n yo r g a n i z a t i o n st o d a yh a v ea d o p t e dc o n c u 汀e n t e n g l n e e r l n gp r a c t i c e sd e s i g n e dt os h o rt e n d ev e l o p me n t c y c l et i me s . S u c c e s s f u l d e p l o y me n t o fc o n c u r r e n t e n g l n e e r l n gi sd i f f i c u l t a n de v e ni n h i g h l yc o n c u r r e n t p r o g r a mst h ed e g r e eo fo v e r l a pb e t we e nd i f f e r e n t p h a s e sc a nb et o oa g g r e s s i v e , l e a d i n gt oe x c e s s i v er e wo r k . S e eF o r da n dS t e r Ta n( 1 9 9 8 a )a n d( 1 9 9 8 b )f o rs y s t e md y n a mi . C s mo d e l so fc o n c u r r e n t e n g l ne e r l n g , Wi t ha p p l i c a t i o n st OS e mi c o n d u c t o rd e s i g n . S e ea ls os e c t l O n1 4 . 5 . Cha pte r2 Sys t e mDy na mi c si nAc t i o n 61 t i mei si nc r e a s l n g l yc o ns ume dbyme e t l ngSt OWO r ko utc o nf li c t sa r i s l ngf r o mt he a c c e l e r a t e ds c he d ul ea nda dho c, l a s t ‑ mi n ut ec oo r d i na t i o nofout ‑ of ‑ S e que nc ea c t i v i t i e s ・ St r e s sf r o mwo r kpr e s s u r e , i nc r e a s e df i r ef i g ht i ng, a ndc o ns t a ntc ha nge si n s c he d ul e sc a nl e a dt omo r a l epr o bl e mst ha tc utp r od uc t i vl t ya ndq ua l i t ya ndi n‑ c r e a s ea bs e nt e e i s ma nda t t r i t i o n・ The s ee fe c t sa r ef ur t he rmul t i pl i e dbyt her e wo r k c yc l e ・ Lo we rq ua l i t yme a nsmo r et a s ksc o nt a i ne r r o r s . Be c a us ema nye r r o r sa r eno t d i s c o ve r e di mme d i a t e l y , s ubs e q ue ntwo r kbe g i nsus l ngd e s i g ns , ma t e r i a l s , a ndi n‑ f o r ma t i o nt ha ta p pe a rt obec o r r e c ta tt het i mebuta r el a t e rr e c a l l e df o rr e wo r k. Thusc us t o me rc ha ng e sc a nd i s r u pta ndde l a yu ps t r e a ma c t i v i t i e ss uc ha ss ys ‑ t e m de s i g n・ The s ep ha s e smus tt he nr e c a l ls o mepr e vi o us l yr e l e a s e dwo r k,s od e ‑ l a ysa ndqua l i t yp r o bl e msc a s c a det odo wns t r e a mpha s e ss uc ha sd e t a i l e dde s i gn, ma t e r i a l spr o c ur e me nt ,a ndc o ns t r uc t i o n. Thedowns t r e a mpha s e smus tt he nr e do muc hoft he i rj o b,o f t e na tgr e a te xpe ns e( pa r t i c ul a r l ywhe nc ons t r uc t i o nha sa l ‑ r e a dybe g un) ・ Tot hee xt e ntd i f f e r e ntpr o j e c t ss uc ha st heDDa ndLHApr ogr a ms r e ,a ndma na ge ‑ s ha r er e s o ur c e ss uc ha swor ks i t e s ,wor ke r s ,s uppo r ti nf r a s t uc r t u me nt , pr o bl e msi no nec a ns pi l lo ve rt oa not he r , Thed i a g r a msa bovea r ehi ghl ys i mpl i f i e d,a ndma nyo t he ri mpo r t a ntf e e d‑ ba c ksc a pt ur e di nt hef u l lmode la r eo mi t t e d( ho wma nyo t he rs uc he f f e c t sc a nyo u i de nt i f yf r o m yo uro wne xpe r i e nc e? ) .Butt he yi l l us t r a t ehow a ppa r e nt l ys ma l l c ha nge si nc us t o me rs pe c i f i c a t i onsc a ns nowba l li nt omuc hl a r g e rde l a ya nddi s ‑ r u pt l O nd es pl t ema na ge me nt ' sbe s te fo r t st oge tt hepr o j e c tba c ko nt r a c k.The mode la ugme nt e dt r a di t i o na lpr o j e c ta na l ys i st hr o ug ht hee x pl i c i tr e c ognl t l OnOf t her e wo r kc yc l e , va r i a bl es t a f fpr od uc t i vl t ya ndq ua l i t y ,a ndt heba neo fmos tde ‑ l y ,a nyi ndi r e c te fe c t s ve l o pme ntpr o j e c t s ‑u ndi s c o ve r e dr e wo r k・Co nve nt i o na l we r evi e we da sas ma l la dd i t i o na lpe r c e nt a g eove rt hedi r e c tc os t s ・ Ex pl i c i tr e c og‑ ni t i onoft hef e e d ba c ks t r u c t ur ede s c r i be dhe r ehe l pe de x pl a i nho wt hei nd i r e c te f ‑ f e c t so fc us t o me rc ha ng e sc o ul dbema nyt i me sl a r ge rt ha nt h ed i r e c te f f e c t s . ‑ 21 3・ 4 TheModel 岳 ngPr ocess Themode l i ngt e a ma s s e mbl e dt hef ul lmode lbyr e pl i c a t i ngt hege ne r i cpr o j e c t pha s emodu l et or e pr e s e nt e a c hpha s ef わre a c hs hi pl ne a c hp r o g r a m. Thema j o ra c ‑ t i v i t i e s( s ys t e md e s i g n, de t a i l e dde s i g n, pr oc u r e me nt , c o ns t r u c t i o n, e t c. )we r edi s ‑ a gg r e ga t e df u r t h e rwhe r ene c e s s a r y;f o re xa mpl e ,c o ns t r uc t i onwa sdi vi de di nt o s e ve r a lma j o ra c t i vi t i e s( e. g. ,h ll u ,pi pi ng,e l e c t r i c a l ,e t c. )a ndt hec ons t r uc t i o n wo r kf o r c ewa sd i s a gg r e ga t e dbyma j o rc r a f t s( e. g. , s t e e l wo r ke r s , e l e c t r i c i a ns , e t c. ) . Cons t r uc t i o npr o g r e s sf ore a c hs hi pwa sr e pr e s e nt e ds e pa r a t e l y . Ea c hi ns t a nc eof t hege ne r i cpha s emod ul ewa sc a l i br a t e dt ot hepa r t i c ul a ra c t i v l t yl tr e pr e s e nt e d. Thei ndi v i dua la c t i vi t i e s , pha s e s , a ndpr og r a mswe r el i n ke dbya dd i t i o na ls t r uc t ur e r e pr e s e nt l ngO Ve r a l lpr og r a m ma na ge me nt , pr og r e s smo ni t o r l ng,S C he d ul i ng, hi r ‑ 1 ng, r e s o ur c ea l l o c a t i o n,a nds oon. Amode lo ft h i ss c o pec o ul dne ve rbebui l t ,C a l i br a t e d, ma i nt a i ne d,o runde r ‑ s t o odi fs uc hamo du l a ra r c hi t e c t u r ewe r eno tus e d. Tor e pr e s e n ts uc hadi ve r s ea r ‑ r a yofa c t i vi t i e st h eg e ne r i cmo d ul eha dt obee xt r e me l yr o bus t . Co ns i d e r a bl ee fo r t we nti nt oe xt r e mec o nd i t i o nst e s t st oe ns u r et ha tt hemo de lbe ha ve da ppr o pr l a t e l y unde ra nyc onc e i va bl ec o mbi na t i onofi n put so rc ondi t i o ns( S e ec ha pt e r21 ) . The t e a m wo r ke dt oe ns ur et hemode lwa sc o ns i s t e ntwi t ha l la va i l a bl ei nf わr ma t i on, 62 P a r t I Pe r s p e c t i v ea n dP r o c e s s i nc l udi ngt hequa l i t a t i vea s s es s me nt sgl e a ne d血. omi nt e r vi e wsa ndobs e r va t i onsi n t hef i e l d, notonl yt henume r i c a lda t a. Ea r l yont het e a mc ompa r e dt heout putoft hemode lt ot hehi s t or yoft hepr o‑ j e c t st Oda t e・ Thepur pos eoft hec ompa r i s ont ohi s t o r i c a lbe ha vi orwa snott opr ove t oI nga l l st ha tt hemode lwa sr i ght ,butr a t he rt oi de nt i f ya r ea swhe r et hemode l r e qui r e di mpr ove me nt .Thes ec ompa r i s onss ome t i mesi de nt i f i e domi s s i onsa nd pr obl e ms ,l e a di ngt or e vi s i onsi nmode ls t r uc t ur ea ndpa r a me t e r s .Ot he rt i mes , di s c r e pa nc i esbe t we e nmode la ndda t as ugges t e dt heda t awe r ei nc ons i s t e ntor i nc o mpl e t e, l ea di ngt oa ddi t i ona lda t ac ol l e c t i on, i nt e r vi e ws ,a ndr e f i ne me ntoft he va l uesa ndj us t i f i c a t i onf orpa r a me t e r s ・ Thi spr oc es sl e dt ot hr e ema j ora ndma ny mi nori t e r a t i onsi nt hemode l . Themode lul t i ma t e l yr e pl i ca t e dt hehi s t or i c a lpe r f or ma nc eoft hepr o j e c t s qui t eWe l l . But ,a sdi s c us s e di nc ha pt e r21 , i ti squl t ee a s yt Of i tamode lt oas e tof da t a . I ti sa l s one c es s a r yt ha tt hemode l r e pl i c a t et heda t af o rt her i ghtr e a s ons , r e a ‑ s onst hemode l e r sa ndl nga l l s 'ma na ge me ntunde r s t a nda ndc a ne xpl a i ni npl a i n l a ngua ge. Whi l epa r t i c ul a r l yi mpo r t a nti nt hea dve r s a r i ls a e t t l ngOfal a r gel a ws ui t , he t s ea r ei mpor t a nti na nymode l i ngpr o j e C t ・ Ul t i ma t e l yt hecl i e nt sf ora nymode l ‑ 1 ngPr o j e c tWi l lt a kea c t i onon lyt ot hee xt e ntt he i rme nt a lmode l sha vec ha nge d. I n t um, t hec l i e nt s ' me nt a lmode l sa r eunl i ke l yt oc ha ngeunl es st he yha vec onf i de nc e i nt hei nt e gr l t ya nda ppr opr i a t e nes sOft hef or ma lmode l .De ve l opi ngt ha tc onf i ‑ de nc er e qui r esamode l i ngpr oc e s st ha tgl Ve St hec l i e nt st heoppor t unl t yt Ode l vea s de e pl yi nt ot hede t a i l sa st he ywa nt ,t oque s t i ona nya s s umpt l On,a ndt oc ha l l e nge a nyr es ul t . Ope nl ngt hemode lt or e vi e wbyt hec l i e nt si sa l s oe s s e nt i a lf o rt hemod‑ e l e r st oe ns ur ei ta ddr e s s est hei s s ue st hec l i e ntc a r esmos tde e pl ya bouta ndt oge n‑ e r a t et hebes tmode lf ort ha tpur pos e. Tounc ove rmode lf la wsa ndc r e a t eoppor t uni t i e sf ort heI nga l l st ea mt oc ha l 1 1 e nget hemode lt hemode l i ngt e a mus e ds e ve r a lot he rpr oc e dur es 。Coo pe r( 1 98 0, p. 27)e xpl a i ns : ,W e e s t a bl i s h e da tt h eo u t s e te x pl i c i tl i mi t so fr e a s o na bl e n e s sf o re a c hn u me r i ‑ Fi r s t c a lp a r a me t e ri nt hemo d e l ; t h e s ewo u l dno tb ev i o l a t e di no r d e rt oa c h i e veamore " a c c u r a t e "s i mul a t i o n. Fu r t h e r , t h en u me r i c a l p a r a me t e r si nd i f f e r e n ts e c t i o nso ft h e mod e l we r er e q u i r e dt ob ec o ns i s t e n twi t ho n ea n o t h e ri nt e r mso fr e l a t i v ema g n t u d e . The s eg ui d e l i n e s. Hwe r enev e rv i o l a t e d. Th emo d e lwa sa l s os u b j e c t e dt oa s e r i e so f" S ho c kt e s t s "t oa s s e s sr o b us t n e s si nr e s po n d i nga st hec o mpa n ywo u l dt o l y , s e v e r a ld i fe r e n tp l a us i bl ec o mbi na t i o n s r a d i c a l l yd i f f e r e n tc i r c ums t a n c e s . Fi n a l o fe q ua t i o nsa ndpa r a me t e r swe r et e s t e dt oe x p l o r eH a l t e r n a t i v emo d e l s Ht ha tmi g h t a c c u r a t e l yr e p r e s e n tI ng a uso p e r a t i o ns . l ‑ Ast i mepa s s e dt hemode l ‑ ge ne r a t e dPr oj e c t i o nsf ors c he dul ea ndc os t st ur ne dout t obequi t eC l os et owha ta c t ua l l yha ppe ne d, f ur t he rboos t i ngC Onf i de nc ei nt hea bi l 1 1 t yOft hemode lt oc a pt ur et heunde r l yi ngs t r uc t ur eoft hepr o j e c t s . Themode l i ngt e a ma s s e s s e dt hes ys t e mwi dee fe c t soft heNa vy' sde s i gn c ha nge sbyc ompa r l ngt woS i mul a t i ons . The" a s ‑ bui l t Hc a s ewa st hehi s t o r i c a ls i m‑ ul a t i oni nc l udi nga l lt heNa vydes i gnc ha nge s ;t hi swa scompa r e dt ot heH woul d ha ve "C a s ei nwhi c ht hede s i gnc ha nge swe r er e move d. Thedi f f e r e nc ei nt ot a lc os t s a ndc ompl e t i ont i mesr e pr es e nt e dt hec umul a t i vei mpa c toft hedes i gnc ha nge s . Se ns i t i vi t ya na l ys i st he npl a c e dc onf i de nc ebo undsa r oundt hees t i ma t e dc os toft he de l a ya nddi s r upt l On. Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n 63 Themode la l s oa l l owedl nga l l st oes t i ma t et her ol eofi t sownma na ge me ntde‑ c i s i onsi nt heove r mn.Si mul a t i onsofa l t e r na t i vepol i c i ess howedhowmuc hl owe r pr o j e c tc os t sa nddur a t i onmi ghtha vebe e ni fI nga l l sha dma na gedt hepr o j e c tmor e e f f e c t i ve l yLThea bi l i t yt oqua nt i f yt hec ont r i but i onofc us t ome ri nt e r f er encea nd c ont r a c t ormi s ma na ge me ntt ot hede l a ysa ndc os tove r r unwasac r i t i ca lpa r tof山e 999)des c r i be dt hedi s put er es ol u‑ pr oc es s ・Gol dba c h( pe r s ona lcommuni c a t i on,1 t i onpr oc es spr l O rt Ot hede vel opme ntoft hes ys t e m dyna mi csmode las J us tab un c ho ff i nge r ‑ po l nt l ng. Ac on t r a c t o rwo ul ds a y" He r e ' swha tt hegove r n‑ me ntd i dwr o ng "a ndbl a mea l lt he i rp r o bl e mso nt ha t . The nt hegove r nme ntwoul d s e n dt heGAOl Ge ne r a l Ac c ou nt i ngOfi c e ]i nt of i n da l lt het hi ngst hec o nt r a c t o r di dwr o ng. I twe n tnowhe r e . Th epr o bl e mwa st ha twi t ht he[ pr qj e c tma na g e me nt ]t e c hno l ogi e sa va i l a bl e a tt het i met he r ewa snowa yt os e pa r a t et hei mpa c to fgo ve r n me nta ndc ont r a c t o r p r o bl e mso re x a mi net hes y ne r gybe t we e nt he m. I nt h ee ndweha dt oha vet he a bi l i t yt os a yH h e r ea r et het hi ngst hec o nt r a c t o rd i d n' tdowe l la ndhe r ea r et he t hi ngst hego ve r n me ntdi dn' tdowe l l , a n dhe r e ' sho wmu c he a c hc o nt r i but e dt o c os t sa ndt i me . " Thea dve r s a r i a ls e t t l ngOfal a r gedi s put ea cc e nt ua t est hene e df orar obus t ,we l l ‑ unde r s t oodmode lwhos epa r a me t e r sa ndas s umpt 1 0nSCa nbej us t i f i edwi t hi nde pe nde ntda t a. Aspa r toft hedi s cove r ypr oces si nt hel a ws ui tl nga l l sha dt ot u仙 t he mode l ,doc ume nt a t i on,a na l ys t s ,a nds uppor t i ngda t aove rt ot heNa vy,whi c hhi r ed i t sowne xpe r t st ot r yt ode bunki t . Acommonc r i t i c i s m ofs uchmodel s ,a ndone us e dbyt heNa vy, i st ha tt hepa r a met e r sa nda s s umpt l OnSa r e" COOkedHt oa c hi e ve apr es e l ec t e dout c ome." Ga r ba gei n,ga r ba geo叫 日仏eywoul ds a y,a nda r gue d血a t t hemode lwa sme r el yac ompl i ca t e dr us edes i gne dt oi mpr es st hec our t . TheNa vy' Sout s i dee xper t se xa mi ne da ndc r i t i c i ze dt hemode l . Af t e rt he yde‑ l i ve r e dt he i rr e po r t s ,t hemode l i ngt ea m,a l ongwi t hl nga l l sma na ge me nta ndt he i r a t t or ne ys ,Na vyofi c i a l s ,t hegove r nme nt ' sa t t or ne ys ,a ndt heNa vy' Sout s i dee xI pe r t sme tf ors e ve r a lda ysi nal a r gec onf e r e nc er oom t odi s c us st hec r l t l que.Ea c h i s s uewa sdi s c us s e di ndet a i l , f r om hi ghl e ve li s s uesofmode l i ngme t hodol ogya nd mode la r c hi t e c t ur et os pec i f i ce qua t i onsa ndpa r a me t e r s ・ I nga l l sa ndt hemode l i ng t e a mt he nha dac ha ncet or es pond.The yr e vi s edt hemode lt oaddr es st hec r i t i ‑ c i s msl e ve l edbyt heNa vy' se xpe r t s .I nt hene xtr oundofmee t i ngs ,t he ys howed t heNa vyt ea m how t he yha dmodi f i e dt hemode lt oi ncor por a t et hec ha ngest he Na vy' sexpe r t swa nt e d.Re pea t l ngt hecompa r i s onoft heas ‑ bui l tt owoul dha ve c as es ,t hemode l i ngt ea mf oundt ha tt hef r a c t i onoft heove r r una ndde l a yca us ed byt heNa vy' sde s i gnc ha ngeshada ct ua l l yl nC r eaS e d・10 TheNa vyc l e a r l ye xpec t e dt ha ti ncor por a t i ngt hec r i t i quesa ̲ ndpa r a me t e res t i 一 ma t esofi t se xpe r t si nt ot hemode lwoul ds how mor eoft heove r r unwasdue t oc ont r a c t ormi s ma na ge ment .Thecount e r i nt ui t i ver es ul tt ha tt hec l a i m va l ue ‑ mGi v e nt h et e c h n o l o g yo ft h e t i me( ma i n f r a mec o mp u t e r so p e r a t i n gwi t ht i me ‑ s h a r i n g , t e l e t y p e p r i n t e r s 7 a n d100b a u da c o u s t i cc o u p l e rmo d e ms )i t wa sn o t f e a s i b l et or 望t h emo d e l l i v ei nt h e me e t l n g S ・ Th emo d e l d e v e l o p e r sp a i n f u l l yr e c a l l o v e mi g h ts e s s i o n sr u n n l n gt h emo d e l o nt h e l a r g e s t c o mp u t e rt h e na v il a a b l e . To d a yi t i sp o s s i b l et ob r i n gt h emo d e l t os u c hme e t l n g SO nal a p t o p a n dma k ema n yc h a n g e si na s s u mp t 1 0 n SO nt h es p o t , S l a s h i n gt h ec y cl et i mef or e x p e r i me n t a t i o n a n dg r e a t l yl n Cr e a S l n gC li e n t i n v o l v e me n t . 64 Pa r t IP e r s p e c t i v ea n dP r oc e s s i nc r e a s e dd e mo ns t r a t e dt oa l lt ha ti ti sa c t ua l l yqui t edi f f i c ul tt oe ngl ne e ramod e l t oge ne r a t eap r e s e l e c t e dr e s ul t . Go l d ba c hc o mme nt e d, " Fo rt he丘r s tt i met heNa v y s a wt ha tl nga l l sha dac r e d i bl ec a s e . "I nt e ns i vene go t i a t i o nst he nbe ga na tt hehi g h‑ e s tl e ve l so fLi t t o na ndt heNa vy . I nJ une1 9 78t hepa r t i e ss e t t l e do uto fc our t . I n‑ ga l l sr e c e i ve d$ 447mi l l i o n. Thust hec l i e nt sf o rt hemo de l i n gwo r kwe r eno to nl yI nga ll s ' ma na g e me nta nd a t t o r ne ysbuta l s ot hec o u r ta ndt heNa v y. I tma ys e e mc o unt e r i n t ui t i vet oi nc l ud e t heo ppos l ngS i dea mo ngt hec l i e n tg r o u pf o ramode l us e di nal a ws ui t . An di nd e e d t heNa vya t t e mpt e dt od i s c r e d i tt hemod e la ndha vei te xc l ude df r omt hepr oc e e d‑ l ngS . Howe ve r , t ot hee xt e n tt hemo de l be c a met hef o c us , e ve nt h r oug ht hec r l t l qu e oft heNa vye xpe r t s , t hes t r u c t u r e si nt hemo de la ndt hedyna mi c st he yge ne r a t e d s t a r t e dt obe c o met hec o mmo nf r a me wo r kf o rdi s c us s i onoft hec l a i mbya l lpa r ‑ t i e s . Thepr oc e s so fc ha ng l ngme nt a lmo de l swa swe l lunde r wa y. Thi spr o c e s sha s s i n c ebe e no bs e r ve di nma nyo t he rc o nf li c t s( s e e , e. g. , We i la ndEt he r t o n1 9 9 0, Re ‑ i c he l ta ndSt e ma n1 990) . Ex pe r i e nc es ho wst ha tt hebe t t e rt heo ppos i t i o ns ' unde r ‑ s t a nd i ngoft hemode l , t hemo r el i k e l yl tWi l lbei nf lue nt i a li nt her e s o l ut i o no ft he di s put e. Tho ug ht hes e t t l nghe r ewa sal a ws ui t ,t hepr oc e s sa ppl i e st oa n ymo de l i ng pr o j e c t .Eve nwhe nt hec l i e nt sf o rt hewo r ka r ea l lf r om t hes a mema na ge me nt m, t he r ewi l la l wa ysbed i fe r e n ts i de sa ndf a c t i ons , pr o pone nt sa ndo ppo ne nt s t e a ofe a c hpo l i c y .Onl yt hei nt e ns i vei nvol ve me ntoft hec l i e nt si nt hemode l i ng pr oc e s sc a nc r e a t et heunde r s t a nd i ngo ft hei s s ue sne e de dt oc ha ng ee n t r e nc he d me nt a lmode l sa ndl e a dt oc o ns e ns usf o ra c t i on. 2. 3. 5 Cont i nui ng】 mpact Thes ys t e md yna mi c smode lwa st h es o l et e c hni c a lba s i sf o rt hed e l a ya ndd i s r u p‑ t i o nc o mpo ne ntofI nga l l s 'c l a i ma ga l nS tt heNa vy・ Es t i ma t e sf r omt hea t t o r ne ys a ndl nga l l sma na ge me ntH pl a c et hemode l ' sdo l l a rc o nt r i but i ont ot hes e t t l e me nt be t we e n$1 70 ‑3 50mi l l i onH( Coo pe r1 98 0, pp.28 ) . Butt he s es ums , l a r gea st he y r e ,unde r e s t i ma t et hebe ne f i t so ft hemo de l i ngpr o c e s s . Thel a ws ui ti t s e l fc a nbe a vi e we da sal a r gepr o j e c tt ha tge ne r a t e di t sownr i ppl ee f f e c t s . Bya c hi e v i ngas e t ‑ t l e me ntal i t t l eove r2ye a r sa f t e rbe g i nni ngt hemode l i ngp r oc e s s( av e r ys ho r ti n‑ t e r va li ns uc hl a r gedi s put e s ) , Th ed i r e c td o l l a rc o s t so fc o n t i n u i n gt h ec l a i me 恥r twe r ea v o i d e d[ l e g a l f e e sa n d c o u r t c o s t s ] . Ev e nmo r es i g n i f i c a n t , h o we v e r , wa st h ev a s ta mo u n to fma n a g e r i a l a n dp r o f e s s i o n a l t i mea n dt a l e n t( a ne n t i r e" c l a i mo r g a n i z a t i o n "o fo v e r1 0 0I n g a l l s pe r s o n n e l )t h a two u l dh a v ec o n t i n u e dt ob es p e n to ns o me t h i n go t h e rt h a ns h i p d e s i g na n dc o n s t r u c t i o n‥. Ab o v ea l l , t h ee l i mi n a t i o no ft h ea d v e r s a r yr e l a t i o n s h i p , be t we e nl n g a l l sa n di t sb e s t c u s t o me rwa sami l e s t o n ea c h i e v e me n t( Co o p e r1 9 8 0 p. 28 ) . Si nc et hi sg r o und br e a ki ngwo r kPug h ‑Ro be r t sa ndo t he rf i r msha veg o neo nt oa p‑ pl ys ys t e m dyna mi c st od i s put e st ot a l i ngma nybi l l i onso fdol l a r s .The s er a nge f r o m ot he rmi l i t a r ya ndc o mme r c i a ls hi pbui l di ngpr o j e c t st oa e r os pa c ea nd we a ponss ys t e ms , po we rpl a nt s , c i v i lwo r kss uc ha st hec r os s ‑ c ha nne lt unne l ,a nd s of t wa r epr o j e c t s . I nmos tc a s e sc o nt r a c t o r sus et hemode l si na c t i onsa ga i ns tt he i r c us t o me r s .I ne a c hc a s et hede f e nda nt sha ves o ug htt ode bun kt hemode l sa nd 6 5 Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n e xc l udet he mf r om t hea l l owa bl ee xpe r tt e s t i monybute a c ht i met hemode l sha ve be e na l l owe da ndha vec o nt r i but e dt of a vor a bl es e t t l e me nt s . Whi l et hedol l a rva lueoft hes ea c io t nsi si mpr e s s i vea ndofundoubt e dbe ne f i t t ot hepl a i nt i f f s , t heda ma ge( t hec os tove m n)ha sa l r e a dybe e ndone ,a ndt hedi s ‑ put ei sonl yove rwhopa ys .Ther e a ll e ve r a gel i e si nus l ngt hes emode l spr oa c t i ve l ys oove r r u nsa ndde l a ysa r ea voi de di nt hef i r s tpl a c e.Si nc et hef i r s tI nga l l s mode l ,ma nyor ga ni z a t i onsha vegoneont oa ppl ys i mi l a rmode l st ot hema na ge ‑ me ntofl a r ge‑ s c a l epr o j e c t si nawi der a ngeofi ndus t r i es( f ore xa mpl e ss e es e c t i ons6. 3. 4a nd1 4. 5)l lI nga l l si t s e l fha sus e dde s c e nda nt soft ha tf i r s tmode lt o he l pma na gevi r t ua l l ye ve r ypr ogr a ms i nc et heLHAa ndDD. Thebe ne f i t sofs uc h pr oa c t i vemode l i nga r eha r de rt oqua nt i f ybutl i ke l yo ut we i ght heva l ueofdi s put e s e t t l e me nt sma n yt l meS . Asonei l l us t r a t i on,Ri c hGol dba c hl e f tl nga l l si nt hel a t e1 970st ohe a dup Me t r oMa c hi ne, as hi pya r di nNor f o l k, Vl r gl ni a. The ns ma l la nds t r uggl i ng, Me t r o t oda yl Sahi ghl ys uc c es s f ulya r ds pe c i li a z i ngl nr e Pa l ra ndr e f i t t i ngwor kf o rt he Na vywi t ha bout700e mpl oye esa nds a l e sofa bout$90ml l l i oI Vye a r . Gol dba c hi n‑ t r oduc e dawi der a ngeofi nnova t i vema na ge me ntpr a c t i c esi nc l udi nge mpl oye ei n‑ vol ve me nt ・ Thef i r mi sl OO% e mpl oye eowne d, wi t huni ve r s a lpa r t i c i pa t i oni nt he e mpl oye es t oc kowne r s hi ppl a n. Me t r oha swons e ve r a la wa r dsf ort hehi ghqua L 1 t yOft he i rwor k,i nc l udi ngNa t i ona lSma l lBus i ne s sPr i meCont r a c t oroft heYe a r a ndt heUSNa vyAEGI SExc e l l e nc eAwa r d" f o rs upe r i orpe r f or ma nc ei nqua l i t y, r e l i a bi l i t y,de l i ve r ya ndc os t " ‑t hef i r s te ve rgl Ve nt Oar e Pa l rya r d・ Mode l sc ont i nuet opl a ya ni mpo r t a ntr ol e.Gol dba c hc ommi s s i one dt hede ‑ ve l o pme ntofas i mul a t i onmode lt opr o j e c tt hef i na nc i a lc ons e que nc e sofva r i ous de c i s i onsf orupt o1 0ye a r s .Me t r ous est hemode lt oa s s es sa c qui s i t i ons ,c a pi t a l i nve s t me ntde c i s i ons ,ne wve nt ur e s , a nda l la s pe c t sofbi ddi ngf orj obs . ‑ . ‑ Web u i l tt hemo d e l t oas p e c l i f i c a t i o n ]Ip r o v i d e dba s e do nwha t Il e a r n e df r o mt h e l n g a l l smo d e l . Th emo d e lhe l pst heg o v e r n me n tu n d e r s t a n do u rbi d sbe t t e r . I tl e t s t h eDCAAl De f e ns eCo n t r a c t Aud i t Ag e n c y , aDe pa r t me n to fDe f e ns ea g e nc yt h a t a u d i t sd e f e ns ec o nt r a c t o rbi dsa n da s s e s s e st h e i ra b i l i t yt od ot hewo r k日o o ka ta t e r na t i v es c e na r i o s . Weus et hemo d e li n t e r a c t i v e l ywi t ht h e m. The r ei sa no n ‑ S i t e DCAAa u d i t o rwhok no wst h emo d e l . Sh ec a na s kust or u na n ys e to fa s s u mp t l O nS , a n dweus u a l l yg e tt h ea ns we rba c ki na nh o u r( Go l d ba c h, pe r s o n a lc o mmu n i c a t i o n, 1 9 9 9 ) . ト Thef i na nc i a ls i mul a t i onhasbe e nve r ye fe c t i ve , butf a rmor ei mpor t a nt , Gol dba c h s a ys ,a r et hel e s s onshel e a r ne da boutt hec ha l l e ngesofma na gl ngC Ompl e x S ys t e ms : Fo rt h e[ s hi p bu i l d i n g ]i nd us t r yit ho u g h tiwa sap r e t t ys o p h i s t i c a t e dma na g e r , b u ti t chan g e dmywh o l epe r s pect i v e . In e v e rh a dt h ea b i l i t yIt hi n kIg o tf r o mwo r k i n g wi ths ys t e md y n a mi c st oas k" ho wwi l l t h i sd e c i s i o nr l p pl eo u t ? MIg o tt ot hepo l n t t hat Iha dt h eme n t a ls e l f ‑ d i s c i pl i n et of i g h tmyI mp u l s e sa n dn o t J us td ot h ema c ho h i t n gwh e nt h e r e ' sap r obl e m・ Th ep l a y l n gf i e l dc ha n g e swhi l ey o u' r epl a y i n gt h e l l s e ea l s oAb d e l ‑ Ha mi da n dMa d n i c k( 1 9 8 9 a ‑ C , 1 9 9 0 , 1 9 9 1 ) ; Co o p e r( 1 9 9 3 a ‑ C , 1 9 9 4 ) ; Co o p e r a n dMu l l e n( 1 9 9 3 ) ; F o r da n dS t e r ma n( 1 9 9 8 a ‑ b ) ; Ho me re t a l . ( 1 9 9 3 ) ; We i l a n dEt h e r t o n( 1 9 9 0 ) ; a n dYo u r d o n( 1 9 9 3 ) . 66 Pa r t IP e r s p e c t i v ea n dP r oc e s s g a me . No wIa s kho wc us t o me r s , e mp l o y e e s , S u p p l i e r sa n ds oo nwi l l r e a c tt owha t we mi g h td o. So me t i me slg e t i t r i g h ta n ds o me t i me sId o n' t . I tp e r me a t e se v e r ya s ec p to fmyt h i n ki n g. I ' mad i fe r e n tp e r s o nt ha nIwa s b e f o r e . 2. 4 PLAYl NG THEMNNTENANCEGAME12 I n1 991 ,Wi ns t onLe de t ,t he nama na ge ri nGul fCoa s tRe gi ona lMa nuf a c t ur l ng Se r vi ce sa tDuPont ,r e le f c t e dont her es ul t sofa ni n‑ hous ebe nc hma r ki ngs t udy doc ume nt l ngal a r gega pbe t we e nDuPont ' sma i nt e na nc er e cor da ndt hos eoft he be s t ‑ pr a c t i c ec ompa ni e si nt hegl o ba lc he mi c a l si ndus t r y. Thebe nc hma r ki ngs t udyr e ve a l e da na ppa r e ntpa r a dox:DuPonts pe ntmor e onma i nt e na nc et ha ni ndus t r yl e a de r sbutgotl e s sf ori t .DuPontha dt hehi ghe s t numbe rofma i nt e na nc ee mpl oye e spe rdol l a rofpl a ntva l ueye ti t sme c ha ni cs wor ke dmor eove r t i me.Spa r epa r t si nve nt or i eswe r ee xc es s i veye tt hepl a nt sr e ‑ 1 i e dhe a vi l y on c os t l ye xpe di t e dpr oc ur e me ntofc r i t i c a lc ompone nt s .Mos t di s t ur bi ng,DuPonts pe nt1 0‑3 0% mor eonma i nt e na nc epe rdol l a rofpl a ntva l ue t ha nt hei ndus t r yl e a de r s ,whi l ea tt hes a met i meove r a l lpl a ntupt l meWa sS Ome 1 0‑1 5% l owe r . Ma nype opl ef oundt her es ul t soft hebe nc hma r ki ngs t udyt obec ount e r i nt u‑ i t i ve. The i rme nt a lmode l ss ugges t e dt ha te qui pme ntqua l i t ys ho ul ds ufe ra ndup‑ t i mes ho ul dbel owi nac ompa nyt ha ts pe ndsl i t t l eonma i nt e na nc e, whi l es pe ndi ng mor eonma i nt e na nc es houl dyi e l dhi gh‑ qua l i t ye qui pme nta ndhi g hupt l me.How c oul dDuPontbes pe ndi ngmor ea ndge t t l ngl es s ? Ma nype opl ebl a me dt hepr obl e m ont hedi f f i c ul tc ompe t i t i vee nvi r onme nt . Thec he mi c a l si nd us t r yl Sma t ur ea ndi nt e ns e l yc o mpe t i t i ve・ Be c a us et he r ei sl i t t l e pr oduc tdi fe r e nt i a t i onf o rbul k( C ommodi t y)f e e ds t oc ks ,C he mi c a lma nuf a c t ur e r s c ompe t eonot he rdi me ns i o ns ,mos t l yc os ta ndde l i ve r yr e l i a bi l i t y・Si nc et hee a r l y 1 970St hei ndus t r ywa shi tbyonec r i s i sa f t e ra not he r :Twos e ve r ee ne r gyc r i s es wr e a ke dha vocwi t hi nputa ndope r a t l ngc os t s . Al wa ysc yc l i c a l , t het hr e ewor s tr e ‑ c e s s i onss i nc et heGr e a tDe pr es s i onc a us e dwi des pr e a de xc e s sc a pa c i t y. Ne wc om‑ pe t i t o r sf r omt hePa c i f i cr i ma ndt heoi l ‑ r i c hna t i onsoft heMi ddl eEa s te nt e r e dt he ma r ke t , Envi r onme nt a lc onc e r nsa ndr e gul a t i onswe r egr owl ng. Le de tkne wa l lt hi s ; heha dl i ve dt h r oughi tdur i nghi s25ye a r swi t hDuPont . Butbl a mi ngOut s i def or c e sf ort hepr obl e ms ,whi l eps yc hol ogi c a l l ys a f e,di dn' t pr ovi dea nyl e ve r a get oi mpr ove. Le de tf e l tt ha tt hee xpl a na t i onoft hepa r a doxl a y noti nt heout s i depr e s s ur e st hec ompa nyha df a c e ddur i ngt wot ur bul e ntde c a des buti ni t sr es pons et ot hos epr e s s ur e s . Le de ta ndhi st e a mne e de dawa yt oe xpl o r et hewa ysi nwhi c hdi f f e r e ntpa r t s oft hema i nt e na nc es ys t e mi nt e r a c t e d,e xpl a i nwhypa s ta t t e mpt st oi mpr oveha d f a i l e d,a ndas s i s ti nt hedes i gnofne w pol i c i es . Andt he yne e de dt oe xpl a i nt hes e nc e dpl a ntope r a t i onsa ndma i nt e na nc epe opl e c ompl e xdyna mi cst ot hee xpe r i e w ho h a dt ot a kea c t i on. 1 2 Ⅰ ' mi n d e b t e dt oWi n s t o nP . Le d e t a n dWi n s t o n∫.Led e t ( p r i n c i p a l s , Th eMa n u f a c t u r i n gGa me), Pa u l Mo n u s( BPCh e mi c ls a ) , a n dMa r kP a l C h( Co l o r a d oCo l l e g e ) f o rp e r mi s s i o nt op r e s e n t he t i r wo r ka n dt h e i ra s s i s t a n c ei nt h ep r e p a r a t i o no ft h ema t e r i l・ a Th a n k sa l s ot oT o n yCa r d e l l a , Ma r k Do wn l n g , Vi n c eFl y n n , a n dt h er e s t o ft h eDuPo n t t e a m. Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n 67 Le de ta ndhi st e a mbe ga nt hede ve l o pme ntofas i mul a t i o nmode lt oc a pt u r e t hes ys t e mwi de ,dy na mi cbe ne f i t sa ndc os t sofdi fe r e ntma i nt e na nc ei ni t i a t i v e s . The yde ve l o pe dt hemode lwi t ht hea s s i s t a nc eofa ne xpe r i e nc e dmo de l e r , Ma r k Pa i c h. Themod e lwa sd e ve l o p e di nt e r a c t i ve l y , wi t ht h epa r t i c l pa t i o no fLe d e ta nd ot he rke yt e a mme mbe r s ・ Ther ol eo ft hee x pe r tmod e l e rwa smo r eofac oa c ha nd f a c i l i t a t o r ,a ndt hemode l i ngp r oc e s si nvo l ve de xt e ns i veha nds ‑ onwo r ks ho psi n whi c ht hemod e lwa sdi s c us s e d, t e s t e d, a ndc ha nge di nr e a lt i mea sme mbe r so ft he . mode l i ngt e a mi d e nt i f i e dpr o bl e mso ra r e a sne e d i ngl mPr O Ve me nt DuPont , l i kemos tl a r gef i r ms ,a l r e a d yus e danu mbe rofma i nt e na nc epl a n‑ nl ngt o ol s . The s et oo l st e ndt of oc uso nt hede t a i lc o mpl e xl t yOft hema i nt e na nc e c ha l l e nge ,f o re xa mpl e ,da t a ba s e st ot r a c kt hema i nt e na nc ehi s t o r yo fe a c hi nd i ‑ , v i d ua lpi e c eofe q ui pme nt ,S t a t i s t i c a lmod e l st oopt l mi z ema i nt e na nc es c he d ul e s s c he dul i ngs ys t e mst oa s s l g nme c ha ni c st opl a nne da ndr e a c t i vewo r k,a nds oo n. The s et oo l sa r ei mpo r t a ntf o r仙eda y‑ t o ‑ da yma na g e me ntofl a r g epl a nt sbutt he y don' tc a pt ur et h edyna mi cc ompl e x l t yOft hema i nt e na nc es ys t e m. Whe r et hede ‑ t a i l e dpl a nnl nga nds c he d ul i ngmo de l st r a c ke de a c hpumpa ndmot o ri nt hepl a nt s e pa r a t e l y , t hed y na mi cmod e l d i vi d e da l le q ul pme nti nt oJ us tt h r e ec a t e go r i e s : o p‑ e r a bl e , br o ke ndo wn, o rt a ke ndownf o rpl a nne dma i nt e na nc e. Butwhe r et hee x‑ i s t l ngmo de l sa s s u me df a i l u r er a t e sa ndr e pa l rc os t sa ndd ur a t i o nswe r ee xo ge no us , t hedyna mi cmo d e lt r e a t e dt he s ef a c t o r se ndoge no us l y . I te nc o mpa s s e dt e c hni c a l i s s ue ss uc ha se q u l pme n tC ha r a c t e r i s t i c s ; l og l S t i c a li s s ue ss uc ha ss pa r epa r t sa va a bi l i t y , ma i nt e na nc es c he d ul i ng,a ndme c ha ni ca s s l gnme nt S ;huma nr e s ou r c e si s ‑ l l ,t r a i ni ng,a ndmo t i va t i o n;a ndf i na nc i a li s s ue s s ue ss uc ha sme c ha ni cs ki i nc l udi ngma i nt e na nc ebud g e t s , r e s o u r c ea l l o c a t i o n, a ndo ve r a l l pl a nt pe r f o r ma nc e . Thes ys t e md yn a mi c smod e lwa sac ompl e me ntt o,a ndno tar e pl a c e me ntf o r , e x‑ i s t l ngpl a nnl nga n ds c he du l i ngt oo l s . i 一 2. 4. 1 Dynami cHypot hes套 s Us i ngt hemo de la sal a bo r a t o r yt ode s i g na ndt e s td i fe r e nt pol i c i e s , t het e a mg r a d‑ ua l l yde ve l o pe da na ppr e c i a t i o nf o rt hed yna mi cc ompl e xl t yO ft hema i nt e na nc e s ys t e m.Thedy na mi chypot he s i st he yde ve l o pe de x pl a i ne dt hepa r a do xt ha tDu Po nts pe ntmo r eo nma i nt e na nc ea ndgo tl e s sf o rl tl nt e r msofu pt l mea nde q ul p‑ me ntr e l i a bi l i t y . Themode l i ngpr oc e s sl e dt os e ve r a li mpo r t a ntc o nc e pt ua ls hi f t si nt hewa y t he yvi e we dma l n t e na nc e・Pr i o rt ot hemod e l i ngwo r kma i nt e na nc ewa sl a r ge l y s e e na sapr oc e s sofde f e c tc o r r e c t i o n( r e pa i roff a i l e de q ui pme nt )a ndt hema i nt e ‑ na nc ef unc t i o nwa svi e we da sac os tt obemi ni mi z e d・ Thef i r s tc onc e pt ua ls hi f t wa st oc ha ng et hef o c usf r o m de f e c tc o r r e c t i ont ode f e c tpr e ve nt i ona ndde f e c t e l i mi na t i o n.Themode lt he r e f o r ec e nt e r e dont hephys i c so fbr e a kdo wnsr a t he r t ha nt hec os tmi ni mi z a t i onme nt a l i t yt ha tpr e va i l e dt hr o ug ho utt heo r ga ni z a t i o n. Equi pme ntf a i l swhe nas uf f i c i e ntn umbe rofl a t e ntd e f e c t sa c c umul a t ei ni t . La t e nt d e f e c t sa r ea nypr obl e mt ha tmi g htu l t i ma t e l yc a us eaf a i l ur e . The yI nc l udel e a ky o i ls e a l si npumps ,di r t ye qul pme ntt ha tc a us e sbe a r i ngwe a r ,pumpa ndmot o r s ha f t st ha ta r eo uto ft r uea ndc a us ev i br a t i o n, poo r l yc a l i br a t e di ns t r ume nt a t i o n, a nds oo n. Ap umpwi t hal e a kyo i ls e a lo rdi r t ybe a r l ngSC a nS t i l l r u nbutwi l le ve n t ua l l yf a i lunl e s st he s el a t e ntde f e c t sa r ee l i mi na t e d. ‑ 68 Pa r t IP e r s p e c t i v ea n dPr o c e s s Thet ot a lnumbe rofl a t e ntdef e ct si napl a nt ' sequi pme nti sas t oc k( Fi gur e 21 8) ・De f e ct sa r ec r ea t e dbyope r a t i ons( nor ma lwea ra ndt ea r )a ndbycol l a t e r a l da ma gea r i s i ngf r om br ea kdowns( whe nt heoi ll ea ksoutoft hepumpbea r i nga nd t hebea r l ngS e i z es ,t hes ha f tmaybebe nt ,t hemot orma yove r hea t ,a ndt hevi br a ‑ t i onma ybr e a kcoupl i ngsa ndpi pes ,i nt r oduc i ngne w pr obl e ms ) IMor es ubt l y, ma i nt e na nc ea c t i vl t yCa nC r ea t enewde f e c t s , t hr oughme c ha ni ce r r or sort heus eof poorqua li t yr e pl a ce me ntpa r t s ・ Thel owe rt hei nt r i ns i cdes i gnqua l i t yoft heequ me nt ,t hemor ede f e c t st hes ea ct i vi t i esc r ea t e. Thes t oc kofde f e c t si sdr a i ne dbyt wof lows :r e a c t i vema i nt e na nce( r e pa i rof f a i l edequi pme nt )a ndpl a nne dma i nt e na nce( pr oa c t i ver e pa i rofope r a bl eequi p me nt ) . 1 3Ea c hoft hes ea c t i vi t i esf or msaba l a nc i ngf e edba c kl oop. Asde f ec t sa cI c umul a t e, t hec ha nc eofabr ea kdowni nc r eas es . Br ea kdownsl e a dt omor er ea ct i ve l P ‑ ‑ FI GURE2‑ 8 Def ec tcr eat i onandel i mi nat i on Thedi agr am i ssi mpl i f i ed.l nt hef ul lmodel equl PmentWasdi vi dedi n t ooper abl e,br ok en down,andt ak endownf orpl annedmai nt enance, wi t hanas soci at eds t ockofl at ent def ec t sf oreachcat egor y . i v e( t i me ‑ b a s e d )wo rk , e . g . , r e p l a c ewo r np a r t so n 1 3 pl a n n e dma i n t e n a n c ei n c l u d e sp r e v e n t p u mp se v e r ynmo n t h s , a n dp r e d i c t i v e( c o n d i t i o n ‑ b a s e d )wo r k, e . g , ,r e p l a c ewo r np a r t so nap u mp i fv i b r a t i o ne x c e e d sac e r t a i nt ol e r a n c e . 69 Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n ma i nt e na nc e,a nd,a f t e rr e pa l r ,t hee qul Pme nti sr e t ur ne dt os e r vi c ea ndt hes t oc k ofde f e c t si sr e d uc e d( t heRe a c t i veMa i nt e na nc el oopBl ) .Si mi l a r l y,s c he dul e d ma i nt e na nc eore qui pme ntmoni t or i ngma yr e ve a lt hepr e s e nceo fl a t e ntde f e c t s( a vi br a t i ngpump, a no i ll e a k) . Thee qui pme nti st he nt a ke noutofs e r vi c ea ndt hede ‑ f e c t sa r ec or r e c t e dbe f or eabr e a kdownoc c ur s( t hePl a nne dMa i nt e na nc el oo pB2) . Obvi ous l yb r e a kdownsr e duc epl a ntupt l me.I na ddi t i on,mos tpl a nne dma i n‑ t e na nc ea c t i vi t ya l s or e d uc esupt l meS i nc epl a nne dma i nt e na nc ef r e que nt l yr e ‑ qul r e SOpe r a bl ee qul pme ntbet a ke noutofs e r vi c es ot hene e de dwo r kc a nbedone・ Fi gur e2‑ 8S howsonl yt hemos tba s i cphys i csofde f e c ta c c umul a t i on.Thet wo ne ga t i vef e e d ba c ksr e gul a t i ngt hes t oc kofde f e c t sa ppea rt obes ymme t r i ca l :De ‑ f e c t sca nbee l i mi na t e de i t he rbypl a nne dma i nt e na nc eorr e pa i rOff a i l e de qul p‑ me nt .Thef ul ls ys t e mi smo r ec ompl e x,howe ve r ,a ndi ncl ude sanumbe rof pos i t i ve,s e l f ‑ r e i nf or c i ngf e e dba c ks( Fi gur e21 9) . Fr GURE2‑ 9 Posi t i vef eedback sunder cu t t i ngpl ann edmai nt enan ce + 70 Pa r t IP e r s p e c t i v ea n dP r o c e s s Cons i de rt hei mpa c toft hef i r s toi lc r i s i si nl a t e1 973. I nputa ndo pe r a t l ngc os t s s kyr oc ke t e d. Butt hes e ve r er e c es s i ont ha tbe ga ni n1 974me a ntc he mi c a lpr oduc ‑ e r sc oul dnotpa s st hee nt i r ec os ti nc r e a s eont oc ons ume r s . Unde ri nt e ns ef i na nc i a l pr e s s ur e,a l lpl a nt sa ndf u nc t i onsha dt oc utc os t s ・ I fma i nt e na nc ede pa r t me nt sa r e a s ke dt oc ute xpe ns esne a r l ya l loft hec utha st oc omef r o ma ct ivi t i ess uc ha spl a n一 ml nga ndpr e ve nt i vema i nt e na nc e:Whe nc r i t i c a le qul pme ntbr e a ksdown,i tmus t bef i xe d. Att hes m et a i me, f i na nc i a lpr es s ur el e a dst oot he ra c t i ons( e. g. , pos t pon1 1 ngr e pl a c e me ntofol de r , l e s sr e l i a bl ee qul pme ntOrr unnl nge qul pme ntl onge ra nd mo r ea gg r e s s i ve l yt ha nor i gi na ldes i gns pe c i f i c a t i onsi ndi c a t e ) , whi c hi nc r e a s et he ma i nt e na nc ewo r kl oa d. Wi t hr es our c e sf o rpl a nne dma i nt e na nc edi mi ni s hi nga nd ma i nt e na nc ene e dsi nc r e a s i ng,t hes t oc kofde f e c t sgr ows . Br e a kdownsi nc r ea s e. Br e a kdownsc a us ec ol l a t e r a lda ma ge,di r e c t l yi nc r e a s i ngt hes t oc kofde f e c t sf ur ‑ t he ra ndl e a di ngt os t i l lmor ebr e a kdownsi navi c i ousc yc l e( t hepos i t i vel oopRl ) . Be c a us et het ot a lnumbe rofme c ha ni c si sl i mi t e d,mor ebr e a kdownsne c e s s a r i l y pul lme c ha ni c sof fpl a nne dwor ka sma na ge me ntr e a s s l gnSme c ha ni c st or e pa l r wo r k. Butma nyme c ha ni c sa ls opr e f e rr e pa l rWOr k. Apl a nne dma i nt e na nc ema n‑ a ge ri nonepl a ntc omme nt e d,H We ' Veha ds e ve r a lpe o pl ewhos a yt he ywa ntt oge t i nvol ve di npr e ve nt i vewor kbutwhe na nout a gec o me sa nd[ t he y]ha veac ha nc e t owo r k1 4‑1 6hour spe rwe e kove r t i met he ys a ỳ t ohe l lwi t ht hi svi br a t i on[ mo n‑ i t or i ng]s t uf F ,Ⅰ ' mgoi ngt ot heout a gea r e a. "' Wi t hl e s spl a nne dwor k, br ea kdowns i nc r e a s es t i l lmor e ,f or ml ngt her e i nf or c i ngGot ot heOut a gel oopR2. Ther i s i ngbr e a kdownr a t emea nsmor ec r i t i c a le qul Pme ntWi l lbeoutofs e r ‑ vi c ea wa i t l ngr e pa i r . Pl a ntupt l mef a l l s .Pl a ntope r a t or sf i ndi tha r de rt ome e tde ‑ ma nd. Whe name c ha ni corma i nt e na nc es upe r vi s o rr e q ue s t st ha tac e r t a i npl e C eOf e qui pme ntbet a ke nof fl i net oc or r e c tl a t e ntde f e c t s ,t heha r r i e dl i nema na ge ri s l i ke l yt os ho uts ome t hi ngl i keH Ic a nba r e l yme e tde ma nda si ti sa ndyouwa ntme t ot a ket hi sl i nedo wn?Nowa yJfyouma i nt e na nc epe o pl ewe r edoi ngyourj ob, I woul dn' tha ves oma nydownpumpsi nt hef i r s tpl a c e.Nowge toutofhe r e,I ' ve gotapl a ntt or un. "Theba l a nc i ngTooBus yf orPM l oop( B3)me a nso pe r a t or sa r e l e s swi l l i ngt ot a kewor ki nge qul pme ntdownf orpl a nne dma i nt e na nc ewhe nup‑ t i mei sl ow. Thes i dee f f e c toft ha tpol i c y, howe ve r , i saf ur t he ri nc r e a s ei nde f e c t s a ndbr e a kdownsa nds t i l ll owe rupt l me・Thepl a nts l owl ys l i de sdownt hes l i ppe r y s l ope( r e i nf o r c i ngl oopR3)i nt oat r a pofhi ghbr e a kdownsa ndl owupt i me,Wi t h ne a r l ya l lma i nt e na nc er e s our c esde vot edt oc r i s i sma na ge me nt ,f i r ef i ght i ng,a nd r e pa i rwor k. Thepos i t i vef e e dba c ksRlt oR3Ope r a t ef a i r l yq ui c kl ybuta r enott heonl y vi c i ousc yc l e st ha tc a ndr a gapl a nti nt ot het r a pofl owr e l i a bi l i t ya ndhi ghc os t s . Theo pe r a t i ona lf e e dba c ksi nFi gur e2‑ 9a r ee mbe dde di nal a r g e rs ys t e ms howni n Fi g ur e2‑ 1 0. Ahi ghe rbr e a kdownr a t ei nc r ea s esc os t s( duet oove r t i me, t henonr out i nea nd of t e nha z a r dousna t ur eofout a ges ,t heneedt oe xpe di t epa r t spr oc ur e me nt ,c ol ‑ l a t e r a lda ma ge ,e t c. ) .Ther es ul t i ngpr es s ur et oc utcos t sl e a dst oar e duc t i oni n t hequa l i t yofpa r t s ,i nc r e a s l ngt hes t oc kofe qui pme ntde f e c t sa ndl e a di ngt o s t i l lmo r ebr e a kdownsa nds t i l lhi ghe rc os t s( t hePa r tQua l i t yl oo pR4) . Cos tpr e s ‑ s ur ea l s or e duc e si nves t me nti ne qul pme ntupgr a de sa ndo t he rde s i gni mpr ove ‑ me nt s ,s obr e a kdownsi nc r ea s ef ur t her( t heDes i gnI mpr ove me ntl oopR5) .As c os t sr i s et r a i nl ngf orma i nt e na nc ewor ke r si sc ut ,pa r t i c ul a r l yt r a i ni ngl nPl a nne d 71 Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n 10 Addi t i onal posi t i vef eedback sr eadi ngt oar eac t i vemai n t en an c ecul t ur e FJ GURE2‑ Thecon t en t soft her oundedr ec t angl er epr es en tt hes t r uc t ur ei nFi gur e29 ‑ . ma i nt e na nc et e c hni que s( t heTr a i ni ngl oopR6) . Cos tpr e s s ur ea l s of o r c est hema i n‑ t e na nc ede pa r t me ntt odowns i z e.Thef i r s tt ogoa r et hepl a nne r sa nds c he d‑ ul e r s ‑ unl i keme c ha ni c s , he t ydon' ta c t ua l l yf i xa nyt hi ng,a ndwi t hl es sa ndl es s pl a nne dma i nt e na nc egc ・ l ngOnt he r ei sl e s sf ort he mt odo・ Wi t houta dva nc epl a n‑ nl ng,pa r tki t s ,e q ul pme nthi s t or i es ,a nde ngl ne e r l ngdr a wl ngSf わrma i nt e na nc e wor ka r el es sa va i l a bl e ,l owe r i ng血equa l i t yofwor ks t i l lmor e( t hePl a nni ng Ca pa bi l i t yl oopR7) . Apa r a l l e ls e tofs e l f ‑ r e i nf or c i ngf e e dba c ksope r a t et or e duc et hema i nt e na nc e budge te ve na sc os t sr i s e.Lowe rupt l medi r e c t l yc ons t r a i nspr oduc t i ona nd t he r e f or er e ve nue,f o r c l ngbudge tc ut st hr oug h outt heo r ga ni z a t i on.Wo r s e,hi gh 72 P a r tI P e r s p e c t i v ea n dP r o c e s s br e a kdo wnr a t e sa ndl owupt l meme a nt hepl a nti sl e s sa bl et ome e ti t sde l i ve r y c o mmi t me n t s ・ Asi td e ve l o psar e put a t i o nf o rpoo rd e l i v e r yr e l i a bi l i t yt hepr l C ei t c a nc ha r gea ndvol umeo fbus i ne s si ta t t r a c t sd e c l i ne , f ur t he re r o di ngr e v e nuea nd pr of i ta ndf o r c i ngs t i l lmo r ebudge tc ut s . Cos t pr e s s ur er i s e ss t i l lf ur t he r , a c c e l e r at ‑ 1 ngt hepa r tqua l i t y , t r a i nl ng,de s i g ni mp r ov e me n t ,a ndpl a nnl ngC a pa bi l i t yl oo ps ・ The s el o o psa r es umma r i z e da st heRe ve n ueEr os i o na ndRe put a t i o nEr os i o nl oo ps ( R8a ndR9) . Af t e rye a r so fc os tpr e s s ur e , DuPo n t ha dd e ve l o pe dac ul t ur eofr e a c t i vema i n‑ t e na n c e・ Un r e l i a bl ee q ul pme nta ndf r e q ue ntb r e a kdownsha dbe c o mea na c c e pt e d o c c u r r e nc e . Or ga ni z a t i o na lno r msa ndr o ut i ne sf o rwr l t l ngupwo r ko r de r s ,s c he d‑ u l i ngma i n t e na nc ee fo r t , a ndo r d e r i ngpa r t sha dc o met or e le f c tawo r l do ff r e q ue nt br e a kdo wns .Me c ha ni c ss pe ntmos toft he i rt i mef i g ht i ngf i r e s .Me c ha ni c swho we r es c he d ul e df orpl a nne dma i nt e na nc ewe r er o ut i ne l ypul l e do f ft odor e a c t i ve wo r k・Me c ha ni c sk ne wt he yc o ul dwo r ko ve r t i meo nar e gul a rba s i sa ndc o ns i d‑ e r e do ve r t i mepa yapa r toft he i rr e g ul a ri nc o me・ Theknowl e dget ha te q ul pme nt wa sun r e l i a bl eha de ve nl e dt oi ns t a l l a t i o no fba c ku ppumpsi nma nys i t e s , e mbe d‑ d i ngt hel o w‑ r e l i a bi l i t yc ul t ur ei nt heph ys i c a l l a yo uta ndc a pl t a lc os t so ft hepl a nt s . Ast heye a r spa s s e dt hewo r k f o r c ei nc r e a s i ng l yc o ns i s t e dofpe o pl ewhoha dne v e r e x pe r i e nc e da nyt hi ngot he rt ha nt her e a c t i ver e g i me. Fo rt he m, t hee q ui pme n tWa s i nt r i ns i c a l l yunr e l i a bl e ,l ow upt l meWa sno r ma l ,a ndr e a c t i vema i nt e na nc ewa s . bus i ne s sa sus ua l( t heRe a c t i veCul t ur el oo pRIO) Ast hemode lde ve l o pe dt he yc a l i br a t e di tt or e pr e s e ntat y pi c a lpl a nt ・ Ⅰ nt he e a r l y1 9 90sat y pi c a lDuPo ntc he mi c a l pl a n twa sva l ue da t$ 400mi l l i ona nds pe nt a bout3 ‑3. 5% o fi t sva l uea nnua l l yonma i nt e na nc e,o r$1 2t o$1 4mi l l i o n / ye a r . Thes pa r epa r t ss t o r es t o c ke dmo r et ha n6 0, 000pa r t s . I te mpl o ye da bout90ma i n‑ t e na nc eme c ha ni c swhomi g htc ompl e t ea sma nya s25, 000wo r ko r de r spe rye a r . Ave r a geu pt l meWa s8 3. 5%.Ma i nt e na nc ee x pe ns e sa c c ount e df o r1 5 140% of d i r e c tpr oduc t i o nc os t s ,de pe nd i ngo nt hepr oc e s sa ndpr oduc t .Thea mo untof mo ne yDuPo nts pe ntc o mpa nywi deonma i nt e na nc ei nt hel a t e1 98 0swa sa bo ut $1bi l l i o n / ye a r , as i gni f i c a ntf r a c t i o no fne ti nc o me . Onc et hemode lwa sa de qua t e l yc a l i b r a t e dt ot hehi s t o r i c a lda t a , t hene xts t e p wa st od e s i g nhi g hl e ve r a gepo l i c i e st oe s c a pe丘. o mt her e a c t i ver e gl me. Thet e a m s i mu l a t e dt hei mpa c to fd i fe r e ntpo l i c i e s , i nc l ud i ngt hos et ha tha dbee nt r i e di nt he ons . pa s ta ndf a i l e d. Ta bl e21 1s howst her e s ul t so fs e l e c t e ds i mul a t i Opt i ml Z l ngt heus eo fs c he d ul i nga l o ne ,wi t hi nt het r a di t i ona lcos t ‑ mi ni mi z a ‑ i ngt hep l a ntc o ul d t i o nmi nds e t , ha do nl yamode s ti mpa c t ・ Thr o ug hbe t t e rs c he dul s t i l lme e ti t st r a di t i ona lupt l meO f83. 5%wi t hl O% f e we rmecha ni cs ,g e ne r a t i ng s a vi ngso f$3 50, 000 / ye a r . I mpl e me nt i ngaf u l ls ui t eo fpr oa c t i vema i nt e na nc epo l i ‑ l ng,a nds oo n, a l ‑ c i e s , i nc l ud i ngbe t t e rpl a nnl ngS ys t e ms , pa r t s , r e l i a b i l i t ye ng l neer l o we dt hepl a ntt oa c hi e vet het r a d i t i ona lu pt l meWi t ho nl y61mecha ni c s ,s a vl ng $1 . 2mi l l i o n / ye a r . t houtdowns i z l ng Howe ve r ,d e pl o yl ngt hes a mes ui t eo fpr oa c t i vepol i c i e swi yea ri na dd i t i ona l a l l owe dupt i met or i s ea bove93% a ndge ne r a t e d$9mi l l i on / nsa nyl mPr O Ve ‑ p r of i t ・ Whyt hedi f f e r e nc e?Thec os t ‑ mi n i mi z a t i o na p pr oa c hme a me nti npr oduc t i vl t yge ne r a t e dbyt hea do pt i o nofi mpr ove dma i nt e na nc et e c h‑ cesf orp l a n ne d nl que Si si mme di a t e l yha r ve s t e da she a dc o untr e duc t i o n・Re s o ur ma i nt e na nc er e ma inc o ns t r a i ne d・Theo r ga ni z a t i o nc ont i nue st of i ghtf i r e sa nd Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o l l TABL E21 1 ResuJ t sf r om s e一 ec t edpo一 i c y si muf at i ons 73 Changei n Head Pr of i t Count Upt i me ( Smi ni on/ year ) Por l CyMi x 0・Ty pi c af pl an tunderexl r S t i ngpol i ci es 91 83. 5 0. 00 Cases1and2: l l U s es c h e d u l i n g t om i n i m i z e Mi ni mi z e mai nt enan c ec os t s 82 83. 5 0. 35 mai nt en ance 2.Mi ni mi z ec o s t svi af ul l sui t eof c os t ss ub j ectt o 61 83. 5 1. 20 pr oac t i v emai n t enanc epol i ci es upt i me≧i ni t i al 3.Ma xi mi z ep l an tpr of i tvi af uHsui t eof upt i me. 91 93. 3 9. 00 p r o a c t i v e m a i n t e n a n c ep o l i c i e s Cas e3:Maxi mi z e pf antpr of i tsub j ec t Source・ ' Wi n s t o nL e d e t , Ma r kP a i c h , T o n yCa r d e l l a , a n dMa r kDo wn ' l n g( 1991) , " T h eV a l u eo f t omech ani c l n t e g r a t j n gt h eCML TK e yP u r s u i t s , "D uP o n t I n t e r n a l r e p o r t . headc oun t≦ i ni t i al h eadcoun t . f oc usonr e a c t i v ema i nt e na nc ebutdoess omo r ee fi c i e nt l y.I nc ont r a s t ,i mpl e ‑ me nt l ngt hene wpol i c i e swi t houtdowns i z i ngf r e e supr e s our c e st ha tc a nber e i n‑ Ve s t e di ns t i l lmo r epl a nne dma i nt e na nc e. Asbr e a kdownsf a l l , S t i l lmor eme c ha ni c s a r er e l e a s e df r o mf i r ef i ght i nga ndout a gest odoe ve nmo r epl a nne dwor k. Ma i n‑ t e na nc ee xpe ns e sdr op,r e l e a s l ngr es our c e st ha tc a nbei nve s t e di nt r a i nl ng, pa r t s qua l i t y, r e l i a bi l i t ye ngl ne e r l ng, Pl a nni nga nds c he dul i ngs ys t e ms ,a ndot he ra c t i vi t i e st ha tc utde f e c t sa ndbr e a kdownss t i l lmor e. Hi ghe ru pt l meyi e l dsmor er e ve nue a ndpr ovi desa dd i t i ona lr e s our c esf わrs t i l lmor ei mpr ove me nt . Fore xa mpl e,UPI gr a di ngt oamo r edur a bl et y peofpumps e a li mpr ovesr e l i a bi l i t y,a l l owl ngma i n‑ t e na nc ei nt e r va l st obel e ngt he ne da ndi nve nt or i e sofr e pl a c e me nts e a l st obec ut . Al lt hepos i t i vel oops血a tonc ea c t e da svi c i ousc yc l e st odr a gr e l i a bi l i t ydown be c omevi r t uousc yc l e s , pr ogr e s s i ve l ya ndc umul a t i ve l yr e duc i ngbr e a kdownsa nd i mpr ovi nguPt l me . Ther es ul ti sat r e me ndouss yne r gy, wi t ht hec ombi ne de f f e c tof t hei ndi vi dua lpo l i c i esgr e a t l ye xc e e di ngt hes um oft he i ri mpa c t swhe ni mpl e ‑ me nt e di ndi vi d ua l l y. Themode la l s or e ve a l e da ni mpor t a nti ns i ghta boutt het r a ns i t i onpa t hf ol l ow‑ 1 ngl mpl e me nt a t i o noft hene wpol i c i es . Thes i mul a t i onr e s ul t si nTa bl e2‑ 1s how t ha tpr oa c t i vema i nt e na nc epol i c i eswi t hr e i nves t me ntoft her e s ul t sul t i ma t e l y l owe r sma i nt e na n c ec os t sa ndboos t supt l me. I mme di a t e l ya f t e ri mpl e me nt a t i on, howe ve r ,ma i nt e n a nc ec os t si nc r e a s ea ndupt l mef a l l s ・ Why?I tt a ke st i mef ort he pl a nne dwor kt oc utt hebr ea kdownr a t e;i nt hes hor tr unt hepl a ntmus tbe a rt he c os tofbot ht her e pa i rwor ka ndt hea ddi iona t lpl a nne dma i nt e na nc ee for t . Upt i me f a l l sbe c a us ea dd i t i ona lope r a bl eequl Pme ntmus tbet a ke no fl l i nes opl a nne d ma i nt e na nc ec a nbepe r f or me d・Onl yl a t e r ,a st hes t oc kofl a t e ntde f e c t ss t a r t st o f a l l ,doest hebr e a kdownr a t edr op. Asi tdoe s , e xpe ns e sf a l la ndupt l mer i s e s . Thi s wor s e ‑ be f or e ‑ be t t e rbe ha vi ori squl t eC OmmOni nc ompl e xs ys t e ms .Howe ve r ,i f ma na ge r sdonotu nde r s t a ndwhyi toc c ur so rhowl ongl tmi g htl a s t , t he yma yI n‑ t e r pr e tt hes hot ‑ r unde t e r i or a t i oni npe r f わr ma nc ea se vi de nc et ha t血epol i c i es don' two r ka ndt he na ba ndont he m. ‑ r 74 Pa r t I P e r s p e c t i v ea n dP r o c e s s 2. 4. 2 The芸 mp始ment at i onCh; 州enge Le de ta ndhi sc ol l e a guesf e l tt ha tt hene w pe r s pe c t i vest heyde ve l ope dont he ma i nt e na nc epr obl e mc oul di mpr ovet hec ont r i but i onofDuPont ' sma i nt e na nc e pr og r a mt oc or por a t epr of i t a bi l i t y.Now t he i rc ha l l e ngewast oi mpl e me ntt he ne e d e dc ha nges . Thet e a m wr ot eawhi t epa pe rd e t a i l i ngt her es ul t soft hemode l ‑ 1 ngS t udya ndga vepr e s e nt a t i onst hr ougho utt heor ga ni z a t i onTher e s ul t ?Not hi ng ha ppe ne d.Pe opl ewoul ds a y,H Wea l r e a dyknow t ha tpl a nne dma i nt e na nc ei sa goodi de a , "" Wet r i e dt hos epol i c i e sa ndt he ydi dn' twor k, "o r" Yourmode ldoe s n' t a c c o untf orx, " Le de tr e a l i z e dt ha tt hec l i e ntgr oupf ort hepr o j e c t ‑t hegr oupofpe opl ewhos e be ha vi orha dt oc ha ngef ora nyr es ul t st ober e a l i z e d‑wa sf a rbr oa de rt ha nt he ma na ge me ntt ea mr es pons i bl ef orma i nt e na nc e・ Not hi ngc oul dha ppe nwi t houtt he c oope r a t i ona ndwi l l i ngpa r t l C l pa t i onofhugenumbe r sofl i nema na ge r s ,e qul p‑ me ntope r a t or s ,a ndma i nt e na nc eme c ha ni c s ・Thec l i e ntgr oupnumbe r e di nt he t hous a nds .Re le f c t i ngOnt he i rownl e a r nl ngPr oc es s ,model i ngt e a m me mbe r s r e a l i z e dt ha tt he i rvi e wsha dc ha nge dr a di c a l l ybe c a us et he yha dpa r t i c i pa t e di na n i t e r a t i vepr oc es sofmode l i ng. The yha ds e e nt hemode le vol ve, ha dc ha l l e nge da nd ques t i one di t , ha ds e e nt he i rc onc e msa ddr e s s e d, a ndha dgonet h r ought hepr oc e s s ofwor ki ngoutt hef e e dba c ks t r uc t ur e st ha te xpl a i ne dt hedyna mi c soft hes ys t e m. Some howt he yha dt or e c r e a t et ha tl e a r ni ngPr oc e s st hr oughoutt hepl a nt s , f r omt o p ma na ge me ntt ot hel owes t ‑ gr a deme c ha ni c s . I twa sobvi ous l yi mpos s i bl ef ort het hous a ndsofpe opl et he yha dt or ea c ht o pa r t i c l pa t ei nmode l i ngwor ks hopsore ve nt ogl Vet he mt hemode ls ot he yc oul d wor kwi t hi tt he ms e l ves . Noneha dt r a i nl ngl nS ys t e m dyna mi csorc omput e rmod‑ e l i ng. Li nes upe r vi s or sa ndma i nt e na nc eme c ha ni csa r ea c t i onor i e nt e da ndha ve l i t t l epa t i e nc ef orpr es e nt a t i onswi t hl ot sofc ha r t sa ndgr a phs ・ Le de twa sf a mi l i a rwi t ht heBe e rDi s t r i but i onGa me,ar ol e ‑ pl a yl ngma na ge 一 me n tf l i ghts i mul a t orofama nuf a c t ur l ngS uppl yc ha i nde ve l ope dbyt heMI TSys ‑ t e m Dyna mi csGr oupa sa ni nt r oduc t i ont os ys t e mst hi nki ng・ 1 4wor ki ngwi t hhi s s o n, Le de tc onve r t e dt hema i nt e na nc emode li nt oa ni nt e r a c t i ver ol e ‑ pl a ys i mul a ‑ t i ont ha tt he yc a l l e dt heMa nuf a c t ur i ngGa me( s e eLe de t1 999) .Thega mewa s e mbe dde di na2‑ da ywor ks hoporl e a r nl ngl a bor a t or ydes i gne dt obehi ghl yi nt e r ‑ a c t i ve,t oputpe opl ea te a s e,a ndt oc r e a t ea ne nvi r onme ntf orl e a r nl ngt ha ta d‑ dr es s e de mot i ona la swe l la sc ognl t i vei s s ue s ・ Thega mes i mul a t esa C a lpl a nt . The r ea r et hr e er ol e s :ope r a t i onsma na ge r , mai nt e na nc ema na ge r ,a sa r epa r t ss t or e sma na ge r . Theope r a t i onsma na ge ri s c ha r ge dwi t hme e t l ngde a a ndha se qul pme nt ,r e pr es e nt e dbyc hi ps ,t odos o・ Asp r oduc t i onpr oc e e c L Se a r ke r sr e pr es e nt i ngl a t e ntde f e c t sa r epl a c e dont he e qul pmentC hi ps ・Whe ne noughr e dma r ke r sa c c umul a t e,t hee qul pme ntbr e a ks downandc a pa c i t yf a l l s . Thema i nt e na nc ema na ge rmus tt he na l l oca t eme c ha ni c s t or e pairt hee qul pme nta ndmus tgot ot hes pa r epa r t ss t or et os e ei ft hene e de d ty p l n d p m n d , r d m 1 4 Th eBe e rDi s t r i b u t i o nGa mei sa ne n j o y a b l ea n de f f e c i t v ei n t r o d u c t i o nn o t o n l yt os u p p l y c h a i nma n a g e me n t b u t a l s ot ot h ep r i n c i p l e so fs y s t e mst h i n k i n gi ng en e r a l ( S e ec h a p t e r1 7 ; a l s o S t e r ma n1 9 8 9 b , 1 9 9 2a n dS e n g e1 9 9 0f o rd e s c np t l O n S , b u t n o t u n t i l a f t e ry o uh a v ep l a y e dt h e g a me). Ch a p t e r2 S y s t e mDy n a mi c si nAc t l O n 75 pa r t s( de t e r mi ne dbyar ol loft hedi c e )a r ea va i l a bl e・ I ft hepa r t sa r ei ns t oc k,t he e qul pme nti sr e pa i r e dJfnot ,t heme c ha ni c smus twa i tunt i lt he ya r ea va i l a bl eor pa yt oha vede l i ve r ye xpe di t e d. Al t e ma t i ve l y , t hema i nt e na nc ema na ge rc a ns c he d‑ ul epl a nne dwo r k,or de r i ngt hene e de dpa r t sa nda l l oc a t l ngme c ha ni csi na dva nc e. Pl a nne dma i nt e na nc ec a nonl ybedone, howe ve r , i ft heope r a t i onsma na ge ra g r e e s t ot a keo pe r a t l nge qul pme ntOutOfs e r vi c e. Ea c hr oundt hepa r t i c i pa nt sma kede c i ‑ s i onss uc ha sho wmuc he qui pme ntt Ot a kedownf orpl a nne dma i nt e na nc e, howt o a l l oc a t eme c ha ni c sa ndma i nt e na nc er e s our c e s , a ndhowma nys pa r epa r t st oor de r ・ Re ve nuea ndc os ta r er e c or de d,a l ongwi t hpr oduc t i on, upt l me, i nve nt o r i es , a nds o on. Whi l et hega mei shi ghl ys i mpl i f i e dc ompa r e dt or e a lpl a nt s ,a nde ve nc om pa r e dt ot heor l gl na ls i mul a t i onmode l ,i tr e a l i s t i c a l l yca pt ur est het i mede l a ys , c os t s ,a ndot he rpa r a me t e r sc ha r a c t e r i z i ngaPl a nt . De s pl t ei t sma nys i mpl i f i c a t i onst hega mer a pi dl ybe c ome si nma nywa ysa r e l pl a a nt ,wi hr t e a le mot i o nsa ndc onf li c t sa mongpl a ye r s .I ni t i a l i z e dwi t hhi gh br e a kdownsa ndl ow upt l me,t hema i nt e na nc ema na ge r ' sa t t e mpt st oi nc r e a s e pl a nne dma i nt e na nc ea r eof t e nr e buf f e dbyt heo pe r a t i onsma na ge r ,whof a c e si n‑ t e ns epr e s s ur et ome e tde ma nd, j us ta si nt her e a lwor l d・ Te a mswhos t i c kwi t ht hepr e va i l i ngc os t ‑ mi ni mi z a t i on, r e a c t i vema i nt e na nc e pol i c i e sa r ea bl et oke e pc os t sl owf orawhi l e・Buta sde f e c t sbui l dupt he yf i nd t he i rupt l meS l owl ys i nki nga ndc os t sgr a dua l l yr l S l ng.Te a mswhodof ol l ow t hr o ughwi t hapl a nne dma i nt e na nc es t r a t e gyI mme di a t e l yf i ndc os t sr i s i nga ndup‑ t i mef a l l i nga se qui pme nti st a ke nof fl i nef orpl a nne dma i nt e na nc e.Soon,how‑ e ve r ,c os t sbe gi nt of a l la ndupt l mer i s es .Byc ompr e s s l ngt l met hega mea l l ows pe o pl et oe xpe r i e nc et hewor s e ‑ be f o r e ‑ be t t e rdyna mi ci naf e whour si ns t e a dofa f e wmont hs . Twome mbe r soft hei mpl e me nt a t i o nt e a ma tDuPont ' SWa s hi ngt onWo r ks g, Wes tⅥr gi ni a ,de s c r i be dhowt he yus e dt hega met oc a ト c ompl e xi nPa r ke r s bur a l yz eabr oa d‑ ba s e di mprove me ntpr ogr a m: ‑ Th et e a mwa si n i t i a t e dwi t hat wo ‑ d a yl e a r n l n gl a b. I ・ 1 e a r n l n gt h ec o n c e p t so fd e ‑ f e ct e l i mi na t i o na n de x pe r i e nc l n gt heMa n u f a c t u r l n gGa me. . . Theba s i cc o n c e p t s a r ep r e s e n t e di nd i f f e r e n tma n n e r ss ot h a ta l l l e a r n l n gmo d e sa r eu t i l i z e d ‑v i s u a l , a ud i t o r ya ndk i n e s t he t i c . Th ema t e r i a l i sp r e s e n t e di nt h ef わr mo fl e c t u r e s , S k i t sa n d p a r t i c I Pa t i v ee x e r cise si na no f‑ s i t ee n v i r o n me n t . Po s t e r sa ndmus i ca r eus e d・ The a t mo s p h e r ei smuchd i f f e r e n tt ha nr o u t i n ep l a n tme e t i n gsO rt r a i n l ng, t OO Pe nu P t h e i rt h i n k i n g‑. Th r o u g hi n t e r a c t i v ee x e r c i s e s , t h et e a md e v e l o pst he i rpe r s o na l a s p i r a io t n sf o ri mp r o v i ngt h ea r e awhe r et he yha v ec ho s e nt owo r k・ ・・l The n ] t h e y・ ‑d e v e l o pa na c t i o npl a nt oi mme d i a t e l ys t a r two r k i ng・ 1 5 Thega mea ndl e a r 王 1 1 ngl a bor a t or ypr ove dpo pul a rt hr oughoutt hecompa ny・But pl a yl ngl tOnc eWi t has ma l lgroupofma na ge r swa s n' te nough・Thet ea mf ound t ha tt he yhadt or uns e ve r a lworks ho psf oragl Ve npl a ntbe f or eac r i t i c a lma s sof pe o pl ee mergedt ol ea dac t i ont eamst ha tputpr oa c t i vema i nt e na nc epol i c i e si nt o pr a c t i c e・ Oft ent hepl a ntne e dedt ode ve l o pI t sOWnC a pa bi l i t yt or unt hega mea nd tc oul dbe doneonde ma ndbyl oc a lpe opl e,wi t ht he i rs i t e ‑ s pe c i f i c wo r ks hopsoi r y , R. , a n dR. S t e wa r d(1997)I mp r o v e dP r o d u c t i o nCa p a b i l i t yP r o g r a ma t 1 5 T e wk s b u o c i e t yf o rMa i n t e n a n c ea n dRe l i a b i l i t y DuPo n t ' sWa s h i n g t o nWo r k s , P r o c e e d i n g so ft he1997S a n n u a l c o n f e r e n c e . 76 P a r t IP e r s p e c t i v ea n dP r o c e s s e x pe r i e nc ea nda ut ho r i t y . Le de t ' St e a mt h usha dt ode ve l o pag r o upo ft r a i ne df a C i l i t a t o r sa ndat r a i n l ngp r oc e s sS Ot ha tt heq ua l i t yo ft hewo r ks ho pc o ul dbema i n‑ t a i ne da si ts pr e a di n t ot hepl a nt s . Thede ma ndf o rt hewo r ks ho pg r e ws l owl ya t f i r s t , buta sf a vo r a bl ewo r do fmo ut ha bo utt hee xpe r i e nc ea ndr e s ul t ss pr e a d, mo r e a ndmo r epl a n t sa s ke dLe d e t ' sg r o upt or unt hepr og r a mf o rt he m. Thes u r gei nd e 一 ma nds t r e s s e dt hen umbe ro fs ki l l e df a c i l i t a t o r s , whi c hl a gge dbe hi nd. Byt hee nd of1 992s o me1 2 00pe o pl eha dpa r t l C I Pa t e di nt hewo r ks ho pa ndmo r et ha n5 0f a c i l i t a t o r sha dbe e nc e r t i f i e d. ‑ ‑ 2. 4. 3 Resul t s By1 99 4an umbe ro fpl a nt st hr oug ho utt heGul fCoa s tr e g l O nha da dopt e dt he l e a r ni ngl a ba nda s s o c i a t e dpo l i c i e s . Fi g ur e2‑ 1 1s ho wst hedi r e c tma i nt e na nc ec os t s a vl ngSf o rapa r t i c ul a rpl a n ta f t e ri mpl e me nt a t i o no ft hepr og r a m. J us ta ss e e ni n t hemode la ndt hega me , t hef i r s te f f e c to ft hene wpol i c i e si sa ni nc r e a s ei nc os t s . Onl ya f t e rs e v e r lmo a nt hsd i dt hec os ts a v l ngSbe g i nt oa c c umul a t e . Amongpl a nt st ha ti mpl e me nt e dt hepr og r a m byt hee ndo f1 993,t heme a n t i mebe t we e nf a i l ur e( MTBF)f o rpt l mPS( t hef oc uso ft hepr og r a m)r os ebya na v‑ e r a geo f1 2% e a c ht i mec umul a t i veo pe r a t l nge x pe r i e nc edou bl e d,whi l ed i r e c t ma i nt e na nc ec os t sha df a l l e na na ve r a geo f20%・ I n23c o mpa r a bl epl a n t sno ti m‑ pl e me nt l ngt hepr og r a mt hel e a r n l ngr a t ea ve r a ge dj us t5%pe rd o ubl i ngofc umu‑ pa na ve r a g eo f7% ( Ca r r ol l ,St e r ma n,a nd l a t i v ee xpe r i e nc ea ndc os t swe r eu Ma r c us1 9 98 ) . Thep r og r a ma tWa s hi ng t o nWo r ksboos t e dne tpr od uc t i o nc a pa bi l ‑ l l i t y2 0%,i mpr ove dc us t o me rs e r vi c e90%,a ndc utde l i ve r yl e a dt i meb y50%,a wi t hmi ni ma lc a pi t a li nve s t me nta ndar e duc t i o ni nma i nt e na nc ec os t s . I ti sd i fi ‑ l e ,but c ul tt oe s ima t t et het o t a lbe ne f i to ft hepr og r a mf ort hec o mpa nya sawho c o ns e r va t i vee s t i ma t e se xc e e d$3 50mi l l i o I Jye a ri na vo i de dma i n t e na nc ec os t s . Thes t o r ydoe sno te ndhe r e ,howe ve r 。Suc c e s sc r e a t e si t so wnc ha l l e nge s . Wha tha ppe nst oapl a nta f t e ri ts uc c e e dsi ni mpr o vl ngMTBFsa ndc ut t l ngma i n‑ t e na nc ee xpe ndl t u r e s ?Onei s s uer e l a t e dt ot hepe r s i s t e nc eo ft hec os t ‑ s a vl ng / 0 3 0 2 0 1 0 U ISO3 a^! lt 21 n∈ n ( pa s!nBs!p a一L,3S) Gr aphs h o ws di r ec tc os t sa vl n gSa f t er i mpl emen t at i on oHh el eaml n g l abor a t or yan d ne wmai n t enan c e po一 i c i esa ta t ・ par t i c ul arp l an Ver t i c al ax i s di s gui s e dL sBu! ^E 2 S FI GURE2 ‑ ll Wor s e ‑ b e f or e‑ be t t erb eh a vi oro f mai n t en an c ec os t s atat y pI C al pl an t l Sour ce: A" e n( 1 9 9 3 ) . 2 / 9 2 l / 9 21 1 / 93 2/ 93 3/ 93 Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n 77 me nt a l i t y . Ame mbe roft hemode l i ngt e a mc omme nt e d," Ass oo na syo ug e tt he pr o bl e msdown, pe opl ewi l lbet a ke na wa yf r o mt hee fo r ta ndt hepr o bl e mswi l l goba c kup} 'I nf a c t ,c os t ‑ c ut t l ngPr og r a msma nda t e dbyc or po r a t ehe a dq ua r t e r s d i dc a us es i gni f i c a ntdowns i z l ngt h r o ug ho u tt hee nt ir ec o mpa nya ndl i mi t e dt he i r a bi l i t yt oe xpa n dt hepr og r a m. Ano t he rpr o bl e mf o rDuFontwa sr e wa r d i ngt hemode l i ngt e a m.Le d e tbe ‑ l i e ve dt hega mea ndl e a r nl ngl a bo r a t o r yha dg r e a tpot e nt i a lt os t i mu l a t ei mp r ov e 一 me れti nawi der a ngeo fc o mpa ni e sa ndi nd us t r i e s ・ Hebe ga nt or e c e i vel nq ul r l e S f r o mo t he rf i r msi n t e r e s t e di nus i n gt hega me . Le de ta c q ui r e dt her i g ht st ot hega me f r o m DuPont , t oo ke a r l yr e t i r e me n t ,a ndbe c a mea ne nt r e pr e ne ur ,wo r ki ngwi t h o t he rc ompa ni e st oi mpl e me ntt hea ppr oa c h, The s e丘r msi nc l udeo t he rc he mi c a l s ma n uf a c t ur e r sa l o ngwi t hf i r msi nt hee ne r g y , a ut o mot i ve , a ndhi g h‑ t e c hs e c t o r s ・ 2, 4. 4 Tr ansf er r 妻 ng帥eLeani ng: TheLi maExper 岳 ence Oneoft heo r ga ni z a t i o nst ha ta do pt e dt hema i nt e na nc ega mea ndot he rs ys t e md y‑ na mi c st oo l swa sBr i t i s hPe t r ol e um( BP) . 1 6BP' sLi ma , Ohi o, r e f ne i r ywa sbu i l ti n 1 8 8 6byJ o hnD. Roc ke f e l l e rt os up pl yf ue la ndpe t r oc he mi c a l st ot heMi dwe s t 1 Onc et he" Que e no ft heFl e e t , "c os tc ut t i ngd ur i ngt he1 98 0Sha dl e dt ot hes a me s pl r a lo fi nc r e a s i ngbr e a kdo wns , de c l i nl ngpe r f わr ma nc e , a nds t i l l mo r ec os tc ut t l ng t ha tha dpl a g ue dDuPo nt . Byt hee a r l y1 9 9 0si twa sapoorpe r f o r me ra ndl a g ge d we l lbe hi ndot he rUSr e f i ne r i e s . An umbe ro fi mpr ove me ntpr og r a mswe r et r i e d, wi t hl i t t l es uc c e s s , a ndBPbe ga nt ot hi nka bo uts e l l i ngo rc l os i ngt hef a c i l i t ywhi l e t r yl ngt OC utC O S t S ・ I n1 994t heLi maf a c i l i t yI nt r o d uc e dt hema i nt e na nc el e a r nl ngl a ba ndga me a l o ngwi t hs omeo t he rt oo l so fs ys t e md yna mi c ss uc ha st heBe e rDi s t r i but i o n Ga me. Thi swa sno tat o pma na ge me nti nt e r ve nt i on: Thega mewa si ni t i a l l yc ha m‑ pl O ne dbya ne q ul pme ntS pe c i a l i s t , ama i nt e na nc et r a i nl ngS u pe r vi s o r , a nda ne ng 1 ‑ ne e r ,Pa ulMo n us ,t he nwo r ki ngl nC O nt i n uo usi mpr ove me nt .Suc c e s s f u lpi l o t pr o j e c t sl e dr e f i ne r yma na ge me n tt or u n8 0% ofa l le mpl o ye e st hr o ug ht hepr o‑ g r a m. Soondoz e nsofi mpr ov e me nt t e a mswe r ei npl a c e . Du r i ngt hef i r s t6mo n t hs ma i nt e na nc ec o s t sba l l oo ne dby3 0%. Ma na ge me ntwa spr e pa r e df o rt hi swo r s e ‑ be f o r e ‑ be t t e rd y na mi c , howe ve r ,a ndf o c us e do nt hei mpr ove me nt sge ne r a t e dby t hea c t i o nt e a ms . Mome n t umbe ga nt ob ui l d. I nJ a nua r y1 9 96BPa nno unc e dt ha ti ti nt e nde dt os e l lt heLi mar e f i ne r ya nd s t e ppe du pi t sc os tC ut t i nga ndd owns i z l ng. Af e wmo nt hsl a t e rBPs t unne dt hee m‑ pl o ye e sbya nn ou nc i ngt ha ti tc o ul dno tf i ndabuye ra tas a t i s f a c t o r ypr i c ea nd wo ul dt he r e f o r ec l os et her e f i ne r y . Thea nno unc e me ntwa sade e pbl o wt ot hewo r ke r sa ndt hec i t y・TheLi ma f a c i l i t ywa son eoft hemos ti mpo r t a nte mpl oye r si nt hec ommunl t y ,OC C u pyl ng l l ,u t i l i t y , 6 50a c r e sofp r l mer e a le s t a t ea ndg e ne r a t l ng400j o bswi t hpa yr o a ndo t he rpa yme nt spumpi ngmo r et ha n$ 6 0mi l l i o n/ ye a ri nt oLi ma ' sde pr e s s e d e C O nO my・ a f t e r t h ewo r kd e s c r i b e dh e r ewa sd o n e ・ 1 6 BPme r g e dwi t hAmo c oi n1998, 78 I P e r s p e c t i v ea n dP r o c e s s Pa r t Somee mpl oye e sbe ca medi s cour a ge da ndques t i onedt heva l ueofc ont i nui ng t hepr ogr a m ofdef e c te l i mi na t i ona ndpr oa c t i vema i nt e na nc e. Af e wt r a ns f er r e dt o ot he rBPf a c i l i t i esorl e f ta l t oge t he r . Wi ns t onLedetdes c r i be dwha tha ppe nedne xt : Fo rt hos ewhode c i d e dt os t a ywi t ht hes hi p, ane ws pl r i te me r g e d. The yr e a l i z e d ha t tt he yne e d e daf ut ur ei nLi maa nds ho ul dt a ker e s pons i bi l i t yf o rc r e a t l ngt ha t f ut u r e . Thef i r s ts t e pwa st oe ns ur et ha tt hee xi to fma nye x pe r i e nc e dpe o pl edi dno t t h r o wt he mba c ki nt her e a c t i vemod e. Thi she i ht g e ne dt hes e ns eo fu r g e nc yt od o d e f e c te l i mi na t i on. I ta c t ua l l yc r e a t e dac l e a r e rf oc usf o rt hepe o pl ewhor e ma i ne d. The ywe r ea l lt he r ebe c a us et he yha dc hos e nt obet he r e・17 Soont hec umul a t i vei mpa c toft henew ma i nt e na ncepol i ci esa nda t t i t udeswas cl ea r l yvi s i bl ei nt hepe r f or ma nceoft hepl a nt .Ta bl e21 2hi ghl i ght ss omeoft he r es ul t s . Thedr a ma t i ci mpr ove me nt si nt her ef i ne r ydi dnotgounnot i c ed.OnJ ul y2, 1 998,t heba me rhea dl i neoft heLi maNe wsannounced"Oi lRe f i ne r yRes c ued. " Cl a r kUSA,apr i va t e l yhe l dFor t une500Compa nywi t hr e f i ni nga nddi s t r i but i on i nt e r es t s ,a gr e e dt obuyt heLi mar e f i ne r yf r om BPf or$21 5mi l l i ona ndke e pi top‑ e r a t l ngaSar e f i ne r y.Ma nypeopl ea ndor ga ni za t i onsc ont r i but edt ot her es c ueof t her e f i ner y. Ye twi t houtt hedr a ma t i ci mpr ove me nt si nr e f i ne r yope r a t i onss t i mu‑ r k,ora nybuye r ,Woul d l a t e dbyt hes ys t e mst hi nki ngI nt e r ve nt i oni ti sunl i ke l yCl a ha veofe r e de noughf ort hef a c i l i t yt oke e pl tr unnl ng. TABLE2‑ 2 I mpr ovementat t heLi mar ef i ner y 1.Li maRef i ner ypumpMTBFupf r om 12t o58mont hs( pumpf a‖ ur es downf r om mor et han640i n1991t o131j n1998) .Di r ec ts avi ngs: $1. 8mi l l i on / year . 2.Tot al f l ar e1 0f fofhy dr ocar bondownf r om l. 5% t o0. 35%.Di r ec ts avl ngs: $0. 27/ bar r el .l mpr ovedenvi r onment al qual i t y. 3.On」i neanaJ yzerupt i mei mpr ovementf r om 75% andnott r us t edt o97% andt r us t ed,per mi t t i ngr eaHi meopt i mi zat i onofpr oduc tf l ow.Savi ngs: $0. i 010. 1 2/ bar r el 4.Thi r t y‑ f ourpr oduc t i onr ecor dsset . 5.Saf et yl nci den t sandI os thour scutbyf ac t orof41 6.Cashmar gi ni mpr ovedby$0. 77perbar r el ofoi lpr ocess ed. 7.Tot alnewva山ecr eat ed:$43mi l l i on / year . Tot al cos t :$320, 000 / year . Rat i o:1 43: 1. 8.BPwi del ear nl ngl ni t i at i veunderwayf oral l ot herr ef i ner i esandpl ant s. Over2000peopl ef r omsi t esi nt heUS,UK, Aus t r al i a,Nor t hSea, Al ask a, andEur opehadpar t i cI Pat edi n的ewor k shopandgameby1 998. Sour ce:P a u l Mo n u s , p e r s o n a l c o mmu n i c a t i o n ; Mo n u s , P . ( 1 9 9 7 ) " Pr o a c t l v eMa n u f a c t u r l n ga tBP' s L i maOi l Re f i n er y , "p r e s e n t e da t Na t i o n a l Pe t r o l e u mRe f E n e r SAs s o c l a t l 0 nMa l n t e n a n C eCo n f e r e n c e , 2 0 ‑ 2 3Ma y1 9 9 7, Ne wOr l e a n s , a n dGr l f f l t h , 」 . ,D . Ku e n z l l , a n dPMo n u s( 1 9 9 8 ) " Pr o a c t 】 v eMa n u f a c ‑ "N PRAMa i n t e n a n c eCo n f e r e n c e, t u n n g . Ac c el e r a t i n gSt e pCh a n g eBr e a k t h r o u g h sl nPe r f o r ma n c e , MC‑ 9 8 ‑ 9 2. 1 7 TMGNe ws ,1 5S e p t e mb e r1 9 9 8 ・ Ch a p t e r2 S y s t e mDy n a mi c si nAc t i o n 79 Thes uc c e s soft hel e a r nl ngl a bo r a t o r ya ndma i nt e na nc ega mei l l us t r a t e st he r e a lp ur pos eoft hemode l i ngp r o c e s s . Themo de l , ga me , a ndwo r ks ho pdo n' tt e a c h , a nyo nehowt oma i nt a i napumpbe t t e ro rhowt odovi br a t i o nmo ni t o nng. DuPo nt BP , a ndo t he ro r ga ni z a t i o nsa l r e a d yha vepl e nt yoft e c hni c a lt oo l sa ndkno wl e d ge . I ns t e a d,t hega mea ndl e a r nl ngl a bo r a t or ye na bl epe o pl et oe xpe r i e nc et hel o ng‑ t e r mo r ga ni z a t i o nwi dec o ns e q ue nc e so ft he i ra c t i o ns , t oe na c taf u t ur ei nwhi c hol d wa ysofbe ha v i nga r ec ha nge d,a ndt oe x pe r i e nc ee mo t i ona l l ya swe l la sc og nl ‑ t ・ t i ve l ywha ti tmi g htbel i ket oma ket het r a ns i t i o nt oahi g h‑ pe r f o r ml ngPl a n TheLi mae x pe r i e nc ei l l us t r a t e st hepo we ro fas hi f ti nme nt a l mod e l s . TheBP r o,g e ne r a t i nga nn ua ls a vi ngsof$1 . 5mi l l i o n / t e a mr e duc e dbut a nef la r e ‑ Of ft oz e ye a ra ndr e duc i ngpol l ut i o na swe l l .Thee fo r tt oo k2we e ksa ndc os t$ 50 00,a r e t u r noni nve s t me nto f3 0, 0 009 も / y e a r . Wha t ha ds t o ppe dt he mf r omi mpl e me nt l ng t hi si mpr ove me ntl o nga go?Me mbe r so ft het e a m kne wa bo utt hepr o bl e ma nd ho wt os ol vei tf o r8ye a r s . The ya l r e a d yha da l lt h ee ngl ne e r l n gknow‑ ho wt he y ne e de dt os ol vet hepr o bl e ma ndmos to ft hee qui pme nta ndma t e r i a l swe r e a l r e a d yo ns i t e . Theo nl yba r r i e r swe r et heme nt a lmo de l st hr oug hwhi c he mpl o y‑ e e sc a met obe l i e vet ha tt he ywe r epowe r l e s s ,t ha tt hepr o bl e mwa si mpos e dby ol ,a ndt ha taf e wpe o pl ec o ul dne ve rma kea e xt e r na lf or c e sbe yondt he i rc o nt r d i f f e r e nc e . Thes ee nt r e nc he dme nt a lmode l sc ha nge di nf oure s s e nt i a lwa ys . Thebe l i e f t ha tt hepr o bl e m wa so utt he r eha dt oc ha ngef r om " o ure qui pme n ti sl o us ya nd t he r e' sno t hi ngwec a nd oa bo uti t "t o" O ure q ui pme n tPe r f om spoo r l ya sar e s u l t o r , t hee q ul pme ntWi l lr e s po nd. H o fo urownpa s t po l i c i e s ‑1 fwec ha ng eo u rbe ha vi Thef o c uso nd e f e c tc o r r e c t i o nt hr o ug hr e pa i r sha dt os h i f tt oaf oc uso nd e f e c tp r e ve nt i o na nde l i mi na t i o n. Thef o c usonmi ni mi z i ngma i nt e na nc ec os t sha dt os hi f t t oma xi ml Z l ngOVe r a l lo r ga ni z a t i o na lpe r f o r ma nc e. Andt he yha dt or e a l i z et ha te s ‑ C a pl ngt het r a po fr e a c t i vema i nt e na nc ene c e s s a r i l yi nvo l ve dawo r s e ‑ be f o r e ‑ be t t e r t r a de of f . Thef or ma lmode lwa se s s e nt i a l , a si tl e dt ot hei ni t i a li ns i ght si n t ot hed y na m‑ i c sofpr oc e s si mpr ove me nta ndt hes yne r g l S t i ce f f e c t so fhi g hl e ve r a g epo l i c i e s . Themode la l s oa l l owe dt hemode l i ngt e a mt ode ve l o pt hega mea ndhe l pe dma ke i tr e a l i s t i c . Ul t i ma t e l yi mpl e me n t a t i o ns uc c e s sr e q ui r e dt hemode l i ngt e a mt oe m‑ be dt he i ri ns i g h t si nt oal e a r nl nge nvi r o n me n tt ha ti nvol ve dt hea c t i vepa r t i c i pa t i o n o ft hepe o pl eo nt hef r o ntl i ne s , t ha te na bl e dpe o pl et odi s c ove rt hos ei ns i g h t sf o r , a n dt ha ts po ken o to n l yt ot h e i rh e a d sb u ta l s ot ot he i rhe a r t s ・ t he ms e l ve s ‑ 2. 5 SuMMARY:PR; NC! PLESFORSl j CCESSF J uLUSEOF SYsTEM DyNAM; CS Tho ug ht hepr o j e c t sde s c r i be da bo ved i fe r e di nma nywa ys ,t he ya l li l l us t r a t ea numbe ro fpr i n c i pl e sf o re f f e c t i vede ve l o pme n ta ndi mpl e me nt a t i o no fs ys t e md y‑ na mi c smode l s( S e ec ha pt e r3;s e ea l s oFo r r e s t e r1 961 ;Ro be r t s1 9 77 / 1 978;a nd Mo r e c r of ta ndSt e r ma n1 99 4) : 1 . De ve l o pamode lt os ol veapar t i c ul arpr obl e m,nott omode lt hes y s t e m. Amode lmus tha veac l e a rp ur pos ea ndt ha tpur pos emus tbet os o l vet he pr o bl e mofc o nc e r nt ot h ec l i e n t . Mod e l e r smus te xc l ud ea l lf a c t o r sn ot 80 P a r t I P e r s p e c t i v ea n dP r oc e s s r e l e va n tt ot hepr o bl e mt oe ns ur et hepr o j e c ts c o pei sf e a s i bl ea ndt her e s ul t s t i me l y. Thegoa li st oi mpr ovet hepe r f o r ma nc eo ft hes ys t e ma sd e f i ne dby t hec l i e nt . Fo c uso nr e s ul t s . 2.Mo de l i ngs ho ul dbei nt e gr at e di nt oapr o j e e Wr omt hebe innmg. g Thev a l ueo ft hemo de l i ngpr o c e s sbe g i nse a r l yo n, i nt hepr o bl e m d e f i ni t i o npha s e . Themod e l i ngpr oc e s she l psf oc usdi a g nos i so nt he s t r uc t ur eoft hes ys t e mr a t he rt ha nbl a ml ngpr o bl e msont hepe o pl ema ki ng d e c i s i onsi nt ha ts t r u c t ur e . 3.Bes ke pt i c a labol l tt heva l ueo fmode l i ngandf or c et heH whydowe ne e di t "di s c us s i o natt hes t rto a ft hepr o j e c t . ・ The r ea r ema n ypr o bl e msf o rwhi c hs ys t e mdy na mi c si snotus e f ul Ca r e f u1 1 yc o ns i d e rwhe t he rs ys t e md yna mi c si st her i g h tt e c hni q uef ort he pr o bl e m. Mod e l e r ss ho ul dwe l c o med i f f i c ul tq ue s t i o nsf r o mt hec l i e nt s a bo utho wt hep r o c e s swo r ksa ndhowi tmi g hthe l pt he mwi t ht he i r pr o bl e m. Thee a r l i e rt he s ei s s ue sa r edi s c us s e d, t hebe t t e r . 4. Sys t e m dyna ic m sdoe snots t anda l one . Us eo t he rt oo l sa ndme t hodsas a ppr o pr i a t e . Mos tmod e l i ngpr o j e c t sa r ePa r tO fal a r ge re f f o r ti nvo l v i ngt r a d i t i o na l s t r a t e gl Ca ndo pe r a t i o na la na l ys i s , i nc l udi ngbe nc hma r k i ng, s t a t i s t i c a lwo r k, ma r ke tr e s e a r c h, e t c . Ef f e c t i vemode l i ngr e s t so nas t r o ngba s eo fda t aa nd und e r s t a nd i ngo ft hei s s ue s , Mode l i ngwo r ksbe s ta sac ompl e me ntt oo t he r t o ol s , no ta sas u bs t i t u t e. t . 5.Foe l l SO ni mpl e me nt a t i o nf r om t hes t ar to ft hepr o j e c I mpl e me nt a t i o nmus ts t a r to nt hef i r s tda yoft hepr o J e C LCo ns t a nt l ya s k, Howwi l lt hemo d e lhe l pt hec l i e ntma kede c i s i o ns ?Us et hemode lt os e t pr l O r i t i e sa n dde t e r mi net hes e que nc eofpo l i c yl mpl e me nt a t i o n・ Us et he mod e lt oa ns we rt heque s t i on, Ho wdowege tt he r ef r o mhe r e ?Ca r e f ul l y c o ns i de rt her e a lwo r l di s s ue si nvol ve di npul l i ngva r i o uspo l i c yl e ve r s . Qua nt if yt hef ul lr a n geo fc os t sa ndbe ne f i t so fpo l i c i e s , no to n l yt hos e a l r e a d yr e po r t e dbye xi s t i nga C C O unt l ngS yS t e mS ・ 6.Mo de l i ngwor ksbe s ta sa ni t e r at i vepr oc e s so fj oi nti nqui r ybe t we e n . di e ntandC ons ul t ant Mode l i ngl Sapr oc e s sO fdi s c ove r y・ Thegoa li st or e a c hne wunde r s t a ndi ng ofhowt hep r o bl e ma r i s e sa nd血e nus et ha tunde r s t a nd i ngt od e s i gnhi g h l e ve r a gepo l i c i e sf ori mpr o ve me n t ・ Mode l i ngs ho ul dno tbeus e da sat ool f c L ra d voc a c y . Do n' tbu i l dac l i e nf jspr i o rOPl ni o na bo utwha ts ho ul dbe donei nt oamo de l . Us ewo r ks ho pswhe r et hec l i e nt sc a nt e s tt hemod e l t he ms e l ve s , i nr e a lt i me. 7.Avo i dbl ac kboxmo de l i ng. Mode l sbu i l to uto ft hes i g htoft hec l i e ntwi l lne ve rl e a dt oc ha ngei n de e pl yhe l dme nt a lmo de l sa ndt he r e f o r ewi l lnotc ha ngec l i e n tbe ha vi o r . I nvo l vet hec l i e nt sa se a r l ya nda sde e pl ya spos s i bl e . Sho wt he mt hemode l ・ Enc ou r a get he mt os ug ge s ta ndr unt he i ro wnt e s t sa ndt oc r i t i c i z et he mod e l . Wわ r kwi t ht he mt or e s ol vet he i rc r i t i c i s mst ot he i rs a t i s f a c t i on. Ch a p t e r 2 S y s t e mDy n a mi c s i nAc t i o n 81 8.Va l i dat i o ni sac ont i nuo uspr o c e s so ft e s t i ngandbui l di ngc onf i de nc ei n t hemode l . Mode l sa r eno tva l i da t e da f t e rt he ya r ec o mpl e t e dno rbya nyon et e s ts uc h a st he i ra b i l i t yt of i thi s t o r i c a ld a t a . Cl i e nt s( a ndmod e l e r s )bu i l dc o nf i d e nc e i nt heut i l i t yofamo de lg r a d ua l l y , b yc ons t a nt l yc onf r o nt i ngt hemo d e lwi t h da t aa nde x pe r to pi ni o n ‑t he i rowna ndo t he r s ' . Thr o ught hi spr o c e s sbot h mo de la nde x pe r to pi ni o nswi l lc ha ngea ndde e pe n. Se e ko uto ppo r t uni t i e s t oc ha l l e n get hemo de l ' sa bi l i t yt or e pl i c a t eadi ve r s er a ngeo fhi s t o r i c a l e X l j e r l e nC e S . ⊥ 9.Ge tapr e l i mi nar ymode lwor ki nga ss oonaspos s i bl e 。 Addde t ilo a nl y aSne e e S S a r y ・ De ve l o pawo r ki ngs i mul a t i o nmod e la ss oo na spos s i bl e. Don' tt r yt o de ve l o pac ompr e he ns i vec o n c e pt ua lmode lp r l O rt Ot hede ve l o pme nto fa s i mul a t i o nmode l , Co nc e pt ua lmod e l sa r eo nl yhypo t he s e sa ndmus tbe t e s t e d. Fo r ma l i z a t i o na nds i mul a t i o no f t e nu nc o ve rf la wsi nc o nc e pt ua l ma psa ndl e a dt oi mpr o ve dunde r s t a nd i ng・ Ther e s ul t sofs i mul a t i o n e x pe r i me nt si nf o r mc onc e p t ua lunde r s t a ndi nga ndhe l pbui l dc o nf i de nc ei n t her e s ul t s . Ea r l yr e s ul t spr o v i dei mme d i a t eva l uet oc l i e nt sa ndj us t i f y c o nt i nue di nve s t me nto ft he i rt i me. 1 0.Abr oadmode lbo undar yl Smor ei mpo r t a ntt hanagr e atde lo a fde t il a . Mo de l smus ts t r i keaba l a nc ebe t we e naus e f u l , o pe r a t i ona lr e pr e s e n t a t i o n oft hes t r u c t ur e sa ndpo l i c yl e ve r sa va i l a bl et ot hec l i e nt swhi l ec a pt u r l ng t hef e e d ba c ksg e ne r a l l yuna c c o unt e df o ri nt he i rme nt a lmode l s . I ng e ne r a l , t hed yna mi c so fas ys t e me me r g ef r o mt hei nt e r a c t i o nsoft hec o mpo ne nt s i nt hes ys t e m‑C a pt u r i ngt hos ef e e d ba c ksi smo r ei mpo r t a ntt ha nal o to f de t a i li nr e pr e s e nt i ngt hec o mpo ne n t st he ms e l ve s . l l .Us ee xpe r tmo de l e r s , notnovi c e s . Whi l et hes of t wa r ea va i l a bl ef o rmo de l i ngl Se a s i l yma s t e r e dbyahi g h s c hoo ls t u d e nto rCEO, mo de l i ngl SnotC Omput e rp r Og r a mml ng. Yo uc a n no t de ve l o paq ua li t a t i v edi a g r a ma ndt he nha ndi tof ft oapr og r a mme rf o r c odi ngI nt oaS i mul a t i o nmo d e l . Mode l i ngr e qui r e sad i s c i pl i ne da pp r oa c h a nda nun de r s t a ndi ngo fbus i ne s s , s ki l l sde ve l o pe dt h r o ug hs t ud ya nd e xpe ie r nc e . Ge tt hee x pe r ta s s i s t a nc eyo une e d. Us et hepr o j e c ta Sa n o ppo r t u nl t yt Ode ve l o pt hes k i l l so fo t he r so nt het e a ma ndi nt hec l i e n t o r ga ni z a t i o n, 1 2。I mpl e me nt at i ondoe snote ndw it has i ngl epr o j e c t . I na l1t h r e ec a s e st hemode l i ngwo r kc o nt i nue dt oha vei mpa c tl o nga f t e r t hei ni t i a l pr o j e c tWa so ve r . Mo de l sa ndma na ge me ntf li g hts i mul a t o r swe r e a ppl i e dt os i mi l a ri s s ue si no t he rs e t t l ngS . Themode l e r sde ve l o pe de x pe r t i s e t he ya ppl i e dt or e l a t e dpr o bl e msa ndc l i e nt smo ve di nt one wpos i t i onsa nd ne wo r ga n i z a t i o ns , t a ki ngt hei ns i g ht st he yga i ne da nd,s o me t i me s , ane w wa yoft h i n ki ng, wi t ht he m. Ⅰ mpl e me nt a t i o ni sal o ng‑ t e r mpr oc e s so f pe r s o na l , o r ga ni z a t i ona l , a nds o c i a lc ha nge. 甘言 はき呈 t , 畠曽 呈 主嘩 苧 i t 串 ∈ e 軍 § Pe r h a pst h ef aul tl f ort hepoori mpl e me nt at i o nr e c of l df ormode l s ]l i e si nt he or i gi nso fmana ge r i almode l ‑ ma k i n g‑t het r a ns l at i ono fme t ho dsa ndpr i n‑ C i pl e so ft heph y s i c als c i e nc e si nt owar t i meo pe r at i on sr e s e ar c h. .I f h y pot he s i s ,d at a ,an da nal y s i sl e adt opr oo fandne wk nowl e dgei ns c i e nc e , s houl dn' ts i mi l arpr oc e s s e sl e adt oc hangei nor gani z at i o ns?Thea ns we ri s ob vi ou s INO!Or gani z at i o nalc hange s( orde c i s i onsorpol i c i e s )donot i ns t a nt l yj l o wf r ome v i de nc e ,d e du c t i v el ogi c ,a ndmat h e mat i c alo pt i mi z at i on. IEd wa r dB.Ro b e r t s l l nc ha pt e r1t hec onc e ptofavi r t ua lwor l dwa si nt r oduc e dasawa yt os pe e dt he l e a r nl ngpr oc es s , a ndc ha pt e r2s howe dhowmode l sbe c a mevi r t ua lwor l dst ohe l p s ol vepr o bl e msi nt hr e edi f f e r e nts i t ua t i ons .How c a nvi r t ua lwor l ds( mode l s )be us e dmos te fe c t i ve l y?Howc a nus e f ulvi r t ua lwor l dsbec r e a t e d?Mode l i ngt a ke s pl a c ei nt hec ont e xtofr e a lwor l dpr obl e ms ol vi ng,wi t ha l li t sme s s i nes s ,a mbi ‑ gui t y,t i mepr es s ur e ,pol i t i c s ,a ndi nt e r pe r s ona lc onf li c t . Thepur pos ei st os o l vea pr obl e m,notonl yt oga i ni ns i ght( t houghi ns i ghti nt ot hepr obl e mi sr e qui r e dt o des i gne f f e c t ̲ i vepol i c i e s ) , Mode l i ng,a sapa r toft hel e a r ni ngpr oc es s ,i si t e r a t i ve, ac ont i nua lpr oc e s soff or mul a t i nghypot hes e s , t e s t l ng, a ndr e vi s i on, o fbo t hf o r ma l a ndme nt a lmod e l s . Expe r i me nt sc onduc t e di nt hevi r t ua lwo r l di nf o r mt hede s i gn a nde xe c ut i ono fe x pe r i me nt si nt her e a lwor l d;e xpe r i e nc ei nt her e a lwor l dt he n l e a dst oc ha nge sa ndi mpr ove me nt si nt hevi r t ua lwor l da ndi npa r t i c l pa nt S ' me nt a l 1 Ro b e r t s , E.( 1 9 77 ) , " S t r a t e g i e sf o re f f e c t i v ei mp l e me n t a t i o no fc o mp l e xc o r p o r a t emo d e l s , " I n t e r f a c e s7( 5) ; a l s oc h a p t e r4i nRo b e r t s(1978) . Th ep a p e rr e ma i n sas u c c i n c t a n ds t i l l r el e v a n t s t a t e me n t o f t h en e e df o ra ni mp l e me n t a t i o nf o c u s丘 . o mt h ev e r ys t a r t o f a n ymo d e l ngp i r o j e c t . 8 3 84 P a r tI P e r s p e c t i v ea n dP r o c e s s mode l s . Thi sc ha pt e rd i s c us s e st hepu r pos eo fmod e l i ng, de s c r i be st hepr oc e s so f s ys t e md yna mi c smode l i ng, t her ol eoft hec l i e nt ,a n dt hemod e l e r ' Spr of e s s i ona l a nde t hi c a lr e s po ns i bi l i t i e s ・ 3. 1 THEPuRPOSEOFMoDELI NG: M ANAGERSASORGANI ZAT1 0N DESI GNERS J a yFo r r e s t e ro f t e na s ks , Whoa r et hemos ti mpo r t a n tpe o pl ei nt hes a f eo pe r a t i on o fa na i r c r a f t ?Mos t pe o pl er e s po nd, Thepi l o t s . I nf a c t , t hemos ti mpo r t a ntpe opl e ‑ t r a i ne dpi l o t sa r ec r i t i c a l , b utf a rmo r ei mpo r t a nti s a r et hede s i g n e r s . Ski l l e d, wel d e s i g nl nga na i r c r a f tt ha ti ss t a bl e , r o bus tunde re xt r e mec o nd i t i o ns , a ndt ha tor di ‑ na r ypi l ot sc a nf lys a f e l ye ve nwhe ns t r e s s e d, t i r e d, o ri nun f a mi l i a rc o ndi t i ons . I n t hec o nt e x to fs o c i a la ndbus i ne s ss ys t e ms , ma na g e r spl a ybo t hr o l e s . The ya r ep1 ‑ l o t s ,ma ki ngd e c i s i ons( whot ohi r e ,wha tpr i c e st os e t ,whe nt ol a unc ht hene w , pr oduc t )a ndt he ya r ede s i gne r s ,s ha pi ngt heo r ga ni z a t i o na ls t r uc t u r e s ,S t r a t e gi e s a ndd e c i s i o nr ul e st ha ti nf lue nc ehowde c i s i o nsa r ema de . Thede s i gnr o l ei st he mos ti mpo r t a n t but us ua l l yg e t st hel e a s ta t t e nt i o n. T わoma nyma na ge r s , e s pe c i a l l y s e ni o rma na ge r s , s pe ndf a rt oomuc ht i mea c t i nga SPi l o t s ‑ma ki n gd e c i s i ons , t a k1 1 ngc o nt r o lf r o ms u bor d i na t e s ‑r a t he rt ha nc r e a t l nga nO r ga ni z a t i o na ls t r uc t ur e c o ns i s t e nt wi t ht he i rv i s i o na ndva l ue sa ndwhi c hc a nbema na ge dwe l lbyo r d i na r y pe o pl e( s e eFo r r e s t e r1 96 5) . Tbda yd e s i g nl ngane wa i r c r a 氏i si mpos s i bl ewi t ho utmo d e l i nga nds i mul a t i o n・ Ma na ge r ss e e k i ngt oe nha nc et he i ro r ga ni z a t i o na ld e s i g ns 女i l l s , ho we ve r , c o nt i nue t ode s i g nbyt r i a la nde r r or ,bya ne c do t e ,a ndbyi mi t a t i o no fot he r s ,t houg ht he 氏・ Ⅵr t ua lwo r l dspr ovi de c o mpl e xl t yOft he i ro r ga ni z a t i o nsr i va l st ha tofa na i r c r a a ni mpo r t a n tt oo lf o rma na ge r si nbot ht heo pe r a t i o na nde s pe c i a l l yt hede s i g no f t he i ro r ga ni z a t i o ns 。 The r ei sc l e a r l yar o l ef o rmode l st ha the l pma na g e r spi l o tt he i ro r ga ni z a t i o ns be t t e r ,a nds ys t e md yna mi c si so f t e nus e f ulf o rt he s epur pos e s . Butt her e a lva lue oft hepr o c e s sc o me swhe nmode l sa r eus e dt os u ppo r to r ga n i z a t i o na lr e de s i g nJn I ndus t r i al Dynami c s ,Fo r r e s t e rc a l l sf o rc o ur a gei nt hes e l e c t i o no fpr o bl e ms , s a yl l ng,H Thes o l ut i o nst os ma l lpr o bl e msyi e l ds ma l lr e wa r ds‑・ Thegoa ls ho ul dbe t o丘ndma na ge me n tpo l i c i e sa ndo r ga ni z a t i o na ls t r uc t u r e st ha tl e a dt og r e a t e rs uc ‑ c e s s , "Foc usyo u rmo de l i ngwo r ko nt hei mpo r t a nti s s ue s , O nt hepr o bl e mswhe r e yo u rwo r kc a nha vel a s t i ngbe ne f i t ,O nt hepr o bl e msyo uc a r emos tde e pl ya bo ut ・ l 3. 2 THECuENT. ANDTHER I l oDELEF 篭 Mode i i ngdo e snott a kepl a C ei l lS Pi e r l di di s o l a t i o n. I ti se mbe dde di l la nO r ga ni ‑ z a t i o na nds oc i a lc o nt e xt .Eve nbe f わr et hemode l i ngpr o c e s spe rs ebe gi ns ,血e mod e l e rmus tga l na c c e s st Ot heo r ga ni z a t i o na ndi d e nt i f yt hec l i e nt . Thec l i e nti s no tt hepe r s o nwhobr i ngsyo ui nt oa no r ga ni z a t i o no rc ha mpl O nSyo u rWo r k, no r e ve nt hepe r s onwhopa ysf ort hemode l i ngs t udy ,t ho ughi ti she l pf u lt oha ve c o nt a c t s ,c ha mpi o ns , a ndc a s h. Yourc l i e nt sa r et hepe o pl eyo umus ti nf lue nc ef o r yo urwo r kt oha vei mpa c t ・ The ya r et hos epe o pl ewhos ebe ha v i o rmus tc ha nget o s o l vet hepr o bl e m. Yo urc l i e ntc a nbeaCEOo rama c hi neo pe r a t o ro nt hef a c t o r y f l oo r .Cl i e nt sc a nbei nd i vi dua l s ,gr oups ,o re nt i r ec o mmuni t i e s ・ Thec l i e ntf ora 85 Ch a p t e r3 Th eMo d e l i n gP r oc e s s mode l i ngs t udyc a nbeyo ura c a de mi cc ol l e a gue s , t hepubl i ca tl a r ge, o re ve nyo s e l f ・ I nt hedi s c us s i o nt ha tf ol l ows , Iwi l lf oc usonmode l i ngpr o j e c t sc onduc t e df o r or ga ni z a t i ons . Thepr oc e s s , howe ve r , i ss i mi l a rf ort hes eot he rc ont e xt sa swe l l . Tobee fe c t i vet hemode l i ngpr oc es smus tbef oc us e dont hec l i e nt s 'ne e ds . Thec l i e nt sf oramode l i ngpr o j e c ta r ebus y. The ya r ee mbr oi l e di no r ga ni z a t i ona l pol i t i cs .The ya r el ooki ngoutf ort he i rownc a r e e r s .The i rc onc e r ni ss ol vi nga pr obl e ma ndt a ki nga c t i oni nt her e a lwor l d.The yc a r el i t t l ef ort hee l e ga nc eof yourt he or yorc l e ve r nes sofyourmode l ・Mode l i ngi sdonet ohe l pt hec l i e nt ,not f ort hebe ne f i to ft hemode l e r . Thec l i e ntc ont e xta ndr e a lwo r l dpr obl e mde t e r mi ne t hena t ur eoft hemode l ,a ndt hemode l i ngpr oc es smus tbec ons i s t e ntwi t ht he c l i e nt s 's k i l l s ,c a pa bi l i t i e s , a ndgoa l s . Thepur pos ei st ohe l pt hec l i e nt ss ol vet he i r pr o bl e m. I ft hec l i e nt spe r c e i veyo urmode ldoe snota ddr e s st he i rc onc e r nsorl os e c onf i de nc ei ni t ,yo uwi l lha vel i t t l ei mpa c t .Foc usyourmode l i ngwor kont he pr o bl e mst ha tke e pt hec l i e nt su pa tni ght . Thepol i t i c a lc o nt e xtofmode l i nga ndt hene e dt of oc uso nt hec l i e nt s ' pr o bl e m doe snotmea nmode l e r ss houl dbehi r e dguns ,wi l l i ngt odowha t e ve rt hec l i e nt s wa nt ・Mode l e r ss ho ul dnota ut oma t i c a l l ya c c e det oc l i e nt s 'r e ques t st oi nc l ude mor ede t a i lort of oc usonones e tofi s s ue swhi l el gnOr l ngOt he r s , J us tt Oke e pt he c l i e nt sonboa r d・ Agoodmod e l i ngpr oc es sc ha l l e nge st hec l i e nt s ' c onc e pt l OnOft he pr obl e m.Mode l e r sha vear es pons i bi l i t yt or e qul r et he i rc l i e nt st oJ us t i f yt he i r opl ni ons ,gr oundt he i rvi e wsi nda t a,a ndc ons i de rne w vi e wpol nt S .Whe nt he c l i e nt sa s kyout odos ome t hi ngyout hi nki sunne c e s s a r yorml S g ui de d,yo umus t wor kwi t ht he mt or es ol vet hei s s ue. Unf or t una t e l y ,f a rt ooma nyc l i e nt sa r enoti nt e r es t e di nl e a r ni ngbuti nus l ng mode l st os uppor tc onc l us i onst he y' Vea l r e a dyr e a c he dora si ns t r ume nt st oga l n powe ri nt he i ro r ga ni z a t i ons .Sa dl y ,f a rt ooma nyc ons ul t a nt sa ndmode l e r sa r e onl yt ooea ge rt oo bl i ge. Asamode l e ryo uha vea ne t hi c a lr e s pons i bi l i t yt oca r r y outyourwor kwi t hr i go ra ndi nt e g r l t y.Youmus tbewi l l i ngt ol e tt hemode l i ng pr oc e s sc ha ngeyourmi nd・ Yo umus tH s pe a kt r ut ht opowe r , Ht e l l i ngt hec l i e nt st ha t t he i rmos tc he r i s he dbe l i e f sa r ewr ong,i ft ha ti swha tt hemode l i ngpr oc e s sr e ve a l s , e ve ni fi tme a nsyo uwi l lbef i r e d.I fyourc l i e nt spus hyo ut oge ne r a t ear es ul t t he y' ves e l e c t e di na dva nc eort ha ti snots uppo r t e dbyt hea na l ys i s , pus hba c k.I f yourc l i e nt s 'mi ndsa r ec l os e d,i fyouca n' tc onvi nc et he mt ous emod e l i nghon‑ e s t l y , y o umus t q u i t ・ Ge t y o u r s e l fab e t t e rc l i e nt ・ 2 u 3, 3 r ‑ STEPSOFTHEM oDEuNG PROCESS I npr a ct i c e,a samode l e ryoua r ef i r s tbr oughti nt oa nor ga ni z a t i onbyac ont a c t whot hi nksyouo ryourmode l i ngt ool smi ghtbehe l pf ul . Yourf i r s ts + L e Pi St Of i nd outwha tt her e a lpr o bl e mi sa ndwhot her e a lc l i e nti s . Youri ni t i a lc o nt a c tma ynot bet hec l i e nt ,butonl ys e r vea saga t e ke e pe rwhoca ni nt r od uc eyout ot hec l i e nt . Ast hemode l i ngpr o j e c tPr oc e e ds ,youma yf i ndt hec l i e ntgr oupe xpa ndsor c ha nges . As s umet ha tyo u' ves uc c e s s f u l l yne got i a t e de nt r yt ot heor ga ni z a t i ona nd 2 wa l l a c e(1994)p r o v i d e sag o o dc o l l e c t i o no fa r t i c l e sa d d r e s s i n gt h ee t h i c a l i s s u e s f a c i n g mo d e l e r s . 86 TABLE3 1 l St epsoHhe model i ngpr ocess Pa r tI Pe r s pe c t i vea ndPr o c e s s 1.Pr obl em Ar t i cul at i on( Boundar ySel ect i on) oThemese] ect i on:Whati st hepr obl em?Whyi si tapr obl em? oKeyvar i abl es:Whatar et hek eyvar i abl esandc oncept swemus t consi der ? 。Ti mehor i z on:Howf ari nt hef ut ur eshoul dweconsi der ?Howf arbacki n t hepas tl i et her oot soft hepr obl em? oDynami cpr obl em def i ni t i on( r ef er encemodes) :Whati st hehi s t or i cal behavj oroft hekeyconcept sandvar i ab‑ es?Whatmi ghtt hei rbehavi or bej nt hef u t ur e? 2.For mul at i onofDynami cHypot hesi s 。hi t i alhypot hesi sgener at i on:Whatar ecur r en Hheor i esoft hepr obl em‑ at i cbehavi or ? .Endogenousf ocus:For mul at eadynami chypot hesi st hatexpl ai nst he dynami csasendogenousconsequencesoft hef eedbacks t r uc t ur e. oMappng:Devel opmapsofcausal s t r uc t ur ebasedoni ni t i alhypot heses, k eyv ar i abl es,r ef er encemodes,andot heravai l abl edat a,usl ngt ool s suchas oModel boundar ydi agr ams, oSubs ys t em di agr ams, .Caus aHoopdi agr ams, oSt ockandf l owmaps, 。Pol i cys t r uc t ur edi agr ams, ・Ot herf aci l i t at i ont ool s. 3.For mul at i onofaSi mul at i onModel oSpeei f i eat i onofs t r uc t ur e,deci sJ r Onr ul es. 。Est i mai i onofpar amet er s,behavi or alr el at i onshi ps,andi ni t i al condi t i ons 。Test sf orconsi s t enc ywi t ht hepur poseandboundar y. . 4・Test i ng oCompar i sont or ef er encemodes:Doest hemodelr epr oducet hepr ob‑ 1 em behavi oradequat el yf oryourpur pose? 。Robust nessunderext r emeeondi t j ons:Doest hemodelbehaver eal i s‑ t i caH ywhens t r essedbyex t r emecondi t i ons? 。Sensi t i vi t y:Howdoest hemodel behavegF Venuncer t ai nt yJ nPar ame‑ t er s,i ni t i a一 condi t i ons,modelboundar y,andaggr egat i on? Manyot hert est s( Seechapt er21) . . 日 . 5.Po一 i cyDesi gnandEval uat i on oScenar i ospeci f i cat i on:Whatenvi r onment a一 c ondi t i onsmi ghtar i se? oPol i cydesi gn:Whatnewdeci si onr u一 es,S t r at egl eS,ands t r uc t ur esmi ght bet r i edi nt her eal wor l d?Howcant heyber epr es en t edi nt hemodel ? . " Whatj f" }'anar ysi s: Whatar et heef f ec t soft hepol i ci es? oSensi t i vi t yanal ysi s:How r obus tar et hepol l C yr ecommendat i onsunder di f f er ents cenar i osandgi venuncer t ai nt i es? oht er act i onsofp0日 i ci es:Dot hepol i ci esi nt er ac t ?Ar et her es yner gl eSOr compensat or yr esponses? Ch a p t e r3 Th eMo d e l i n gP r o c e s s 87 i de nt i f i e dt he( i ni t i a l )c l i e nt s . Howdoyo upr oc e e dt ode ve l opamode lwhi c hc a n behe l pf ult ot he m? 3 The r ei snoc ookbookr e c i pef ors uc c es s f ulmode l i ng,nopr oc e dur eyouc a n f ol l ow t ogua r a nt e eaus e f u lmode l .Mode l i ngl Si nhe r e nt l yc r ea t i veJndi vi dua l mode l e r sha vedi f f e r e nts t yl esa nda ppr oa c he s . Ye ta l ls uc c e s s f ulmode l e r sf ol l ow adi s c i pl i ne dp r oc e s st ha ti nvol vest hef ol l owi nga c t i vi t i e s :( 1 )a r t i c ul a t i ngt he ynami ch y pot he s i sort he or ya boutt he pr o bl e mt obea ddr e s s e d,( 2)f o r mul a t i ngad ca us esoft hepr o bl e m,( 3)f or mul a t i ngas i mul a t i onmode lt ot es tt hedyna mi chy‑ ,( 4)t e s t i ngt hemode lunt i lyoua r es a t i s f i e di ti ss ui t a bl ef oryo urpur pos e, pot hesis ‑ 1l i s t st hes e a nd( 5)de s i gni nga nde va l ua t i ngpol i c i e sf ori mpr ove me nt .Ta bl e3 s t e psa l ongwi t hs omeoft heques t i onse a c hs t e pa ddr e s s e sa ndt hepr l nC l pa lt ool s us e di ne a c h( s e ea l s oRa n°e r s1 980) . 3. 4 M oDELI NG I sI TERATI VE Be f or edi s c us s l nge a c hoft hes es t e psi nmor ede t a i l ,i ti si mpor t a ntt opl a c et he mode l i ngpr oc e s si nc ont e xtwi t ht heongol nga c t i vi t i e soft hepe opl ei nt hes ys t e m. Mode l i ngl Saf e e dba c kpr oc es s , notal i ne a rs e que nc eofs t e ps ・ Mode l sgot hr ough 1 1r e‑ cons t a nti t e r a t i on,c ont i nua lque s t i onl ng,t es t i ng,a ndr e f i ne me nt .Fi gur e3 ‑ 1mor ea c c ur a t e l ya sa ni t e r a t i ve Ca s t st hemode l i ngpr oc e s ss howni nTa bl e3 c yc l e・ Thei ni ia t lpur pos edi c t a t est hebounda r ya nds c o peoft hemode l i nge for t , butwha ti sl ea r ne df r om t hepr oc es sofmode l i ngma yf e e dba c kt oa l t e rourba s i c t .I t e r a t i onc a noc c ur unde r s t a ndi ngoft hepr o bl e ma ndt hepur pos eofoure f f or f r om a nys t e pt oa nyot he rs t e p( i ndi c a t e dbyt hei nt e r c onne c t i onsi nt hec e nt e rof t hedi a gr a m) ・I na nymode l i ngpr qj e c tonewi l li t e r a t et hr ought he s es t e psma ny t i mes . 4 FI GURE3 ‑ 1 Themode‖ ng pr oc es si s i t er a t i v e. Resul t sofan y s t epc anyi el d i nsi gh t st hatl ead t or e vi s i onsi n an yea仙ers t ep ( i ndi c a t edbyt h e l i nk si nt h ecen t er oft hedi agr am) ・ 3 Th e r ei sah u g el i t e r a t u r eo nme ho t d sf o rp l a n n e do r g ni a z a t i o n a l c h a n g ea n dg r o u pl n t e r Ven‑ t i o n s ・ S e ep a r t i c u l a r l yAr g y r i sa n dS c h 6 n(1996) , Be c k h rda a n dHa r r i s(1987) , Dy e r( 1 995) , Mi c h a e l( 1 997) , a n dS c h e i n(1987,1988). 4 Ho me r(1996)p r o v i d e sa ne x c e l l e n t d i s c u s s i o . no ft h ev a l u eo fi t e r a t i o na n dr i g o ri ns y s t e m d y n a mi c s , n o t o n l yl na c a d e mi cr e s e a r c hb u t a l s ol nC O n S u l t i n gwo r k , wi t hav a ri e t yo fe x a mp l e s ・ 88 I P e r s p e c t i v ea n dP r o c e s s Pa r t Mos ti mpo r t a nt l y, mode l i ngl Se mbe dde di nt hel a r ge rc yc l eofl e a r nl nga nda c ‑ t i onc ons t a nt l yt a ki ngpl a c ei nor ga ni z a t i ons( a nddes c r i be di nc ha pt e r1 ) ・Pi l ot s s t e pI nt oa na i r c r a f tf li g hts i mul a t ora ndl e a r nmor eq ui c kl y, e f f e c t i ve l y, a nds a f e l y howt oo pe r a t et her e a la i r c r a f t ,t he nputt he s es ki l l st ous ei nt her e a lt hi ng. The y f e e dba c kwha tt he yl e a r nf lyi ngt her e a lt hi ngt ot hes i mul a t ordes i gne r ss ot he s i mul a t o r sc a nbec ont i nua l l yl mpr OVe d.Wha tpi l ot sa nddes i gne r sl e a r ni nt he s i mul a t o ri sus e di nt her e a lwor l d. Andwha tt he yl e a r ni nt her e a lwor l di sus e dt o c ha ngea ndi mpr ovet hevi r t ua lwor l doft hes i mul a t or ・Soi ti swi t hma na ge me nt li f ghts i mul a t or sa nds ys t e m dyna mi c smode l s .Fi gur e3‑ 2S howst hemode l i ng pr oc e s se mbe dde di nt hes l ngl e ‑a nddoubl e ‑ l oopl e a i ngf m e edba c ksdi s c us s e di n c ha pt e rI .Si mul a t i onmode l sa r ei nf or me dbyourme nt a lmode l sa ndbyi nf o r ma ‑ t i ongl ea ne df r om t her e a lwor l d.St r a t e gi e s ,S t r uc t ur es ,a ndde c i s i onr ul e sus e di n t her e a lwor l dc a nber e pr es e nt e da ndt e s t e di nt hevi r t ua lwor l doft hemode l . The e xpe r i me nt sa ndt es t sc onduc t e di nt hemode lf e e dba c kt oa l t e rourme nt a lmode l s a ndl e a dt ot hedes i gnofne ws t r a t e gl e S ,ne wS t r uc t ur es ,a ndne wde c i s i onr ul e s ・ Thes ene wpol i c i esa r et he ni mpl e me nt e di nt her e a lwor l d,a ndf e e dba c ka bout t he i re fe c t sl e a dst one wi ns i ght sa ndf ur t he ri mpr ove me nt si nbot ho urf or ma la nd FI GURE3 ‑ 2 Mode一 i n gl S embeddedi n t hedynami cs oft hes y s t em. Ef f ec t i v emode= ng i n vo一 vesc ons t an t i t er at i onb et ween exper i men t san d l ear n‑ ngJ nt he vi r t ual wor l dand exper i men t s andl eaml ngl n t her eal wor l d. Ch a p t e r3 Th eMo d e l i n gP r o c e s s 89 me nt a lmode l s . Mode l i ngl SnotaOne ‑ S hota c t i vi t yt ha tyi e l dsTheAns we r , buta n ongo l ngpr oc e s sOfc ont i nua lc yc l i ngbe t we e nt hevi r t ua lwor l doft hemode la nd t her e a lwor l do fa c t i on. 3. 5 0vERV日 EW OFTHEMoDELE NG PROCESS 3. 5. 1 Pr obl em Ar t i cul at i on: The! mPOi 、 t anceofPur pose Themos ti mpo r t a nts t e pl nmode l i ngl Spr obl e ma r t i c ul a t i on・ Wha ti st hei s s uet he c l i e nt sa r emos t c onc e r ne dwi t h?Wha tpr o bl e ma r et he yt r yl ngt Oa ddr es s ?Wha ti s t her e a lpr o bl e m,notj us tt hes ympt om ofdi f f i c ul t y?Wha ti st hepur pos eoft he mode l ? Ac l e a rpu r pos ei st hes i ngl emos ti mpo r t a ntI ng r e di e ntf oras uc c es s f ulmod‑ e l i ngs t udy.Ofc our s e,amode lwi t hac l e a rpur pos ec a ns t i l lbemi s l e a di ng,un‑ wi e l d y,a nddi fi c ul tt ounde r s t a nd.Butac l e a rpur pos ea l l owsyourc l i e nt st oa s k q ue s t i onst ha tr e ve a lwhe t he ramode li sus e f uli na ddr e s s i ngt hepr o bl e mt he yc a r e a bout . Be wa r et hea na l ys twhopr opos e st omode la ne nt i r ebus i nes so rs oc i a ls ys t e m r a t he rt ha napr o bl e m.Eve r ymode li sar e pr e s e nt a t i onofas ys t e m‑ agr oupof f unc t i ona l l yi nt e r r e l a t e de l e me nt sf or mi ngaC OmPl e xwhol e. Butf o ramode lt obe us e f ul , i tmus ta ddr e s sas pe c i f i cpr obl e ma ndmus ts i mpl i f yr a t he rt ha na t t e mptt o mir r o ra ne nt i r es ys t e mi nde t a i l . Wha ti st hedi f f e r e nc e?Amode ldes i gne dt ounde r s t a ndhowt hebus i ne s sc y‑ C l ec a nbes t a bi l i z e di samode lofapr o bl e m・ I tde a l swi t has pe c i f i cpol i c yi s s ue. Amode lde s i g ne dt oe xpl or epol i c i est os l owf os s i lf ue lus ea ndmi t l ga t egl oba l wa r ml n gl Sa l s oamode lofapr obl e m;i tt ooa dd r e s s esonl yal i mi t e ds e tofi s s ues . Amode lt ha tc l a i mst obear e pr es e nt a t i onoft hee nt i r ee c ono myl Samode lofa whol es ys t e m. Whydoesi tma t t e r ?Theus e f ul ne s sofmode l sl i esi nt hef a c tt ha t t he ys i mpl i f yr e a l i t y,C r e a t l ngar e pr es e nt a t i onofi twec a nc ompr e he nd. At r ul y c ompr e he ns i vemode lwoul dbej us ta sc ompl e xa st hes ys t e mi t s e l fa ndj us ta si n‑ S c r ut a bl e. YonCl a us e wi t zf a mous l yc a ut i one dt ha tt hema pl Sno tt het e r r i t or y. I t ' s agoodt hi ngi ti s n' t : Ama pa sde t a i l e da st het e r r i t or ywoul dbeofnous e( a swe l l a sbe i ngha r dt of o l d) . Thea r tofmode lbui l di ngi sknowi ngwha tt oc utout ,a ndt hepur pos eoft he mode la c t sa st hel ogi c a lkni f e.I tpr ovi de st hec r i t e r i at ode c i dewha tc a nbei g‑ no r e ds ot ha ton l yt hees s e nt i lf a e a t ur e sne c e s s a r yt of ul f i l lt hepur pos ea r el e f t . I n t hee xa mpl ea bo ve ,s i nc et hepur pos eoft hec ompr e he ns i vemode lwoul dbet or e p‑ r e s e ntt hee nt i r ee c onomi cs ys t e m,not hi ngc oul dbee xc l ude d. Tba ns we ra l lc on一 c c i va bl eques t i onsa boutt hee c onomy ,t hemode lwoul dha vet oi nc l udea n ove r whe l ml nga r r a yOfva r i a bl e s . Be c a us ei t ss c opea ndbo unda r ya r es obr oa d, t he mode lc oul dne ve rbec ompl e t e d. I fi twe r e , t heda t ar e qui r e dt ous ei tc oul dne ve r bec ompi l e d.I ft he ywe r e ,t hemode l ' sunde r l yi nga s s umpt l OnSC Oul dne ve rbe e xa mi ne dort e s t e dJft he ywe r e,t hemode lbui l de r sc oul dne ve runde r s t a ndi t s be ha vi ora ndt hec l i e nt s 'c onf i de nc ei ni two ul dde pe ndont hea ut hor i t yoft he mode l e ra ndo t h e rnons c i e nt i f i cgr ounds . Mi ha i l oMe s a r ovi c ,ad e ve l ope rofe a r l y 90 P a r t I Pe r s p e c t i v ea n dP r o c e s s gl oba ls i mul a t i ons , ca pt ur e dt hei mpos s i bi l i t yofbui l di ngmode l sofs ys t e mswhe n hes a i d,H Noma t t e rhow ma nyr es our c e soneha s ,oneca ne nvi s i onac ompl e x e noughmode lt or e nde rr e s our c e si ns uf f i c i e ntt ot het a s k. "( Mea dows , Ri c ha r ds on, a ndBr uc kma nn1 982, p.1 97) . Amode ldes i gne df orapa r t i c ul a rpur pos es uc ha sunde r s t a ndi ngt hebus i ne s s c yc l eorgl oba lc l i ma t ec ha ngewoul dbemuc hs ma l l e r ,s i nc ei twoul dbel i mi t e dt o t hos ef a c t or sbe l i e ve dt ober e l e va ntt ot heque s t i ona tha nd. Fore xa mpl e , t hebus i ‑ ne s sc yc l emodelne e dnoti nc l udel o ng‑ t e n t r e ndsi npo pul a t i ongr owt h, r e s o ur c e de pl e t i on, orc l i ma t ec ha nge. Thegl o ba lwa r ml ngmode lc oul de xc l udes ho r トー e r m dyna mi c sr e l a t edt oi nt e r e s tr a t es ,e mpl oyme nt ,a ndi nve nt or i es .Ther e s ul t i ng mode l sc oul dbes i mpl ee noughs ot ha tt he i ra s s umpt l OnSC Oul dbee xa mi ne d. The r e l a t i onoft he s ea s s umpt l OnSt Ot hemos ti mpor t a ntt he or i esr ega r di ngt hebus i ne s s c yc l ea ndc l i ma t ec ha ngec oul dt he nbea s s es s e dt ode t e r mi nehowus e f u lt hemod‑ e l swe r ef ort he i ri nt e nde dpur pos e s . Ofc our s ee ve nmode l swi t hwe l l ‑ de f i ne dp pos e sca nbet ool a r ge.Butwi t houtac l e a rpur pos e,t he r ei snoba s i st os a y" we don' tne e dt oi nc l udet ha t "whe name mbe roft hec l i e ntt e a m ma kesas ugges t i on. I ns um: Al wa ysmode lapr o bl e m. Ne ve rmode las ys t e m・ Us ua l l yt hemode l e rde ve l o pst hei ni t i a lc ha r a c t e r i za t i onoft hepr obl e m t hr oughdi s c us s i onwi t ht hec l i e ntt e a m,s uppl e me nt e dbya r c hi va lr e s e a r c h,da t a c ol l e c t i on,i nt e r vi e ws ,a nddi r e c to bs e r va t i onorpa r t i c i pa t i on.The r ea r ema ny me t hodsa va i l a bl et owor kwi t hagr ou pt oe l i c i tt hei nf or ma t i onne e de dt ode f i ne t hepr o bl e mdyna mi c a l l ywhi l es t i l lke e pl ngt hec onve r s a t i onf oc us e df i r ml yo nt he c l i e nt sa ndt he i rpr obl e m. 5T wooft hemos tus e f ulpr oc es s esa r ees t a bl i s hi ngr e fe r ‑ e nc emode sa nde xpl i c i t l ys e t t i ngt het i mehor i z on. u r ‑ Ref er enceModes Sys t e m dyna mi csmode l e r ss e e kt oc ha r a c t e r i z et hepr obl e m dyna mi c a l l y ,t ha ti s a sapa t t e r nofbe ha vi or , unf ol di ngove rt i me, whi c hs howshowt hepr obl e ma r os e a ndhowi tmi h te g vol vei nt hef ut ur e. Yous ho ul dde ve l o par e fe r e nc emode ,l i t e r ‑ a l l yas e tofgr a phsa ndot he rdes c r l pt l Veda t as howi ngt hede ve l opme ntoft he pr obl e m ove rt i me.Re f e r e nc emode s( s o‑ C a l l e dbe c a us eyour e f e rba c kt ot he m t hr oughoutt hemode l i ngpr oc es s )he l pyoua ndyourc l i e nt sbr e a koutoft hes hor t ‑ t e r me ve nt ‑ or i e nt e dwo r l dvi e ws oma nype opl eha ve・ Tbdos oyoua ndt hec l i e nt s mus ti de nt i f yt het i mehor i z ona ndde f i net hos eva r i a bl esa ndc onc e pt syo u c ons i de rt obei mpo r t a ntf orunde r s t a ndi ngt hepr o bl e ma ndde s i gni ngPOl i c i e st o s ol vei t . , Ti meHon ' zon Thet i mehor i z ons houl de xt e ndf a re no ughba c ki nhi s t or yt os howhowt hepr ob‑ l e me me r ge da ndde s c r i bei t ss ympt o ms .I ts houl de xt e ndf a re noughi nt ot he f ut ur et oc a pt ur et hede l a ye da ndi ndi r e c te f f e c t sofpot e nt i a lpol i c i es . Mos tpe o pl e dr a ma t i ca l l yunde r es t i ma t et hel e ngt hoft i mede l a ysa nds e l e c tt i mehor i z onst ha t 5 se et h er e f e r e n c e si nn o t e9f o rmo d e l i n gt o o l st h a t a r ee fe c t i v ef o rr e a 一 t i memo d e l i n gwi t h o r g a n i z a t i o n sa n dt e a msi n c l u d i n ge l i c i t i n ga n ds t r u c t u r l n gt h eme n t a l mo d e l so fag r o u pt od e f i n e t h ep r o b l e m. 91 Ch a p t e r3 Th eMo d e l i n gP r o c e s s a r ef a rt oos hor t ・ A pr l nC I Pa lde f i c i e nc yl nOurme nt a lmode l si sourt e nde nc yt o t hi nkofc a us ea n de f f e c ta sl oc a la ndi mme di a t e. Buti ndyna mi c a l l yc ompl e xs ys t e ms , C a us ea nde f f e c ta r edi s t a nti nt i mea nds pa c e. Mos toft heuni nt e nde de fe c t s ofde c i s i onsl e a di ngt opol i c yr es i s t a nc ei nvol vef e e d ba c kswi t hl ongde l a ys , f a rr e ‑ move df r omt hepol ntOfde c i s i ono rt hepr o bl e ms ympt om・ Wor kwi t hyourc l i e nt s t ot hi nka boutt hepos s i bl er e a c t i onst opol i c i e sa ndhowl ongt he ymi ghtt a ket o Al ongt l mehor i z o ni sa pl a youta ndt he ni nc r e a s et het i mehor i z one ve nf u r t he r . c r i t i c a la nt i dot et ot hee ve nLo r i e nt e dwor l dvi e ws oc r l ppl i ngt ooura bi l i t yt oi de n‑ t i f ypa t t e r nsofbe ha vi ora ndt hef e e dba c ks t r uc t ur e sge ne r a t l ngt he m. Thec hoi c eoft i mehor i z ondr a ma t i c a l l yi nf lue nc e syourpe r c e pt i onOft he pr o bl e m. Fi gur e3‑ 3s howspr oduc t i on, c ons umpt l On,a ndi mpor t sofpe t r ol e umi n t heUni t e dSt a t e sf r om 1 986t o1 996. Thehi s t or i c a lt i mehor i z oni s1 0yea r s ,a l ‑ r e a dyal ongt i mer e l a t i vet omos tdi s c us s i onofe ne r gypol i c y( t heoi ls hoc ksof t h e1 970sa r ec o ns i de r eda nc i e nthi s t or yi nmos tpol i c yde ba t et oda y) . Thegr a phs s how pr od uc t i ons l owl yt r e ndi ngdown,c ons umpt l Ont r e ndi ngs l owl yup,a nd t he r e f or ei mpo r t sg r owl ngmode s t l y.Pr i c e sf luc t ua t ei nana r r ow ba ndbe t we e n , l owe rt ha na nyt i mes i nc et he丘r s toi lc r i s i si n1 973( t houg h $1 4a nd$23pe rba n℃1 pr i c e sdi ds pi ket o$40 / ba r r e la f t e rt heI r a qii nva s i onofKuwa i t ,t he ys oonf e l l ba c k) ・ Thee ne r g ys ys t e ma ppe a r st ober e l a t i ve l ys t a bl e; t he r ei sl i t t l ee vi de nc eof al ong‑ t e r mpr o bl e m. ‑ FI GURE3 ‑ 3 USoi l pr oduc t i on, c on sump t i on, i mp or t s, andpr ] ce o vera1 0‑ year t i mehor i zon 1986 $ J 0 q M L 6 1988 1990 1992 1994 1996 EIA E gency) ormatl0nA nf nergyl (US S A w ource: nergyF7 nnualE evi e r 92 P a r t I P e r s p e c t iv ea n dP r o c e s s Nowc ons i de rFi gur e3‑ 4, s howi ngt hes a meva r i a bl e sf r omne a rt hebe gi nni ng oft heoi le r a( t hepe t r ol e um i ndus t r ybe ga ni ne a r nes ti n1 859wi t hCol one l Dr a ke' sf a mouswe l li nTi t us vi l l e,Pe nns yl va ni a ) ・Thei mpr es s i oni sc ompl e t e l y di fe r e nt .Thehi s t o r yoft heoi li ndus t r yl nt heUni t e dSt a t esi sdi vi de di nt ot wo r e gl me S ・ Fr om 1 920t hr ough1 973, c ons umpt l Ongr e we XpOne nt i a l l ya ta na ve r a ge r a t eof4・ 3%/ yea r ・Pr oduc t i onnea r l yke ptpa c e,a se xpl or a t i ona ndbe t t e rdr i l l i ng t e c hni quesmor et ha nof f s e tde pl e t i on. St a r t i ngl nt he1 950S , i mpo r t sg r e ws l i ght l y, S t i mul a t e dbyt hea va i l a bi l i t yofc he a pf or e i gnOi l . Pr i c e sf luc t ua t e d, of t e nd r a ma t ‑ l y, buta l ongas l owl yde c l i nl ngt r e nda st e c hnol ogyl mpr OVe d. Al lt hi sc ha nge d i c a l i n1 970・I n1 970,dome s t i cpr oduc t i onofoi lpe a ke d. I t ' sbe e nf a l l i nge ve rs i nc e, des pi t et hei nt e ns ee xpl or a t i ons t i mul a t e dbyt hemuc hhi ghe rpr l C eSOft he1 970s a nde a r l y1 980S ・ USpr oduc t i o nf r omt hel owe r48s t a t e sa nda d j a c e ntofs hor ea r e a i n1 996s t ooda tonl y54%ofi t spe a kl e ve l . Eve nt hea ddi t i onofPr udhoeBa ya nd t het r a ms ‑ Al a s kapl pe l i nedi dnotha l tt hes l i de,a ndAl a s ka npr oduc t i onpe a ke di n 1 988・Hi ghe rpr l C e Sf ol l owl ngt he1 970Soi ls hoc ks ,a l ongwi t ht hede e pe s tr e c es ‑ s i onss i nc et heGr e a tDe pr e s s i on, c utt hegr owt hofc ons umpt l On, buti mpor t sne v‑ e r t he l e s sr e a c he d61 % oft ot a lo i lc ons umpt i onby1 996. Cha ngl ngt het i mehor i z o nc o mpl e t e l yc ha nge st hea s s es s me ntoft hepr o bl e m. Vi e we dwi h at t i mes c a l ec o ns i s t e ntwi t ht hel i f eoft her e s o ur c e, i ti sc l e a rt ha tt he pe t r ol e umpr obl e mwa s n' ts ol ve di nt he1 980sbutha sbe e ns t e a di l yge t t l ngwor s e. 8 ¶ m 2 , ■ l 6 ≡! y U ^e c l J S]aJJt 2g uO FI GURE3‑ 4 USoi l pr oduc t i on, consump t i on, i mpor t s,andpr l C e overa1 30‑ year t i mehor i z on 1870 1890 1910 1930 1950 1970 1990 1870 1890 1910 1930 1950 1970 1990 Sour ce:P r o d u c t i o n&c o n s u mp t i o n : 1 870 ‑1 949, Da v i d s e n( 1 988) ,1 950‑1 966, EI AAnnua/Ener gy Pr i c e : 1 880 ‑1 968, Da v l d s e n( 1 988) ;1 968 ‑1 996, EI AAnnualEner gyRev i ew , Re f i n e r s F 7 ev i ew・ Ac q u l S i t 1 0 nCo s t . a C h p te r 3 T h eM ode l i ngP r 93 s s o ce Pe t r ol e um i saf i ni t enonr e ne wa bl er e s our c e. I nt heUS,de pl e t i onbe ga nt odomi ‑ na t ef i nd i ngr a t e si nt he1 960S , l e a di ngt oa ni ne vi t a bl ede c l i nei npr oduc t i on, ade ‑ c l i net ha tbe ga ni n1 970.TheUni t e dSt a t e si st hemos thea vi l ye xpl or e da nd de ns e l yd r i l l e dr e gi onOft hewor l d. Theve r ys uc c es sofe a r l ywi l dc a t t e r si nf i nd‑ 1 ngOi lme a nst he r ei sl e s sl e f tt of i ndnow. Whi l enota l lt hepe t r ol e um i nt heUS ha sbe e nf oundo rr e c ove r e d,c ons umpt l OnC Ont i nue st oe xc e edt her a t ea twhi c h wha tr e ma i nsi sf ound.Cons e que nt l y,1 mpO r t SC Ont i nuet ogr ow,l ea di ngt os t i l l gr e a t e rde pe nde nc yont heuns t a bl ePe r s i a nGul fr e gl On,S t i l lmor epol i t i c a la nd e c onomi cpowe rf ort heoi le xpor t l ngC Ount r i e sa ndl es sf ort heUS,a nd,e ve nt u‑ a l l y, hi ghe roi lpr i c e s , e i t he ra tt hepumpo ri nt hede f e ns ebudge t ・ 6 Theoi li ndus t r yi l l us t r a t est heda nge r sofs e l e c t i ngat i mehor i z ont oos hor tt o c a pt ur et hei mpo r t a ntdyna mi csa ndf e e dba c ksc r e a t l ngt he m.Ofc our s e,onec a n e r rt oof a ri nt heot he rdi r e c t i on.Fi gur e3‑ 5S howsagr a phdeve l ope dbyt hel a t e K血gHubbe r t . Hubbe r ti nv ent e dt hemos ts uc c e s s f u lt e c h‑ pe t r ol e umge ol og i s tM・ ni quef orf or e c a s t l ngf os s i lf ue lpr oduc t i one ve rc r e a t e d. I n1 956hees t i ma t e dt he ul t i ma t er e c ove r a bl epe t r ol e umr e s our c e soft heUSt obebe t we e n1 50a nd200bi l ‑ l i onba r r e l sa ndf or e c a s tt ha tH t hepe a ki npr oduc t i ons houl dpr oba bl yoc c urwi t hi n t hei nt e r va l1 966 ‑ 1 971 "( Hubbe r t1 975, p. 3 71 ) ・ Hi spr e di c t i onofde c l i nec a mea t at i mewhe nt heUSGe ol ogi ca lSur ve ypr o j e c t e dul t i ma t er e cove r a bl er e s our c e s ne a r l yt hr e et i me sa sl a r gea ndc l a i me dH t hes i z eoft her es our ceba s ewoul dnot l i mi tdomes t i cpr oduc t i onca pa c l t yG i nt hene xt1 0t o20ye a r sa tl e a s t ,a ndpr o ba ‑ bl yl not ]f oramuc hl onge rt i me" ( Gi l l e t t e1 974) .Thea c t ua lpe a koc c ur r e di n 1 970a ta l mos tt hepr e c i s eva l ueHubbe r tha dpr e di c t e d,oneoft hemos ta c c ur a t e l o ng‑ t e r mf o r e c a s t sonr e c or d. Hubbe r t ' ss uc c e s sl a yl ne xpl i c i t l ymode l i ngoi la s anonr e ne wa bl er es our c e. Pr oduc t i onc oul dgr owe xpone nt i a l l yi nt hee a r l ypha s e s l u o! t onpod^6J auu FI GURE3 ‑ 5 Thef os s i l f uel er ash ownwi t ha t i mehor i z onof 1 5, 000y ear s l ] SSOm 1 1 0 , 0 0 0 ‑ 5 0 0 0 g n e i r o Ye a r o . n d u s . Z もS . 。i .5 0 0 0 R e v o l u t l 0 nS h o c k Sour ce: Ad a p t e df r o mHu b b e r t ( 1 9 6 2 ) 6 Th e r ei sal a r g el i t e r a t u r eo fe n e r g ymo d e l i n gl nS y s t e md y n a mi c s 7 0 r l g l n a t l n gWi t hwo r ki n l ・( 1 9 7 4 ) ・ S e e , e . g . , Ba c k u s( 1 9 9 6 ) , Bu n na n dLa r s e n( 1 9 9 7 ) , Fi d d a ma n( 1 9 9 7 ) , Me a d o wse t a F o r d( 1 9 9 0 , 1 9 9 7 , 1 9 9 9 ) , Fo r da n dBu l l ( 1 9 8 9 ) , Na i l l( 1 9 77 , 1 9 9 2) , a n dNa i l l e t a l.( 1 9 9 2 ) f o r wo r ko nn a t i o n a l a n dg l o b a l e n e r g yma r k e t s , e l e c t r i cu t i l i t i e s , g l o b a l c l i ma t ec h a n g e , a n do t h e r en e r g yp o l i c yl S S u e S ・ 94 P a r t I P e r s p e c t i v ea n dP r oc e s s ofi t sl i f ec yc l ebutha dt of a l lt oz e r oa si twa sde pl e t e d, f or ci ngat r a ns i t i ont or e ‑ a‑ ne wa bl ee ne r gys our c e s ・ 7Tbe mpha s i z et het r a ns i t or yna t ur eoff os s i lf u e lc i vi l i z t i on,Hubbe r ts howe dt hepr oduc t i onoff os s i lf ue l sonat i mes c a l ef r om t he 000yea r sa got o5000ye a r si nt hef u‑ be gi nnl ngOft hea g r l C ul t ur a lr e vol ut i on 0, t ur e.Aga i ns tt hi sba c kdr op,t hef os s i lf ue le r ai ss e e na sat r a ns i t or ys pi ke ‑a unl quepe r i oddur i ngwhi c hhuma nl t yl i vese xt r a va ga nt l yof far i c hi nhe r i t a nc eof i r r e pl a c e a bl ena t ur a lc a pi t a l . Thepi c t ur ei ss obe r i ng.ButHubbe r t ' spl mPl e ,a si t wa sc a l l e dbyc r i t i c s ,t a ke sat i mehor i z ont ool ongt obeus e f u lt opol i c yma ke r s whoi nf lue nc epubl i cpol i c yo rc or por a t es t r a t e gya fe c t i nge ne r gypr i c e s ,r e gul a ‑ t i ons ,c a pi t a li nve s t me nt ,a ndR&D. Thec hoi c eoft i meho r i z onc a ndr a ma t i c a l l yi nf l ue nc et hee va l ua t i onof pol i c i es . I nt hee a r l y1 970saUSgove r nme nta ge nc yc onc e r ne dwi t hf o r e i gna i d s pons or e damode lf oc us e dont heSa he lr e gl OnOfs ub‑ Sa ha r a nAf r i c a . TheSa he l wa st he ne xpe r i e nc l ngr a pi dpo pul a t i ongr owt ha tt hes a met i met hedes e r twa s e xpa ndi ngs out hwa r d,r e duc i nggr a z l ngl a ndf ort henoma di che r de r s 'c a t t l e. The pur pos eoft hemode lwa st oi de nt i f yhi ghl e ve r a gepol i c i e st os pure c onomi c de ve l opme nti nt her e gi on. Themode lwa sus e dt oa s s es st hee fe c t sofma nyof t hepol i c i e st he ni nus e, s uc ha sdr i l l i ngbor ehol e st oi nc r e a s et hewa t e rs uppl yf or c a t t l ebyt a ppi ngde e pa qui f e r sors ubs i di z i ngc r opss uc ha ss or ghum a ndgr ound nut s . Runnl ngt hemode lt ot heye a r2000,ar oundnumbe rs e ve r a lde c a de si nt he f ut ur ea tt het i me,S howe dt ha tt hepol i c i esl e dt oi mpr ove me nt .Subs i di e si n‑ c r e a s e da gr l C ul t ur a lout put . Bo r ehol e spe r mi t t e dc a t t l es t oc kst ogr ow, i nc r e a s l ng t hes uppl yofmi l ka ndme a ta ndt hewe a l t hoft hehe r de r s . Howe ve r ,r unnl ngt he mode li nt ot hef i r s tde c a de soft he21 s tc e nt ur ys howe dadi f f e r e nto ut c ome: l a r ge r s t oc ksofc a t t l ebe ga nt oout s t r i pt hec a r r yl ngC a pa C l t yOft her e gl O n. Ast hec a t t l e ove r br ows e da ndt r a mpl e dt hegr a s s l a nds ,e r os i ona nddes e r t i f i c a t i oni nc r e a s e d. Thec a t t l epo pul a t i o nd r o ppe ds ha r pl y, c r e a t i ngaf oodde f i c i ti nt her e gl O n. Se l e c t l l ngat i meho r i z ont oos hor tt oc a pt ur et hes ef e e dba c ksf a vor e da dopt i onOfpol i ‑ c i esc ount e rt ot hel ong‑ t e r mi nt e r e s t soft her e gl On' spe o pl ea ndt hemi s s i onoft he c l i e ntor ga ni z a t i on・8 Mode l e r smus tgua r da ga l nS ta C C e pt l ngt hec l i e nt ' si ni t i a la s s e s s me ntoft hea p‑ pr opr i a t et i mef r a me. Of t e nt he s ea r eba s e donmi l es t onesa ndr oundnumbe r sha vl l ngl i t t l et odowi t ht hedyna mi c soft hepr obl e m, s uc ha st hee ndoft hef i s c a lye a r , Ort hene xt5‑ ye a rpl a n n l ng C y c l e . Ag o o dr u l eo ft hu mbi s t os e tt het i mehor i z on s e v e r a l t i me s a s l o n ga s t h el o n g e s t t i med e l a y s i nt h es y s t e m, a n dt h e ns o me. 1 3息2 For mu月 a抽 gaDynami cHypo竜 的es岳 s Onc et hepr obl e m hasbe e ni de nt i f i e da ndc ha r a c t e r i z e dove ra na ppr o pr i a t et i me hor i z on, mode l e r smus tbe gi nt ode ve l o pat he or y,c a l l e dad ynami ch y pot he s i s ,t o 7 s t e r ma na ndRi c h a r d s o n(1985) , S t e r ma net l.( a 1 988) , a n dS t e r ma n , Ri c h a r d s o n , a n dDa v i d s e n ( 1 990)mo d e l hewo t r l da n dUSp e t r o l e u ml i f ec y c l e sa n ds t u d yt h ee . V o l u t i o no fe s t i ma t e so f t h e r e s o u r c eb a s e , S h o wi n gwh yHu b b e r t wa ss oa c c u r a t ewh i l eo t h er e s t l ma t i o nme t h o d sp r ov e ds o wi l d l yo v e r o p t l mi s t i c . 8 p i c a r d i a n dS e i f e r t ( 1 976)d e s c r i b eo n eo fs e v e r a l mo d e l so ft h eSahe l r e g i o n( t h emo d e l d e s c r i b e da b o v ewa sn o t p u b l i s h e d ) . Ch a p t e r3 Th e Mo d e l i n gP r oc e s s 95 a c c ountf ort hepr obl e ma t i cbe ha vi o r . Yourhypot hes i si sdyna mi cbe c a us ei tmus t pr ovi dea ne xpl a na t i onoft hedyna mi c sc ha r a c t e r l Z l ngt hepr o bl e mi nt e r msoft he unde r l yi ngf e e d ba c ka nds t oc ka ndf lows t uc r t ur eoft hes ys t e m. I ti sahypot he s i s be c a us ei ti sa l wa yspr ovi s i ona l ,s ub j e c tt or e vi s i onora ba ndonme nta syoul e a r n f r omt hemode l i ngpr oc e s sa ndf r omt her e a lwor l d. Adyna mi chypot he s i si sawor ki ngt he or yofhowt hepr o bl e ma r os e. I tgui de s mode l i nge f f or t sbyf oc us l ngyoua ndyourc l i e nt sonc e r t a i ns t r uc t ur e s . Muc hof t her e ma i nde roft hemode l i ngpr oc e s she l psyout ot es tt hedyna mi chypot hes i s , bot hw it ht hes i mul a t i onmode la ndbye xpe r i me nt sa ndda t a ̲ col l e c t i oni nt her e a l wor l d. h pr a c t i c e,di s c us s i onoft hepr obl e ma ndt he or i esa boutt hec a us e soft he pr obl e ma r eJ umbl e dt oge t he ri nc onve r s a t i onwi t hc l i e ntt ea ms . Ea c hme mbe rof at e a ml i ke l yha sadi fe r e ntt he or ya bo utt hes our c eoft hepr obl e m;youne e dt o a c knowl e dgea ndc a pt ur et he ma l l . Ma nyt l me St hepur pos eoft hemode li st os ol ve ac r i t i c a l l yI mpo r t a ntpr obl e mt ha tha spe r s i s t e df orye a r sa ndge ne r a t e dgr e a t c onf li c ta ndnotal i t t l ea ni mos l t ya mongme mbe r soft hec l i e ntt e a m.Al lwi l l t e na c i ous l ya dvoc a t et he i rpos i t i onswhi l ede r i di ngt hevi e wsofot he r si nt he gr oup・ Ea r l yl nt hemode l i ngpr oc e s s , t hemode l e rne e dst oa c ta saf a c i l i t a t o r , c a p‑ t ur l ngt he s eme nt a lmode l swi t houtc r i t i c i z l ngOrf i l t e r i ngt he m.Cl a r i f yi nga nd pr obi ngques t i onsa r eof t e nus e f ul , butt hemode l e r ' sr ol edur i ngt hi se a r l ypha s ei s t obeat hought f u ll i s t e ne r ,notac ont e nte xpe r t ・ Ava r i e t yofe l i c i t a t i ont e c hni que s a nddi a gr a mml ngt ool sha vebe e nde ve l ope dt oa s s i s tyoui nf a c i l i t a t l ngaPr od uc ‑ t i vec onve r s a t i ont oe l i c i tpe o pl e' St he o r i e sa boutt heca us e soft hepr obl e m・ 9Y our goa li st ohe l pt hec l i e ntde ve l opa ne ndoge nouse xpl a na t i onf ort hepr o bl e ma t i c dyna mi cs . EndogenousExpl anat l r on Sys t e m dyna mi c ss e e kse ndoge nouse xpl a na t i onsf orphe nome na. Thewor d" e n‑ doge nous "me a ns" a r i s i ngf r o m wi hi t n・ ' ' Ane ndoge noust he or yge ne r a t e st hedy‑ na ic m sofas ys t e mt hr oug ht hei nt e r a c t i onoft heva r i a bl e sa nda ge nt sr e pr e s e nt e d i nt hemode l ・ Bys pe c i f yi nghowt hes ys t e mi ss t r uc t ur e da ndt her ul e sofi nt e r a c ‑ t i o n( t hede c i s i onr ul e si nt hes ys t e m) , yo uc a ne x pl or et hepa t t e r nso fbe ha vi o rc r e ‑ a t e dbyt hos er ul esa ndt ha ts t r uc t ur ea nde xpl or ehowt hebe ha vi ormi ghtc ha nge i fyo ua l t e rt hes t r uc t ur ea ndr u l es . Ⅰ nc o nt r a s t , at he or yr e l yi ngone xoge nousva r i ‑ a bl e s( t hos e" a r i s i ngf r om wi t hout , "t ha ti s ,f r om out s i det hebounda r yoft he mode l )e xpl a i nst hedyna mi csc ・ fva r i a bl e syouca r ea bouti nt e r msofot he rva r i ‑ a bl e swhos ebe ha vi oryou' vea s s ume d. Exoge nouse xpl a na t i onsa r er e a l l ynoe x‑ pl a na t i on a ta l l ;t he ys i mpl ybe gt heques t i on,Wha tca us edt hee xoge nous va r i a bl e st oc ha ngea st he ydi d?Thef oc usi ns ys t e mdyna mi c sone ndoge no use x‑ pl a na t i onsdoesnotme a nyous houl dne ve ri nc l udea nye xoge nousva r i a bl e si n yourmode l s . Bu tt henumbe rofe xoge nousI nput sS houl dbes ma l l ,a nde a c hc a n‑ di da t ef ora ne xoge nousI nputmus tbec a r e ul f l ys c r ut i ni z edt oc ons i de rwhe t he r 9 Th el i t e r a t u r eo ng r o u pmo d e l b u i l d i n gi sg r o wi n gr a p i d l y . Re a g a n ‑ Ci r i n c i o n ee t l. a ( 1 9 9 1 ) , Mor e c r o f t a n dS t e r ma n( 1 9 9 4 ) , Ve n n i x( 1 9 9 6 ) , a n dVe n n i xe t a l . ( 1 9 9 7 ) p r o v i d eg o o do v e r v i e wso f t o o l sa n dt e c h n i q u e st oe l i c i t a n dc a p t u r et h eme n t a l mo d e l so ft e a msa n dc l i e n t g r o u p s . 96 Pa r tI Pe r s p e c t i v ea n dPr oc e s s t he r ea r ei nf a c ta nyI mpo r t a n t f e e dba c ksf r o mt hee nd og e no use l e me n t st ot hec a n‑ d i da t e. I fs o, t hebo unda r yo ft hemode l mus t bee x pa nd e da n dt heva r i a bl emus t be mo de l e de ndo g e no us l y. Thec o ns e q ue nc e so fna r r o w mode lbo unda r i e sa ndr e l i a nc eo ne xo ge nous va r i a bl e sa r eo f t e ns e r i o us . At ypi c a le xa mpl ei spr ov i de db yt hePr o j e c tI nde pe n‑ de nc eEva l ua t i o nSys t e m( PI ES)mode l , ahy br i dmo d e lba s e do nl i ne a rpr og r a m‑ ml ng, e C O nO me t r i c s , a ndi n pu t / ou t puta na l ys i sus e di nt he1 9 70sbyt heUSFe de r a l Ene r gyAd mi ni s t r a t i o n( FEA)a ndl a t e rbyt heUSDe pa r t me nto fEne r gy . Asde ‑ s c r i be dbyt hePEA, t h epu r pos eo ft hemode lwa ‑ st oe va l ua t ed i f f e r e r ‑ l te ne r g yPOl i ‑ c i e sa c c o r di ngt ot hef ol l owl ngC r i t e r i a:t he i ri mpa c to nt hede ve l o pme nto f a l t e na r t i vee ne r g ys o u r c e s ; t he i ri mpa c tone c o no mi cg r owt h, i nf la t i o n, a ndune m‑ pl oyme nt ;t he i rr e gl O na la nds oc i a li mpa c t s ;t he i rv ul ne r a bi l i t yt oi mpo r tdi s r up‑ t i ons ; a ndt he i re n vi r o nme nt a le fe c t s . Su r pr l S l ng l y , c o ns i d e r i ngt hes t a t e dpur pos e , t hePI ESmode lt r e a t e dt hee c on‑ omya se xog e nous .Themod e le c ono my( i nc l udi nge c o nomi cg r owt h,i nt e r e s t r a t e s , i nf la t i o n, wo r l do i lpr i c e s ,a ndt hec os t so func o nv e nt i o na lf ue l s )wa sc o m‑ pl e t e l yuna f f e c t e dbyt hee ne r gys i t ua t i o n( i nc l ud i ngpr i c e s , pol i c i e s ,a ndpr o d uc ‑ t i on) . I nt hemo de l , e v e naf u l le mba r goofi mpo r t e do i lo rado u bl i ngo foi lpr i c e s wo ul dha venoi mpa c to nt hee c o nomy . Tr e a t l ngt hee c o nomye xoge nous l yma det hePI ESmode li nhe r e nt l yc o nt r a ‑ di c t o r y . Be c a us ei ta s s ume dh i ghr a t e sofe c o no mi cg r o wt ha ndl o wpr i c ee l a s t i c i ‑ t i e s , l tpr q】 e C t e dh ug ei n c r e a s e si ne ne r g yde ma nd, r e q ul r l nge v e ng r e a t e ri nc r e a s e s i nt hec a pi t a lr e q ul r e me nt SOft hee ne r gys e c t o ra sc he a pdo me s t i coi lwa sc on‑ s ume d. I nt hemo de l , t he s eh ugei nve s t me nt si ne ne r gyp r o duc t i o nwe r es a t i s f i e d wi t ho utr e d uc i ngl nVe S t me ntO rC OnS umpt l O ni nt her e s to ft hee c o no mya ndwi t h noi mpa c to ni n t e r e s tr a t e so ri nf la t i o n. I ne f f e c t , t hemod e ll e tt hee c o no myha ve i t spl ca nde a ti tt o o. I npa r t be c a us ei tI g no r e dt hef e e d ba c ksbe t we e nt hee ne r g ys e c t o ra ndt her e s t oft hee c o no my , t hePI ESmod e lc o ns i s t e nt l ypr ove dt obeo ve r o pt l mi s t i cJn1 974 t hemode lpr qe c t e dt ha tby1 98 5t heUSwoul dbewe l lo nt hewa yt oe ne r g y i nde pe nde nc e:e ne r gyI mpo r t sWOul dbeonl y3. 3mi l l i o nba n℃l spe rda ya nd pr oduc t i o no fs ha l eo i lwo ul dbe250, 000ba r r e l spe rda y.Fur t he r mo r e ,t hes e l( 1 98 4 de ve l o pme nt swo ul dbea c c o mpa ni e dbyoi lpr i c e so fa bo ut$ 22pe rba r r e dol l a r s )a ndbyvi go r o use c o nomi cg r owt h.I tdi dn' tha ppe n.Ⅰ mpo r t si nt hel a t e 1 98 0Swe r ea bo u t5. 5mi l l i onba r r e l spe rda ya ndg r e wt omo r et ha nha l fo fo i lc o n‑ i z e d・ s umpt l O nbyt hemi d1 99 0S . Sha l eoi la ndo t he re xo t i cs y nf u e l sne ve rma t e r i a l Thi ss i t ua t i o np r e va i l e dd e s pi t eh uger e d uc t i o nsi noi lde ma ndc a us e dbyo i l pr l C e S i nt hee a r l y1 98 0sg r e a t e rt ha n$30 / bbla ndt hemos ts e r i o usr e c e s s i ons i nc et he Gr e a tDe pr e s s i o n. Abr oa dmod e lbo unda r yt ha tc a pt ur e si mpor t a ntf e e d ba c ksi smor ei mpor ‑ t a ntt ha nal oto fd e t a i li nt hes pe c i f i c a t i o nofi nd i vi d ua lc o mpo ne nt s . I ti swo r t h no t l ngt ha tt hePI ESmod e l pr o vi de dabr e a kdowno fs uppl y , d e ma nd, a ndp r i c ef o r doz e nso ff ue l si ne a c hr e g l O nOft hec o unt r yye ti t sa g gr e ga t epr o j e c t i ons we r e n' te ve nc l os e. Wha tpu r pos ewa ss e r v e dbyt hee f f o r tde vo t e dt of o r e c a s t l ng t hede ma ndf o rJ e tf ue lo rna ph t hai nt hePa c i f i cNo r t hwe s twhe nt heba s i ca s I s umpt l OnSWe r eS Opa l pa bl yI na de qua t ea ndt hema i nr e s ul t swe r es owoe f u l l y e r r one o us ? 97 Cha pt e r3 TheMo de l i ngPr o c e s s Ma p pl n gSy s t e mSt r u c t u r e Sys t e mdyna mi c si nc l ude sava r i e t yoft ool st ohe l pyouc ommuni c a t et hebound一 打yofyourmod e la ndr e pr e s e nti t sc a us a ls t r uc t ur e・ The s ei nc l udemode lbound‑ a r ydi a gr a ms ,s ubs ys t e m di a gr a ms ,ca us a ll oopdi a gr a ms ,a nds t oc ka ndf l ow ma pS ・ Modelboundar ychar t Amode lbo unda r yc ha r ts umma r i z e st hes c opeoft he mode lbyl i s t l ngWhi c hke yva r i a bl e sa r ei nc l ude de ndoge nous l y, whi c ha r ee xoge ‑ nous ,a ndwhi c ha r ee xc l ude df r omt hemode l . Toi l l us t r a t e , Ta bl e31 2s howsamode lbounda r ydi a g r a mf oramode lde s i gne d t os t udyt hef e e dba c ksbe t we e nt hee ne r gys ys t e ma ndt hee c onomy( St e r ma n 1 983) . Pa r t l yi nr e a c t i ont ot hel i mi t a t i onsofe xi s t i ngmode l ss uc ha sPI ES, t heDe ‑ pa r t me ntofEne r gyl nt hel a t e1 970ss oughtt ode ve l opdyna mi cmode l swi t ha br oa de rbounda r y( Na i l l1 97 7,1 992) . Thepur pos eoft hemode lwa st oe xpl o r et he i mpa c tofhi ghe re ne r gypr i c e sOne c onomi cgr owt h, une mpl o yme nt , i nf la t i on, a nd i nt e r es tr a t esa ndhowt he s ema c r oe c ono mi cc ons i de r a t i onsmi ghtc o ns t r a i nt hede ‑ ve l opme ntofne we ne r gys our c es . Thet i mehor i zonoft hemode lwa squi t el ong ( 1 9501 2050)t oc a pt ur et hef ul lt r a ns i t i onf r om f os s i lf ue l st or e ne wa bl eorot he r e ne r gys our c esa ndc ons i s t e ntwi t ht hel ongt l mede l a ysi nt hede ve l o pme nt ,c on‑ s t r uc t i on,a ndus e f ull i f eofe ne r gy‑ pr oduc i nga nde ne r gy‑ cons umi ngC a pi t a l s t oc ks . I nc ont r a s tt one a r l ya l lmode l sus e dt oa ddr es st hes ei s s uesa tt het i me,t he mode lha dabr oa dbounda r y,wi t ha l lma j orma C r Oe C OnOmi cva r i a bl e sge ne r a t e d e ndoge nous l y. Unl i ket hePI ESmode l , t hec a pl t a l , l a bor ,a nde ne r gyr e qul r e me nt S . TABLE 3 1 2 Model boundar y char tf orar ong‑ t er mmode一 of ener g y‑ ec onomy i nt er ac t i ons Endogenous Exogenous GNP Consump t i on i n ves t ment Popul a t i on I n ven t or i es Technol ogl C al change I n t er nat i on al t r ade ( ex c ep twi t hOPEC) Taxr at es En vi r onment a一 c ons t r ai n t s En er gypol i ci es Savi ngs Pr i c es( r eal andn omi nal ) Wages( r eal an dnomi nal ) l n f l at i onr at e L aborf or cepar t i c l pat i on Emp一 oymen t Unempl oymen t l n t er es tr at es Moneysuppl y Debt Ener gypr oduc t i on Ener gydeman d Ener gyI mpor t s Sour ce:St er man( 1 9 83 ) . Excl uded Nonener gyr es our c es l nt er f uel subs t i t u t i on Di s t r i bu t i on al equi t y 98 P a r t I P e r s p e c t i v ea n dP r o c e s s oft hee ne r g yi ndus t r i e swe r ee nd og e no usa ndt hee ne r g yi ndus t r yha dt oc ompe t e a ga l nS tO t he rs e c t o r sf o rt he s er e s ou r c e s . Themod e ls t i l lc o nt a i ne ds e ve r a le xoge ‑ no usva r i a bl e s .The s ei nc l udepo pul a t i o n,t her a t eofove r a l lt e c hnol ogl C a l pr og r e s s ,a ndt hepr l C eOfi mpo r t e do i l ・We r et he s ee 呆oge nousva r i a bl e sa c c e pt ‑ a bl e?Po pul a t i ong r o wt ha ndt heove r a l lr a t eoft e c hni c a lpr og r e s smi ghtbea f ‑ f e c t e dbyc ha ng e si ne ne r g yp r l C e Sa ndc ons e q ue ntc ha ng e si nt her a t eofe c o no mi c g r owt h.Ho we ve r ,t he s ef e e d ba c kss e e me dl i ke l yt obes ma l l ・Thede c i s i o nt o mode lt hep r l C eO fi mpo r t e do i le xog e no us l yi smo r ep r o bl e ma t i c ・ Cl e a r l yt hepr l C e o foi la f f e c t sbo t ht hed e ma ndf o ra nds u ppl yo fe ne r g yl nt heUni t e dSt a t e s , de t e r ‑ mi ni ngt heq ua nt i t yI mpo r t e d. Asama j o ri mpo r t e r , c ha nge si nUSo i li mpo r t sc a n d r a ma t i c a l l ya l t e rt hes u ppl y/ de ma ndba l a nc eo ft heo i le x po r t l ngna t i ons , f e e di ng ba c kt ot hepr i c eO foi li nt hewo r l dma r ke tTr e a t l ngI mpo r tPr l C e Se XOge nO uS l y c u t sa ni mpo r t a n tf e e d ba c kl oo p. I nd i s c us s i ngt hebo unda r yo ft hemode lIa r g ue d ha t tt he r ewe r ei nf a c ti mpo r t a ntf e e d ba c ksbe t we e nt heUSe ne r g ys ys t e ma ndt he wo r l do i lma r ke t . Butla l s oa r g ue dt ha tt hedy na mi c soft hewor l dpr l C eWe r eS O c o mpl e xt ha ti nc o r po r a t l ngt he me ndoge no us l ywa sbe yo ndt hes c o pea ndpur pos e o ft hepr q 】 e c t . Iha dp r e vi ous l yhe l pe dbui l damod e lo ft hewo r l do i l ma r ke tf o rt he USDe pa r t me nto fEne r gya ndhope dt ha tul t i ma t e l yt het womode l sc o ul dbe J O i ne d. Th emod e lbo unda r yc ha r ta l e r t e dt hec l i e nt st oaq ue s t i o na bl ea s s umpt l O n s ot he yc o ul de va l ua t ewha tt hee f f e c toft hemi s s l ngf e e d ba c kmi g htbe. Thel i s to fe xc l ude dc o nc e pt sa l s opr ovi de si mpo r t a ntwa r nl ngSt Ot hemode l us e r . Themo d e lo mi t t e di nve nt o r i e so fgo odsa ndma t e r i a l s( a ndhe nc es ho r t ‑ t e n bus i ne s sc yc l e s ) ‑nopr o bl e mi ns uc hal o ng‑ t e r mmod e H nt e r na t i o na lt r a dewa s e xc l ude d, e xc e ptf o rt hef lowso foi l ,goods ,c a pi t a l ,a ndmone ybe t we e nt heUS a ndt heo i le x po r t l ngna t i o ns . Thepe t r odol l a r sf lo wl ngt OOPECa ndt he i rr e c y‑ c l i nga se x po r t so rf br e l g ni nve s t me n tha dt obei nc l ud e d, butt oi nc l udeno ne ne r gy t r a dewo ul dha v ee x pa nde dt hemode li nt oag l o ba lma c r o e c ono mi cs ys t e m, a ndI wo ul dpr o ba bl ys t i l lbewo r ki ngoni t , Envi r o nme nt a lc ons t r a i nt sa ndno ne ne r gy r e s o ur c e ss u c ha swa t e rt ha tmi ghtl i mi tne we ne r g ys o u r c e sl i kes yn f ue l swe r ee xI c l ude d, me a nl ngC O nC l us i o nsa bo utt her a t eofd e v e l o p me ntoft he s ee xo t i ce ne r g y s o ur c e swo ul dbeov e r o pt l mi s t i c. Themode la l s ot r e a t e dt hee ne r gys ys t e mi na f a i r l ya g g r e g a t ef a s hi on, s oi nt e r f ue ls u bs t i t u t i o n( o i lvs ・ ga s , f o re xa mpl e ) , wa sno t c o ns i de r e d,a no t he ropt l mi s t i ca s s umpt i o n.Fi na l l y ,t hemode ld i dno tc o ns i de r i nc o med i s t r i but i o n, e ve nt ho ug hs omee ne r gypo l i c i e ss uc ha sga s o l i net a xe sa r e r e gr e s s i v eu nl e s so f f s e tbyc ha nge si nt hei nc o met a xc od e・ Thepur pos eo fl i s t i ng a l lt he s eo mi s s i o nsf r omt hemod e lwa st ohe l pmod e lus e r sde c i def o rt he ms e l ve s whe t he rt hemod e lwa sa ppr o pr l a t ef o rt he i rpu r pos e ・ Mod e lbo unda r ydi a g r a msa r es ur pr i s i ng l yus e f ula nds ho c k i ngl yr a r e ・ Of t e n, mode l sa r eus e dnota st ool sofi nq ul r ybuta swe a ponsi nawa ro fa dvoc a c y, I ns uc hc a s e smo de l e r ss e e kt ohi det hea s s umpt 1 0 nSO ft he i rmode l sf r ompo t e n t i a l c r i t i c s . Bute ve nwhe nt hemode l e r s ' mo t i ve sa r ebe ni g n, ma nyf e e lunc o mf o r t a bl e l i s t l ngWha tt he y' vel e f tout ,s e et heo mi s s i o nsa sf la wsa ndpr e f e rt os t r e s st he s t r e ngt hso ft he i rmo de l . Whi l et hi st e nde nc yl Sna t u r a l , i tunde r c ut st heut i l i t yo f yo urmode la ndwe a ke nst hea bi l i t yo fpe o pl et ol e a r n丘. o ma ndi mpr o veyo ur wo r k.Bye x pl i c i t l yl i s t l ngt hec o nc e pt syo uha vec hos e nnott oi nc l ude,a tl e a s t f o rnow, yo up r o vi deavi s i bl er e mi nde ro ft hec a ve a t st ot her e s ul t sa ndl i mi t a t i o ns o ft hemode l ,Wi t ho utac l e a rund e r s t a nd i ngoft hebo unda r ya nda s s umpt l OnS , 99 Ch a p t e r3 Th eMo d e l i n gP r o c e s s mode l sc ons t uc r t e df oronepur pos ea r ef r e que nt l yus e df o ra not he rf orwhi c ht he y a r ei l l ‑ s ui t e d, S o me t i me spr oduc i nga bs ur dr e s ul t s . Al lt ooof t e nmode l swi t hcom ‑ pl e t e l yI na ppr op r i a t ea nde ve nbi z a r r ea s s umpt l OnSa bo ute xoge nousa nde xc l ude d va r i a bl esa r eus e di npol i c yma ki ngbe c a us et hemode lus e r sa r euna bl et oe xa m‑ i net hebounda r yoft hemode l st he ms e l vesa ndt hemode l e r sha venotpr ovi de d t ha ti nf or ma t i onf ort he m( c ha pt e r21pr ovi dese xa mpl es ;s e ea l s oMe a dowsa nd Robi ns on1 98 5) . Su b s y s t e md i a gr a m.Asubsystem diagram showstheoveral la r c hi t e c t ur eof amode l . Ea c hma j orS ubs ys t e mi ss howna l ongwi t ht hef lowsofma t e r i a l , mone y goods , i nf or ma t i o n, a nds oonc oupl i ngt hes ubs ys t e mst oonea not he r . Subs ys t e ms c a nbeor ga ni za t i o nss uc ha st hef i r ma ndt hec us t ome roror ga ni z a t i ona ls ubuni t s s uc ha sope r a t i ons ,ma r ke t i ng,a ndpr oduc tde ve l o pme nt ・Subs ys t e m di a gr a ms c onve yi nf o r ma t i onont hebounda r ya ndl e ve lofa ggr e ga t i oni nt hemode lby s howi ngt henu mbe ra ndt ypeofdi f f e r e nto r ga ni z a t i onsora ge nt sr e pr es e nt e d. The ya l s oc ommu ni c a t es omei nf or ma t i ona boutt hee ndoge nousa nde xoge nous va r i a bl es . , I nt he1 960SJ a yFor r e s t e rs e r ve dont heboa r dsofs e ve r a ls uc c e s s f u lhi gh‑ t e c h c ompa ni esa ndbe c a mei nt e r e s t e di nt hedyna mi csofc or po r a t egr owt h.Tbhe l p hi mt hi nka bou tt hes t r a t e gi ci s s uesf a c i ngt hes ef i r ms ,For r es t e r( 1 964,p.32) c r e a t e damode ld es i gne d" t os howhowt hedi fe r i ngki ndsofc or por a t egr owt h pa t t e r nsc a nbec r ea t e dbydi f f e r e ntc or por a t epol i c i esa ndma na ge me nta t t i t udes t . HFi gur e3‑ 6s howst he a ndbyt hei nt e r a c t i o nsbe t we e nac ompa nya ndi t sma r ke r e f e r e nc emode . For r e s t e r( pp. 321 33)e xpl a i ne d: Theve r yr ar ec o mpa n yg r o wss mo o t h l y , a si nc u r v eA, a n de v e n t u a l l yr e a c he s ahe a l t h ys us t a i n e dp l a t e a uo fma t u r el i f e . Mo r ef r e q u e n t l y , t hec o mpa n yf o l l o wsa pa t t e r n , a si nc u r v eB, wh e r ei ta p pe a r st os u c c e e da tf i r s ta n dt h e ne n c o u n t e r sa s e v e r ec r i s i st h a t l e a dst ob a n k r u p t c yo rme r g e r . Of t e n, t h epa t t e r ni sg r o wt hs t a g ‑ na t i o n, a si nc u r v eC, ma r ke db yn e i t h e rs u c c e s sn o rf a i l u r e . Oft ho s ec o mp a n i e s wh i c hd os ho wal o ng ‑ t e r mg r o wt ht r e nd, t hemo s tc o mmo npa t t e r ni st ha t i n c u r v eD, wh e r eg r o wt hi sa c c o mpa n i e db yr e pe a t e dc r i s i s . FI GURE3 ‑ 6 Pat t er n sof c or por a t egr owt h Ti me Sou/ ℃e. ' Ad a p t e df r o mF o r r e s t e r ( 1 964) . 1 0 0 P a r t iP e r s p e c t i v ea n dP r o c e s s For r e s t e ra r gue dt ha t" c ont r a r yt of i r s ti mpr e s s i ons ,onec a nnote xpl a i nt he s e di fe r e nc e sont heba s i soft hepa r t i c ul a ri nd us t r yo rt het ypea ndde s i gnofpr od‑ uc t s . . .Onemus tt he r e f or el ookde e pe ri nt ot hes t r uc t ur eofi nf or ma t i onf lowsa nd t hepol i c i e swhi c hgui deope r a t i ngde c i s i ons "( p・ 33) ・ Todos ot hemode lc ons i s t e d oft wos ubs ys t e ms , t hec ompa nya ndt hema r ke t( Fi g ur e3‑ 7) ・ Thet wos ubs ys t e msa r ec oupl e dbyt heo bvi o usf lowsofor de r s , pr oduc t ,a nd mone y: Thef i r mr e c e i ve sor de r sf r omt hema r ke t , s hi pspr oduc t , a ndr e c e i ve spa y‑ me nt .Buti na ddi t i on,t hef i r ms e ndss i gna l st ot hema r ke ti nc l udi ngt hepr i c eOf t hepr oduc t ,i t sa va i l a bi l i t y( me a s ur e dbyt hede l i ve r yde l a y) ,i t sf unc t i ona l i t y, qua l i t y,s ui t a bi l i t yt oc us t ome rne e ds ,a ndot he ri nt a ngi bl ea t t r i but esoft hec om‑ pa ny' sr e put a t i on. Thema r ke tr e s pondst ot he s es l gna l st hr ought heor de rr a t ea nd t hr oughc us t ome rf e e dba c ka boutpr l C e,qua l i t y ,s e r vi c e, pr oduc tf ea t ur e s ,a nds o on.Thedi a g r a me l e ga nt l ypr es e nt st hees s e nt i a lf e e dba c kpr oc es s esc oupl i nga f i r mt oi t sma r ke t , S t r es s e st ha to r de r sde pe ndonmuc hmor et ha npr l C e ,a ndbe gi ns t os ugge s tt hes t r uc t ur ewhi c hmus tbec a pt ur e dwi t hi ne a c hs ubs ys t e m・ For r es t e r r e le f c t e dont hei mpor t a nc eoft hi sc onc e pt ua lf r a me wor ki nhi st hi nki ng: De f i n i n gt hes ys t e mbo u n da r ya ndt h ed e g r e eo fa g g r e g a t i o na r et woo ft h emo s t d i f f i c u l ts t e psi ns u c c e s s f u lmo d e l i ng. I nt h i spa r t i c u l a rs t u d y , p a r Lt i mee f f o r tf o r a bo ut t woy e a r swa sde v o t e dt of a l s es t a r t sb e f o r ea r r i v l nga t t hepo i nts ho wni n [ Fi g u r e3 ‑ 7 ] . Th e r e a f t e r , o n l ye i g h twe e kswe r er e q u i r e dt oc r e a t et h ee n t i r es ys t e m o fs o me2 0 0e q ua t i o ns . Cha pt e r1 5pr e s e nt sas i mpl eve r s i onoft hi smode l ,For r es t e r ' S" ma r ke tg r owt h mode l , "a nds howshow di f f e r e ntma na ge me ntpol i c i e sc a nc r ea t et hepa t t e r nsof gr owt hde s c r i be di nFi gur e3‑ 6. A mo r ede t a i l e ds ubs ys t e m di a gr a mi ss howni nFi gur e3‑ 8・Thedi a g r a m s howst hea r c hi t e c t ur ef oramode lofas e mi c onduc t orma nuf a c t ur e r( St e r ma n Re pe nni ng,a ndKof ma n1 997) .Thepur pos eoft hemode lwast oe xpl or et he dyna mi c sofpr oc es si mpr ove me ntpr ogr a ms .Thef i r m ha di mpl e me nt e dave r y , FI GUR E3 ‑ 7 Sub s s t e m di ag mf o r For r e t e r ' s cor p at egr o wt m od e一 y ra s or h Sour ce: Ad a p t e df r o mF o r r e s t e r( 1 964) . Ch a p t e r3 Th eMo d e l i n gP r o c e s s 101 s uc c e s s f ulqua l i t yI mpr ove me ntpr ogr a m.Howe ve r ,de s pi t edr a ma t i ci mpr ove‑ me nt si nqua l i t y ,pr oduc t i vi t y,a ndc us t ome rr e s pons i ve ne s s ,o pe r a t l ngPr of i t a ndt hes t oc kp r l C ef e l l ,l e a di ngt ol a yofS ・Expl or ingt hi spa r a doxr e qui r e da mode lwi t habr oa dbo unda r ybot hwi t hi nt her e pr e s e nt a t i onoft hef i r ma ndi n i nt e r a c t i onsoft hef i r m wi t hi t se nvi r onme nt .Be s i dest heus ua ls ubs ys t e msf or ma nuf a c t ur l ng,Pr od uc tde ve l opme nt ,a nd a c c ount l ng,t hemode li nc l udesa pr oc e s si mpr ove me nts e c t ora ndas e c t orl a be l e d" Fi na nc i a lSt r e s s . "TheFi na nc i a l St r es ss ubs ys t e mi snota nor ga ni za t i ona ls ubuni tbutr e pr es e nt st opma na ge 一 me ntde c i s i onsr e ga r di ngl a yofs ,i nves t me nt ,a ndt hea t t e nt i ongl Ve nt OPr oc e s s FI GURE3・ 8 Subsyst emdi agr amf ormodel ofas emi c onduc t orf i r man di t squ al i t y i mpr ovemen t∑pr ogr am Sour ce: Ad a p t e df r o mS t e r ma n ,R e p e n n i n g , a n dK o f ma n( 1 9 9 7 ) . 102 P a r t I P e r s p e c t i v ea n dP r o c e s s i mp r o ve me nt . The s ede c i s i o nswe r ea f f e c t e dbyt hef i r m' sf i na nc i a lhe a l t ha ndt he t hr e a to ft a ke o ve r( a si nf lue nc e dbyt hema r ke tva l ueo ft hef i r mr e l a t i vet oboo k va l uea ndc a s hf low) .Thedi a gr a ma l s os howst ha tt hef i r m' ss a l e sa ndma r ke t s ha r ea r ee ndo ge no us , a si sc o mpe t i t o rbe ha v i o r( no t et ha tc o mpe t i t o r sr e s po ndno t o n l yt ot hef i r m' spr i c ebuta l s ot oi t sq ua l i t yi mpr o ve me n te fo r t s ) . Thes t oc kpr i c e a ndma r ke tva l ua t i ono ft hef i r ma r ea l s oe ndo ge no us . l . Su bs ys t e m di a g r a msa r eove r vi e wsa nds ho ul dno tc ont a i nt oomuc hde t a i Thed i a g r a mi nFi gu r e3‑ 8i squl t eC Ompl e x; s u bs ys t e md i a g r a mss ho ul dge ne r a l l y bes i mpl e r . Mul t i pl es ubs ys t e m di a g r a msc a nbeus e dt oc o nve yt hehi e r a r c hi c a l s t r uc t u r eo fl a r g emode l s . CausaHoopdi agr ams, Modelbounda r yc ha r t sa nds ubs ys t e md i a g r a ms s ho wt hebo unda r ya nda r c hi t e c t ur eo ft hemod e l butdo n' ts howhowt heva r i a bl e s a r er e l a t e d.Ca us a ll oo pdi a g r a ms( CLDs )a r ef le xi bl ea ndus e f ult ool sf o rd i a ‑ g r a mml ngt hef e e d ba c ks t r uc t ur eofs ys t e msi na nydo ma i n・ Ca us a ldi a g r a msa r e s i mpl yma pss howi ngt hec a us a ll i nksa mo ngva r i a bl e swi t ha r r o wsf r o m ac a us e t oa ne f f e c t . Cha pt e r2pr ovi d e se xa mpl e s ; c ha pt e r5c o ve r st her le u sf o rt he i rc o n s t r uc t i o na ndi nt e r pr e t a t i oni nde pt h. ‑ St ockandf l ow maps. Ca us a ll oo pd i a g r a mse mpha s i z et hef e e d ba c ks t r uc ‑ t ur eo fas ys t e m.St oc ka ndf lOwd i a g r a mse mpha s i z et he i runde r l yi ngphys i c a l s t uc r t ur e . St oc ksa ndf lowst r a c ka c c umul a t i o nso fma t e r i a l , mo ne y ,a ndi nf or ma t i o na st he ymovet hr oug has ys t e m.St oc ksi nc l ud ei nve nt or i e sofpr od uc t , po pul l a t i o ns ,a ndf i na nc i a la c c ount ss uc ha sde bt , boo kva l ue ,a ndc a s h. Fl owsa ret he r a t e so fi nc r e a s eo rde c r e a s ei ns t o c ks ,s uc ha spr od uc t i ona nds hi pme nt s ,bi r t hs a ndde a t hs , bo r r owi nga ndr e pa yme nt , i nve s t me nta ndde pr e c i a t i o n,a ndr e c e i pt s a nde x pe nd i t ur e s .St oc ksc ha r a c t e r i z et hes t a t eo ft hes ys t e ma ndge ne r a t et hei n‑ f o r ma t i o nu po nwhi c hde c i s i onsa r eba s e d.Thed e c i s i o nst he na l t e rt her a t e so f low,a f l t e r i ngt hes t oc ksa ndc l os i ngt hef e e d ba c kl oo psi nt hes ys t e m.Cha pt e r2 s ho wse xa mpl e s ; c ha pt e r s6a nd7d i s c us st hema ppl nga ndbe ha vi o rofs t oc ksa nd lo f ws . ‑ Pol i c ys t r uct ur edi agr ams. Thes ea r ec a us a ld i a gr a mss ho wi ngt hei nf o r ma ‑ t i o nl n Put St OaPa r t i c ul a rde c i s i onr ul e . Po l i c ys t r uc t ur edi a g r a msf oc usa t t e n t i o n o nt hei nf o r ma t i onc ue st hemode l e ra s s ume sd e c i s i o nma ke r sus et ogo ve r nt he r a t e so ff l owi nt hes ys t e m.The ys howt hec a us a ls t r uc t ur ea ndt i mede l a ysi n‑ vo l ve di npa r t i c ul a rd e c i s i o nsr a t he rt ha nt hef e e d ba c ks t r uc t u r eo ft heo ve r a l ls ys ‑ t e m. Cha pt e r1 5pr ovi d e se xa mpl e s ;s e eMo r e c r o f t( 1 98 2)f o rde t a i l s . 3. 5 . 3 F or mul a t i n gaS… mut t l t i onMode E Onc eyo u' Vede ve l o pe da ni ni t i a ld yna mi ch ypo t he s i s , mode lbo unda r y ,a ndc o n‑ c e pt ua lmod e l , youmus tt e s tt he m. So me t i me syo uc a nt e s tt hed yna mi chypo t he ‑ s i sd i r e c t l yt hr oughda t ac o l l e c t i o no re x pe r i me nt si nt her e a ls ys t e m. Mos toft he t i me , ho we ve r , t hec onc e pt ua lmod e li ss oc ompl e xt ha ti t sd yna mi ci mpl i c a t i o ns a r eu nc l e a r . Asd i s c us s e di nc ha pt e r1 , O u ra bi l i t yt oi n f e rc o r r e c t l yt hed yna mi c sof ac o mpl e xmode li se xt r e me l ypoo r . Fur t he r , i nma nys i t ua t i o ns , e s pe c i a l l yhuma n s ys t e ms , i ti sdi fi c ul t ,da nge r ous , une t hi c a l ,O rs i mpl yl mPOS S i bl et oc ond uc tt he Cha pt e r3 TheMo d e l i ngPr oc e s s 103 r e a lwor l de xpe r i me nt st ha tmi ghtr e ve a lt hef la wsi nadyna mi chypot he s i s . I nt he ma J Or l y ofc t a s e s , youmus tc onduc tt hes ee xpe r i me nt si navi r t ua lwor l d. Todos o, youmus tmovef r omt hec onc e pt ua lr e a l mofdi a gr m st a oaf ul l ys pe c i f i e df or ma l mode l ,c ompl e t ewi t he qua t i ons , pa r a me t e r s , a ndi ni t i a lc ondi t i ons . Ac t ua l l y ,f o r ma l i z l ngaC OnC e Pt ua lmode lof t e nge ne r a t esi mpor t a nti ns i ght e ve nbe f o r ei ti sr e a dyt obes i mul a t e d. For ma l i z a ionhe t l psyo ut or e c ognl Z eVa gue c onc e pt sa ndr e s ol vec o nt r a di c t i onst ha twe ntunnot i c e dorundi s c us s e ddur i ngt he c onc e pt ua lpha s e.Fo r ma l i z a t i oni swhe r et her ea lt es tofyourunde r s t a ndi ngoc‑ c ur s :C omput e r sa c c e ptnoha ndwa vi nga r gume nt s . I nde e d,t hemos te xpe r i e nc e d mode l e r sr out i ne l ywr i t es omee qua t i onsa nde s t i ma t epa r a me t e r st hr oughoutt he mode l i ngpr oc e s s , e ve ni nt hee a r l i e s tpha s e sofpr obl e ma r t i c ul a t i ona ndc onc e p t ua l i z a t i on10f t e nwi t ht hec l i e nt s ‑a sawa yt or es ol vea mbi gul t ya ndt e s ti ni t i a l hypot hes e s .Sys t e m dyna mi c spr a c t i c ei nc l ude sal a r geva r i e t yoft e s t sonec a n a ppl ydur ingt hef om ul a t i ons t a get oi de nt i f yf la wsi npr opos e df or mul a t i onsa nd i mpr oveyourunde r s t a ndi ngoft hes ys t e m. ‑ 3. 5. 4 1 T esl i ng Tes t i ngbe gi nsa ss oo na syouwr i t et hef i r s te qua t i o n. Pa r toft es t i ng,Ofc our s e,i s c ompa r l ngt hes i mul a t e dbe ha vi oroft hemode lt ot hea c t ua lbe ha vi oroft hes ys ‑ t e m. Butt e s t l ngI nvol ve sf a rmor et ha nt her e pl i c a t i onofhi s t o r i c a lbe ha vi o r . Eve r y va r i a bl emus tc o r r e s pondt oame a ni ngf lc u onc e pti nt her e a lwor l d.Eve r ye qua ionmus t tbec he c ke df o rdi me ns i ona lc ons i s t e nc y( s oyo ua r e n' ta ddi nga ppl e sa nd or a nge s ) . Thes e ns i t i vi t yofmode lbe ha vi ora ndpol i c yr e c omme nda t i onsmus tbe a s s e s s e di nl i ghto ft heunc e r t a i nt yl na S S umpt l OnS , bot hpa r a me t r i ca nds t r uc t ur a l . Mode l smus tbet es t e dunde re xt r e mec ondi t i ons ,c ondi t i onst ha tma yne ve r ha vebe e nobs e r ve di nt her e a lwor l d.Wha tha ppe nst ot heGDPofas i mul a t e d e c onomyi fyous udde nl yr e duc ee ne r gys uppl i e st oz e r o?Wha tha ppe nsi namode l ofa na ut oma ke ri fyo ur a i s et hepr l C eOfi t sc a r sbyaf a c t orofonebi l l i on?Wha t ha ppe nsi fyous udde nl yI nc r e a s ede a l e ri nve nt o r i e sbyl OOO%?Eve nt hought hes e c ondi t i onsha vene ve ra ndc oul dne ve rbeobs e r ve d,t he r ei snodoubta boutwha t t hebe ha vi oroft hes ys t e mmus tbe: Wi t houte ne r gy,t heGDPofamode r ne c on‑ omymus tf a l lne a r l yt oz e r o; wi t hapr l C eOnebi l l i ont i me shi ghe r , t hede ma ndf or t hef i r m' sc a r smus tf a l lt oz e r o; Wi t hahuges ur pl usofc a r sonde a l e rl ot s , pr oduc ‑ t i ons houl ds oonf a l lt oz e r obutca nnotbe c omene ga t i ve. Youmi ghti ma gi net ha t mode l swoul dne ve rf a i lt opa s ss uc hobvi oust e s t s , t ha tpr od uc t i onwi t houte ne r gy, de ma ndf o rgoodst ha tc os tmor et ha nt het ot a lwe a l t hofma nyna t i ons ,a ndne ga ‑ t i vepr oduc t i onwoul dne ve ra r i s e. Butyou' dbewr o ng. Ma nywi de l yus e dmode l s i ne c onom ic s , Ps yc hol ogy , ma na ge me nt , a ndot he rdi s c i pl i nesvi ol a t eba s i cl a wsof phys i c s , e ve nt ho ught he yma yr e pl i c a t ehi s t or i c a lbe ha vi orqui t ewe l l( S e es e c t i on 9. 3. 2a ndc ha pt e r21 ) . Ext r e mec ondi t i onst e s t s , a l ongwi t hot he rt e s t sofmode lbe ‑ ha vi or ,a r ec r i t i c a lt ool st odi s c ove rt hef la wsi nyourmode la nds e tt hes t a gef or i mpr ove dunde r s t a ndi ng. ‑ 3. 5. 5 Po‖Cy Desi gn and Eva一 uati on Onc eyoua ndt h ec l i e ntha vede ve l ope dc onf i de nc ei nt hes t r uc t ur ea ndbe ha vi or oft hemode l ,yo uc a nus ei tt odes i gna nde va l ua t epol i c i e sf ori mpr ove me nt . 104 P a r t IP e r s p e c t i v eandP r o c e s s Pol i c yde s i g ni smuc hmo r et ha nc ha ng l ngt heva l ue sofpa r a me t e r ss uc ha sat a x S , r a t eo rma r kupr a t i o. Po l i c yde s i g ni nc l ud e st hec r e a t i o nofe nt i r e l yne ws t r a t e g l e S t r uc t ur e s , a ndde c i s i onr ul e s . Si nc et hef e e d ba c ks t r uc t ur eo fas ys t e mde t e r mi ne s i t sdy na mi c s ,mos to ft het i mehi ghl e ve r a g epo l i c i e swi l li nvol vec ha ng l ngt he do mi na ntf e e d ba c kl oopsbyr e de s i gn l ngt hes t o c ka ndnows t uc r t ur e , e l i mi na t i ng t i med e l a ys , c ha ng l ngt hef lowa ndq ua l i t yo fi nf o r ma io t na va i l a bl ea tke yd e c i s i o n po l n t S , O rf u nda me n t a l l yr e i nve n t l ngt hed e c i s i o npr o c e s s e so ft hea c t o r si nt hes ys t e m. Ther o b us t ne s so fpo l i c i e sa ndt h e i rs e ns i t i vl yt t ounc e r t a i nt i e si nmod e lpa r a ‑ me t e r sa nds t r uc t ur emus tbea s s e s s e d,i nc l udi ngt he i rpe r f o r ma nc eunde rawi de r a ngeo fa l t e r na t i ves c e na r i os . Thei nt e r a c t i onso fdi f f e r e ntpol i c i e smus ta l s obe c o ns i de r e d: Be c a us er e a ls ys t e msa r ehi g hl yno nl i ne a r ,t hei mpa c to fc o mbi na t i o n pol i c i e si sus ua l l ynott hes um o ft he i ri mpa c t sa l o ne.Of t e npol i c i e si nt e r f e r e wi t ho nea no t he r ;s ome t i me st he yr e i nf o r c eo nea no t he ra ndge ne r a t es u bs t a nt i l a S yne r gl e S ・ ‑ 3】 6 SuMMARY Thi sc ha pt e rd e s c r i be dt hemod e l i ngp r o c e s s . Whi l et he r ea r ec e r t a i ns t e psa l l mo d‑ e l e r sgot hr o ug h,mode l i ngl Sno taC OO kboo kpr o c e d ur e . Ⅰ ti sf u nda me nt a l l yc r e ‑ , a t i ve. Att hes a met i me , mod e l i ngl Sad i s c i pl i ne d, s c i e nt i f i c , a ndr i go r o uspr oc e s s c ha l l e ngl ngt hemode l e ra ndc l i e nta te ve r ys t e pt os ur f a c ea ndt e s ta s s umpt l O nS , ga t he rda t a , a ndr e vi s et he i rmod e l s ‑bo t hf o r ma la ndme nt a l . Mode l i ngl Si t e r a t i ve.Noo nee ve rbui l tamode lbys t a r t l ngWi t hs t e p1a nd p r og r e s s l ngl nS e q ue nc et h r o ug hal i s to fa c t i vi t i e s ・ Mo de l i ngl SaC O nt i n ua l pr oc e s s o fi t e r a t i o na mongpr o bl e ma r t i c ul a t i on,hy po t he s i sge ne r a t i on,da t ac ol l e c t i o n, mod e lf o r mul a t i o n, t e s t i ng, a nda na l ys i s . The r ea r er e vi s i o nsa ndc ha ng e s , bl i nda l l 1 e ysa ndba c kt r a c k i ng. Ef f e c t i vemod e l i ngc o n t i nua l l yc yc l e sbe t we e ne x pe r i me n t s i nt hevi r t ua lwor l do ft hemode la nde x pe r i me nt sa ndda t ac ol l e c t i o ni nt her e a l wo r l d. Mode l smus tbec l e a r l yf oc us e do napur pos e・ Ne ve rbui l damod e lo fas ys ‑ t e m. Mod e l sa r es i mpl i f i c a t i o ns ; wi t ho utac l e a rpur pos e , yo uha venoba s i sf o re x‑ C l ud i nga nyt hi ngf r omyo urmod e la n dyo ure fo r ti sdoo me dt of a i l ur e . The r e f o r e t hemos ti mpo r t a nts t e pi nt hemo de l i ngpr oc e s si swo r ki ngwi t hyo urc l i e ntt oa r ‑ t i c ul a t et hepr o bl e m‑t her e a lpr o bl e m, no tt hes ympt omsoft hepr o bl e m, t hel a ト e s tc r i s i s ,o rt hemos tr e c e n tf a d. Ofc o ur s e ,a st hemode l i ngp r oc e s sl e a dsyo ut o de e pe ri ns i ght , yo urd e f i n i t i ona nds t a t e me ntoft hepr obl e mma yc ha nge . I nd e e d, s uc hr a di c a lr e f r a ml ngSa r eOf t e nt hemos ti mpo r t a nto ut c o meofmode l i ng. Thep ur pos eofmode l i ngl St Ohe l pt hec l i e nt ss ol vet hei rpr o bl e m. Tho ug ht he mode l i ngpr oc e s sof t e nc ha l l e nge st hec l i e nt s 'c onc e pt 1 0nOft hepr o bl e m,ul t i ‑ r n, you ma t e l y , i ft hec l i e ntpe r c e i ve st ha tyo u rmod e ldoe sno ta dd r e s st he i rc o nc e c a nha vel i t t l ei mpa c t . Themod e l e rmus tno tg r o wa t t a c he dt oamod e l , noma t t e r howe l e ga nto rho wmuc ht i meha sbe e ni nve s t e di ni t . I fi tdoe s n' the l pt hec l i e n t s s ol vet he i rpr o bl e m, i tne e dst ober e vi s e dun t i li tdoe s . Mo de l i ngt a ke spl a c ei na no r ga ni z a t i o na la nds o c i a lc on t e xt ・ Thes e t t i ngma y beabus i ne s sbutc a na l s obeag ove r nme n ta g e nc y , as c i e nt i f i cc o mmuni t y , aP ubl l i cpo l i c yde ba t e ,o ra nyo t he ro r ga n i z a t i o n. Mode l e r sa r ei n e vi t a bl yc a ug htu pl n Cha p t e r3 TheMo d e l i ngPr oc e s s 105 t hepo l i t i c so ft h ec ommu nl t ya ndpe r s o na l i t i e so fi t sme mbe r s . Mode l e r sr e q ul r e bo t hf i r s t ‑ r a t ea n a l yt i c a ls k i l l sa nde xc e l l e nti nt e r pe r s o na la ndpol i t i c a ls ki l l s . l y , mo d e l e r sha v ea ne t hi c a l r e s po ns i bi l i t yt opu r s uet hemod e l i ngpr oc e s s Fi na l wi t hr i go ra ndi n t e gr i t y. Thef a c tt ha tmo de l i ngl Se mbe dde di na no r ga ni z a t i ona l c o nt e x ta n ds ub j e c tt opol i t i c a lpr e s s ur e sdo e sno tr e l i e veyo uofyo urr e s po ns i bi l ‑ l t yt OC a r r yO uty ou rwo r kwi t ht hehi ghe s ts t a nda r dso fs c i e nt i f i ci nq ul r ya ndpr o‑ f e s s i o na lc onduc t .I fyourc l i e nti sno twi l l i ngt opur s uet hemode l i ngpr o c e s s ho ne s t l y , q ui ta n df i ndyo ur s e l fabe t t e rc l i e nt . St r ut , hi r ea ndBe ha v i o ro f eSys 患 e ms Dy 弧盈m 量 L , i k eal ls y s t e ms ,t hec ompl e xs ys t e mi sani nt e r l oc k i ngs t r u c t ur eo ff e e dbac k , l oo ps. .Thi sl oo ps t r uc t ur es ur r ou ndsal lde c i s i onspubl i corpr i v at e c o n s c i ou so ru nc on s c i ou s .Thepr oc e s s e so fma na ndna t ur e ,o fps y c hol o g yan d ph y s i c s ,o fme di c i neande n gi ne e r i n gal l f al lwi t hi nt hi ss t r uc t ur e . lJ a yW. F o r r e s t e r ,Ur b a nDy n a mi c s( 1 969) ,p.1 07, Thebe ha vi orofas ys t e ma r i s e sf r omi t ss t r uc t ur e . Tha ts t r u c t ur ec o ns i s t soft he f e e d ba c kl oo ps ,s t oc ksa ndmows ,a ndno nl i ne a r i t i e sc r e a t e dbyt hei nt e r a c t i o nof t hephys i c a la ndi ns t i t ut i ona ls t r uc t u r eoft hes ys t e m wi t ht hede c i s i on一 ma ki ng p r o c e s s e so ft hea g e nt sa c t l ngWi t hi ni t ・ Thi sc ha pt e rpr o vi de sa no ve r v i e wo fd y‑ na mi c sf o c us l ngOnt her e l a t i ons hi pbe t we e ns t r u c t ur ea ndbe ha vi o r .Theba s i c mode so fbe ha v i o ri ndyna mi cs ys t e msa r ei de nt i f i e da l o ngwi t ht hef e e d ba c k s t uc r t ur e sg e ne r a t i ngt he m. The s emod e si n c l ud eg r owt h, c r e a t e dbypos i t i vef e e d‑ ba c k;goa ls e e k i ng,c r e a t e dbyne ga iv t ef e e d ba c k;a ndos c i i l a t i ons( i nc l ud i ng da mpe dos c i l l a t i ons ,l i mi tc yc l e s ,a ndc ha os ) ,C r e a t e dbyne ga t i vef e e d ba c kwi t h t i med e l a ys . Mo r ec o mpl e xmod e ss uc ha sS‑ S ha pe dg r o wt ha ndo ve r s hoota ndc ol ‑ l a ps ea r i s ef r o mt heno nl i ne a ri n t e r a c t i o no ft he s eba s i cs t uc r t u r e s . Thec ha pt e ra l s o e fer e nc emode st oc a pt ur ed yna mi cbe ha vi o ra ndcaus al i l l us t r a t e st hec o n c e ptofr l oo pdi agr amsa same t hodt or e pr e s e n tf e e d ba c ks t uc r t ur e. 107 108 4. 1 P a r t IP e r s p e c t i v ea n dP r o c e s s FuNDAMENTALMoDESOFDYNAMI C BEHAV1 0R Cha ng et a kesma nyf o r ms ,a ndt heva r i e t yo fdyna mi c sa r o undusi sa s t o undi ng. Yo umi g hti ma g l net ha tt he r emus tbeac o r r e s po nd i ngl yh ugeva r i e t yo fdi fe r e nt f e e d ba c ks t r uc t u r e st oa c c o u ntf o rs uc har i c ha r r a yofdyna mi c s . I nf a c t , mos tdy‑ na mi c sa r ei ns t a nc e so faf a i r l ys ma l lnumbe rofdi s t i nc tpa t t e nso r fbe ha v i o r , s uc h a se xpo ne n t i a lg r o wt ho ros c i l l a t i on. Fi g ur e4‑ 1s howst hemos tc o mmo nmo de sof be ha v i o r . Themos tf u nda me nt a lmode sofbe ha vi o ra r ee x po ne nt i a lg r o wt h,g oa ls e e k‑ 1 ng,a ndos c i l l a t i on.Ea c ho ft he s ei sge ne r a t e dbyas i mpl ef T e e d ba c ks t r uc t ur e: g r owt ha r i s e sf r o mpos i t i v ef e e d ba c k, goa ls e e ki nga r i s e sf r o mne ga t i vef e e d ba c k, a ndos c i l l a t i ona r i s e sf r o mn e ga t i vef e e d ba c kwi t ht i mede l a ysi nt hel oo p. Ot he r c ommonmod e so fbe ha vi o r ,i nc l ud i ngS‑ s ha pe dg r owt h,S‑ S ha pe dg r owt hwi t h o ve r s hoota ndos c i l l a t i o n,a ndo ve r s hoo ta ndc o l l a ps e ,a r i s ef r omno nl i ne a ri nt e r ‑ a c t i o nsoft hef unda me nt a lf e e d ba c ks t r uc t ur e s . 4t lE I Exponent i a;Gr owt h Ex pone nt i lg a r o wt ha r i s e sf r o mpos i ive( t s e l f ‑ r e i nf o r c i ng)f e e dba c k・ Thel a r g e rt he q ua nt l t y , t heg r e a t e ri t sne t i nc r e a s e , f ur t he ra ug me nt l ngt heq ua nt l ya t ndl e a d i ngt o e ve r ‑ f a s t e rgr owt h( Fi g ur e41 2) . Thepa r a d i gmc a s e sa r ec o mpo un di nt e r e s ta ndt he g r owt ho fpopul a t i o ns . Themo r emo ne yyouha vei nve s t e d, t hemo r ei nt e r e s tyo u e a r n, s ot hegr e a t e ryo urba l a nc ea ndt heg r e a t e rs t i l l t hene xti nt e r e s t pa y me ntwi l l be. Thel a r g e rt hepo pul a t i o n, t heb i g ge rt hene tbi r t hr a t e , a ddi ngt ot hepo pul a t i o n l . Pur ee x‑ a nde ve nt ua l l yl e a di ngt os t i l lmo r ebi r t hs , i na ne ve r ‑ a c c e l e r a t i ngS pi r a Pone n t i a lg r owt hha st her e ma r ka bl epr o pe r t yt ha tt hedoubl i ngt i mei sc o ns t a nt : t hes t a t eoft hes ys t e m do ubl e si naf i xe dpe r i odoft i me ,noma t t e rho wl a r ge. FJ GURE4‑ 1 Commonmodesofbeh a vi ori nd yn ami cs y s t ems Exponent i al Gr owt h Over shootandCoH aps e ノ ′ \ Ti me‑ 1 09 Ch a p t e r4 S t r u c t u r ea n dBe h a v i orofDy n a mi cS y s t e ms I tt a kest hes a mel e ngt hoft i met ogr owf r o m oneuni tt ot woa si tdoest og r ow f r omonemi l l i o nt ot womi l l i on. Thi spr o pe r t yl Sadi r e c tc ons e que nc eofpos i t i ve f e e dba c k:t hene ti nc r ea s er a t ede pe ndsont hes i z eoft hes t a t eoft hes ys t e m( S e e c ha pt e r8) .Pos i t i vef e e dba c kne e dnota l wa ysge ne r a t egr owt h.I tc a na ls oc r e a t e s e l f ‑ r e i nf or c l ngde c l i ne, a swhe nadr o pl nS t oc kpr l C eSe r ode si nve s t orc onf i de nc e whi c hl e a dst omor es e l l i ng, l owe rpr l C eS ,a nds t i l ll owe rc onf i de nc e. Wha ta boutl i ne a rgr owt h?Li ne a rg r owt hi sa c t ua l l yqul t er a r e. Li nea rgr owt h r e qui r est ha tt he r ebenof e e dba c kf r omt hes t a t eoft hes ys t e mt ot hene ti nc r e a s e r a t e,be ca us et hene ti nc r ea s er e ma i nsc ons t a nte ve na st hes t a t eoft hes ys t e m c ha nges .Wha ta ppea r st obel i ne a rg r owt hi sof t e na c t ua l l ye xpone nt i a l ,but vi e we dove rat i meho r i z ont oos ho r tt oo bs e r vet hea c c e l e r a t i on. Fi gur e4‑ 3s howss omee xa mpl esofe xpo ne nt i a lgr owt h. Gr owt hi sne ve rpe r ‑ f e c t l ys moot h( d uet ova r i a t i onsi nt hef r a c t i ona lg r owt hr a t e s ,c yc l e s ,a ndpe r t ba t i ons ) ,buti nea c hc a s ee xpone nt i a lgr owt hi st hedomi na ntmodeofbe ha vi o r . Tho ug ht hedou bl i ngt i mesva r ywi de l y( f r oma bout40ye a r sf o rwor l dpopul a t i on t oa bout2yea r sf o rs e mi c onduc t orpe r f o ma nc e ) ,t hes es ys t e msa l le xhi bi tt he s a mee nor mo usa c c e l e r a t i onc a us e dbypos i t i vef e e dba c k. u r ‑ Pr ocessPoi nt :WhenaRat el sNotaRat e I ndyna mi cmo de l i ng,t het e r m" r a t e "ge ne r ll a yr e f e r st ot hea bs ol ut er a t eof c ha ngei naq ua nt l t y・ Thepo pul a t i ong r owt he xa mpl ea boves t a t es ,H t hel a r ge rt he FI GURE4 ‑ 2 Exponen t i algr owt h: S t r u c t ur eandbeh avi or Thecausall oo pdi agr am i nt hebo t t omhal f oft hef i gur eshowst h ef eedbacks t r u c t ur e t h atgener at esexponen t i al gr owt h. Ar r o ws i ndi c at et hedi r ec t i onofc aus al i nf l uen ces. Her e,St at eoft heSy s t emde t er mi nesNet l n cr eas eRat e( t he一 owerar r ow) ,andNet l n cr eas eRat eaddst oSt at eoft heSy s t em ( t heupperar r o w) . Si gn sa tar r owhea ds ( + or‑)i ndi ca t et hep ol ar i t yoft he r el at i on s hi p, Aposi t i v epol ar i t y ,i ndi ca t ed ncr eas ei nt he b y+,meansani i n depen dentvar i abl ec au s est he dependen tvar i abl et or i s eabovewha ti t woul dh avebeen( andadecr eas ec au s es adecr eas e) .Negat i vesi gns( s eeFi gur e 4‑ 4)me anani ncr eas e( decr eas e)i n t hei ndep enden tvar i abl ec aus est he dependen tvar i abl et odecr eas e( i ncr e as e) beyondwhati twoul dhavebeen.L oop i den t i f i er sshowt hepol ar i t yoft hel oop, ei t herpos i t i ve( s el f ‑ r ei n f or ci ng, denot ed byR)orn egat i ve( bal anci ng, denot ed byB; s eeFi gur e4‑ 4) . Chap t er5 di s cu s s escau s aHoopdi agr amsi ndep t h. I‑ ‑ i = ;=‑ I ‑ = : ‑ ‑ ‑ ‑ = =: ‑ s芯 O !t O6 6 L. 996L O96 L Sト6 L OL6 L 00 0 N OO9L OO e uo! )el ndod Pl J0 き OON L OO 寸 ・ a一 T 3DSB oT! L uaSuOa3ueL u Ot ad sNLOLIS taSu]. uO! Pun t2!tuOuOdxa l! itSeq ^Jn O. ( 966L )) 空 91 60「⁚aDueL uJ Ot ad j ossaooj doL Df m. 966L ・ 006L SきOuS laSu一.⊃謡 Ln皿 SnSuaO S ⊃ ' t uaSaJd・ 096L■SateLullSO SnO!Jt2^ 10 ^L e∈ i L J nS コ詔 Ln皿 SnSuaO S ⊃ ' 096LO二 Oud ‖ u PEndod P一 」0き 9 ・ 3一 lS n 0 ・l da凸 S ⊃ ■ S66L ・ 096L 川(寸66L) ut?!JnN E096L・0卜6L :S ⊃ aLn OSUl t S!lt2tS e ID !)0TS!H '0ト6 L ・ 986L: UO!1e一n dod uOSud tn IPV ssau! sn血 luaJLnO J 0 ^aN nS =tuaSaJ d・ 6N6L r dq9 一 ea正 .S ⊃ aLJ O SD一tS1 ! t 2 1S 一C3! J OISH ! i 6 N6LO 0! J d ‖d N9 一 t ! au JSaOJnOS S66 L t t 2 JaPaj Put Za l t 2 1 SS ・一 S^T 一 3 uV U!uj OuO3山10 neajn竺 )0 0 N JoIS! SuE u1 s 望 寸 ? 寸 u ttn 虹 J t 2 8人/ 令Z66LuOl . I l l . g N 寸 C O al doaduO‖! g ⊂) ⊂ 〉 L D ⊂) ‑ = 〉 CI X甘 353 d凸9 ‑t 2 at J Sn sa一 dL ut 2 XO⁚ L J t l V LO L6 1 e! 1 ueuOdx山 110 s Jossa30 Jdo J3! M I alu l 'd !LJU lad Sn uo! lt 2l ndod uOS! Jd aJ doad Put 2 SnOL l l 【 i】 F< ⊂l 0 ⊂〉 d! L J 〇/ SJ OI S! Sut 2 J ⊥uOM胴 可' O C O ⊂〉 O N Ch a p t e r 4 S t mc t u r ea n dBe h a v i o ro f Dy n a mi cS y s t e ms i ll popul a t i on, t heg r e a t e rt hebi r t hr a t e. "Thet e r m" bi r t hr a t e "he r er e f e r st ot henum‑ be rofpe opl ebo m pe rt i mepe r i od. Fore xa mpl e, t hebi r t hr a t ei nac l t yOfo nemi L l i onpe opl emi ghtbe20, 000pe opl epe ryea r .Of t e n,howe ve r ,t het e r m" r a t e "i s us e da ss hor t ha ndf ort hefr ac t i onalr a t eofc ha ngeofava r i a bl e. Fore xa mpl e, t he bi r t hr a t ei sof t e ni nt e r pr e t e da st henumbe rofbi r t hspe rye a rpe rt ho us a ndpe opl e ( a l s oknowna st hec r udebi r t hr a t e ) . Thec r udebi r t hr a t ei nt hec i y ofonemi t l l i on woul dbe20bi r t hspe rye a rpe rt hous a ndpe opl e ,or29 uye a r .Si mi l a r l y,wec om‑ monl ys pe a ko ft hei nt e r es tr a t eort heune mpl oyme ntr a t e.Thewo r dH r a t e "i n t he s ec a s e sa c t ua l l yme a ns。 r a t i o": t hei nt e r es tr a t ei st her a t i ooft hei nt e r e s tpa y一 me nt syoumus tma kee a c hpe r i odt ot hepr l nC l pa lout s t a ndi ng; t heune mpl oyme nt r a t ei st her a t i oo ft henumbe rofune mpl oye dwo r ke r st ot hel a bo rf o r c e. Youmus tc a r e f ul l ydi s t i ngui s hbe t we e na bs ol ut ea ndf r a c t i ona lr a t e sofc ha nge a ndbe t we e nr a t esofc ha ngea ndr a t i os .Se l e c tva r i a bl ena mest ha tmi ni mi z et he c ha nc ef orc on f us i on.Bes ur et oc he c kt heuni t sofme a s ur ef oryourr a t e s .The uni t sofme a s u r ef orr a t e soff lOwa r euni t s / t i mepe r i od;t heuni t sofme a s ur ef or f r a c t i ona lr a t eso ff lo wa r euni t spe runl tPe rt i mepe r i od‑ 1 / t i mepe r i ods . Fo re x‑ a mpl e,t hei nt e r e s tr a t eo nyo urc r e di tc a r di snot ,s a y,1 2%,but1 2%pe rye ar ;or , e qui va l e nt l y,1 %permont h( 0・ 1 2 / ye a rorO・ Ol / mont h) I Thee c onomydoe s n' tgr ow a t ,s a y,3. 5%, b uta taf r a c t i ona lr a t eof3. 5%/ ye a r 。 4. 1x 2 GoaESeeki ng Pos i t i vef e e dba c kl oopsge ne r a t egr owt h,a mpl i f y de vi a t i ons ,a ndr e i nf or c e cha nge.Nega t i v el oopss e e kba l a nc e ,e qui l i br i um,a nds t as i s .Ne ga t i vef e e d ba c k l oopsa c tt obr i ngt hes t a t eoft hes ys t e mi nl i newi t hagoa lo rde s i r e ds t a t e. The y c ount e r a c ta nyd i s t ur ba nc e st ha tmovet hes t a t eoft hes ys t e ma wa yf r omt hegoa l . Al lne ga t i vef e e dba c kl oopsha vet hes t r uc t ur es howni nFi gur e4‑ 4. Thes t a t eof FI GURE4 ‑ 4 Goal s eek i ng: s t r uc t ur eand behavi or + St at eoft he Syst em Goal ( Desi r ed St at eofSyst em) c r e e) D i sp a n c y o r r e c t i ve A c t i o n C 11 2 P a r t IP e r s p e c t i v ea n dP r oc e s s l . I ft he r ei sad i s c r e pa nc ybe t we e nt hede s i r e d t hes ys t e mi sc ompa r e dt ot hegoa a nda c t ua ls t a t e , c o 汀e C t i vea c t i o ni si ni t i a t e dt ob r i ngt hes t a t eoft hes ys t e m ba c k i nl i newi t ht heg oa l . Whe nyo ua r ehung r y , yo ue a t ,s a t i s f y i ngyo u rhunge r ; whe n t i r e d,yo us l e e p,r e s t o r l ngyoure ne r gya nda l e r t ne s s ・Whe naf i r m' si nve nt or y d r o psbe l o wt hes t o c kr e qui r e dt opr ovi degoods e r vi c ea nds e l e c t i o n,pr oduc t i on . i nc r e a s e su nt i li nve nt o r yl SOnc ea ga l nS uf f i c i e nt Eve r yne ga t i vel o o pl nC l ude sapr oc e s st oc o mpa r et hed e s i r e da nda c t ua lc o n di t i o nsa ndt a kec o r r e c t i vea c t i on.So me t i me st hede s i r e ds t a t eoft hes ys t e ma nd c o r r e c t i vea c t i o na r ee x pl i c i ta ndunde rt hec o nt r o lofade c i s i o nma ke r( e. g. ,t he d e s i r e dl e ve lo fi nv e n t o r y) . So me t i me st hegoa l i si mpl i c i ta ndno tu nde rc o ns c i o us c o nt r o l , O rund e rt hec o nt r o lo fhuma na g e nc ya ta l l . Thea mo un to fs l e e pyo une e d t of e e lwe l lr e s t e di saphys i o l og i c a lf a c t o rno tund e ryo u rc o ns c i o usc ont r o l ・ The e q ui l i br i u ms ur f a c et e mpe r a t ur eo ft hee a r t hde pe ndso nt hef luxofs o l a re ne r gy a ndt hec o nc e nt r a t i o no fg r e e nho us ega s e si nt hea t mo s phe r e, a mo ngot he rphys i ‑ c a lpa r a me t e r s . Andac upofc ofe ec ool svi ane ga t i vef e e d ba c kunt i li tr e a c he s r oo mt e mpe r a t ur e ・ I nmos tc a s e s , t her a t ea twhi c ht hes t a t eoft hes ys t e ma ppr oa c he si t sgoa ldi ‑ mi ni s he sa st hed i s c r e pa nc yf a l l s . Wedonotof t e no bs e r veac ons t a ntr a t eofa p‑ p r oa c ht ha ts ud de nl ys t o psJ us ta St hegoa ll sr e a c he d・ Theg r a d ua la ppr oa c ha r i s e s be c a us el a r g ega psbe t we e nde s i r e da nda c t ua ls t a t e st e ndt oge ne r a t el a r ger e ‑ s pons e s ,whi l es ma l lga pst e ndt oe l i c i ts ma l lr e s po ns e s ・ Thef lo w ofhe a tf r om you rc o fe ec u pt ot hea i ri nt her oo mi sl a r ge rwhe nt het e mpe r a t u r ega pbe t we e n t he mi sl a r gea ndd i mi ni s he sa st hega pf a l l s . Whe nc o f f e ea ndr oo mt e mpe r a t ur e s a r ee qua l , t he r ei snone the a tf lowbe t we e nt he m. Whe nt her e l a t i ons hi pbe t we e nt hes i z eo ft hega pa ndt hec or r e c t i vea c t i o ni s l i ne a r , t h er a t eo fa d j us t me nti se xa c t l ypr o po r t i o na lt ot hes i z eo ft hega pa ndt he x pone nt i alde c a y・ Ast hega pf a l l s ,s ot oodo e s r e s ul t i ngg oa l‑ S e e k i ngbe ha vi o ri se t hea d j us t me n t r a t e . Andj us ta se x po ne nt i a lg r o wt hi sc ha r a c t e r i z e dbyi t sdou bl i ng ‑ fl l f e ‑t het i mei tt a ke sf or t i me , p ur ee x p? ne nt i a ld e c a yi sc ha r a c t e r i z e dbyi t shal ha l ft her e ma l nl ngga pt Obee l i mi na t e d( S e ec ha pt e r8 ) ・ Fi g u r e4‑ 5s howse xa mpl e sofgoa l ‑ s e e ki ngbe ha vi o r . Th et o pl e f t pa ne ls ho ws t her a t eo fde f e c tge ne r a t i o ni nt hewa f e rf a br i c a t i o npr oc e s sofama j o rS e mi ‑ c ond uc t o rma nuf a c t u r e r .I n1 98 7,t hec ompa nybe ga napr oc e s si mpr ov e me nt pr og r a mus i ngpr i n c i pl e sofTot a lQua l i t yMa na ge me nt ・ Thegoa loft hepr og r a m wa sz e r od e f e c t s . I n4ye a r st hede f e c tr a t ede c l i ne df r om 1 50 0ppm t oa bo ut1 50 p pm.No t et ha ta st hed e f e c tr a t ef e l l ,t her a t eofi mpr ove me ntde c l i ne d. Thet o p ig r htpa ne ls ho wst hea ve r a gel oa df a c t o r( u pt i me )f o rt woFi nni s hnuc l e a rpowe r pl a nt ss t a r t e du pi n1 9 78.Thef r a c t i onoft heye a rt hepl a nt so pe r a t e di nc r e a s e d r a pi dl ya tf i r s t , t he nmo r es l owl y , unt i lama xi mumo fa bo ut9 4%wa sr e a c he d. The bot t o ml e f tpa ne ls howst hes ha r eofa l la dve r t i s i ngdo l l a r ss pe nto nt e l e vi s i oni n t heUS. Gr owt hwa sr a pi di nt he1 950S , butr e a c he daf a i r l ys t e a dyl e ve lo fa bout 2 0‑ 25%by1 98 0. Thebot t omr i g ht pa ne ls howst her o ug hl ye xpone nt i a lde c l i nei n a ut o mo bi l e ‑ r e l a t e df a t a l i t i esi nt heUSpe r1 00mi l l i onv e hi c l emi l e sdr i ve n. De ‑ s pi t et h es u bs t a nt i a lde c l i nei nde a t hr i s kpe rmi l e , t hen umbe ro fmi l e sd r i ve nha s g r o wne x po ne nt i a l l y ,S ot het o t a lnumbe rki l l e do nt her oa dse a c hye a rha sf luc t u‑ a t e dbe t we e na bo ut3 0a nd5 0t ho us a nds i nc et he1 93 0S . l .( ( 4766L )ut3unと ⁚ 8u一SItJa^PV 096L O66 L 896 L ‑‑1 ‑ L 寸96 L L u J O96 S⊃ 0 寸6L N9 6 L . \ O N6 L . . S⊃ OS6L L SN ON ∽ 0i . S 0 S O!lS!tt21S It= U! J OIS!H :Sa!l!1凛 2 j Bu!uuada ∝ ' ut2uJLatS I.S3 t①1aC]J SaDJnO S ト96L u佃L uち と P uで 9ト6 I. 996 L aL l t L O1 0tZJ1SqV leO!tS! 1 t = l S' S ⊃ aLl1O 4 e9 6L . 八 \ r ′く 1 7 ニV ‑0 aJt 2L JS uO! S! ^al a ! 010 nPuOO E aS JI sn' 6u!S!lLa^PV N66 L dajtenuuv :Jo1 3ej Pt201.i ( L66 こ f b66LE put 2 I ⊆jh ( ○ > 1)^O t2 0 .1 ^ uaPnnS≡ 091 4 0 亡O 096L 996 、‑ ・ ・ ‑1 1 、. . . . atE ! t ]I Ua‑a凸 uO! leU! J l qt 2j 9・守 山t ]n 9 広 H al ! ≡ a一 U! L J a^ Jad sa! )! ] t 2 1t 2 j O! I IE Z J1 N66 L Il 1 J I 0 0ej Pt =01 tut 2l d J l eaP nN saI dL ueX① ‖ 」 0! ^eL l a q6u葛 aS・l eO9 ( ul dd)al et 〇a l aq % ⊂l ⊂l 的 ⊂) ( ⊃ く ) ▼ yI T N N 可■ SaHM ∂P ! L I a^ uO! l l ! M OOI . / SL l l eaq aBe J a ^Ⅴ ol こ 柁∃ Pt ZOl ̀J % o O t D O N O 0 C O o ⊂ : 〉 ■ l ‑ 113 114 P a r t I P e r s p e c t i v ea n dP r o c e s s 4. 1. 3 0sc‖at i on Os c i l l a t i o ni st het hi r df unda me nt a lmodeo fbe ha vi o ro bs e r ve di ndyna mi cs ys t e ms .Li kegoa l ‑ s e e ki ngbe ha vi or ,os c i l l a t i o nsa r ec a us e dbyne ga t i vef e e d ba c k l oo ps . Thes t a t eo ft hes ys t e mi sc ompa r e dt oi t sg oa l ,a ndc o r r e c t i vea c t i o nsa r e t a ke nt oe l i mi na t ea n yd i s c r e pa nc i e s . I na nos c i l l a t o r ys ys t e m, t hes t a t eo ft hes ys t e mc o ns t a n t l yo ve r s hoo t si t sgoa lo re q ui l i b r i ums t a t e , r e ve r s e s , t he nunde r s hoo t s , a n ds oo n・ Theov e r s hoo t l nga r i s e sf r omt hep r e s e nc eo fs i g ni f i c a ntt i mede l a ysi n t hen e g a t i vel oo p. Thet i mede l a ysc a us ec o r r e c t i vea c t i o nst oc o nt i nuee ve na f t e r t hes t a t eoft hes ys t e mr e a c he si t sg oa l , f o r c i ngt hes ys t e mt oa d j us tt oomuc h, a nd t r i g ge r i ngane wc or r e c t i o ni nt heo ppos i t ed i r e c t i o n( Fi g ur e4‑ 6) ・ Os c i l l a t i o nsa r ea mo ngt hemos tc ommo nmo d e so fbe ha vi o ri ndyna mi cs ys ‑ t e ms . The r ea r ema nyt y pe sofos c i l l a t i o n, i nc l ud i n gda mpe dos c i l l a t i ons , l i mi tc y‑ c l e s , a ndc ha os( S e es e c t i o n4. 3. 3 ) . Ea c hva r i a nti sc a us e dbyapa r t i c ul a rf e e d ba c k s t r uc t ur ea nds e tofpa r a me t e r sde t e r mi nl ngt hes t r e ng t hsoft hel oo psa ndt he l e ng t hso ft hede l a ys . Bute ve r yt y peofos c i l l a t i o nha s , a ti t sc o r e , ane ga t i vef e e d‑ ba c kl o o pwi t hde l a ys . Os c i l l a t i o nsc a na r i s ei ft he r ei sas i g ni f i c a ntd e l a yl na nyPa r tO ft hene ga t i ve l o o p. Ass ho wni nFi g ur e4‑ 6, t he r ema ybede l a ysi na n yo ft hei nf o ‑a t i o nl i n ks ma ki ngu pt hel oo p.The r ema ybede l a ysi npe r c e i vl ngt hes t a t eo ft hes ys t e m c a us e dbyt heme a s u r e me nta ndr e po r t l ngS ys t e m. The r ema ybed e l a ysi ni ni t i a t ‑ 1 ngc o r r e c t i vea c t i onsa f t e rt hedi s c r e pa nc yl SPe r c e i ve dd uet ot het i mer e q ui r e d ‑ ‑ FI GURE4 ‑ 6 0s c i H a t i on: s t r u c t ur eand beh a vi or Del a y sc anexi s t i nan yo Hhe c au s aHJ ‑ nk si na nega t i v ef eedb ack l oop. Os c i H a t i on c anoc c uri ft h er e ar edel a ysi na t J eas ton eo f t h e一 i nk si na nega t i v el oop. Measur ement , Re por t i ng,and Per ce pt i on Del ays Ac t i o n De l a ys\ 阜 互cr + St at eott he Sys t em / G.a日 ( Desi r ed St a t eotSys t em) ) Di s epanc y Cor r ec t i ve Ac t j on \ 孟e dc Tf ; i s n t ̲ r At i ' zf na g nd Del ays Ch a p t e r4 S t uc r t u r ea n dBe h a v i o ro fDy n a mi cS ys t e ms 11 5 t or ea c hade c i s i on. Andt he r ema ybedel a ysbe t we ent hei ni t i a t i onofacor r ec t i ve a c t i ona ndi t se f f e c tont hes t a t eoft hes ys t e m. I tt a kest i mef oracompa nyt omea‑ s ur ea ndr e por ti nve nt or yl eve l s ,t i mef orma na ge me ntt omee ta nddec i dehow muc ht opr oduc e,a ndmor et i mewhi l er a wma t e r i a l spr oc ur e me nt , t hel a borf or c e, a ndot he rnee de dr es our c esr es pondt ot henewpr oduc t i ons chedul e.Suf f i ci e nt l y l ongdel a ysa ta nyoneoft hes epol nt SCOul dca us ei nve nt or yt oos c i l l a t e. Fi gur e4‑ 3s howe dr e a lGDPi nt heUS. Thedomi na ntmodeofbe ha vi ori nt he da t ai se xpone nt i a lgr owt h. Butt hegr owt hi snots moot h Out putf luc t ua t esa r ound t hegr owt ht r e nd.Ⅰ nt het oppa ne lofFi gur e4‑ 7t hes eos c i l l a t i onsa r er e vea l e dby de t r e ndi ngt heGDPda t a( r e movi ngt hebes tf i te xpone nt i a lf unc t i on) . Af t e rt hee x‑ pone nt i a lgr owt hi sr e moved,t hebus i nes sc yc l ei scl ea r l yvi s i bl easaf luct ua t i on a ve r a gl nga bout5% i na mpl i t udea ndwi t ha na ve r agepe r i odofa bout4yea r s . A l onge ra ndl a r ge rf luc t ua t i oni nr ea lpr oduc t i oni sa l s oa ppa r e nt , Wi t hpe a ksr e l a t i ve t ot r e nda r ound1 91 0a nd1 970‑ t hes o‑ c a l l ede conomi cl ongwa ve・ lThebot t om pa ne l sofFi gur e4‑ 7s howt woc r i t i ca lbus i nes sc yc l ei ndi ca t or s ‑ ca pa c i t yut i l i za‑ t i oni nt heUSma nuf a c t ur i ngS e c t ora ndt hec i vi l i a nune mpl oyme ntr a t e. Thea m‑ pl i t udeoft hebus i nes sc yc l ei nt hes ei mpor t a ntva r i a bl esi squi t el a r ge. Ut il i za t i on ypi t ca l l yf luc t ua t es1 5poi nt sf r om pea kt ot r ough( nea r l y20% ofi t sa ve r a ge va l ue ) ,whi l eune mpl oyme ntdur i ngt hepos t wa rpe r i odi nt heUShasr a nge df r om unde r3% t one a r l yIl 啄 oft hel a borf or c e,wi t hmuc hhi ghe rva l uesi nEur ope. Not et ha tt hebus i nes sc yc l e( a ndmos tr ea lwor l dos c i l l a t i ons )i snotpe r f e c t l y r egul a r . Yous houl dnote xpe c ti tt obe. Ma nype opl et hi nkac yc l emus tbeaspr e‑ di ct a bl east heda wn,asr egul a rast heor bi t soft hepl a ne t s ,a ss moot ha nds ym met r i cast hes wl ngOfape ndul um cl oc k.Butt hes epa r a di gmsofpe r i odi c i t ya r e s pec i a ls ys t e ms . Thepl a ne t si nt e r a c tma i nl ywi t ht hes una ndonl ywea kl ywi t hone 2Ap e ndul um c l oc khasbee nca r e f ul l ydes i gne dt oge ne r a t ear egul a rmo‑ a not he r ・ t i onbyi s ol a t i ngI t sC OmPOne nt Sf r om t hee nvi r onme nt ・ Bi ol ogi ca l ,s oci a l , a ndec o‑ nomi cs ys t e ms ,i nc ont r as t ,i nvol vehugenumbe r sofi nt e r a c t i onsa mongt i ght l y coupl e del e me nt s .The ya r econt i nuous l ybomba r dedbype r t ur ba t i onst ha tca us e t hei rmot i ont obes ome wha ti r r egul a r ,a( us ua l l ynonl i nea r )c ombi na t i onoft hei r e ndoge nousdyna mi csa ndt hes ee xogenouss hoc ks( S ees e c t i on4・ 3・ 2) ・ 一 l Th el o n gwa v e , o rKo n d r at i e vc y c l e , h a sa na v e r a g ep e r i o do fa b o u t 6 0y e a r sa n d , a ss e e ni nt he d at a , a na mpl i t u d emu c hl a r g e rt ha nt hes h o r トt e r mb u s i n e s sc y c l e ・ S t e r ma n( 1 9 8 6 )a n dForr e s t e r ( 1 9 77 ,1 9 8 3 )p r e s e n t t h e o r ya n de v i d e n c ef o rt h ee x i s t e n c ea n dfe e d b a c ks t r u c t u r eg e n e r a t i n gt h e l o n g†a v e ・ S t e ma n( 1 9 8 5 b )p r e s e n t sas i mp l emo d e l o ft h el o n gwa v e ;S t e r ma n1 9 8 9 ar e p o r t sa n e x p e . r l me n t lt a e s t o ft h emo d e l , ndS a t e r ma n( 1 9 8 9 C )s h o wst ha t m. nyo a ft h ed e c i s i o nr u l e sc h a r a c ‑ t e r l Z l n gh u ma ns u b j e c t si nt h ee x p e r i me n tg e n e r a t ec h a o t i cd y n a ml C S l 2A c t ua 1 1 y , t h ea p p a r e n t r e g u l a r l t yO ft h es o l a rs y s t e mi si l l t l S O r y ・ Th el e n g t ho ft h ed a yi si n c r e a s ‑ 1 n ga St i d la a n df r l C t i o n lf a o r c e sd i s s i p a t et h ee a r t h' sr o t a t i o n a len e r g y ・ Re c e n t r e s e a r c hs h o wst h a t t h eo r b i t so fmo s t o ft h ep l a n e t sa r ec h a o t i ca n dt h a t c h a o t i cr e s o n a n c e sa mo n gt h ep l a n e t sc a nh u r l me t e o r i t e sa n da s t e r o i d sf ro md i s t a n to r b i t si n t ot r a j e c t o r i e st h a t c r o s st h ee rt a h' so r b i t , p e r h a psa c c o u n t i n gf o rt h ei mp a c t sn o wb e l i e v e dt oha v ec a u s e dt hema j o re x t i n c t i o n s ・ I t i so n l yo u rs h o r t ( b y h e a v e n l ys t a n d a r d s )r e c o r do fo bs e r v a t i o n st h a tc a us e su st op e r c e i v e也es o l a rs y s t e mt ob es t a b l e a n dp r e d i c t a b l e . P e t e r s o n( 1 9 9 3 )p r o v i d e sa ne x c e l l e n t n o n t e c h n i c a l t r e a t me n to fc h a o t i cd y n a mi c s i nt h es o l a rs y s t e m; Di a c ua n dHo l me s( 1 9 9 6 )c o v e rt h eo r やn so fc h a o si nt h e o r i e so fc el e s t i a l me ‑ c h a n i c s . J a c kWi s d o mo fMI Tp i o n e e r e dc o mp u t e rs i mu l a t l O n St h a t r e v e a l e dt h ec h a o t i cc h a r a c t er o ft hes o l a rs y s t e m( s e eWi s d o m1 9 8 7f o rar e v i e w) . S e es e c t i o n4. 3 . 3f o rmo r eo nc h a o s . ‑ 116 uS RealGOP Devi at i onf r om Tr end J 0 0 1u10と uO 葛 t =J I) Pua d. ^a 凸 T op:De vi at i on ofr ea一 GDP f r omL ong‑ t er m expon en t i a=r end. 4 0 ( uo葛 FI GURE4 ‑ 7 0s cHat i on: ex ampl es Th ebusi nes s c y cl el nt he Uni t edSt at es. Pa r tI P e r s p e c t i v ea n dP r o c e s s MI ' ddl e:Capac i t y u t i l i z at i on. Bot t om:Ci vi l i an t . unempl oymen 1850 95 1900 1950 2000 Capaci t y Ut i l i zat i on.US Manuf act ur i ng 90 85 80 75 70 1945 1955 1965 1975 1985 1995 US Unempl oymentRat e 12 10 8 ㌔ 6 4 2 0 1945 1955 1965 1975 1985 1995 Sour ce:H i s t o r i c a l S t a t l S t i c so f t h eUn l t e dS t a t e s , USBu r e a uo f E c o n o mi cAn a l y s I S . 4. 1. 4 Pr ocessPoi nt Thec onne c t i onbe t we e ns t uc r t ur ea ndbe ha vi orpr ovi desaus e ulhe f ur i s t i cf o rt he c onc e pt ua l i z a t i onpr oc e s s ・ Anyt l meyouO bs e r vee xpone nt i a lgr owt hi nava r i a bl e , youknowt he r ei sa tl e a s tonepos i t i vef e e dba c ki nwhi c ht heva r i a bl esofi nt e r e s t pa r t i c i pa t e( a ndpos s i bl ymor e ) .The r ewi l l ,ofc our s e,bema nyne ga t i vel oo ps pr e s e nta swe l l ・ Howe ve r , i ft hes ys t e mi se xhi bi t i nge xpone nt i a lgr owt h, t he nyou knowt ha tpos i t i vel oopsa r edomi na nt( a tl e a s tdur i ngt her e gi mei nwhi c hg r owt h Ch a p t e r4 S t r u c t u r ea n dBe h a v i o ro fDy n a mi cS y s t e ms 117 oc c u r s ) . Yo uc a nt he ng ui det hed i s c us s i o na mongt hec l i e n tg r o upt owa r dt hei de n‑ t i f i c a t i o no fs e l f ‑ r e i n f o r c i ngpr oc e s s e s I Typi c a l l y , t heg r o upwi l l bea bl et oi d e nt if y ma nypos i t i v el o o psi nvol vi ngt heva r i a bl e sofi n t e r e s t . Ofc ou r s e ,i ti sno tpos s i ‑ bl et ot e l lwh i c ho ft he s ec a ndi da t el oo psa r ea c t i vea ndc o n t r i b ut i ngt ot hebe ha v i o r , no rt he i rr e l a t i ves t r e ng t hs , wi t ho utr e c o u r s et oda t aa nd / ormod e ls i mul a t i o ns . Butf oc us l ngO nt hec onne c t i onbe t we e ns t r uc t u r ea ndbe ha vi orhe l psge ne r a t e f ui r t f ulhy po t h e s e sa bo utt heke yl o o ps . Si mi l a r l y , a n yt l meyo uO bs e r vet heot he rc o r emod e so fbe ha vi o r , yo ui mme ‑ di a t e l yk no wwh a tt ype sofl oo pmus tbedo mi na n t , gui di ngyo uri ni t i a ls e a r c hf o r t hes t r uc t u r e sr e s po ns i bl e ・ Os c i l l a t i o n, f o re xa mpl e , mus tme a nt he r ei sa ni mpor t a ntne g a t i vef e e d ba c kwi t hs i g ni f i c a ntt i med e l a ys . Yo uc a nt he na s ka bo utt hede ‑ c i s i onp r o c e s s e sbywhi c ht heva r i a bl ei sr e g ul a t e da ndt het i mede l a ysi nt he pe r c e pt i ono ft h es t a t eoft hes ys t e m, i nt hede c i s i o npr oc e s s ,a ndi nt her e s pons e o ft hes ys t e mt ot hec o r r e c t i vea c t i o nsoft hede c i s i o nma ke r s . Ac a ve a t : Th i she ur i s t i che l psi nt hei d e n t i f i c a t i o noft hef e e d ba c ks t r uc t ur e s r e s po ns i bl ef o rt heo bs e r ve dbe ha vi o r . I na dd i t i o n, i ti se s s e nt i a lt oc ons i de rwha t s t r u c t u r e se xi s t b utha veno tye tpl a ye das i gni f i c a n tr o l ei nt hehi s t o r yo ft hes ys ‑ t e mo rl e f tat r a c ei nt hea va i l a bl eda t a. Ast hes ys t e me vo l ve st he s el a t e ntf e e d ba c ksma ybe c o medo mi na nt , d r a ma t i c a l l yc ha ng i ngt hed yna ic m s , s hi f t i ngt r e nds a ndpa t t e ms ,a n da l t e r i ngt hes ys t e m' sr e s pons et opo l i c i e s ・ I de nt i f yi ngpo t e nt i a l s hi f t si nl oo pd o mi na nc ea r i s i ngf r om l a t e nts t r uc t u r e si sava l ua bl ef unc t i ono f mod e l i n g. Tbi l l us t r a t e ,r e t ur nt ot hec a s eo fe xpo ne nt i a lg r o wt h・Nor e a lq ua nt l t yC a n g r owf o r e ve r .Eve n t ua l l y ,Oneormo r ene ga t i vel oo pswi l lbe c o medomi na nta s va r i o usl i it m st og r o wt ha r ea ppr oa c he d. I mme d i a t e l ya f t e ri de nt i f yi ngs o mepos i ‑ t i v el oo pspo t e n t i a l l yr e s po ns i bl ef o ro bs e r ve dg r o wt h, y o us ho ul da s k, Wha tne g‑ a t i vel oo psmi g h ts t o pt heg r owt h?Mos tpe o pl ec a ne a s i l yge ne r a t eawi der a nge ofpo t e n t i a ll i mi t sa ndc o ns t r a i nt st ot hegr o wt ho ft hes ys t e m・ I de nt i f yi ngt hepo‑ t e nt i lc a ons t r a i n t st og r owt hi sapowe r f ulwa yt oi d e n t i f ypos s i bl ef ut ur ebot te ne c ksa ndl i mi t s ,e ve ni ft he r ei snoe vi de nc eo fas l owdo wni nt heda t a. Aswi t h t hei de nt i f i c a t i o no fpos i t i vel oo ps ,e mpl r i c a li n ve s t i ga t i ona ndmode l i nga r er e ‑ qui r e dt ode t e r mi newhi c hne ga t i vel oo psa r es t r o ng e s t , wha tl i mi t st og r owt ht he y e l a xe do rt i ght e ne dbyot he rf e e d ba c kso r r e le f c t , a ndwh e t he rt hos el i it m scanber c t i on4. 2. 1 ) . t h r o ug hpol i c yi n t e r ve nt i ons( S e es e ‑ ‑ ‑ l ‑ E dent ≡ 晋 yE L ngFeedbackSt r uc官 ur ef i ' om Sysモ em Behav励 l・I d e nt i f yt h epos i iv t el oo psr e s po ns i bl ef o rt heg r o wt hi nt hee xa mpl e s s ho wni nFi gu r e4‑ 3. Ske t c hac a us a ll oo pd i a g r a mt oc a p t u r et hel oopsyo u i de nt i f y . I d e n t i f ya sma nyne ga t i vef e e d ba c kst ha tmi g htha l tg r o wt hi n t he s es ys t e msa syo uc a n. 2・I d e nt i f yt h ene ga t i vel oo pst ha tmi g htber e s po ns i bl ef o rt heg oa l ‑ s e e k i ng be ha v i o r ss ho wni nFi g ur e41 5. I de nt i f yt hes t a t eo ft hes ys t e m, t hegoa l , a n dt hec o r r e c ivea t c t i o n( S )f o re a c hc a s e . Wha tc o un t e r f o r c e smi ght pr e ve n tt h es t a t eoft hes ys t e mf r omr e a c hi ngl t Sg oa l ? 118 P a r t I P e r s p e c t i v ea n dP r o c e s s 3.I de nt i f yt hene ga t i vel oo psa ndt i mede l a yst ha tmi g htber e s po ns i bl ef o rt he os c i l l a t i onsi ne c o no mi ca fa i r si l l us t r a t e dbyFi gu r e4‑ 7. I de nt i f yt hes t a t e oft hes ys t e m, t hegoa l , t hec o r r e c t i vea c t i o n, a ndd e l a ys . Es t i ma t et he l e ng t hoft het i mede l a ysyo ui d e nt i f y . 4. 2 l NTERACTr ONSOFTHEFUNDAMENTALMoDES Thet h r e eba s i cmode sofbe ha v i o r ‑e x po ne nt i a ̲ Ig r owt h, goa ls e e ki ng,a ndos c i l l l a t i o n ‑a r ec a us e dbyt hr e eba s i cf e e d ba c ks t r u c t u r e s : pos i t i vef e e d ba c k, ne ga t i ve f e e d ba c k, a ndne ga t i vef T e e d ba c kwi t hde l a ys . Ot he r , mo r ec o mpl e xpa t t e nso r fbe ‑ ha vi o ra r i s et hr o ug ht henon l i ne a ri n t e r a c t i o no ft he s es t r uc t u r e swi t ho nea no t he r . 4E 2. 1 S‑ ShapedGr owt h Asd i s c us s e da bove , nor e a lq ua nt i t yc a ng r o w( o rde c l i ne )f o r e ve r : e ve nt ua l l yo ne o rmo r ec o ns t r a i nt sha l tt heg r owt h. Ac ommo nl yo bs e r ve dmodeofbe ha v i o ri n d y na mi cs ys t e msi sS‑ s ha pe dgr o wt h ‑g r o wt hi se x po ne nt i la a tf i r s t , butt he ng r a d‑ ua l l ys l o wsunt i lt hes t a t eoft hes ys t e mr e a c he sa ne q ui l i br i u ml e ve l . Thes ha peof t hec u r ver e s e mbl e sas t r e t c he d‑ o ut" S"( Fi g u r e4‑ 8 ) ・ Tbunde r s t a ndt hes t r uc t u r e und e r l yi ngS‑ S ha pe dgr owt hi ti she l pf ult ous et hee c ol ogi c a lc o nc e ptofc ar T yl n g c a paci y・Th t ec a r r yl ngC a Pa C l t yO fa nyha bi t a ti st henumbe rofo r ga ni s msofa pa r t i c ul a rt ypei tc a ns uppo r ta ndi sd e t e r mi ne dbyt her e s o ur c e sa va i l a bl ei nt he FIG URE 4‑ 8 S‑s ha p e dgr o wt h: st ru c t ur eand be h av ior S t a t e o f t h e //一、1私† Ne t Fr ac t i ona一 C . 百 ease Net cr at e h R 吋 p̲ W ‖r , Re s ou c e Ad equacy 普‑ \一 一一/ . 7 u Car r yi ng Capac i t y Ch a p t e r4 S t mc t ur ea n dBe h a v i o ro fDy n a mi cS y s t e ms 1 1 9 e nvi r onme nta n dt her es our c er e qui r e me nt sOft hepopul a t i on・Asapopul a t i on a ppr oa c he si t sc a r r yl ngCa pa C l t y,r e s our c e spe rC a pi t adi mi ni s ht he r e byr e duc i ng t hef r a c t i ona lne ti nc r ea s er a t eunt i lt he r ea r eJ us te noughr e s our c espe rc a pl t at O ba l a nc ebi r t hsa ndde a t hs ,a twhi c hpoi ntt hene ti nc r e a s er a t ei sz e r oa ndt hepop‑ ul a t i onr e a c hese q ui l i br i um. Anyr e a lqua nt l t yunde r gol nge xpone nt i a lgr owt hc a n bei nt e r pr e t e da sapopul a t i ondr a wl ngOnt her e s our c e si ni t se nvi r onme nt ・ Ast he c a pa c l t yOft hee nvi r onme nti sa ppr oa c he d, t hea de q ua c yoft her e qui r e dr e s our c es di i ni m s he s ,a ndt hef r a c t i ona l ne ti nc r e a s er a t emus tde c l i ne. Thes t a t eoft hes ys ‑ t e mc ont i nue st og r ow,buta tas l owe rr a t e, unt i lr e s our c esa r eJ us tS Ca r C ee nough t oha l tgr owt h. I nge ne r a l ,apopul a t i onma yde pe ndonma nyr e s our c es ,e a c hc r e ‑ a t l ngane ga t i vel oo pwhi c hmi ghtl i ml tgr OWt h・ Thec ons t r a i ntt ha ti smos tbi nd‑ i ngde t e r mi neswhi c hoft hene ga t i vel oopswi l lbemos ti nf lue nt i a la st hes t a t eof t hes ys t e mg r ows . Thec a r r yi n gc a pa c i yc t onc e pti ss ubt l ea ndc ompl e x. Whi l ei ti sa ppr opr i a t et o c ons i de rt hec a r r yl ngC a pa C l t yOfa ne nvi r onme ntt obec ons t a nti ns omes i t ua t i ons , i nge ne r a lt hec a r r yl ngC a pa C l t yOfa ne nvi r onme nti si nt i ma t e l yi nt e r t wi ne dwi t h t hee vol ut i ona n ddyna i csoft m hes pe c i esi ts uppo r t s . Wehuma nsa lt e rt hec a r r y‑ 1 ngC a pa C l t yOft hepl a ne ti nwa ysbot hi nt e nde da nduni nt e nde d,t h r ought hede ‑ ve l o pme ntoft e c hnol ogye na bl i nggr e a t e rut i l i z a t i o nofr e s o ur c es , t hr oughc ha nges i nc ul t ur a lpr a c t i c esa ndnor msf orc ons umpt l OnOfr e s our c espe rc a pl t a ,a nd t h r oughc ons umpt l On,de pl e t i on,a nde r os i onoft heva r i o usr es our c e suponwhi c h wede pe nd. Eve ns o‑ C a l l e dl owe rs pe c i esi nt e r a c twi t ht he i re nvi r onme ntt oa l t e r t hec a r r yi ngC a pa c i t y. Thec o‑ e vol ut i onoff lOwe r sa ndpol l i na t i ngI ns e c t sPe r mi t ‑ t e dg r e a t e rpopul a t i onde ns i t i esf orbot h.Si mi l a r l y,a l lbus i ne s s e sa ndor ga ni z a ‑ t i o nsgr ow i nt hec ont e xtofama r ke t ,s oc i e t y,a ndphys i c a le nvi r onme ntt ha t i mpos esl i mi t st ot he i rgr owt h. Aswi t hna t ur a lpopul a t i ons ,t hes el i mi t sca ni n‑ c r e a s eorde c r e a s e, bot he xoge nous l ya nd, mor ei mpor t a nt l y, e ndoge nous l y ,a st he or ga ni z a t i oni nt e r a c t swi t hi t sc us t ome r s ,c ompe t i t or s ,S uppl i e r s ,r e gul a t or s ,a nd ot he re nt i t i e si nt hes ys t e m. I nge ne r a l ,Onemus tmode lt heva r i ousr es our c e st ha t t oge t he rde t e r i net m hec a r r yl ngC a Pa C l t y‑f o ras pe c i e so ra nor ga ni z a t i on‑ a sa n e ndoge no use l e me ntoft hes ys t e m. Des pi t et hedyna mi cc ha r a c t e roft hec a r r yl ngCa pa C l t y,t he r ei s ,a ta nymo‑ me nt ,al i mi tt ot hes i z eoft hepopul a t i on( t hec ur r e ntc a r r yi ngc a pa c i t y) , wh i c h, i f e xc e e de d, c a us e st hepopul a t i ont of a l l . Fur t he r , t hec a r r yl ngC a Pa C l t yI t s e l fc a nnot gr owf or e ve r . Thel a wsoft he m odyna r i csdi m c t a t ea na bs ol ut el i mi tt ot hec a r r yi ng c a pa c l t yO ft hee a r t h, t hought he r ei snoa gr e e me nta mongs c hol a r sa st owha tt ha t l e ve li s ,howi ti sc ha ngi ng,Whe t he rpo pul a t i ons houl dg r owt ot heca r r yl ngCa ‑ pa c l t yOrbevol unt a r i l ys t a bi l i z e dbe l owi t ,O rwhe t he rapopul a t i ona sl a r gea st he c a r r yl ngC a Pa C l t ywoul de na bl ear ea s ona bl equa l i t yofl i f eorpr ovi deonl yt heba r e mi ni mumf o rs u bs i s t e nc e. 3 As ys t e m ge ne r a t esSI S ha pe dgr owt honl yi ft woc r i t i ca lc ondi t i onsa r eme t . Fi r s t ,t hene ga t i vel oo psmus tnoti nc l udea nys i gni f i c a ntt i mede l a ys( i ft he ydi d, t hes ys t e mwoul dove r s hoota ndos c i l l a t ea r oundt hec a r r yl ngCa pa C l t y;S e eS e c t i on 3 F o rg o o dd i s c u s s i o no ft h eu n c e r t a i n t yi nd e f i n i t i o n sa n de s t i ma t e so f hee t a r t h' sc a r r y l n g c a p a c i t y ,s e eCo h e n( 1 9 9 5 ) ・ F o rs y s t e md y n a mi c smo d e l si nwh i c ht h ec a r r y i n gc a p a c i t yo ft h e e a r t hi st r e a t e de n d o g e n o u s l ya n dd y n a mi c a l l y , S e eM e a d o ws , Me a d o ws , a n dRa n ° e r s( 1 9 9 2 ) ・ 120 Pa r t i Pe r s p e c t i v ea n dPr o c e s s FI GURE4 ・ 9 Gr ‑ owt hofSunf l ower s S‑ shapedgr owt h: exampl es 0 14 28 42 Days 56 70 84 US Cabl eTel evi si on Subscr i ber s 100 75 50 25 0 1950 100 1960 1970 1980 1990 2000 Adopt i onofCar di acPacemakerbyPhysi ci ans 0 L L ) !ZS ^L J dP sut2U 5 7 % 1960 1962 1964 1966 1968 1970 1972 u n f l o we r s : L o t k a( 1956, p . 74) ;C a b l eTV:Ku r i a n( 1994) , St a t l S t l C a l Ab s t r a c t o f t h eUS; Sour ce:S P a c e ma k e r a d o p t i o n : Ho me r( 1 983,1 987) . 4・ 21 2) ISecond,t hec a l Tyi ngca pa c i t ymus tbef i xe d.I tca nnotbec ons ume dbyt he gr owt hoft hepopul a t i on,l es tt hepopul a t i one xha us ti t sr es our cesa ndf or cei t s e l f i nt oe xt i nct i on,asapopul a t i onofyeas tcons umest hes uga ri nacas kofwi ne,ul ‑ t i ma t e l yca us i ngf e r me nt a iont t os t op( S e es e c t i on4. 23) . 1 21 Ch a p t e r4 S t r u c t ur ea n dBe h a v i orofDy n a mi cS y s t e ms Ake ya s pe c toft hes t r uc t ur ege ne r a t i ngS‑ S ha pe dgr owt hi st ha tt hei nt e r a c t i on oft hepos i t i vea ndne ga t i vel oopsmus tbenon li ne a r . Atf i r s t , whe nt hes t a t eoft he s ys t e mi ss ma l l r e l a t i vet ot her e s o ur c eba s e, t hel i I 血t st ogr owt ha r edi s t a nta ndt he pos i t i vel oopsdomi na t e. Ana ddi iona t luni ta dde dt ot hes t a t eoft hes ys t e mc on‑ t r i but esmor et ot hene ti nc r e a s er a t et ha ni tde c r e a s est hef r a c t i ona lne ti nc r e a s e r a t ebyr e duc i ngr es our c ea de qua c y. Thes t a t eoft hes ys t e m gr owse xpone nt i a l l y. Howe ve r ,a sadi r e c tc ons e que nc eoft ha tgr owt h,t hea de qua c yoft her e s our c e ba s ef a l l s . Ast hel i mi t st ogr owt ha r ea ppr oa c he d, t hene ga t i vel oopsgr ows t r o nge r a nds t r onge r , unt i lt he ybe gi nt odomi na t et hedyna mi c s I Thei nf le c t i onpoi nti nt he c ur v ei st hepol ntWhe r et hes ys t e m,t houghs t i l lgr owi ng,S hi f t sf r oma c c e l e r a t i on t ode c e l e r a t i on.Thei nf l e c t i onma r kst hepol nta tWhi c ht he r ei sas hi f ti nl oop domi na nc e. I ti st hepol nta tWhi c ha na ddi t i ona luni ta dde dt ot hes t a t eoft hes ys ‑ t e mr e duc e st hef r a c t i ona lne ti nc r e a s er a t emo r et ha ni ta ddst ot het ot a lpopul a t i on d r i vi ngt hegr owt h. Fi gur e4‑ 9s howss o mee xa mpl e sofSI S ha pe dgr owt h・ Whe t he rt hegr owt hof apl a nt ,t hedi f f us i onofane wpr oduc to rs e r vi c es uc ha sc a bl et e l e vi s i on,ort he a dopt i onofane wi de aort e c hnol ogyl i ket heca r di a cpa c e ma ke r ,gr owt ha l wa ys c onf r ont sl i mi t s . 4 . 2. 2 S‑ Sh 叩e dGr ow帥wi t hOv e r sh oo t SI S ha pe dgr owt hr e qul r eSt hene ga t i vef e e dba c kst ha tc ons t r a i ngr owt ht oa c t s wi f t l ya st hec a r r yl ngC a Pa C l t yl Sa PPr Oa C he d・Of t e n,howe ve r ,t he r ea r es i gni f i ‑ c a ntt i mede l a ysi nt he s ene ga t i vel oops . Ⅵmede l a ysi nt hene ga t i vel oopsl e a dt o t hepos s i bi l i t yt ha tt hes t a t eoft hes ys t e mwi l love r s hoota ndos c i l l a t ea r oundt he c a r r yi ngc a pa c i t y( Fi gur e4‑ 1 0) .Fi gur e41 1 ls howss omee xa mpl esofSI S ha pe d g r owt hwi t hove r s hoota ndos c i l l a t i on. FI GURE4‑ 10 S‑ Sh apedgr owt h wi t hover s hoot andos c i l l at i on: s t r u c t ur eand beh avi or + Ne tl hc r e a s e s t a t eoft h e Ra t e 阜R I sy s t em F‑ ・R・ a 控 ラ Fr ac t i on a一 Ne tl n cr ea s e 主ヲ \二 ノ・ R e sour c e Car r yl ng dequa . L capa ci t y . ,‑d Ra t e 1 22 Pa r tI Pe r s pe c t i v ea ndPr oc e s s FI GURE4 1 11 S‑ Shapedgr owt h 8 6 exampl es 4 2 ndod (suo≡ ! M )uO! tt 2r wi t hover shoot andosci l l at i on: Popul at i on ofLondon 1850 1900 1950 2000 US Al umi num Pr oduct i on 1900 1920 1940 1960 1980 2000 Sour c e. ' L on donPopu l a t i on :1 8 00 ‑ 1 9 6 0, Ml t C h e"( 1 97 5, p. 77 ) ;1 9 70 ‑ 1 9 9 5,1 9 9 7An n u al Ab s t r a c to f St a t i s t i c s , UKOf f l C ef orNa t i on al St a t i s t i c s . Al umF numPr o du c t i on: USGS; h t t p' / / mi n er al s. er . u s g s . g o v / mi n er al s / pu b s / C ommodl t y / l den輔yi ngt heLi mi t st oGr owt h W hatar et hel i mi t st ogr owt hf ort hepopul at i onofaci t yandt her i s ei npr oduct i on ofcommodi t i ess uchasal umi num?I dent i f yt henegat i vef eedbackst hathal tt he gr owt hi neachcas e.I dent i f yt het i medel aysr es pons i bl ef ort heover s hootand luct f uat i on. 4 4 I nUr banDynami c s ,Fo r r e s t e r( 1 969 )pr e s e nt samode lo fu r ba ng r o wt ha n ds t a g na t i o n,s ho w‑ i ngho wma nyu r ba nr e ne wa lpol i c i e sa c t ua ll ya c c e l e r a t et hed e c a yo ft hei nn e rc i t y ・ Ma s s( 1 9 75 ) , Swe e ne y , a ndA lf e l d( 1 9 75)e xt e nda nda ppl yt her e s u l t so fUr banDynami c s ,a nd ndSc a hr oe der banDynami c smo d e ls u i t a bl ef o r Al f e l da ndGr a ha m( 1 9 76 )bu i l du pas i mpl i f i e dve r s i ono ft heUr t e a c hi ng. 123 Ch a p t e r4 S t r u c t u r ea n dBe h a v i o r o f Dy n a mi cS y s t e ms 4 . 2 . 3 0V e r s h oo ta n dCoH a p s e Thes e c o ndc r i t i c a la s s umpt 1 0 nund e r l yi ngSI S ha pe dg r owt hi st ha tt hec a r r yl ng c a pa c l t yi sf i xe d・Of t e n,howe ve r ,t hea bi l i t yoft hee nvi r onme ntt os up po r ta , g r owl ngpo pul a t i o ni se r o de do rc o ns ume dbyt hepopul a t i o ni t s e l f ・ Fo re xa mpl e t hepopul a t i onofde e ri naf o r e s tc a ng r o ws ol a r get ha tt he yove r br o ws et he ve ge t a t i on, l e a d i ngt os t a r va t i o na ndap r e c l pl t O uSde c l i nei nt hepo pul a t i o n. Fi g u r e 4‑ 1 2S ho wst hef e e d ba c ks t r uc t u r ea ndt ypi c a lbe ha vi o rf T ort heove r s hoo ta ndc o l ‑ l a ps ebe ha vi o rmod e. Cons umpt l O nO re r os i o no ft hec a r r yi ngC a pa c i t ybyt hepo pul a t i o nc r e a t e sa s e c ondne ga t i vef e e d ba c kl i ml t l ngg r o wt h. Po pul a t i ongr owt hnowc ut sr e s o ur c e a d e q ua c yt wowa ys : byr e d uc i ngt her e s o u r c e sa va i l a bl epe rc a pl t aa ndbyr e d uc ‑ 1 ngt o t a lr e s ou r c e s . Asi nt heS‑ s ha pe dg r owt hc a s e ,whe nr es our c e sa r ei n i t i a l l y a mpl et hepos i t i veg r owt hl oo pdo mi na t e sa ndt hes t a t eoft hes ys t e mg r o wse x po‑ ne nt i a l l y. Asi tg r ows , r e s o u r c ea de q ua c yd r o ps ・ Thene ga t i vel oo psg r a d ua l l yga l a i ns t r e ng t h. Ats o mepo l nt ,t hene ti nc r e a s er a t ef a l l st oz e r o,a ndt hepo p ul a t i o n r e a c he si t sma x i mum・ Butunl i ket heS‑ s ha pe dgr owt hc a s e ,t hes ys t e md o e sno t r e a c he qui l i br i u m・ Wh e nt hepo pul a t i o nr e a c he si t spe a k, t her a t eofd e c l i neo ft he c a r r yi ngc a pa c i t yi sa ti t sma xi mum. Thec a r r yi ngc a pa c i t yc ont i nue st od r o p,r e ‑ s o ur c e spe rc a p i t af a l lf u r t he r , a ndt hene ti nc r e a s er a t eo ft hepo pul a t i o nbe c o me s ne ga t i ve. Thes t a t eoft hes ys t e mde c l i ne s . Eve na si tde c l i ne s , t her e ma i nl ngpo p‑ ul a t i o nc o nt i nue st oc o ns umet hec a r r y l ngC a pa C l t y , S Or e s our c e spe rC a pl t ar e ma i n FI GURE4 ‑ 12 Over sh oo tan d c o‖ ap s e: s t r u c t ur e an dbeh avi or e ‑ N t / 一 一 → 像 † I State ofthe s u mption/ r 1 0 S i onof Carryi n gCapaci t y +c on E \J e u FraL cti onal Cti .nal Ne th cr'ea s e Rate ・ F c Rr a ・t a 吋 h e L q 。 U , C e e s o u r c Ad equa c y 'te R R サ\ ̲メ‑ / 1 ト C a r r y‑ n g c i t y C apa ー/ / L . CB6I L ⁚ ^l 1 0gdtZ U O96 L L 6ト 6L トト 6 L Sト 6 L 9 e 6L L luaSaJ L 寸96 L 096 N96 L 1 O96 L O寸6 L 0 9 6L ON6 L Put 2 LP ! ] 2d ‖ ! jt 21 V ( . N66L ) Oee L 9ト6L . ト89 L ‖ q) C OPPt2H a ・ .D J nOS OO6L Oト6 L ・ oseqet] 2PL ut2aJISeteC ]E aC I ! J d LJSC3 ⁚SaD! J dLa^ニ S. ( C66L )uPL uJ al S d‑096 L 川sel t =1S Pal ! u⊃ aLl OSDuS!t2 t 1 S一 t?。!JOI S一 o Ls 67 u! JC VW ? uO! t CN Lt 2OP n N .aD!N aS Sa盲 LIS一 j e) l ! S Oト6 SaO! Jd Ja^ L .¢ 6L a u]2ピ Put2 'u!N 21j 'uき0品 O 66 I ﹄ C L・寸 uu n9 uO日日M lt 和 人/Su O⊥ 〇! J l l aM 996 L 0 00N i ド L J 31 C3 上UOPPeH PueI 6uu きaN ⁚ sal dL ut = Xa aSdp"oD Pue 1 00L J SLO^O 124 / ゝ1. 3t ?dt 2U Ja≧ Od Jt 2a一 UnN P一 )0き u!a6ut =L J Ul aN ^/ 仙M Put 2 SnOL l ⊥ ー M ' z o^ oJl/令 Jt 2∂ ⊂l ⊂ 〉 ⊂l e q てり 0 ▼ ‑ 0 寸 0 N 0 Ch a p t e r4 S t r u c t u r ea n dBe h a v i o ro f Dy n a mi cS y s t e ms 125 i ns uf f i c i e nta ndt hepopul a t i onke e psf a l l i ng. I ft he r ei snor e ge ne r a t i o noft hec a r r yi ngc a pa c i t y( i fi ti ss t r i c t l ynonr e ne wa bl e ) ,t hee qui l i br i um oft hes ys t e mi se x‑ t i nc t i on:a nyno nz e r opopul a t i onc ont i nue st oc ons umet her es our c eba s e,f or c i ng i tt oz e r o, a ndwi t hi t , t hepo pul a t i on. i ft hec a r r yl ngC a pa C l t yCa nber e ge ne r a t e dor s uppl e me nt e dwi t hr e ne wa bl er es our c e s ,anonz e r oe qui l i br i um c a nbes us t a i ne d・ Fi gur e4‑ 1 3s howss o mee xa mpl esofove r s hoota ndc ol l a ps e・ TheNe wEng‑ l a ndHa ddoc kf i s he r yc ol l a ps e dd uet oove r f i s hi ngofGe or gesBa nk,onc eoneof t hewor l d' Sr ic he s tf i s hi nga r e a s . Ove r f i s hi ngha sa l s os hutdownt heCa na d i a na nd USc odf i s he r y,a nds i mi l a rove r e xpl oi t a ioni t sc ommoni nf i s he r i esa r o undt he wo r l d・ 5Nuc l ea rpowe rc ons t r uc t i ongr oundt oaha l ti nt he1 98 0sa shi gh‑ l e ve l wa s t e ‑a ndpubl i cc o nc e r nove rs a f e t y‑a c c umul a t eda nda st hec os t sofnuc l ea r powe rs t e a di l ye s c a l a t e d. TheAt a r iCo r pora t i onwa st hel ea de roft hef i r s twa veof homea nda r ca d evi de oga me si nt hel a t e1 970S . Sa l e sdoubl e dr o ug hl ye ve r yye a r rom 1 f 976t hr o ugh1 98 2. Abr u pts a t ur a t i o noft hema r ke t ‑de pl e t i onoft hes t oc k ofpot e nt i lc a us t o me r s ‑l e dt oapr e c i pi t ousdr opi ns a l e sf r om $2bi l l i onpe ryea r i n1 982t o$1 00mi l l i onpe rye a ri n1 98 4,Thec ompa nyl os ta bo ut$600mi l l i on dur i ngt hec ol l a ps e.Si l ve re xpe r i e nc e dac l a s s i cs pe c ul a t i vebubbl ei nt hel a t e 1 970S , Wi t hpr i c e sr l S l ngt e nf ol di naye a r , t he nc ol l a ps i nge ve nmo r ePr e C I Pl t O uS l y. Thei nt e r pl a ybe t we e npo pul a t i ona ndca r r yi ngC a pa c i t yl e a di ngt oove r s hoot a ndc ol l a ps ei si l l us t r a t e di nFi g ur e4‑ 1 4,whi c hs howst hepopul a t i onofEa s t e r l s l a nd( Ra paNuii nt hel oc a ll a ngua ge )a ndamea s ur eoft heca r r yi ngca pa c i t yde ‑ r i ve d丘. ompol l e nc or esi ndi c a t l ngt hee xt e ntoft r e ec ove r ・ Ea s t e rI s l a n d,o neoft hemos tr e mot es pot sone a r t h, i sas ma l li s l a ndo fa bout 1 60km2l oca t e di nt hee a s t e r nPa c i f i c・ Ea s t e rI s l a ndi smos tf a mo usf ort hegi a nt s t ones t a t ues ,knowna smoa i ,t ha tdott hei s l a nd・Ra di oca r bonda t i ngput st hea r ‑ r i va loft hef i r s ts e t t l e r s , i nt r e pi ds a i l or sofPol yne s i a nor l gl n, a ta boutt heye a r400 a ndnotl a t e rt ha n690. Popul a t i oni se s t i ma t e dt oha vegr owns l owl yunt i la bout 1 1 00,whe ngr o wt ha c c e l e r a t e ddr a ma t i c a l l y,pe r ha psdoubl i nga boute ve r yc e n‑ t ur y,unt i la boutt heye a r1 400.Pol l e nc o unt sf r om s oi lc or esa ndot he rr e c or ds s howt ha tpr i ort Ot hea l Ti va loft hef i r s thuma ns , Ea s t e rI s l a ndwa sl us hl yf or e s t e d a nds uppor t e dadi ve r s es e toff a una ,pa r t i c ul a r l ybi r ds( Ba hna ndFl e nl e y1 992; St ea dma n1 995 ) .Howe ve r ,a st hehuma npopul a t i ongr e w,t hef o r es t swe r epr o‑ gr es s i ve l yc utt opr ovi dewooda ndf i be rf orboa t s ,S t r uc t ur e s , r ope s ,a ndt ool s ,a s we l la st opr ovi def i r e wood.ThePol ynes i a nr a t ,whi c ha r r i ve dwi t ht heor l gl na l s e t t l e r s ,ha s t e ne dt hede c l i nebyki l l i ngbi r dsa nde a t i ngt hes e e dsa ndnut soft he na t i vepa l m. Bya boutt heyea r1 400,de f o r es t a t i onwasnea r l yc ompl e t e. Thel os soft r e e c ove rdr a ma t i c a l l yr e duc e dt hei s l a nd' sca 汀yl ngCa pa C l t y・The r ei sc l ea rs t r a t i 一 gr a ph i ce vi de nc et ha ts o i le r os i oni nc r e a s e dwi t hdeforest a t i ona sr a i nwa s he d a wa yt heunpr o t e c t e ds oi l .Wi t houtt r e ec ove r ,wi nd speedsa tg r oundl e ve li n‑ c r ease d,Ca r r yl ngS t i l lmor eva l ua bl es oi li nt ot hes ea・Thee r os i onwa ss os e ve r e ‑ 5 Th eH F i s h b a n k s "s i mu l a t i o n( Me a d o ws , F i d d a 聖a n , ndS a h a n n o n1993)i sawo n d e r f u l r o l e ‑ p l a y esourc e ss u c ha sf i s h e r i e s . ma n a g e me n t li f g h t s i mu l a t o ri l l u s t r a t l n gt h ed y n a ml C SO f r e n e wa b l er 126 P a r t I P e r s p e c t i v ea n dP r o c e s s FI GURE4‑ 14 Popul at i onofEast erl sl and Es t i mat ed popul at i onand t r eec ov erof Eas t erl sl and ⊂ 0 ; : 冒 ( 8 ち 5 00 0 ( 1 0 E L 400 800 1200 1600 2000 Tr eeCover q lt ) n 0 ト a a J SPuE ! ・J LJ (20 0%) uニ a O d T op:Po pul at i on es t i mat esf or Eas t erl sl andar e hi ghl yun c enai n. Thegr aphshows t hel i k el yr angeof popul at i onbas ed onda t ai nBahn 1992, andFl en】 ey( pp. 80,1 78f f ) . Bot t om:PoH en r ec or dsf r oms oi l cor ea tRan°Kau, Eas t erl sl and, showl ngdecl i ne i nt hef r ac t i onof poH enf r omt r ees ands hr ubs, i ndi c at i ngt he def or es t a t i o∩ oft hei sl and ( r emai nderof poH enf r om gr as s es, s edges, her b s, andf er ns ) . Def or es t a t i on wases s en t i al E y c ompl et eby abou t1400. 590 ±50 O 910950 ±60±70 Dept h ( met er s) 1400 ±60 Year 10 Not e: T i mea x e sf o r t o pa n db o t t o mg r a p h sd i f f e r . Sour ce:B a h na n dF f e n l e y(1992, p . 174) . t ha ts e di me ntwa s he d血. om t hehi ghe re l e va t i onse ve nt ua l l yc ove r e dma nyoft he moa i ,S ot ha tEur o pe a nvi s i t o r st houghtt hegi a nts t a t ueswe r eJ us thea ds ,whe ni n e e ti nhe i ght . De f or es t a t i ona l s oi n‑ f a c tt he ywe r ec ompl e t et or s osa ve r a gl ng20f c r e a s e de va por a t i onf r om t hes oi la ndma yha ver e duc e dr a i nf a l l . Thef T e ws t r e a ms ont hei s l a ndd ie r dup, f ur t he rr e duc i ngf oodpr od uc t i ona ndt hef r e s hwa t e rs uppl y. Eve nt ua l l y ,f i s hi ng,t heot he rma i ns our c eoff ood,a l s of e l l ,a sboa t s ,l i ne s ,a nd hoo ks , a l lma def r omwood, c oul dnol onge rber e pl a c e d. Whe nt hef i r s tEur ope a ns a r r i ve d, t hei s l a nde r spr i z e dwooda bovea l lot he ri t e msof f e r e di nt r a de. Mos tof t hebi r ds pe c i e sl i vl ngOnEa s t e rI s l a ndbe c a mea tl e a s tl oc a l l ye xt i nc t .Onl y1of a bo ut25i ndi ge nouss pe c i ess t i l lne s t sont hei s l a ndt oda y( St e a dma n1995) . Ch a p t e r4 S t r u c t u r ea n dBe h a v i o ro fDy n a mi cS y s t e ms 127 Ast hec a r r yl ngC a pa c i t yde c l i ne d, popul a t i ongr owt hs l owe d, r e a c hi ngapea k ge ne r a l l yes t i ma t e dt obebe t we e n6000a nd1 0, 000pe opl ea r oundt heye a r1 600. Apr e c l pl t OuSde c l i nei npopul a t i onha ds e ti nbya bout1 680,a c c ompa ni e dby ma J OrC ha nge si ns oc i a l ,pol i t i c a l ,a ndr e l i gi ouss t r uc t ur e s .Spea rpoi nt sa ndot he r t ool sofwa ra ppe a r e df ort hef i r s tt i me,a ndt he r ei se vi de nc eofl a r geba t t l es a mongc ompe t l n ggr OupS ・ Somes c hol a r sbe l i e vet he r ei se vi de nc eofc a nni ba l i s m dur i ngt hi spe io r d. Thef i r s tEur o pe a nsknownt ovi s i tEa s t e rI s l a nda r r i ve di n1 722 a ndf o undas ma l la ndpoorpopul a t i on・Sc hol a r sge ne r a l l ya c c e pta nes t i ma t eof 2000pe opl ei n1 78 6・ Af t e rPe r uvi a ns l a ver a i dsa ndas ubs e que nts ma l l poxe pl ‑ de mi ct hepo pul a t i onf e l lt oIl li n1 8 77. Thepopul a t i onr e c ove r e dt oa bout21 00 byt heea r l y1 99 0S ,l a r ge l yt her e s ul tofi mmi g r a t i ona nds e t t l e me ntf r om Chi l e, whi c hha sgove r n e dt hei s l a nds i nc e1 888. Theove r s ho ota ndc ol l a ps eofEa s t e rl s l a ndi sbutoneofma nys i mi l a r e pi s odesdoc ume nt e di nt hehi s t or yofi s l a ndbi oge ogr a phy( s e eKi r c h1 997) .I n e a c hc a s e, popul a t i ongr owt hl e dt ode f o r es t a t i on, t hee xt i nc t i onofna t i ves pe c i es , a ndunf a vor a bl ec ha ngesi nl oc a lc l i ma t e ,r a i nf a l l ,a nda gr i c ul t ur a lpr oduc t i vi t y, f ol l owe dbys t a r va t i on, c o nf li c t ,a nd,of t e n, popul a t i onc ol l a ps e・6 4. 3 0THER M oDESOFBEHAV; OR Gr owt h,goa ls e e k i ng,os c i l l a t i on,a ndt he i rc ombi na t i ons :a r et hes et heonl ypa レ ー e mso fbe ha vi o rs ys t e msc a ne xhi bi t ?No, butt he yc ove rt heva s tma J O r l t yOfdy‑ na mi c s ・ The r ea r eot he rpa t t e r ns ,f T ore xa mpl e:( 1 )s t a s i s ,ore qui l i br i um, i nwhi c h t hes t a t eoft hes ys t e mr e ma i nsc ons t a ntove rt i me;a nd( 2)r a ndomva r i a t i on. 4. 3. 1 St asi s,crEqL 毒 川br i L 汀n Cons t a nc ya r i s e se i t he rbe c a us edyna mi csa fe c t i ngt hes t a t eoft hes ys t e ma r es o s l owt ha tc ha ngei si mpe r c e pt i bl eorbe c a us et he r ea r epowe r f ulne ga t i vef e e dba c k pr oc e s s eske e pi ngt hes t a t eoft hes ys t e m ne a r l yc ons t a nte ve ni nt hef a c eofe nvi ‑ r onme nt a ldi s t ur ba nc e s . I nt hef om e rc a s e ,c ha ngei st oos l owr e l a ivet t oyourt i me hor i z ont obeme a ni ngf ul . I nt hel a t t e rc a s e, c ons t a nc yl Sa ne xa mpl eofhi ghl ye f ‑ f e c t i vegoa l ‑ s e e k i ngbe ha vi or . Thef i m nes r sa ndr e l i a bi l i t ywi t hwhi c hyour e ma i n i ncont a c twi t ht heg r oundwhe ns t a ndi ngr e le f c t st hee qui l i br i um c a us e dbya powe r f ulne ga t i v ef e e dba c kl oo p:a sg r a vl t yC a us e syout OS i nki nt ot hee a r t h,t he e l e c t r onsi nt hea t omsoft hegr ounde xe r tgr e a t e ra ndgr e a t e rupwa r df わr c eon t hee l e c t r onsi nt hea t omsofyourf e e tu nt i lt he氏) r c eoft he i rmut ua le l e c t r os t a t i c r e pul s i onj us tof f s e t st hef or c eofgr a vl t y ,a tWhi c hpoi ntyouc o met or e s t . 43. 2 Randomness . Ma nyva r i a bl esa ppe a rt ova r yr a ndoml y. I nmos ts i t ua t i ons , r a ndo mnes si same a s ur eofouri gno r a nc e,noti nt r i ns i ct ot hes ys t e m.( Exc e pti nqua nt um me c ha ni c s , ‑ 6 Th eEa s t e rI s l a n dd a t aa b o v ea r ed r a wnp r i ma r i l yf r o mBa h na n dF l e n l e y( 1 992) , ir K c h( 1 98 4) , a n dVa nTi l b u r g( 1 9 9 4) . Th e s ewo r k s , lo a n gwi t hK ir c h( 1 99 7)a n dS t e a d ma n( 1 99 5) , p r o v i d ea g o o ds u r v e yo fr e c e n t r e s e a r c ho nt h eb i o l o g l C a l a n dh u ma nh i s t o r yo f Ra p aNu i a n do t h e ri s l a n d e C O S y S t e mS ・ 1 28 P a r t IP e r s p e c t i v eandP r o c e s s whe r eEi ns t e i n' sf a mo usl a me ntH Goddo e snotpl a ydi c ewi t ht heuni ve r s e! " a p pe a r st obewr ong・ Ho we ve r ,t her a n do mbe ha v i o ro fe l e me nt a r ypa r t i c l e sne a r t hePl a nc ks c a l eha sl i t t l ei fa n ybe a r l ngO nt hed y na mi c so fma c r os c o pl CS ys t e ms s uc ha sac o mpa ny) ・ Whe nwes a yt he r ea r e" r a ndo mMva r i a t i onsi n,s a y ,t hed e ‑ ma ndf o raf i r m' spr od uc t , wha twea c t ua l l yme a ni st ha twedon' tknowt her e a ‑ s o nsf o rt he s eva r i a t i o ns ・ Wea r er e v e a l i ngt hel i mi t a t i o nsofo urunde r s t a ndi ng, no t c ha r a c t e r i z l ngaf e a t ur eo fr e a l i t y ・ Thed e ma ndf o raf i r m' spr od uc tma ybeg r o w 1 nga ndma ya l s oe xpe r i e nc eas e a s o na lc yc l e . Thef i r mma yunde r s t a nda ndc a n pe r ha pse ve nf or e c a s tt het r e nda nds e a s o na lc yc l ewi t hs o mea c c ur a c y . Buta f t e r a c c o unt i ngf o rt he s es o ur c e sofc ha nge , pe o pl et e ndt oc a l lt her e s i d ua lva r i a t i on r a ndo ma si ft hec us t ome r swe r es ome ho wr ol l i ngdi c et od e c i dewhe t he rt obu y t hepr od uc t . Pe o pl ege ne r a l l yha ver e a s onsf o rbe ha vi nga st he ydo, butt hema n‑ a g e r so ft hef i r ma r eno ta wa r eo fe i t he rt he i rd e c i s i o nr u1 e so rt hei nf o r ma t i o nt he y us et oma ket he i rde c i s i ons .Thema na ge r s 'mode lo fc us t ome rbe ha vi ori si m‑ pe r f e c t .I ft hef i r mc o ul d,t hr o ug ha dd i t i o na lmode l i nga ndf i e l dwo r k,d i s c o ve r t hos er ul e sa ndt he i rI n put s , t he yc o ul de x pl a i nmo r eoft het ot a lva r i a t i o ni nd e ma nd,a nds omeofwha twa sf o r me r l yd e e me dr a ndom wo ul dnowber e s ol ve d i nt ot he i rt he o r yoft hes ys t e ms t r uc t ur e . Asapr a c t i c a lma t t e r , noonec a nne ve rknowa l lt hel oc a lc o ndi t i o nsa ndi di o‑ s ync r a s i e sc a us l ngaC us t ome rt Opl a c ea no r de rt oda yo rwa i tunt i lt omor r owo r c a us eama c hi net obr e a kdownnowi ns t e a do f3ho u r sf r omnow. Thea gg r e ga t e i mpa c toft hei ndi vi dua lde vi a t i onsf r o ma ve r a g ebe ha vi o rme a nss ys t e msa r e ba t he di nac ont i nuousr a i nofr a ndo ms ho c ks 。 Engl ne e r St e r mt he s er a ndo mpe r ‑ "a f t e rt hed i s t o r t i o nh e a r do nt e l e p ho nel i ne sc a us e dbyt he ma r l t u r ba t i o ns" no i s e , luc f t ua t i o nso ft hea t omsi nt hewi r e s .Ofc o u r s e ,t her a i nofr a ndom s hoc ksi n‑ c l ude st heoc c a s i ona ldo wnpo ur ,o re ve nf loo d( f ore xa mpl e,no t et hei mpa c to f W WI Io ne c onomi co ut puti nt heUS, Fi g u r e4‑ 3 ) . Ther a i no fr a ndo mnoi s ef a l l i ngo nou rs ys t e msdo e spl a ya ni mpo r t a nt r o l ei n dy na mi c s , howe ve r . Byc ons t a nt l yk no c k i ngs ys t e msa wa yf r omt he i rc u r r e ntt r a ‑ j e c t o r y ,no i s ec a ne xc i t emode so fbe ha vi ort ha to t he r wi s ewoul dl i edo r ma nt . A pe nd ul um s wl ng l ngl nt hea i rwi l lt e ndt o wa r dse q ui l i br i uma sf r i c t i o nd i s s i pa t e s i t se ne r gy; e ve nt ua l l yt hebo bo ft hepe nd ul u mc o me st or e s t , s t r a i g htdown. Ho w‑ e ve r ,pe r t ur bt hebobwi t hs ma l l ,r a ndo mj o l t s ,a nds oo ni twi l lbe gi ns wl ngl ng, s o me wha ti r r e g ul a r l y , Wi t har hyt hmc l os et oi t sna t ur a lf r e q ue nc y . Thes t r uc t u r eo f t hes ys t e mha st hepo t e nt i a lt oos c i l l a t e , b ute ne r g y丘. oms o mee x t e ma ls o u r c es uc h a shi g h‑ f r e q ue nc yr a nd omnoi s ei sr e qu i r e dt oe xc i t ei t sl a t e ntd yna mi c s( c ha pt e r s 1 8 1 20pr ovi d ee xa mpl e s ) . Ra nd omno i s ec a na l s ounf r e e z es ys t e mst ha ta r es t uc k onl o c a lo pt i ma,s e nd i ngt he mi nt oane wne i g hbo r ho odwhe r et hedyna mi c sa r e q ui t ed i fe r e nt , a ndc a nde t e r mi newhi c ho fma nye qua l l ya t t r a c t i vepa t hsas ys t e m t a ke s , c o nt r i bu t i ngt opa t hde pe nd e nc e( s e ec ha pt e r1 0) . The s edi s t ur ba nc e sc a nbe mod e l e da sr a ndomva r i a t i onsa ro undt hea ve r a gebe ha vi o rgl Ve nbyt hee qua t i o ns c a pt u r i ngt hef e e dba c ks t r uc t ur eo ft hes ys t e m・ Ot he rt i me si ti smo r ea ppr o p r i a t e t omo de lt hei ndi vi dua le l e me nt sa nda c t o r si nt hes ys t e m, i nwhi c hc a s eno na ve r ‑ a gebe ha vi ora r i s e sf r omt hehe t e r og e ne l t yO ft hepo pul a t i onofa ge nt s . The s er ol e s f o rr a ndo mpe r t ur ba t i onswi l lbee xpl o r e di nl a t e rc ha pt e r s . ‑ ‑ Ch a p t e r 4 S t r u c t l l r ea n dBe h a v i o ro fDy n a mi cS y s t e ms 1 29 4. 3. 3 Ch a os l nr e c e ntye a r sc ha osha sbe c omeaubi qul t OuSbuz zwor di nt hepopul a rpr e s sa nd ma na ge me ntl i t e r a t ur e・Booksa nda r t i c l esbyahos tofne wa gema na ge me ntgu‑ r uswa r nc o mpa ni e st oH ma na gea tt hee dgeofc ha os Horbeove r t a ke nbymor e ni mbl ec ompe t i t o r s .Ext r a va ga ntc l a i msha vebe e nma det ha tc ha osi sane wa nd r a di c a l l ydi f f e r e n ts c i e nc e, Onewhi c hi sf unda me nt a l l ynonl i ne a ra ndc ompl e x, One t ha tc a n' tbee xp l a i ne dwi t houts omemys t e r i o usne wt he o r y.Ac t ua l l y,t het e r m " c ha os "ha sana r r owa ndpr e c i s et e c hni c a lme a nl ngi nd yna mi c a lt he or y. Unf or t u‑ na t e l y , t hehunge rf o rt hel a t es tf a di nt hebus i ne s swo r l d, r e i nf or c e dbyma r ke t i ng hy pea t t e ndi ngt hede ve l opme ntofc ha osa ndc ompl e xl t yt he or y,ha sl e dt ot he mi s a ppr opr i a t i ona nddi l ut i onoft het e r m. Toe x pl a i nc ha osIf i r s tdes c r i bes ome mo r ec om ont y pe sofos c i l l a t i ons . DampedOsci l l at l r OnS:LocalSt abi l i t y Onei mpo r t a ntc ha r a c t e r i s t i cofos c i l l a t i onsi sda mpl ng: i fa nos c i l l a t or ys ys t e mi s pe r t ur be do nc ea n dt he nl e f tundi s t ur be d, wi l lt hef luc t ua t i onsdi eout ?I fs o, t hec y‑ c l ei sda mpe d・ Ma nys ys t e msa r eda mpe dos c i l l a t or s ・ Thec l a s s i ce xa mpl ei sape n‑ dul um l i keac hi l d' ss wl ng:Gi ve nas l ngl epus h,t hea r ct r a ve r s e dbyt hes wl ng s t e a di l ydi mi ni s h esa sf r i c t i ondi s s i pa t esi t se ne r gy,unt i li te ve nt ua ll ycomest o t .I fyouc o ul dr e duc et hef r i c t i ona le ne r gyl os s e soft hepe ndul um,da mpl ng r e s wo ul dbewe a ke ra ndi two ul dt a kel onge ra ndl o nge rf ore qui l i br i umt ober e e s t a bl l i s he da f t e ras hoc k.I nt he( una t t a i na bl e )l i mi tofz e r of r i c t i on,as i ngl es hoc k woul dc a us eape r pe t ua los c i l l a t i ona tac ons t a nta mpl i t ude. o c al l ys t abl e IPe r t ur ‑ Thee qui l i br i um oft heda mpe dpe ndul um i ss a i dt obel ba t i onswi l lc a us et hes ys t e mt oos c i l l a t e, buti twi l le ve nt ua l l yr e t ur nt ot hes a me l i f i e r" l oca l l y"i si mpor t a nt .Re a ls ys t e msa r enonl i ne a r , e qui l i br i um.Theq ua me a nl ngt ha tt hef e e dba c kl oopsa ndpa r a me t e r sgove n1 r ngt hedyna mi csva r yde pe ndi ngo nt hes t a t eoft hes ys t e m( whe r et hes ys t e mi so pe r a t i ngi ns t a t es pa c e ‑ t hes pa c ec r ea t e dbyt hes t a t eva r i a bl esoft hes ys t e m) . 7Loc a ls t a bi l i t yme a nst he pe r t ur ba t i onsha v et obes ma l lr e l a t i vet ononl i ne a r i t i est ha tmi ghtc a us eot he rdy一 ma ni c st oe me r ge ,a swhe nt hepe ndul um i ss wungs oha r di tbr e a ks . Ma nyr e a lwor l dos c i l l a t or sa r eda mpe d,butt heos c i l l a t i onsne ve rdi ea wa y be c a us et hes ys t e msa r ec ont i nua l l ybomba r de dwi t hnoi s e. Ma nymode l ss ugge s t t ha tt hes ho r t ‑ t e n bus i ne s sc yc l e( Fi gur e4‑ 7)i sada mpe d, l oc a l l ys t a bl eos c i l l a ‑ t i on( c ha pt e r1 9) ・Theos c i l l a t or ys t r uc t ur ei sas e tofne ga t i vef e e dba c kl oops t hr oughwhi c hf i m sa r d j us tpr oduc t i ont oc ont r olt he i ri nve nt or i e sofpr oduc t sa nd r a wma t e r i a l s . Th es el oo psa r eos c i l l a t or ybe c a us eoft hel a gsi nt hea d j us t me ntof pr oduc t i ont oc ha ngesi nde ma nda ndi nve nt or y, pa r t i c ul a r l yde l a ysi nhi r i nga nd ‑ 7 I nas i mp l ep e n d u l u m, t h e r ea r et wos t a t ev a r i a b l e s : t h ep o s i t i o no ft h ep e n d u l u ma n di t smo me n t u m. Th e s et wos t a t e sd e f i n eat wo ‑ d i me n s i o n a l s p a c e , a n dt h es t a t eo ft hes y s t e mi sd e f i n e da t a n yt im eb yt h ep o i n t i nt h a t s p a c ec o r r e s p o n d i n gt ot h ep o s i t i o na n dmo me n t u mo ft h ep e n d u l u m. st A hep e n d u l u ms wmg st h r o u g hi t sa r c , i t st r a j e c t o r yt r a c e sO u t aC u rv ei ns t a t es p a c e . Mo r ec o m‑ p l e xs y s t e msh a v eh i g h ‑ d i me n s i o n a l s t a t es p a c e s , b u t hec t o n c e p t o fat r aj e c t o r yl nS t a t eS p a c er e ‑ ma i n st h es a me . ‑ 130 P a r t iP e r s p e c t i v eandP r o c e s s ma t e r i a l sa c q ui s i t i o n( Fo r r e s t e r1 961 ; Ma s s1 9 75 ) . I nt he s emod e l s , bot ht hepe r ‑ s i s t e nc ea ndi r r e gul a r l t yO ft hebus i ne s sc yc l ea r ec a us e dbyt hee xc i t a t i o noft he e c o no mybyr a ndoms ho c ks , j us ta st hes i mpl ep end ul umd i s c us s e da bo v ef luc t u‑ a t e ss ome wha ti r r e g ul a r l ywhe npe r t u r be dbynoi s e . Fi g ur e4‑ 1 5S howsa ne xa mpl eofda mpe dos c i l l a t i oni nas i mpl emo de lo fa f i r mba s e dont heBe e rDi s t r i but i o nGa me( St e r ma n1 98 9 b,c ha p.1 7) . Thega me r e pr e s e nt st hes u ppl yc ha i ni nat y pi c a lma nuf a c t ur l ngi nd us t r y・ Thes up pl yc ha i n ha sf o urs e c t o r s : ar e t a i l e r , who l e s a l e r , d i s t r i but o r , a ndf a c t o r y. Ea c hs t a g ei si d e n‑ t i c a la ndma na ge dbyad i f f e r e ntpe r s o n. Thema na ge r ss t r i vet om i ni mi z et he i r c os t sbyc ont r ol l i ngI nve n t o r i e sa st he ys e e kt ome e ti nc o mi ngde ma nd・ Thes i mu‑ l a t i ons howst her e s po ns eo ft hef a c t o r yo r de rr a t et oao ne ‑ t i mec ha ngei nc us ‑ t o me ro r d e r s . Thede c i s i o nr ul eus e dbye a c ha g e n ti nt hes i mul a t i o nwa se s t i ma t e d f r o mt hebe ha vi o ro fa c t ua lpl a ye r s . I nr e s po ns et ot hes ho c ki nde ma nd, f a c t o r yo r ‑ de r se x hi bi tada mpe dos c i l l a t i o nwhi c hr e t ur nst hes ys t e mt oe q ui l i br i um a f t e r a bo ut70we e ks . He r et hene ga t i vel oo pi st hepr o c e s sbywhi c he a c hs t a gei nt he s up pl yc ha i nma na ge si t si n ve nt o r y:o r de r i ngmo r ewhe ni nve nt o r i e sa r ei na de ‑ q ua t ea ndl e s swhe nt he ya r eh i g h.Thede l a ysa r i s e丘. o mt het i mer e q ui r e dt o p r o c e s so r de r sa ndp r o duc ea ndde l i ve rt hebe e r ・ Expandi ngOsci l / at l ' onsandLi m/ ' tCycl es Whi l ema nyos c i l l a t o r ys ys t e msa r eda mpe d,t hee qui l i br i aofot he rs ys t e msa r e l oc a l l yuns t a bl e , me a ni ngt ha ts ma l ld i s t ur ba nc e st e ndt omovet hes ys t e mf a r t he r l nt . I ma gl neaba l lba l a nc e do nt o po fahi l l ・ Asl o ng a wa y血. omt hee qui l i br i u mpo a st heba l ll se xa c t l yba l a nc e do nt hehi l l t o p,i tr e ma i nsi ne q ui l i br i um・Butt he s l i g ht e s tbr e e z epus he st heba l ldo wnt hehi l le ve rs os l i ght l y ,l e a di ngt oas t i l l g r e a t e rf o r c edo wnh i l l , i napos i t i v ef e e d ba c k. Thee q ui l i br i umi suns t a bl e ・ Wh i l e a ne q ui l i br i um ma ybel oc a l l yuns t a bl e ,a nyr e a ls ys t e mmus tbegl o ba l l ys t a bl e・ Gl o ba ls t a bi l i t yme a nst het r a j e c t o r i e soft hes ys t e m donotdi ve r get oi nf i ni t y: het t r a j e c t o r i e sa r ebo unde dbe c a us et hepos i t i vef e e d ba c ksl e a d i ngt ot hea c c e l ‑ e r a t l ngf li g htf r o mt heba l a n c epo i ntmus tul t i ma t e l ybel i mi t e dbyva r i o usne ga ‑ t i vel oo ps .Theba l lc a nnota c c e l e r a t ei nde f i ni t e l y ,butwi l lc o met or e s ta tt he bo t t o moft hehi l l . FI GURE 4 ‑ 15 2 0 0 1 (竜 ¢ き\ Sl!u n ) sL aPL O ^)08 3t = j 0 Damp ed os c i H a t i oni na mode一 o ft heBe er Di s t r i bu t i onGame No t et h e n onl i near i t y: be t weenweek s 30an d45t her e i sal ar ges ur pl u s ofi n ven t or ybu t or der sar e c on s t r ai n e dt ob e nonnega t i v e. 131 Ch a p t e r 4 S t r u c t ur ea n dBe h a v i o ro fDy n a mi cS y s t e ms I fa nos c i l l a t or ys ys t e m wi t hal oc a l l yuns t a bl ee qui l i br i um i sgl Ve naS l i ght nudgeof fi t se qu i l i br iumpoi nt , i t ss wl ngSgr owl a r ge ra ndl a r ge runt i lt he ya r ec on‑ s t r a i ne dbyva r i o usnonl i nea r i t i e s ・Suc hos c i l l a t i onsa r eknowna sl i mi tc yc l e s ,t o de not et henonl i ne a rl i mi t sr es t r i c t l ngt he i ra mpl i t ude. I nl i mi tc yc l es , t hes t a t e sof t hes ys t e mr e ma i nwi t hi nc e r t a i nr a nges( t he ya r el i mi t e dt oac e r t a i nr e gi onofs t a t e s pa c e ) .I nt hes t e a dys t a t e,a f t e rt hee f f e c t sofa nyi ni t i a lpe r t ur ba t i onsha vedi e d o ut , al i mi tc yc l ef ol l owsapa r t i c ul a ror bi t( c l os e dc ur ve )i ns t a t es pa c e・ Thes t e a dy s t a t eor bi ti skno wnasa na t t r a c t or ,s i nc et r a j e c t or i esne a re nought oi twi l lmove t owa r di t , j us ta st heboboft heda mpe dpe ndul umi sa t t r a c t e dt oi t ss t a bl ee qui l i b‑ r i umpol nt . Fi gur e4‑ 1 6S howsa ne xa mpl eofal i mi tc yc l ef r om t heBe e rDi s t r i but i on Ga me. Thes i t ua t i oni nt hef i gur ei st hes a mea sde s c r i be da bovef ort heda mpe d os c i l l a t i one xc e p tt ha tt hepa r a me t e r soft heo r de r i ngde c i s i onr ul ea r es l i g ht l ydi f ‑ f e r e nt . Asi nt hec a s eofh teda mpe dos c i l l a t i o n, t hepa r a me t e r sc ha r a c t e r i z et hebe ‑ ha vi o rofa na c t ua lpl a ye r . Aga i n,t he r ei saone ‑ t i mec ha ngei nc us t ome rde ma nd・ I ns t e a dofdyi ngout ,t hec yc l epe r s i s t si nde f i ni t e l y ,e ve nt ho ught hee nvi r onme nt i sc ompl e t e l yun c ha ngl ng. Thef i gur es ho wst hec yc l ebot ha sat i mes e r i e sa nda s as oI C a l l e dpha s epl otwi t hor de r sont heve r t i c a la xi sa ndi nve nt or yont hehor i ‑ z ont a la xi s ,s howl ngt hec l os e do r bi tpe r pe t ua l l yt r a c e dbyt hes ys t e m・ Ofc our s e,l i mi tc yc l esa r enotpe r pe t ua lmot i onma c hi nes ・Thee ne r gyr e ‑ qui r e dt oma i nt a i nt hec yc l emus tbepr ovi de df r omas our c eout s i det heos c i l l a t o r ・ Li mi tc yc l e sa r equi t ec ommon. Yourl i f ede pe ndsont he m‑yo urhe a r t be a ta nd r es pi r a t i ona r el i mi tc yc l es . Thec i r ca di a nr hyt hms( da i l yf luc t ua t i onsi na l e r t nes s , hor monepr oduc t i on,a ndahos tofot he rphys i ol ogi c a lpa r a me t e r s )obs e r ve di na 1 ‑ mos ta l lo r ga ni s ms , f r omba c t e r i at ope opl e, a r el i mi tc yc l e s ・ Ma nyc yc l e si nt hebi l ol ogi c a lwor l da l s oa ppe a rt obel i mi tc yc l e s ,i nc l udi ngc yc l e si npr e da t or ‑ pr e y po pul a t i ons , C yc l e si nt hema s sf r ui t l ngOfc e r t a i npl a nts pe c i e ss uc ha sPi 畠onpl neS a nds omeba mbo os ,a ndt hepe r i odi cpo pul a t i one xpl os i onsofc e r t a i ni ns e c t ss uc h a st he1 7‑ ye a rc i c a da( s e eMur r a y1 993) . Ma nymode l ss ugge s tt ha tve r yl ong‑ t e r m FI GURE4 ‑ 16 Al i mi tc y cl egener at edi nt heBeerDi s t r i bu t i onGame Lef t : Ti meser i esoff ac t or yor der s. Thec y cl er epeat si ndef i ni t el ywi t h ou tan yex t er nal var i at i on. R/ ' ght : Th eor bi toft h es y s t emi sacl os edcur v e, Shownher ewi t hf ac t or yor der spl ot t edagal nS tnet f act or yi n v ent or y( i n ven t or yl es sback l og) . o^ )01 3t 2 j pj 0 5 1 JL S J lE u n) ( よOaV s Ja 600 700 800 We e k s 900 1000 ‑ 30 ・ 20 ‑ 10 0 10 F a c t o r yNe tl n v e n t o r y 20 132 Pa r tI P e r s p e c t i v ea n dP r o c e s s fuc l t ua t i onsi nt hewor l de c o no myknowna s" l o ngwa ve s "a r es e l f ‑ pe r pe t ua t l ng l i mi tc yc l e s( St e r ma n1 98 5;Fo r r e s t e r1 98 3) .St e r ma n( 1 98 9a )r e po r t sa ne x pe r i ‑ me nti nwhi c hpe o pl ema na ge das i mpl ee c o no mi cmode l ; t heva s tma J O r l t yge ne r a t e dl o ngwa ve smuc hl i ket hebe ha vi o ro ft hemod e l ・ St e ma n( 1 98 9 C )S ho wst ha t ma nyoft hede c i s i o nr ul e sc ha r a c t e r i z l ngt hehuma ns u b j e c t sg e ne r a t ec ha osa nd va r i o usf o r msofl i mi tc yc l e. ‑ Chaot l ' cOsci l l al i ons Cha os ,l i keda mpe df l uc t ua t i onsa ndl i i tc m yc l e s ,i saf or m ofos c i l l a t i o n・How‑ e ve r , unl i kel i mi tc yc l e s ,ac ha o t i cs ys t e mf luc t ua t e si r r e g ul a r l y , ne ve re xa c t l yr e ‑ pe a t l ng, e ve nt ho ug hi t smo t i o ni sc o mpl e t e l yd e t e r mi ni s t i c ・ Thei r r e g ul a r i t ya r i s e s e ndoge no us l ya ndi sno tc r e a t e dbye x t e ma l , r a ndo ms ho c ks ・ Li keal i mi tc yc l e , t he pa t ho fac ha o t i cs ys t e mi sbo unde dt oac e r t a i nr e g l OnO fs t a t es pa c e ・Be c a us e c ha ot i cs ys t e msa r ebo unde d, c ha os ,l i kel i mi tc yc l e s ,c a no nl ya r i s ei nno nl i ne a r s ys t e ms . Howe ve r , unl i kel i ne a rs ys t e mso rl i mi tc yc l e s ,c ha ot i cd yna mi c sdonot ha veawe l l ‑ de f i ne dpe r i o d, a sdo e st hes i mpl epe n d ul u md i s c us s e da bo ve ・ Themo‑ t i o no fac ha ot i cs ys t e mne ve rr e pe a t s ;i ns t e a d, t heo r bi t so ft hes ys t e ma pp r oa c h wha ti sknowna sas t r a ng ea t t r a c t o r ‑as e tofc l os e l yr e l a t e dbuts l i g ht l yd i f f e r e nt o r bi t sr a t he rt ha nas l ngl ec l os e dc ur ve.Fur t he r mor e ,c ha ot i cs ys t e msha vet he pr ope r t yknowna ss e ns i t i vede pe nde nc eoni ni t i a lc o nd i t i ons ・Twone a r byt r a ‑ j e c t or i e s ,noma t t e rho wc l os e ,Wi l ldi ve r gee xpo ne nt i a l l yunt i lt hes t a t eo fone pr o vi d e snomo r ei nf o r ma t i o na bo utt hes t a t eo ft heo t he rt ha na n yr a ndo ml yc ho‑ s e nt r a j e c t or y. Se ns i t i ved e pe nde nc eme a nst ha tt hepr e d i c t i onho r i z o nf o rc ha o t i c s ys t e ms ‑t hel e ng t ho ft i meo ve rwhi c hf o r e c a s t so ff u t u r ebe ha v i o ra r ea c c u r a t e ‑ i sl i ke l yt obes ho r te ve ni fo urmode lo ft hes ys t e ms t r uc t ur ea ndpa r a me t e re s t i ‑ ma t e sa r epe r f e c t .Fur t he r ,t hec os tofi nc r e a s l ngt hepr e di c t i o nho r i z o naf i xe d a mo untbyi mpr o vl ngO urknowl e dgeoft hec ur r e nts t a t eo ft hes ys t e mi nc r e a s e s e x pone nt i a l l y. Fi g ur e4‑ 1 7S howsc ha ot i cbe ha vi o ri nas i mul a t i ono ft heBe e rDi s t r i but i on Ga me . Onl yt hepa r me a t e r so ft hede c i s i o nr ul ef o ro r de r sha vebe e na l t e r e d' , a ga i n, FI GURE4‑ 17 Ch aosi nt heBeerDi s t r i bu t i onGame Lef t : Ti mes er i e ss h owl n gf ac t or yor der s.i ? i ght :Ph a s epl o ts h owl ngor der sv s.n e tf ac t or yl n v en t or y ( i n v en t or yl es sb ac k l og) . 0 4 0 0 4 S 八 U 2 時﹄ 83 n) 700 800 weeks 900 1000 0 2 ^) OD ie j aき \ l! u sjむJ P ^ J0 ( U 6 0 ) tl ( ︼ 盲 sJapLO 600 1 100 ‑ 50 0 50 F a c t o r yN e tnv e n t o r y 100 Ch a p t e r4 S t r u c t u r ea n dBe h a v i o ro f Dy n a mi cS y s t e ms 1 33 t hes epa r a me t e r swe r ee s t i ma t e df r om t hebe ha vi orofa na c t ua lpl a ye r .Li ket he l i mi tc yc l e,or de r sf luc t ua t ei nde f i ni t e l y,i nt hi sc as ewi t ha na mpl i t uder a ngi ng f r o m 0t oa bout50uni t spe rwe e ka nda na ve r a gepe r i odofa bout20we e ks . Un‑ 1 i ket hel i mi tc yc l e,t heos c i l l a t i ondoe snotha vear e gul a ra mpl i t ude,pe r i odi c i t y, ors ha pe,e ve nt hought hee nvi r onme nti sc ompl e t e l yc ons t a nta ndt hes ys t e mi s c o mpl e t e l yf r e eo fr a ndom s hoc ks ・ Thet r a j e c t or yOft hes ys t e mi ns t a t es pa c ef o1 ‑ 1 owsawe l l ‑ de f i ne dpa h, t butonewhi c hne ve rc l os esoni t s e l f・ 8 I na l lt hr e eo ft he s ec a s e s , da mpe dos c i l l a t i on, l i mi tc yc l e, a ndc ha os , t hef e e d‑ ba c ks t r uc t ur ea ndde c i s i onr ul e sa r et hes a me・ Theonl ydi f f e r e nc esa r ei nt hepa ‑ r a me t e r soft heor de r i ngr ul es uc ha st hes i z eofdes i r e di nve nt or ya ndt he a ggr e s s i ve nes swi t hwhi c hma na ge r sr e a c tt ot hedi s c r e pa nc ybe t we e nde s i r e da nd a c t ua li nve nt o r y . 4. 4 SuMMARY Thef e e dba c ks t r uc t ur eofas ys t e m ge ne r a t e si t sbe ha vi or .Mos tdyna mi c sob‑ s e Ⅳe di nt her e a lwor l da r ee xa mpl e sofas ma l ls e tofba s i cpa t t e r nsormodesof be ha vi o r ・ Thr e eoft he s emode sa ref unda me nt a l : e xpone nt i a lg r owt h, goa ls e e ki ng, a ndos c i l l a t i on. Ea c hoft he s emodesi sge ne r a t e dbyapa r t i c ul a runde r l yi ngf e e d‑ ba c ks t r uc t ur e.Expone nt i a lgr owt hi sge ne r a t e dbypos i t i vef e e dba c kpr oc e s s es , goa ls e e ki ngl Sge ne r a t e dbyne ga t i vef e e dba c k,a ndos c i l l a ioni t sge ne r a t e d byne ga t i vef e e dba c kwi t hde l a ys .Mo r ec ompl e xpa t t e r nsofbe ha vi o rs uc ha s SI S ha pe dgr owt h,gr owt hwi t hove r s hoo t ,a ndove r s hoota ndcol l a ps er e s ul tf r om t henonl i ne a ri nt e r a c t i ono ft he s eba s i cf e e d ba c ks t r uc t ur e s . Thepr l nC i pl et ha tt hes t r uc t ur eofas ys t e m ge ne r a t esi t sbe ha vi o rl e a dst oa us e f ulhe ur i s t i ct ohe l pmode l e r sd i s c ove rt hef e e dba c kl oops t uc r t ur eofas ys t e m. Whe ne ve rapa r t i c ul a rpa t t e r nofbe ha vi o ri so bs e r ve d,youknow whi c hoft he ba s i cf e e dba c ks t r uc t ur e smus tha vebe e ndomi na ntdur i ngt hepe r i odc ove r e dby t heda t a.Obs e r vi ngt ha tava r i a bl eofi nt e r es thasbe e nf luc t ua t l ng,f ore xa mpl e, i mpl i est hee xi s t e nc eof( a tl e a s t )o nene ga t i vef e ed ba c kl oopw it hs i gni f i c a ntt i me de l a ys ,whi c hhe l pst og ui det hes e a r c hf ort hepa r t i c ul a rs t r uc t ur es ,de c i s i on pr oc e s s es ,a ndt i mede l a yst ha tc ompr l S et hene ga t i vel oop. Whi l et hi she ur i s t i ci s us e f ula sa na i dt ot hei ni t i a lc onc e pt ua l i z a t i onpr oc es s ,mode l e r smus ta l s ot a ke c a r et os e a r c hf o ra ndi nc l udei nt he i rmode l st hef e e d ba c kl oopsa nds t uc r t ur e st ha t ha venotbe e ni mpo r t a nti nge ne r a t i ngt hedyna mi cst oda t ebutt ha tma ybe c ome a c t i vea st hes ys t e me vol ve s 。 8 Mo s e k i l d e( 1 996)p r o v i d e sa ne x c e l l e n t t r e a t me n t o fc h a o t i ca ndo t h e rn o n l i n e a rd y n a mi c si n teBe h e rDi s t r i b u t i o nGa mea n daw id ev ri a e t yo fo t h e rp h y s i c a l , t e c h n i c a l , a n db i o l o g l C ls a y s t e ms . S t r o g a t z(1994)p r o v i d e sa ne x c e l l e n t ma t h e ma t i c a l i n t r o d u c t i o nt on o n l in e a rd y n a mi c sa n dc h a o s . e蓮 盲 主 § 畠 葺互 ノ 軸i 3i I s 毒 嘩T 3 ; ‑ i i fi S Wes ha peou rbui l di ngs ;t he r e a j t e f ;Ourbui l di ngss ha peus . ‑Wi ns t o nChur c hi l l Fe e d ba c ki so neo ft hec o r ec onc e pt sofs ys t e md yna mi c s . Ye to u rme nt a lmode l s o f t e nf a i lt oi nc l udet hec r i t i c a lf e e dba c ksd e t e r mi ni ngt hedyna mi c so fo ur s ys t e ms ・I ns ys t e m dyna mi c sweus es e ve r a ldi a g r a mml ngt ool st oc a pt ur et he s t r uc t ur eo fs ys t e ms ,i nc l udi ngc a us a ll oo pdi a g r a msa nds t oc ka ndf lowma ps . l s ,a nd Thi sc ha pt e rf oc us e sonc a us a ll oo pd i a gr a ms ,i nc l udi ngg ui de l i ne s , pi t f a l e xa mpl e s . 5. 1 CAL ・ SALDI AGRAM NoTAT5 0N Ca us a ll oo pd i a g r a ms( CLDs )a r ea ni mpo r t a ntt oo lf o rr e p r e s e nt ingt hef T e e d ba c k s t r uc t ur eo fs ys t e ms . Longus e di na c a de mi cwo r k,a ndi nc r e a s l ngl yc ommo ni n bus i ne s s , CLDsa r ee xc e l l e n tf o r ・ Qui c kl yc a p t u r l ngyo urhypot he s e sa bo utt hec a us e so fd yna mi c s ; 。 El i c i t i nga n dc a pt ur l ngt heme n t a lmode l sofi nd i vi d ua l so rt e a ms ; ・ Communi c a t i ngt hei mpo r t a ntf e e d ba c ksyo ube l i e v ea r er e s po ns i bl ef o ra pr o bl e m. Thec o nve nt i o nsf o rd r a wi ngC a us a ldi a g r a msa r es i mpl ebu ts ho ul dbef ol l owe d f a i t hf ul l y . Thi nko fc a us a ldi a gr a msa smus i c a ls c o r e s . Ne a t n e s sc o unt s ,a ndi di o‑ s ync r a t i cs ymbo l sa nds t yl e sma kei tha r df o rf e l l o wmus i c i a nst or e a dyo urs c o r e. Atf i r s t ,yo uma yf i ndi tdi f f i c ul tt oc o ns t r uc ta ndi nt e r pr e tt he s edi a g r a ms . Wi t h pr a c t i c e , ho we ve r , yo uwi l ls oo nbes i g ht ‑ r e a di ng. 137 138 P a r t H T わ o l sf o rS y s t e msTh i n k i n g Ac a us a ldi a g r a mc ons i s t sofva r i a bl e sc onnec t e dbya r r owsde not l ngt he c a us a li nf lue nc e sa mongt heva r i a bl e s . Thei mpo r t a ntf e e dba c kl oo psa r ea l s oi de n‑ t i f i e di nt hedi a gr a m. Fi gur e5‑ 1s howsa ne xa mpl ea ndke yt ot henot a t i on・ Va r i a bl esa r er e l a t e dbycaus all i nk s ,s hownbya r r ows ・I nt hee xa mpl e,t he bi r t hr a t ei sde t e r mi ne dbybot ht hepo pul a t i ona ndt hef r a c t i ona lbi r t hr a t e. Ea c h c a us a ll i nki sa s s i gne dapol a r i t y,e i t he rpos i t i ve( +)o rne ga t i ve( ‑)t oi ndi c a t e howt hede pe nde ntva r i a bl ec ha ngeswhe nt hei nde pe nde ntva ri a bl ec ha nge s . The i mpor t a ntl oo psa r ehi ghl i ght e dbyal oopi de nt i f i e rwhi c hs howswhe t he rt he l oo pi sapos i t i ve( r e i nf or c i ng)orne ga t i ve( ba l a nc i ng)f e e dba c k・ Not et ha tt hel oo p i de nt i f i e rc i r c ul a t e si nt hes a medi r e c t i o na st hel oopt owhi c hi tc or r e s po nds . I nt he e xa mpl e,t hepos i t i vef e e dba c kr e l a t i ngbi r t hsa ndpo pul a ioni t sc l oc kwi s ea nds o i si t sl oopi de nt i f i e r ; t hene ga t i vede a t hr a t el oopI Sc o unt e r c l oc kwi s ea l o ngwi t hi t s i de nt i f i e r . Ta bl e5‑ 1s umma r i z est hede f i ni t i o nsofl i nkpol a r i t y. FI GURE5 ‑ 1 Cau s al l oop di agr amn ot at i on Exampl e , Bi r t hRat e ・・ ( 竿 R p p u L B / I 守 o l at i on Fr act i onal Bi r t hRat e 主 Deat hRat e Aver age Li f et i me Key 了 ⁚二㌧ C a u s a I L i n k , ・ L i n k P o l a r i t y Bi r t hRat e Popul at i on Van' abI e Var i abl e r Q 、 こ .Fl :. )( .L n) r O Loopl dent i f i er IPosl r t i ve( F 7 ei nf or ei ng)Loop Loopl dent i f E ' er :Negat i ve( Bal anci ng)Loop 1 39 Ch a p t e r 5 C a u s a l L o o pDi a g r a ms Apos i t i vel i nkme a nst ha ti ft hec a us ei nc r e as e s ,t hee f f ec ti nc r e as e sabov e whati twoul do t he J Wi s ehav ebe e n,a ndi ft hec a us ede c r e as e s ,t hee f f e c tde ‑ c r e as e sbe l owwhati twoul dot he r wi s ehav ebe e n・ I nt hee xa mpl ei nFi g ur e5‑ 1a n i nc r e a s ei nt hef r a c t i ona lbi r t hr a t eme a nst hebi r t hr a t e( i npe opl epe rye a r )wi l l i nc r e a s ea bovewha ti two ul dha vebe e n, a ndad e c r e a s ei nt hef r a c t i ona lbi r t hr a t e me a nst hebi r t hr a t ewi l lf a l lbe l owwha ti twoul dha vebe e n・ Tha ti s ,i fa ve r a ge f e r t i l i t yr i s e s ,t h ebi r t hr a t e ,gi ve nt hepo pul a t i o n,wi l lr i s e;i ff e r t i l i t yf a l l s ,t he n umbe ro fbi r t hswi l lf a l l . Whe nt hec a us ei sar a t eo ff lo wt ha ta c c umul a t e si nt oa s t oc kt he ni ti sa l s ot r uet ha tt hec a us ea ddst ot hes t o c k. I nt hee xa mpl e , bi r t hsa dd t ot hepo pul a t i on( S e ec ha pt e r6f o rmo r eo ns t o c ksa ndf lows ) . Ane ga t i vel i nkme a nst ha ti ft hec a us ei nc r e a s e s ,t hee f f e c tde c r e as e sbe l ow ,a ndi ft hec a us ede c r e as e s , t hee f f e c ti ne r e as e s whati twoul dot he r wi s ehav ebe e n abov ewhati twoul dot he r wi s ehav ebe e n.I nt hee xa mpl e , a ni nc r e a s ei nt hea ve r ‑ a gel i f e t i meo ft hepopul a t i o nme a nst hede a t hr a t e( i npe o pl epe rye a r )w il lf a l l be l o wwha ti two ul dha vebe e n,a ndade c r e a s ei nt hea ve r a g el i f e t i meme a nst he de a hr t a t ewi l lr i s ea bovewha ti two ul dha vebe e n.Tha ti s ,i fl i f ee xpe c t a nc y i nc r e a s e s , t henu mbe ro fde a t hswi l lf a l l ; a ndi fl i f ee x pe c t a nc yf a l l s , t hede a t hr a t e wi l lr i s e. Li nkpol a r i t i e sd es c r i bet hes t r uc t ur eo ft hes ys t e m. The ydonotde s c r i bet he be ha v i o ro ft hev a r i a bl e s . Tha ti s , t he yd e s c r i bewha two ul dha ppe nI Ft he r ewe r e ac ha n ge . The ydonotde s c r i bewha ta c t ua l l yha ppe ns .Thef r a c t i ona lbi r t hr a t e l l mi g hti nc r e a s e; i tmi ghtde c r e a s e ‑t hec a us a ld i a g r a mdoe s n' 日e l lyo uwha twi ha p pe n. Ra t he r , i tt e l l syo uwha twoul dha ppe ni ft heva r i a bl ewe r et oc ha nge. No t et heph r a s eabov e( orbe l ow)whati tot he r wi s ewoul dhav ebee ni nt he de f i ni t i o no fl i n kpo l a r i t y. Ani nc r e a s ei nac a us eva r i a bl edoe snotne c e s s a r i l y me a nt hee fe c twi l la c t ua l l yi nc r e a s e . The r ea r et wor e a s o ns .Fi r s t ,ava r i a bl eo f ‑ t e nha smo r et ha no neI nput . T bde t e r mi newha ta c t ua l l yha ppe nsyo une e dt oknow howa l lt h ei n put sa r ec ha ngi ng. I nt h epo pul a t i o ne xa mpl e ,t hebi r t hr a t ede pe nds TABL E5・ l Li nkpol ar i t y : d e f i ni t i on san de x ampl es Symbo一 x〜 l nt er pr et at i on Mat hemat i cs Al l el s ee qu al , i fXi n c r eas e s ∂ Y/ ∂ X>0 ( de cr eas e s ) , t h enYi n c r eas es I nt h ec as eo f + ( decr eas es )abo v e( b el o w) , a c c u m u l a t i o n s y wh a tI ' twoul dh av eb een. I ・ t I nt hec a s eo fa c c umul a t i on s, Y‑J t 。 ( x+・‑) ds+Yto Xad dst oY. x a m 一 + 一 1 p一 es E + r u Oad I E . c y t ‑ P Q Ef fo r t S ‑ R su l t s e + Bi r t hs Popul a t i on Al l el s eequ al , i fXi n cr eas es ∂ Y/ ∂ ×<0 pB o , F c u e c ㌫ sal es ( decr eas e s ) , t h enYde c r e as es l nt hec as eo f ( i n cr eas e s )b el o w( ab o v e) ac c umul a t i on s, Y wh a ti twoul dh av eb een. e s Fr us t r a t i 蒜 づ虹Resur I nt hec as eo fac c umu l a t i on s, Y ‑ 仁 × + .・ ・ ) d s+Yt。 一 一二 由一 Xs u b t r ac t sf r omY. Deat hs Popul at i on L‑ x〜 ales 140 P a r tI IT o o l sf o rS y s t e ms T h i n k i n g o nbo t ht he丘. a c t i o na lbi r t hr a t ea ndt hes i z eo ft hepo pul a t i on( t ha ti s , Bi r t hRa t e‑ Fr a c t i ona lBi r t hRa t e* Po pul a t i on) . Yo uc a n nots a ywhe t he ra ni nc r e a s ei nt he f r a c t i ona lbi r t hr a t ewi l la c t ua l l yc a us et hebi r t hr a t et or i s e; youa l s one e dt okno w whe t he rt hepo pul a t i oni sr l S l ngO rf a l l i ng. Al a r gee no ug hdr o pl nt hepo pul a t i o n ma yc a us et hebi r t hr a t et of a l le ve ni ft hef r a c t i ona lbi r t hr a t er i s e s . Whe na s s e s s ‑ i ngt hepol a r i t yofi ndi vi d ua ll i nks , a s s u mea l lot he rva r i a bl e sa r ec o ns t a nt( t hef a ‑ e t er i spar i bus ) .Whe na s s e s s i ngt hea c t ua lbe ha v i o rofa mo usa s s umpt i o nofc s ys t e m,a l lva r i a bl e si nt e r a c ts i mul t a ne o us l y( a l le l s ei snote qua l )a ndc o mput e r s i mul a t i o ni sus ua l l yne e de dt ot r a c eo u tt hebe ha v i o ro ft hes ys t e ma ndde t e r mi ne t . whi c hl o opsa r edo mi na n Se c ond,a ndmo r ei mpo r t a nt l y ,C a us a ll oo pd i a g r a msdonotdi s t i ng ui s hbe ‑ t we e ns t o c ksa ndf lows ‑t hea c c umul a t i o nso fr e s ou r c e si nas ys t e ma n dt her a t e s ofc ha nget ha ta l t e rt hos er e s o u r c e s( S e ec ha pt e r6) ・ I nt hepo pul a t i o ne xa mpl e , t he po pul a t i o ni sas t oc k ‑i ta c c u mul a t e st hebi r t hr a t el e s st hedea t hr a t e . Ani nc r e a s e i nt hebi r t hr a t ewi l li nc r e a s et hepo pul a t i o n, butade c r e a s ei nt hebi r t hr a t ed oe s no tde c r e a s et hepo pul a t i o n・Bi r t hsc a nonl yi nc r e a s et hepo pul a t i o n,t he yc a n ne ve rr e d uc ei t 。Thepos i t i vel i n kbe t we e nbi r t hsa ndpopul a t i o nme a nst ha tt he bi r t hr a t ea ddst ot hepo pul a t i o n. Thusa ni nc r e a s ei nt hebi r t hr a t ei nc r e a s e st he po pul a t i o na bovewha ti to t he r wi s ewo ul dha vebe e na ndade c r e a s ei nt hebi r t h r a t ede c r e a s e spo pul a t i onbe l o wwha ti to t he r wi s ewo ul dha vebe e n. l y , t hene ga t i vepo l a nt yoft hel i n kf r o mt hede a t hr a t et opo pul a t i o ni n‑ Si mi l a r di c a t e st ha tt hed e a t hr a t es u bt r a c t sf r omt hepo pul a t i on. Adr o pl nt hede a t hr a t e doe sno ta d dt ot hepo pul a t i o n. Ad r o pi nd e a t hsme a nsf e we rpe o pl ed i ea ndmo r e hani twoul dot henvi s ehav ebe e n. No t et ha t r e ma i na l i ve: t hepo pul a t i oni shi g he rt yo uc a nnott e l lwhe t he rt hepo pu l a t i o nwi l la c t ua l l ybei nc r e a s l ngO rd e c r e a s l ng: Po pul a t i onwi l lbef a l l i nge ve ni ft hebi r t hr a t ei sr i s l ngi ft hede a t hr a t ee xc e e ds bi r t hs ・ Tok n owwhe t he ras t o c ki si nc r e a s l ngO rde c r e a s i ngyoumuS tk no wi t sne t r a t eo fc ha nge( i nt hi sc a s e , bi r t hsl e s sd e a t hs ) . I ti sa l wa yst ue r , ho we ve r , ha t ti ft he bi r t hr a t er i s e s , po pul a t i o nwi l lr i s ea bo vewha ti two ul dha vebe e ni nt hea bs e nc e o ft hec ha ngei nbi r t hs , e ve ni ft hepo pul a t i o nc o nt i nue st of a l l . Po pul a t i o nwi l lbe he r wi s ewo ul d. Cha pt e r s6a nd7di s c us st hes t r u c ‑ f a l l i nga tas l owe rr a t et ha ni tot lo ws , t ur ea ndbe ha vi o ro fs t oc ksand f Pr ocessPoI ' nt . ・ ANot eonNot at i on l ns omeo ft hes ys t e md y na mi c sl i t e r a t ur e , e s pe c i a l l yt hes ys t e mst hi n k i ngt r a d i t i o n ( s e e , e. g. , Se ng ee ta l .1 99 4a ndKi n1 9 92) , a na l t e r na t ec onve nt i o nf o rc a us a ldi a ‑ g r a l r l Sha sde ve l o pe d.I ns t e a dof幸o r‑t hepol a r i t yOfac a us a ll i nki sde no t e d byso ro,r e s pe c t i ve l y( de no t i ngt hes a meo ro ppos i t er e l a t i o ns hi pbe t we e ni nde ‑ pe nde nta ndde pe nde ntva r i a bl e s ) : S x一一 1輸血 . Yi ns t e a do fX 一一 ‑ 0 + 曲虹 Y x一一 一 一「鮎 . yi ns t e a dofx 一一一「鮎 .Y Cha pt e r5 Ca us a l Loo pDi a g r a ms 1 41 Thel i nkde not e dwi t ha nsi sr e a da s" Xa ndYmo vei nt hes amedi r e c t i o n" ppo s i t ed i r e c ‑ whi l et hel i nkd e no t e dwi t ha noi sr e a da s" Xa ndYmovei nt heo t i o n. "ThusPr o d uc tQua l i t ya ndSa l e st e ndt omo vei nt hes a medi r e c t i o nwhi l e Pr o d uc tPr i c ea n dSa l e st e ndt omov ei nt heo ppos i t ed i r e c t i o n. Thesa ndonot a t i o nwa smo t i va t e dbyade s i r et oma kec a us a ldi a g r a mse ve n e a s i e rt ounde r s t a ndf o rpe o pl ewi t hl i t t l ema t he ma t i c a lba c kg r o und. Whi c hno t a ‑ t i o ni sbe t t e ri sho t l yde ba t e d.Ri c ha r ds on( 1 99 7)pr ovi dess t r onga r g ume nt s a ga l nS tt heus eo fsa ndo.Heno t e st ha tt hes t a t e me n t" Xa ndYmovei nt hes a me d i r e c t i o n"i sno ti nge ne r lc a o r r e c t , f o rt her e a s o nss t a t e da bo ve. Thec o r r e c ts t a t e ‑ me nti s ," I fXi nc r e a s e s , Yi nc r e a s e sabov ewhati twoul dhav ebe e n. "Tha ti s ,a c a us a ll i nki sac o nt l nge ntS t a t e me n tO ft hei nd i vi d ua le fe c tofahypot he s i z e d c ha ng e . Theva r i a bl e sXa ndYma ybepos i t i ve l yl i nke da ndye t Yma yf a l le ve na s Xi nc r e a s e s ,a sot he rva r i a bl e sa l s oa fe c tY.Thesa ndode f i ni t i onsa l s odo n' t wo r kf o rs t oc ka ndf lowr e l a t i o ns hi ps .Bi r t hsa ndpo pul a t i o ndonotmovei nt he s a medi r e c t i o n: ade c r e a s ei nbi r t hsd o e sno tc a us epo pul a t i o nt ode c r e a s ebe c a us e t hebi r t hr a t ei sa ni nf lo wt ot hes t oc ko fpo pul a t i o n. Thec o r r e c tde f i ni t i o ni sg i ve n i nTa bl e51 1 : f o rpos i t i vel i n kpo l a r i t y , i fXi n c r e a s e s , Ywi l la l wa ysbehi g he rt ha n i twoul dha veb e e n;f orne ga t i vepol a r i t y ,i fXi nc r e a s e s , Ywi l la l wa ysbel owe r t ha ni two ul dha vebe e nJnt hi sboo kIwi l lus et he+a nd‑s i gnst Ode no t el i n k pol a r i t y . Asamo de l e ryous ho ul dk no who wt oi n t e r pr e tt hesa ndono t a t i o nwhe n nd‑no t a t i ont ode no t el i n kpo l a r l t y・ yo us e ei t , buty o us houl dus et he+a 5N 望 G u旧EuNESFOR CAUSALLo opDI AGRAMS 5. 2. 1 Causat i onver susCor r e一 at i on Eve r yl i nki nyo urdi a g r a m mus tr e pr e s e nt( wha tyo ube l i e vet obe )C a us a lr e l a t i o ns hi psbe t we e nt heva r i a bl e s . Yo umus tno ti nc l udec o r r e l a t i o nsbe t we e nva r 1 ‑ , s i mul we ,me a ns" t oi mi t a t e. "As ys t e m a bl e s . TheLa t i nr oo toft hewo r ds i mul a t e d y na mi c smode lmus tmi mi ct hes t r uc t u r eo ft her e a ls ys t e mwe l le no ug ht ha tt he mode lbe ha ve st hes a mewa yt her e a ls ys t e mwo ul d・Be ha vi o ri nc l ude sno to nl y r e pl i c a t i nghi s t o r i c a le x pe r i e nc ebuta l s or e s pond i ngt oc i r c u ms t a nc e sa ndpo l i c i e s hav i orofa t ha ta r ee nt i r e l ynove l . Co r r e l a t i o nsa mo ngva r i a bl e sr e le f c tt hepa s tbe s ys t e m. Co r r e l a t i o nsdonotr e pr e s e ntt hes t r u c t u r eo ft hes ys t e m・ I fc i r c ums t a nc e s c ha ng e ,i fpr e vi o us l ydor ma n tf e e d ba c kl o o psbe c o medomi na nt ,i fne wpol i c i e s a r et r i e d, pr e vi o us l yr e l i a bl ec o r r e l a t i o nsa mongva r i a bl e sma ybr e a kdown・ Yo ur mod e l sa ndc a us a ld i a g r a msmus t i nc l udeo nl yt hos er e l a t i o ns hi psyo ube l i e vec a p‑ t u r et heunde r l y i ngc a us a ls t r uc t u r eo ft hes ys t e m.Co r r e l a t i onsa mo ngva r i a bl e s t ・ wi l le me r gef r o mt hebe ha v i o ro ft hemo de lwhe nyo us i mul a t ei Tho ug hs a l e sofi c ec r e a ma r epos i t i ve l yc o r r e l a t e dwi t ht hemur de rr a t e , yo u ma yno ti nc l udeal i nkf r o mi c ec r e a ms a l e st omur d e ri nyo u rmo de l s . I ns t e a d, a s s howni nFi gur e5‑ 2, bot hi c ec r e a ms a l e sa ndmur de rr i s ei ns umme ra ndf a l li n wi nt e ra st hea v e r a get e mpe r a t u r ef luc t ua t e s . Co nf us i ngc o r r e l a t i o nwi t hc a us a l i t y c a nl e a dt ot e r r i b l emi s j udg me nt sa ndpo l i c ye r r o r s . Themod e lo nt hel e f ts i d eof Fi g ur e5‑ 2s ugg e s t st ha tc ut t l ngl C eC r e a mC OnS umpt l OnWO ul ds l a s ht hemu r d e r r a t e , s a vel i ve s , a nda l l ows oc i e t yt oc u tt heb udge tf o rpo l i c ea ndpr i s ons ・ ‑ 1 42 FI GURE5 ‑ 2 Cau s al di agr ams mu s ti n cl u de onl y( wha tyou bel i e v et obe) genu i nec aus al r el a t i on sh i ps. P a r t I IT わ o l sf o rS y s t e ms T h i n k i n g Cor r ect l ncor r ect r 日 ceCr eam Sal es ' Mur der Ra t e l ceCr eam SaJ es ‑ 1 t = t ‑ ‑ Aver age Temper a t ur e Whi l ef e wpe o pl ea r el i ke l yt oa t t r i but emur de r st ot heo c c a s i o na ldo ubl e ‑ di p c o ne ,ma nyc o r r e l a t i o nsa r emo r es u bt l e ,a ndi ti so f t e ndi f f i c u l tt od e t e r mi net he unde r l yi ngc a us a ls t r uc t u r e . Ag r e a tde a lofs c i e nt i f i cr e s e a r c hs e e kst hege nui ne c a us a lne e d l e si nahugeha ys t a c kofc o r r e l a t i ons :Do e svi t a mi nCc u r et hec o m‑ mo nc ol d?Ca ne a t l ngOa tbr a nr e d uc ec ho l e s t e r o l ,a ndi fi tdoe s , wi l lyo u rr i s kof ahe a r ta t t a c kd r o p?Do e se c o no mi cg r owt hl e a dt ol o we rbi r t hr a t e s , o ri st hel owe r r a t ea t t r i but a bl et ol i t e r a c y ,e duc a t i onf o rwome n,a ndi nc r e a s l ngc os t sOfc hi l d r e a r i ng?Doc o mpa ni e swi t hs e r i o usq ua l i t yI mpr o ve me ntp r og r a mse a r nS u pe r i o r r e t ur nsf o rs t oc kho l de r s ?Sc i e nt i s t sha vel e a r ne df r ombi t t e re x pe r i e nc et ha tr e l i ‑ a bl ea ns we r st os uc hque s t i o nsa r eha r dt oc omebya ndr e q ui r ede d i c a t i ont ot he s c i e nt i f i cme t hod ‑c o nt r o l l e de xpe r i me nt s , r a ndo mi z e d, do u bl e ‑ bl i ndt ia r l s , l a r ge s a mpl e s ,l o ng‑ t e r mf o l l ow‑ u ps t ud i e s , r e pl i c a t i o n,s t a t i s t i c a li nf e r e nc e ,a nds oo n. I nt hes oc i a la ndhu ma ns ys t e msweof t e nmode l ,s uc he x pe r i me nt sa r ed i f f i c ul t , r a r e ,a ndof t e ni mpos s i bl e . Mod e l e r smus tt a kee xt r ac a r et oc o ns i d e rwhe t he rt he r e l a t i o ns hi psi nt he i rmod e l sa r ec a us a l , noma t t e rhows t r o ngt hec o r r e l a t i o n, how hi ght heR2 ,0 rhowg r e a tt hes t a t i s ic t a ls l gni f i c a nc eo ft hec oe f f i c i e nt si nar e ‑ e d, gr e s s i o nma ybe.Ast heEng l i s he c o nomi s tPhe l ps ‑ Br own( 1 9 ,p.6)not " Whe r e ,a ss oo f t e n, t hef luc t ua t i onso fdi fe r e nts e r i e sr e s po ndi nc o mmo nt ot he pul s eo ft hee c o no my , l ti sf a t a l l ye a s yt oge tagoodf i t , a ndg e ti tf o rqul t eanum‑ be rofdi fe r e nte q ua t i o ns‥ .Runnl ngr e g r e S S i o nsbe t we e nt i mes e r i e si sonl y l i ke l yt ode c e i ve . 門 7 2 5. 2. 2 Labe圭 i f l gL≡ nkPo知 和 Bes ur et ol a be lt hepol a r l t yO fe ve r yl i n ki nyou rdi a g r a ms . La be lt hepo l a r i t yof t hei mpo r t a r l tf T e e d ba c kl oo psi l lyO l t i i ‑ d i a g r a ms ,‑ t i S i ngt hed e f i n i t i o T I Si l lTa bl e5‑ 1 i t i v ef e e d‑ t ohe l pyoude t e r mi newhe t he rt hel i nksa r epos i t i veo rne ga t i v e.Pos bac kl oo psa r ea l s oc a l l e dr ei n f or c i ngl oo psa nda r ede no t e dbya+o rA,whi l e ne gat i v el oo psa r es o me t i me sc a l l e dbal anc i ngl oo psa nda r ede no t e dbya‑o rA ( Fi g ur e5‑ 3 ) . 143 Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms Ft GURE5 ‑ 3 LabeHi nkan dl oop pol ar i t i es. Not et hatal l l i nk s ar el abel edand l ooppol ar i t y i den t i f i er sshow whi chl oopsar e posi t i v eandwhi ch ar enega t i ve. Loopi den t i f i er s ar ecl ock wi s e f ort hecl ock wi s e l oops( andvi ce ver s a) [ l ncor r ect sa. es. r . r Wor dof .√ ( Cus t omer Base "ouL ノノ \ J ヽ Cus t omer LossRat e j Cor r ect sa. es. r . r Wo r dof ・ .√ Cust omer R J Base 量三 " o ・ u し こ ノ \ ヽ Cus t omer B r LossRat e ̲ i 皇 = j v ・ 5 . 2 . 3 De t e r mi ni n gL oopPo一 a r i t y The r ea r et wome t hodsf orde t e r mi nl ngWhe t he ral oopl Spos i t i veo rne ga t i ve: t he f a s twa ya ndt h er i ghtwa y. 144 P a r t I IT o o l sf o rS y s t e ms Th i n k i n g TheFastWay:Countt heNumberofNegat i v eLI ' nks Thef a s twa yt ot e l li fal oo pl Spos i t i veo rne ga t i vei st oc o untt henumbe rof ne ga t i vel i n ksi nt hel oo p. I ft henumbe rofn e ga t i vel i n ksi se ve n, t hel oo pI Spos i ‑ t i ve;i ft hen umbe ri sod d,t hel oo pl Sne ga t i ve ・ Ther ul ewor ksbe c a us epos i t i ve l oo psr e i nf o r c ec ha ngewhi l ene ga t i vel oo psa r es e l f ‑ c o r r e c t i ng;t he yo ppos edi s ‑ t u r ba nc e s . I ma g l neaS ma l ld i s t ur ba nc ei noneo ft heva r i a bl es . I ft hedi s t ur ba nc e pr o pa g a t e sa r o undt hel o o pt or e i nf o r c et heo r l g l na lc ha nge , t h e nt hel oo pI Spos i ‑ t i ve . I ft hedi s t u r ba nc epr o pa ga t e sa r o undt hel o o pt oo p pos et heo r l g l na lc ha nge , t he nt hel oo pl Sne ga t i ve . T bo ppos et hedi s t u r ba nc e , t hes l g na lmus te xpe r i e nc ea ne ts l g nr e ve r s a la si tt r a ve l sa r o undt hel o o p・ Ne tr e v e r s a lc a nonl yoc c uri ft he nu mbe ro fne ga t i vel i n ksi so dd. As i ng l en e ga t i v el i n kc a us e st hes i gna l t or e ve r s e: a ni nc r e a s ebe c ome sade c r e a s e.Buta not he rne ga t i vel i n kr e ve r s e st hes l gna l l n,S Ot hed e c r e a s ebe c ome sa ni nc r e a s e , r e i nf o r c l ngt heo r l g l na ldi s t ur ba nc e. a ga Se e" Ma t he ma t i c so fLoo pPol a r i t y "be l o wf o raf o r ma ld e r i va t i o noft hi sr ul e. t . Whymi g hti tf a i l ? Thef a s tme t hoda l wa yswo r ks... e xc e ptwhe ni tdoe s n' I nac o mpl e xd i a g r a mi ti sa l lt ooe a s yt omi s c o un tt hen umbe rofne ga t i vel i nksi n al oo p. Andi ti se a s yt omi s l a be lt hepo l a r l t yO fl i n kswhe nyo uf i r s td r a wt hed i a g r a m. Co unt l ngt hen umbe rofne ga t i ves l g nSi sun l i ke l yt or e ve a l t he s ee 汀O r S . The r i g htme t hod, C a r e f ul l yt r a c l ngt hee f f e c to fadi s t u r ba nc ea r o undt hel oo p, wi l lo f ‑ t e nr e ve a lawr o ng l yl a be l e dpol a r i t ya ndwi l l he l pyo ua ndyo u ra udi e nc et og r a s p t heme a n l nga ndme c ha ni s mo ft hel oo p, As s i g nl ngl oo ppol a r i t yt her i ghtwa y r a t he rt ha nt hef a s twa ys a ve st i mei nt hel o ngr un・ ‑ TheRi ghtWay:T r acet heEf f ectofaChangear oundt heL oop Ther i ghtwa yt ode t e r mi net hepol a r i t yo fal oo pI St Ot r a c et hee fe c tofas ma l l I ft hef e e d ba c ke f ‑ c ha ng ei no neo ft heva r i a bl e sa sl tPr o pa ga t e sa r o u ndt hel o o p・ f e c tr e i nf o r c e st heo r l gl na lc ha ng e, i ti sapos i t i vel oo p; i fi to ppos e st heo r l gl na l c ha nge , i ti sane ga t i vel oo p. Yo uc a ns t a r twi t ha n yva r i a bl ei nt hel oo p; t her e s ul t mus tbet hes a me.I nt hema r ke tl oo pss howni nFi g ur e5‑ 3,a s s umes a l e sf r om wo r do fmo ut hi nc r e a s e. Be c a us et hel i nkf r o ms a l e sf r o mwo r do fmout ht ot he c us t ome rba s ei spos i t i ve , t hec us t o me rba s ei nc r e a s e s ・ Be c a us et hel i nkf r o mt he c us t o me rba s eba c kt os a l e sf r o mwo r do fmo ut hi spos i t i ve , hes t i gna lpr o pa ga t e s a r o undt h el oo pt oi nc r e a s es a l e sf r o mwor do fmo ut hs t i l l f u r t he r . Thef e e d ba c ke f ‑ f e c tr e i nf o r c e st heo r l gl na lc ha nge ,s ot hel oo pI Spos i t i ve.Tur ni ngt Ot heot he r , l oo p, a s s u meas ma l li nc r e a s ei nt hec us t o me rl os sr a t e. I fc us t o me rl os s e si nc r e a s e t hec us t o me rba s ef a i l s . Wi t hal owe rc us t o me rba s e ,t he r ea r el r e We rC us t ome r s whoc a nd r o po ut . Thef T e e d ba c ke fe c to p pos e st heo r l g l na lc ha nge ,s ot hel oo pI S ne ga t i ve. Th i sme t hodwo r ksnoma t t e rhowma nyva r i a bl e sa r ei nal oo pa ndnoma t t e r whi c hva r i a bl eyo us t a r twi t h. ( I de nt i f yt hel oo ppo l a r i t i e sf o rt hee xa mpl es t a r t i ng wi t hc us t o me rba s ei ns t e a dofs a l e s丘・ omwo r do fmo ut h: yo us hou l dge tt hes a me r e s ul t ) . Yo uma ya l s oa s s umea ni ni t i a lde c r e a s ei nava r i a bl er a t he rt ha na ni ni t i a l I nc r e a s e. 145 Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms E dent i f yi ngLi nkandLoopPobr i t y I de nt i f ya ndl a be lt hepol a r i t yoft hel i nksa ndl oo psi nt hee xa mpl e ss howni n Fi g ur e5 ‑ 5. e n e s s C u m u 一 a t i v e k t P r o d u c t i o n \ \ l 了 了 C N u m b e r o f M a r k e t U n i t C o s t s o m p e t i t o r s 誓\P p r √一 / ノ ieeJ r i c e A t t r a c t i v o f M a r Shar e ㌧ Pr essur ' et oCl ean F upEnvi r onment㌔ Envi r onment a】 Cl eanup Qual i t y Ef f or t > \ \ ‑ 」 ̲ ノー // ー Pr B a n k C a s h R e s e r v e s \ \ ・ \ 勺 了 P e r c e i v e e t d r a w a l sS o l v e n B a N wi t h d cyof k も \一 一/ / Mat hemat i csofLoopPol ar i t y Whe nyoude t e r mi nel oo ppol a r l t y,youa r eC a l c ul a t l ngWha ti sknowni nc ont r ol t he or ya st hes l g nOft heope nl oo pga i noft hel oop. Thet e r m" ga i n"r e f e r st ot he s t r e ngt hoft hes l gna lr e t ume dbyt hel oop:aga i nOft wome a nsac ha ngei nava r i ‑ a bl ei sdo ubl e de a c hc yc l ea r oundt hel oo p;aga l nOfne ga t i ve0. 5me a nst hedi s t ur ba nc epr opa ga t esa r oundt hel oopt ooppos ei t s e l fwi t has t r e ngt hha l fa sl a r ge. Thet e m H ope nl oo p"me a nst hega l ni sc a l c ul a t e df orJ us tonef e e dba c kc yc l eby br e a ki ng ‑ope n l ng ‑t hel oopa ts omepol nt ・Cons i de ra na r bi t r a r yf e e dba c kl oop c ons i s t l ngOfnva r i a bl es ,x l,.I・,Xn . Youc a nc a l c ul a t et heo pe nl oopga i na ta ny pol nt ; l e txlde n o t et heva r i a bl eyouc hoos e. Whe nyo ubr e a kt hel oop, Ⅹ1S pl i t si nt o a ni nput ,XI I ,a ndout put ,xl O( Fi gur e51 6) .Theope nl oopga i ni sde f i ne dast he ( pa r t i l)de a r i va t i veofxl Owi t hr e s pe c tt oXI I , t ha ti s , t hef e e d ba c ke f f e c tofas ma l l c ha ngei nt hev a r i a bl ea si tr e t ur nst oi t s e l f . Thepol a r i t yoft hel oo pi st hes i gnof t heope nl oopg a l n: ‑ Po l a r i t yo fl o o p‑SGN( ∂ Ⅹ1 0 / ∂ Xi i ) ( 5‑ 1 ) whe r eSGN( )i st hes i gnum ors i gnf unc t i on, r e t ur ni ng+1i fi t sa r gume nti spos i ‑ t i vea nd‑1i ft hea r g ume nti sne ga t i ve( i ft heope nl oo pga i ni sz e r o,t heSGN f unc t i on‑0:t he r ei snol oop) A Theope nl oopga i ni sc a l c ul a t e dbyt hec ha i nr ul e f r om t hega l nSO ft hei ndi vi dua ll i nks ,∂ xl / ∂ xl 【1 : SGN( ∂ xl O / ∂ x1 7 )‑sGN[ ( ∂ xl O / ∂ x n ) ( ∂ X n / ∂ x n ̲1 ) ( ∂ X n ̲1 / ∂ xn ̲2)・・ ・ ( ∂ x2/ ∂ xI I ) ] ( 5‑ 2) 146 Fd GURE5 ‑ 6 Cal c ul a t i n gt h e op en ‑ l oopgal n ofal o op t h e ‑ o p a t a n y p i n t ∴‑ I も t 了x l O 「 e f . u e n c x L3 ) , )4 fe x Lx r ° Pa r tI I ¶) o l sf o rS y s t e ms Th i n k i n g Br e ak t r acet h :n望change t he一 oop a x 4 . PoJ ar i t y=SGN( ∂ xl O / ∂ xl l ) 0/ ∂ xl l ‑( ∂Ⅹ1 0/ ∂Ⅹ4 ) ( ∂ Ⅹ4 / ∂ x3 ) ( ∂Ⅹ3 / ∂ x2 ) ( ∂x2 / ∂x I B ) ∂ xl Si nc et hes i g nofapr od uc ti st hepr o duc toft hes l gnS ,l oo ppol a r l t yl Sa l s o g l Ve nby: SGN( ∂Ⅹ1 0 / ∂ Ⅹ1 Ⅰ )‑SGN( ∂ Ⅹ1 0 / ∂ X 。 )* SGN( ∂ X 。 / ∂ Xn ー1 )辛S GN( ∂ x 。 ̲1 / ∂ X n ̲2 ) *・ ・ ・ *SGN(ax2/axi I ) ( 51 3) Us i ngt her i g htme t hodt ode t e r mi nel oo ppo l a r i t ybyt r a c l ngt hee fe c tofa s ma l lc ha ngea r oundal oo pi se qui va l e ntt oc a l c ul a t i nge qua t i on( 5‑ 3) . Eq ua t i o n ( 5‑ 3 )a l s oe xpl a i nswhyt hef a s tme t ho dwo r ks :Si nc et hepr od uc toft wone ga t i ve s l g nSi sapos i t i ves l gn, ne ga t i v eo pe nl oo ppo l a r l t yr e q ul r e Sa nOddn umbe ro fn e g‑ a t i vel i n ksi nt hel oo p。 Al lLi nksShou/ dHav eUnambi guousPol an ' t i es So me t i me spe o pl es a yal i nkc a nbee i t he rpos i t i veo rne ga t i ve , de pe ndi ngo no 血e r pa r a me t e r soro nwhe r et hes ys t e mi so pe r a t l ng. Fo re xa mpl e ,pe o pl eo f t e nd r a w 血edi a g r a mo nt hel e f ts i deo fFi g u r e5‑ 7r e l a t l ngaf i r m' sr e ve nuet ot hepr l C eO f i t spr o d uc ta ndt he na r g uet ha t t hel i n kbe t we e npr l C ea ndc o mpa nyr e ve nuec a nbe e i t he rpos i t i veo rne ga t i ve ,de pe ndi ngo nt hee l a s t i c i t yOfde ma nd.I fde ma ndi s %i nc r e a s ei npr l C e hi g hl ye l a s t i c ,ahi g he rpr l C eme a nsl e s sr e ve nuebe c a us ea1 %. Thel i nkwoul dha vene ga t i v epol a r i t y. I fd e ‑ c a us e sde ma ndt of a l lmo r et ha n1 i c, t he na1 %i nc r e a s ei np r l C eC a us e sde ma ndt odr o pl e s st ha n1 %, ma ndi si ne l a s t s or e ve nue sr i s e. Thel i nkwo ul dbepos i t i ve . I ta ppe a r snos i ngl epol a r i t yc a nbe a s s l g ne d. Whe nyouha vet r ou bl ea s s l g nl ngaC l e a ra nduna mbi guo uspol a r i t yt oal i n ki t us ua l l yme a nst he r ei smo r et ha no nec a us a l pa t hwa yc o nne c t l ngt het wova r i a bl e s . Yo us ho ul dma ket he s ed i fe r e ntpa t hwa yse x pl i c i ti nyo urd i a g r a m. I nt hee xa m‑ pl e , pr i c eha sa tl e a s tt woe f f e c t so nr e v e nue:( 1 )i tde t e r mi ne showmuc hr e v e nue i sg e ne r a t e dpe runi ts ol da nd( 2)i ta f f e c t st henumbe ro funi t ss ol d. Tha ti s , Re ve ‑ nue‑Pr i c e* Sa l e s ,a nd( Uni t )Sa l e sde pe ndo nPr i c e( pr e s uma bl yt hede ma nd c u r vei sdownwa r ds l opi ng:Hi ghe rp r i c e sr e d uc es a l e s ) .Thepr o pe rd i a g r a mi s 147 Cha pt e r5 Ca us a lLoo pDi a g r a ms FI GURE 5‑ 7 Cau s a川nk s mus th a v e unambi guou s p ol ar i t y . App ar en t l y ambi gu ou s poL ar i t i esusu al l y i n di c a t et h e pr es en c eof mul t i pl ec au s al pat h wa y st ha t s houl dbe r epr es en t ed s epar a t e一 y . Cor r ect l ncor r ect r P r i c e ,( ・o r‑ ) R e v enue r ・ R e v e n u e Pr i ce \ Jメ + sa. es s ho wno nt her i g hts i deofFi gu r e51 7. Th e r ei sno wnoa mbi gui t ya bo utt hepol a r 1 1 t yO fa n yo ft h el i n ks . Thepr i c ee l a s t l C l t yO fde ma ndde t e r mi ne swhi c hc a us a l pa t hwa ydo mi na t e s ・ I f d e ma ndi sq ui t ei ns e ns i t i vet opr i c e( t hee l a s t i c i t yo fd e ma ndi sl e s st ha no ne ) , t he n t hel o we rpa t hi nFi g ur e5‑ 7i swe a k,pr l C er a i s e suni tr e ve nuemo r et ha ni tde ‑ c r e a s e ss a l e s ,a ndt hene te f f e c tofa ni nc r e a s ei npr i c ei sa ni nc r e a s ei nr e ve nue. Co nve r s e l y ,i fc us t o me r sa r equi t epr i c es e ns i t i ve( t hee l a s t i c i t yofde ma ndi s g r e a t e rt ha no n e ) ,t hel o we rpa t hdo mi na t e s . Thei nc r e a s ei nr e ve n uepe runi ti s mo r et ha no f f s e tbyt hede c l i nei nt hen umbe ro fu ni t ss ol d,s ot hene te fe c tofa pr i c er i s ei sad r o pl nr e ve n ue. Se pa r a t l ngt hepa t hwa ysa l s oa l l o wsyo ut os pe c i f y di f f e r e n td e l a ys , i fa ny ,l ne a c h. I nt hee xa mpl ea bove , t he r ei sl i ke l yt obeal o ng de l a ybe t we e nac ha ng ei npr l C ea ndac ha ng ei ns a l e s , whi l et he r ei sl i t t l eo rnode ‑ l a yl nt hee f f e c to fpr i c eo nr e ve n ue. Se pa r a t l ngl i nkswi t ha ppa r e nt l ya mbi g uo uspo l a r i t yI nt ot heunde r l y i ngmul ‑ t i pl epa t hwa ysi saf r ui t f u lme t hodt ode e pe nyo urunde r s t a ndi ngoft hec a us a l e , d e l a ys , a ndbe ha vi oroft hes ys t e m. s t r u c t ur Enl Pi oyeeMo的f at i on Yo urc l i e ntt e a mi swo r r i e da bo ute mpl o ye emot i va t i o na ndi sde ba t i ngt hebe s t wa yst oge ne r a t ema xi mume fo r tf r o mt he i rpe o pl e・ The yha ved r a wnadi a g r a m ( Fi g u r e5‑ 8 )a n da r ea r gui nga bo utt hepo l a r i t yo ft hel i n ks ・ Oneg r o upa r g ue st ha t t heg r e a t e rt hepe r f o r ma nc es ho r t f a l l( t heg r e a t e rt hega pbe t we e nRe qui r e dPe r f o r ma nc ea ndAc t ua lPe r f o r ma nc e ) , t heg r e a t e rt hemo t i va t i ono fe mpl oye e swi l l be . The ya r guet ha tt hes e c r e to fmot i va t i o ni st os e ta gg r e s s i ve , e ve ni mpos s i bl e goa l s( s oI C a l l e ds t r e t c ho b j e c t i ve s )t oe l i c i tma xi mummo t i va t i ona nde fo r t . The o t he rg r o u pa r g ue st ha tt o obi gape r f o r ma nc es ho r t f a l ls i mpl yc a us e sf r us t r a t i o na s pe o pl ec o nc l ud et he r ei snoc ha nc et oa c c o mpl i s ht hegoa l , s ot hel i nkt oe mpl o ye e mo t i va t i o ns ho u l dbene ga t i ve. Ex pa ndt hed i a g r a mt or e s o l vet hea p pa r e n tc o n li f c t byi nc o r po r a t i n gbot ht he o r i e s . Di s c us swhi c hl i n ksdo mi na t eunde rdi f f e r e ntcr c ums t a n c e s . Ca nyougi ves o mee xa mpl e sf r o myou rowne x pe r i e nc ewhe r et he s e di f f e r e ntpa t hwa yswe r edomi na nt ?Howc a nama na ge rt e l lwhi c hpa t hwa yl S l i ke l yt odo mi n a t ei na n ys i t ua t i on?W h a ta r et hei mpl i c a t i o nsf o rgoa ls e t t l ngl nO r ‑ ga ni z a t i ons ?Ac t ua la ndr e q ui r e dpe r f o r ma nc ea r enote xoge no usbutpa r toft he f e e d ba c ks t r uc t u r e .How doe smo t i va t i o nf e e dba c kt ope r f o r ma nc e ,a ndho w mi g hta c t ua l pe r f o r ma nc ea f f e c tt hegoa l ?I nd i c a t et he s el oo psi nyo urdi a g r a ma nd e x pl a i nt he i ri mpo r t a nc e . i ‑ 148 Pa r t I IT わ o l sf o rS y s t em s Th i n k i n g Act ual Per f or mance \ヽ 〆 / / Requi r ed Per f or mance / Per f or mance Shor t f al l Empl oyee Mot i vat i on 5. 2, 4 N・ 3meYourLoops Whe t he ryouus ec a us a ldi a gr a mst oe l i c i tt heme nt a lmode l sofac l i e ntgr oupo rt o c ommuni c a t et hef e e dba c ks t r uc t ur eofamode l , youwi l lof t e nf i ndyour s e l ft r yi ng t oke e pt r a c kofmo r el oopst ha nyouc a nha ndl e・ Yourdi a gr a msc a ne a s i l yove r ‑ whe l mt hepe opl eyoua r et r yl ngt Or e a c h. Tbhe l pyoura udi e nc ena vl ga t et hene t ‑ wor kofl oops , i t ' She l pf ult ogl Veea c hi mpor t a ntf e e d ba c kanumbe ra ndana me. Numbe r i ngt hel oo psRl , R2, B1 , B2, a nds oonhe l psyoura udi e nc ef i nde a c hl oo p a syoudi s c us si t ・ Na ml ngt hel oo pshe l psyoura udi e nc eunde r s t a ndt hef u nc t i onof e a c hl oo pa ndpr ovi de sus e f u ls hor t ha ndf ordi s c us s i on. Thel a be l st he ns t a ndi nf わr ac ompl e xs e tofc a us a ll i nks ・ Whe nwor ki ngwi t hac l i e ntg r oup,l t ' sof t e npos s i ‑ bl et oge tt he mt ona met hel oop. Ma nyt i mes , t he ywi l ls ugge s tawhi ms i c a l phr a s e o rs omeor ga ni z a t i on‑ s pe c i f i cj a r gonf o re a c hl oop. Fi gur e51 9S howsac a us a ldi a gr a mde ve l ope dbye ngi ne e r sa ndma na ge r si na wor ks hopdes i gne dt oe xpl or et hec a us esofl a t ede l i ve r yf ort he i ror ga ni z a t i on' s des i gnwor k。Thedi a gr a mr e pr es e nt st hebe ha vi oroft hee ngl ne e r St r yl ngt O c ompl e t eapr o j e c ta ga l nS tade a dl i ne. Thee ngl ne e r Sc ompa r et hewo r kr e ma i ni ng t obedonea ga i ns tt het i mer e ma i ni ngbe f or et hede a dl i ne. Thel a r ge rt hega p, t he mor eSc he dul ePr e s s ur et he yf e e l ・Whe ns c he dul epr es s ur ebui l dsup,e ngl ne e r S ha ves e ve r a lc hoi c e s . Fi r s t , t he yc a nwor kove r t i meJns t e a doft heno r ma l50hour s pe rwe e k, t he yc a nc omet owor ke a r l y, s ki pl unc h,s t a yl a t e , a ndwo r kt hr ought he we e ke nd.Bybur ni ngt heMi dni ghtOi l ,t he yi nc r e a s et her a t ea twhi c ht he yc om‑ pl e t et he i rt a s ks ,c utt heba c kl ogofwor k,a ndr e l i e vet hes c he dul epr es s ur e( ba l ‑ a nc i ngl oopB1 ) . Howe ve r , i ft hewor kwe e ks t a yst oohi ght ool ong, f a t i g ues e t si n a ndpr oduc t i vl t yS uf f e r s ・Aspr oduc t i vi t yf a l l s ,t het a s kc ompl e t i onr a t edr ops , whi c hi nc r e a s ess c he dul epr es s ur ea ndl e a dst os t i l ll onge rhour s :t her e i nf o r c i ng Bur no utl oopRll i mi t st hee fe c t i ve ne s sofove r t i me. Anot he rwa yt oc ompl e t et he wor kf a s t e ri st or e duc et het i mes pe ntonea c ht a s k.Spe ndi ngl es st i meone a c h t a s kboos t st henumbe roft a s ksdonepe rhour( pr oduc t i vi t y)a ndr e l i e vess c he dul e pr e s s ur e, t husc l os i ngt heba l a nc l ngl oopB2・ Di s c us s i o noft hena mef ort hi sl oop wa shea t e d.Thema na ge r sc l a i me dt hee ngl ne e r Sa l wa ysgol d‑ pl a t e dt he i rwor k; t he yf e l ts c he dul epr es s ur ewa sne e de dt os que e z eoutwa s t ea ndge tt hee ngi ne e r s t of oc usont hej ob. Thee ngl ne e r Sa r gue dt ha ts c he dul epr es s u r eo f t e nr os es ohi gh t ha tt he yha dnoc hoi c ebutt oc utba c kqua l i t ya s s ur a nc ea nds ki pdoc ume nt a t i on 149 Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms FI GURE 5 ‑ 9 T i m Rm a n m g r + e Nameandnumb er yourl oopst o i ncr easedi agr am cf ar i t yandpr ovi de memor abl el abel s f ori mpor t an t f eedback s. e W o r k R e m a m n g 苛 ≡ て 二 M i d n i g h tと Schedub e Pr es sur e F a t i g u e C o m p 一 e t i o n R a t \ 二 色 鼻 + o u t c t i v i t y i u r n 一 一. P r o d u oft he i rwor k. The yc a l l e di tt heCo me rCut t i ngl oo p( B2) . Thee ngi ne e r st he na ト gue dt ha tc or ne rc ut t i ngl SS e l f ‑ de f e a t l ngbe c a us ei ti nc r e a s est hee r r o rr a t e , whi c h l e a dst or e wor ka ndl owe rpr oduc t i vl t yi nt hel ongr un:" Ha s t ema ke swa s t e , Ht he y s a i d,a nds c he d ul epr e s s ur er i s e sf u r t he r ,l e a di ngt os t i l lmo r epr es s ur et oc utc or ‑ ne r s( l oopR2) . Thef ul lmode li nc l ude dma nymor el oops( s e c t i on5. 1pr ovi de sac l os e l yr e ‑ l a t e de xa mpl e;s e ea l s os e c t i on2. 3) . Thena me sgi ve nt ot hel oopsbyonegr oup ( e ngi ne e r s )c ommuni c a t e dt he i ra t t i t ude sa ndt her a t i ona l ef ort he i rbe ha vi ort ot he ma na ge r si nac l ea ra ndc ompe l l i ngwa y. Thec onve r s a t i ondi dnotde ge ne r a t ei nt o a dhomi ne ma r gume nt sbe t we e nma na ge r ss hout i ngt ha te ngi ne e r sJ us tne e dt o ha vet he i rbut t sk i c ke da nde ngl ne e r Sgr l pl ngt ha tge t t l ngpr omot e dt oma na ge me nt t ur nsyourbr a i nt ol f T e r t i l i z e r ] ‑t hemodeofdi s c our s emos tc ommoni nt heo r ga ‑ ni z a t i onpr l Ort Ot hei nt e r ve nt i on. Pa r t i c l pa nt SS OOnbe ga nt ot a l ka boutt heBur nout Loopki c ki ngl na ndt henonl i ne a rr e l a t i o ns hi psbe t we e ns c he dul epr e s s ur e,ove r t i me, f a t i gue,a nde r r or s . Thena mesf ort hel oopsma dei te a s yt or e f e rt oc ompl e x c hunksoff e e d ba c ks t r uc t ur e. Thec onc e pt sc a pt ur e dbyt hena me sgr a dua l l ybe ga n t oe nt e rt heme nt a lmode l sa ndde c i s i onma ki ngoft hema na ge r sa nde ngl ne e r Si n t heor ga ni za t i o na ndl e dt oc ha ngei nde e pl yI ng r a i ne dbe ha vi or s . ‑ 150 Pa r tH To ol sf o rSys t e msTh i n ki ng 5. 2. 5 ; ndi cat e! n l POr t antDe! ays弓 1 1G訓J Saきし . ∃ nks De l a ysa r ec r i t i c a li nc r e a t l ngd y na mi c s . De l a ysgl VeS ys t e msi ne r t i a , c a nc r e a t es c i l l a t i ons ,a nda r eo f t e nr e s pons i bl ef o rt r a de ‑ of f sbe t we e nt hes ho r t ‑a n dl o n g‑ un r e fe c t sofpol i c i e s . Yo u rc a us a ld i a g r a mss ho ul di nc l ud ede l a yst ha ta r ei mpo r t a n t t ot hed yna mi chy po t he s i so rs i g ni f i c a ntr e l a t i vet oyo urt i meho r i z o n. Ass ho wni n c ha pt e rll , de l a ysa l wa ysi nvo l v es t oc ka ndf l ows t r uc t u r e s .So me t i me si ti si m‑ po r t a ntt os ho wt he s es t r uc t u r e se x pl i c i t l yl nyo urd i a gr a ms . Of t e n, ho we ve r , i ti s s uf f i c i e ntt oi nd i c a t et hep r e s e nc eofat i mede l a yl naC a us a ll i n kwi t ho ute x pl i c ‑ i t l ys howi ngt hes t o c ka ndf lows t uc r t ur e. Fi gur e5‑ 1 0s howsho wt i med e l a ysa r e r e pr e s e nt e di nc a us a ldi a g r a ms . Whe nt hepr l C eO fagoo dr i s e s , s uppl ywi l lt e ndt oi nc r e a s e , b uto f t e no n l ya f ‑ t e rs i g ni f i c a ntd e l a yswh i l ene wc a pa c i t yl SO r de r e da ndbui l ta ndwhi l ene wf i r ms e nt e rt hema r ke t . Se ea l s ot het i mede l a ysi nt heBu r no uta ndHa s t eMa ke sWa s t e l oo psi nFi g ur e5‑ 9。 o ‑ Exampl e:Ener gyDemand Ther e s po ns eofga s o l i nes a l e st opr l C ei nvo l ve sl o ngd e l a ys . I nt hes ho r t r un, ga s o‑ l i nede ma ndi squl t ei ne l a s t i c: i fpr i c e sr i s e , pe o pl ec a nc utd owno ndi s c r e t i o na r y t r l pSS O me Wha t , bu tmos tpe o pl es t i l lha vet od r i vet owo r k, s c ho o l , a ndt hes upe r ‑ ma r ke t . Aspe o pl er e a l i z et ha tp r i c e sa r el i ke l yt os t a yhi ht g he yma yo r ga n i z ec a r ‑ poo l so rs wi t c ht opu bl i ct r a ns po r t a t i on,i fi ti sa l r e a d ya va i l a bl e 。 Ove rt i mehi g h pr i c esi nd uc eo t he rr e s po ns e s . Fi r s t ,c o ns ume r s( a ndt hea ut oc o mpa ni e s )wa i tt o s e ei fga spr i c e sa r eg oi ngt OS t a yhi g he no ug ha ndl o nge no ug ht oJ us t i f ybuyi ng orde s i gni ngmo r ee f f i c i e ntc a r s( ape r c e pt ua la ndde c i s i on‑ ma ki ngde l a yofpe r ha psaye a ro rmo r e ) .Onc epe o pl eha vede c i de dt ha tt hepr i c ewon' td r o pba c k downa nyt i mes oo n, t hea ut oc ompa ni e smus tt he nde s i g na ndbui l dmo r ee f f i c i e nt c a r s( ade l a yo fs e v e r a lye a r s ) . Ev e na f t e rmo r ee fi c i e ntc a r sbe c o mea va i l a bl e , t he va s tma j O r l t yOfc a r so nt her oa dwi l lbei ne f f i c i e nt ,o l de rmod e l swhi c ha r eo nl y r e pl a c e da st he ywe a ro uta nda r edi s c a r de d,ade l a yofa bo ut1 0ye a r s .I fp r i c e s s t a yhi g h,e ve nt ua l l yt hede ns i t yOfs e t t l e me ntpa t t e r nswi l li nc r e a s ea spe o pl e a ba ndo nt hes u bu r bsa ndmo v ec l os e rt ot he i r j o bs . Al t o ge t he r , t het o t a lde l a yi nt he l i nkbe t we e np r l C ea ndd e ma ndf o rga s ol i nei ss i gni f i c a nt l ymo r et ha nad e c a d e. As t hes t oc kofc a r so nt her oa di sg r a dua l l yr e pl a c e dwi t hmo r ee f f i c i e ntc a r s , a nda s ( pe r ha ps )ne wma s st r a ns i tr o ut e sa r ede s i g ne da ndbui l t , hed t e ma ndf o rg a s o l i ne woul df a l ls ubs t a n t i a l l y ‑l o ng‑ r unde ma ndi sq ul t ee l a s t i c .Fi g ur e5‑ l lma ke s t he s edi f f e r e ntpa t hwa ysf o rt hea d j us t me nto fga s ol i nede ma nde x pl i c i t . Expl i c i t l ypor t r a yi ngt hema n yde l a ysbe t we e nac ha ngei np r l C ea ndt he r e s ui t i r . gc ha r l gei nde ma r l dma ke si te a s i e i ‑ t OS e et hewo r s e ‑ be f o r e ‑ be t t e rbe ha vi o r ofe xpe nd i t ur e so nga s o l i nec a us e dbyapr l C ei nc r e a s e .Thebo t t o mo fFi g ur e 5 ‑ l ls howst her e s po ns eo fga s o l i nede ma nda nde x pe nd i t u r e st oahypo t he t i c a l ‑ FI GURE5 ‑ 10 Repr e s en t i ng del ay si nc aus al di agr ams P r i c e S u p p l y 151 Cha p t e r5 Ca us a lLoo pDi a g r a ms una nt l Cl pa t e ds t e pI nc r eas ei nt hepr l C eOfgas ol i ne.I nt hes hor tr ungas ol i ne de ma ndi sr a t he ri nf le xi bl e,s ot hef i r s tr es pons et oa ni nc r eas ei nt hepr l C eOfgas i sa ni nc r eas ei nga s ol i nee xpe ndi t ur es ・Ast hehi ghpr i c epe r s i s t s ,e fi ci e ncy FI GURE5‑ ll Di f f er entt i mede一 aysi nt her espons eofgasol i nedemandandexpendi t ur est opr i ce T op: Theshor tr unr esponset ohi gherpr I C eSi sweak,whi l et hel ongr unr esponsej ssubs t ant i al ast he st ockofcar si sgr adua" yr epl acedwi t hmor eef f i ci entmode一 s,andasr i f es t yl eschange. Bot t om:Responset oahypot het i cal per manentunant i cE Pat edi ncr easei ngasoH nepnc e.Consumpt i on s一 owl ydecl i nesduet ot hel ongde一 ay si nad j us t i ngt heef f i ci enc yofau t omobi l esandi nchangl ng set t l ementpat t er nsandmasst r ansi tr out es・Expendi t ur est her ef or ei mmedi at el ynseandonl yI at erf aH bel owt hei ni t i al I evel :awor se‑ bef or e‑ bet t ert r ade一 〇f ff orconsumer s.Ofcour s e, asdemandf a川 s, t her e woul dbedownwar dpr essur eonpnc e,pos si bl yl owenngexpendi t ur ess t i l lmor e,butal sodi s cour agI ng f ur t heref f i ci enc yI mpr ovement s.Thef eedbackt opncei sdel i ber at el yl gnOr edi nt hedi agr am. Ga s ol i ne Ex p e n dj t ur es Expect ed Shor t 一 丁er m Pr i ce Di scr et i onar y + Demandf or Gasol i ne d+ 常 erYear :I ̲ ‑ i CarPoo一 i ngan ̲.′ UseofExi st i ng MassTr ansi t Densi t yof Set t l ementPat t er ns, + Deve6 0pmentofNew MassTr ansi tRout es p ‑ E bf [ f " i c Vi [ e 〉n "c Vyo y〉f Z l r o E f f f ga i r e s n…y n‑ 即 Mar k et Ti me car somRoad 152 P a r t I IT o o l sf o rS y s t e ms Th i n k i n g i mpr o ve me nt sg r a d ua l l yc utc o ns umpt l OnOfga s o l i nepe rve hi c l emi l e ,a nde ve n‑ l y ,s e t t l e me ntpa t t e r nsa ndma s st r a ns i ta va i l a bi l i t ywi l la d j us tt or e d uc et he t ua l nu mbe ro fve hi c l emi l e sd r i ve npe rye a r . I nt hel o ngr un, de ma nda d j us t me nt smo r e t ha no f f s e tt hep r i c ei nc r e a s ea nde x pe ndi t u r e sf a l l . Fr o mt hepo i ntOfv i e woft he c o ns ume r , t hi si sawo r s e ‑ be f o r e ‑ be t t e rs i t ua t i o n. Thet i mede l a ysa ndt het r a de ‑ o f f he t yc r e a t ehe l pe x pl a i nwhyi tha spr o ve ns od i f f i c ul t , i nt heUni t e dSt a t e sa tl e a s t , t oi nc r e a s ega s ol i net a xe s . Al t ho ug ht hel o ng‑ r u nbe ne f i t so ut we i g ht hes ho r t ‑ r un c os t s , e ve ni nne tpr e s e ntva l uet e r ms , t he yo nl ybe g i nt oa c c r uea f t e rma nyye a r s . Go ve r nme nto f f i c i a l sf o c us e do nt hene xtr e e l e c t i o nc a mpa l g nj udget hes ho r t ‑ un r c os t st obepo l i t i c a l l yuna c c e pt a bl e. I nt um, t he yma ket hi sj udg me ntbe c a us et he publ i ci su nwi l l i ngt os a c r i f i c eal i t t l et oda yf o rl a r g e rbe ne f i t st o mo r r o w. 5 . 2. 6 Va r i a bl eNa me s Van ' abl eNamesShoul dBeNounsorNounPhr ases Theva r i a bl ena me si nc a us a ld i a g r a msa ndmode l ss ho ul dbeno unso rno un ph r a s e s . Thea c t i o ns( ve r bs )a r ec a pt ur e dbyt hec a us a ll i nksc o nne c t i ngt heva r i ‑ a bl e s . Ac a us a ld i a g r a mc a pt ur e st hes t r uc t ur eoft hes ys t e m, no ti t sbe ha v i o 一 mO t t u al l yha ppe ne dbutwha twoul dha p pe ni fot he rva r i a bl e sc ha nge di n wha tha sac va r i o uswa ys . Fi g ur e5‑ 1 2S ho wse xa mpl e so fgo oda ndba dpr a c t i c e . Thec o r r e c td i a g r a ms t a t e s : I fc os t sr i s e , t he np r i c er i s e s( a bovewha ti two ul d ha vebe e n) , b uti fc os t sf a l l , t he npr i c ewi l lf a l l( be l owwha ti two ul dha vebe e n) . Ad di ngt heve r b" r i s e s "t ot hed i a g r a mpr e s ume sc os t swi l lonl yr i s e , bi a s l ngt he d i s c us s i o nt o wa r dsonepa t t e r no fbe ha vi o r( i nna t i o n) . I ti sc o nf us i ngt ot a l ko fa de c r e a s ei nc os t sr i s i ngOraf a l li npnC ei nc r e a s e s ‑a r epr l C e Sr i s l ng,r i s l nga ta f a l l i ngr a t e , O rf a l l i ng? Van r abl eNamesMustHaveaCl earSenseofDi r ect I ' On Choos ena me sf o rwhi c ht heme a nl ngO fa ni nc r e a s eo rde c r e a s ei sc l e a r , va r i a bl e s t ha tc a nbel a r g e ro rs ma l l e r . Wi t ho utac l e a rs e ns eofd i r e c t i onf o rt heva r i a bl e s yo uwi l lno tbea bl et oa s s i g nme a ni ng f u ll i n kpo l a r i t i e s . Ont hel e f ts i deofFi g ur e5‑ 1 3ne i t he rva r i a bl eha sac l e a rd i r e c t i o n:I ff e e d‑ ba c kf r o mt hebos si nc r e a s e s ,doe st ha tme a nyo ug e tmor ec o mme nt s ?Ar et he s e FI GURE5 ‑ 12 Var i ab一 en ame s sh oul db en ou ns orn ounp hr as es. FI GURE5 ‑ 13 Var i abl en ame s sh oul dh a vea cl ears en s eof di r e c t i on. l ncor r ect / / / ‑ ′ 一 、 、 ‑洩 + Cos t sRi s e Pr i ceRi s es Cor r ect / 一′ 一 ー \ ‑ 凍 + Cos t s Pr i ce l ncor r ect / / 一一 、 、‑≠ + Feedback Ment al f r omt he At t i t ude Boss Cor r ect r Pr ai s ef r 1 0m t heBoss ・ Mor a一 e 1 53 Ch a p t e r5 Ca t l S a l Lo o pDi a g r a ms FI GURE5 ‑ 14 Ch oos ev ar i abl es whos en or mal s ens eo fdi r ec t i on i spos i t i v e. l ncor r ect r Cos t s / T Cr i t i ci sm Cor r ect . r ・ Losses Cos t s Pr of i t . Unhappi ness r Cr i t i ci sm ̲ Happi ness c omme nt sf r o mt hebos sgoodo rba d?Andwha tdo e si tme a nf o rme nt a la t t i t ude t oi nc r e a s e?Th eme a nl ngOft her i g hts i dei sc l e a r :Mo r epr a i s e丘. o mt hebos s boos t smo r a l e ; l e s spr a i s ee r od e si t( t ho ug hyo us ho ul dp r o ba bl yno tl e tyo urs e l f ‑ e s t e e md e pe nds omuc ho nyo u rbos s フ o pi ni o n) . ChooseVan l abl esWhoseNor malSenseofDl r r eCt i onl sPosl ' t i v e Va r i a bl ena me ss ho ul dbec hos e ns ot he i rno r ma ls e ns eo fdi r e c t i o ni spos i t i ve. Avo i dt heus eo fva r i a bl ena me sc o nt a i ni ngpr e f i xe si nd i c a t i ngn e ga t i o n( no n, un, e t c. ; Fi g ur e5 ‑ 1 4 ) . St a nda r da c c ou nt l ngPr a c t i c ei sPr o f i t‑Re ve n ue‑Cos t s ,s ot hebe t t e rva r i ‑ a bl ena mei sPr o 恥 wh i c hf a l l swhe nc os t sr i s ea ndr i s e swhe nc os t sf a l l . Li ke wi s e , c r i t i c i s m ma yma keyouunha ppy ,buti ti sc o nf us i ngt os pe a kofr i s i ngun‑ ha ppl ne S S ;abe t t e rc ho i c ei st hepos i t i veha ppl ne S S , Whi c hma yf a l lwhe nyo ua r e c r i t i c i z e da ndr i s ewhe nc r i t i c i s md r o ps .Thought he r ea r eo c c a s i ona le xc e p‑ t i o ns , de c r e a s i n gnO nC O mpl i a nc ewi t ht hi spr i nc i pl ewi l ld i mi n i s hyo ura ud i e nc e' s i nc o mpr e he ns i o n. 5. 2, 7 ■ 首 ̀ i ps紬rCaL S SaFL・ C 1 0PDi agr am Layout Toma xi mi z et h ec l a r i t ya ndi mpa c tofyo urc a us a ldi a g r a ms ,yo us ho ul df ol l ow s omeba s i cpr l n C i pl e so fg r a phi cde s i gn. 1 .Us ec ur ve dl i ne sf o ri nf o r ma t i o nf e e d ba c ks . Cu r ve dl i ne she l pt her e a d e r vi s ua l i z et h ef e e d ba c kl oo ps . 2.Ma kei mp o r t a ntl o o psf o l l owc i r c ul a ro rova lpa t hs 。 3.Or ga ni z ey o u rd i a g r a mst omi ni mi z ec r os s e dl i ne s . 4.Do n' tputc i r c l e s , he xa go ns , o ro t he rs ymbo l sa r o undt heva r i a bl e si nc a us a l di a gr a ms . Symbol swi t ho utme a nl nga r eH c ha r t j un k"a nds e Ⅳeonl yt o c l ut t e ra ndd i s t r a c t . Ane xc e pt i on: Yo uwi l lo f t e nne e dt oma ket hes t o c k a ndf lOws t r uc t u r eo fas ys t e me x pl i c i ti nyo u rd i a g r a ms . I nt he s ec a s e st he r e c t a ng l e sa ndva l ve sa r o undt heva r i a bl e st e l lt her e a de rwhi c ha r es t oc ks a ndwhi c ha r ef lows ‑t he yc onve yi mpo r t a nti nf o r ma t i o n( S e ec ha pt e r6) . 5.I t e r a t e . Si n c eyo uof t e nwo n' tk nowwha ta l lt heva r i a bl e sa ndl oo pswi l lbe whe nyo us t a r t , youwi l lha vet or e d r a wyo urd i a g r a ms , o f t e nma nyt l me t of i ndt hebe s tl a yo ut . S, 1 54 Pa r tI I Too l sf o rSys t em s Thi n ki ng FI GURE5 ‑ 15 Mak ei n t er medi a t e l i nk sex pl l Ci tt o cl ar i f yac au s aJ r e一 a t i on shi p. r fyouraudi encewasconf us edby / ‑ー、 ‑ ‑ も ー Mar k e t Shar e Uni t Cos t s youmi ghtmak et hei nt er medi a t ec oncept sexpl i ci tasf ol l ows: /. / メ Cumu一 at i ve 千 pr oduc t i on + + Pr oduc t i on Vo一 ume Exper i enc e Mar k et Shar e 、 鶏 ‑ Uni t Cos t s ‑\ 5 . 2 , 8 Ch oos et h eRi gh tL e v e 弓 o fAggr e ga t i on Ca us a ll oo pd i a g r a msa r ede s i g ne dt oc o mmu ni c a t et hec e nt r a lf e e d ba c ks t uc r t u r e o fyo u rdy na mi chypo t he s i s ・ The ya r eno ti n t e nd e dt obede s c npt l O nSOfamode la t t hede t a i l e dl e ve loft hee q ua t i o ns . Ha v i ngt oomuc hde t a i lma ke si tha r dt os e et he o ve r a l lf e e d ba c kl oo ps t r uc t ur ea ndho wt hed i f f e r e n tl o o psi nt e r a c LHa vi ngt ool i t ‑ t l ed e t a i lma ke si tha r df o ryo u ra ud i e nc et og r a s pt hel ogl Ca nde va l ua t et hepl a u‑ l . s i bi l i t ya ndr e a l i s mofyo u rmode I fyo ura udi e nc edo e s n' tgr a s pt hel o gl CO fac a us a ll i nk,yo us ho ul dma ke c i t . Fi gu r e5 ‑ 1 5s howsa ne xa mpl e . s o meoft hei nt e r me di a t eva r i a bl e smo r ee x pl i Yo umi g ht be l i e vet ha ti nyo uri ndus t r y , ma r ke ts ha r ega i nsl e a dt ol owe runi tc os t s be c a us ehi g he rvol ume smoveyo urc o mpa nydo wnt hel e a r nl ngC ur vef a s t e r ・ The t o ppa ne lc o mpr e s s e st hi sl ogl Ci nt oas l ng l ec a us a ll i nk.I fyou ra ud i e nc ef o und t ha tl i n kc o nf us i ng, yo us ho ul ddi s a gg r e ga t et hed i a g r a mt os howt hes t e pso fyo u r l . r e a s o nl ngl nmo r ed e t a i l ,a ss howni nt h ebo t t o mpa ne Onc eyo u' vec l a r i f i e dt hi sl og l Ct Ot hes a t i s f a c t i o no fa l l ,youof t e nc a n " c h un k"t hemo r ede t a i l e dr e pr e s e nt a t i o ni nt oas i mpl e , mo r ea g gr e ga t ef o r m. The s i mpl e rdi a g r a mt he ns e ve r sa sama r ke rf o rt h er i c he r , u nde r l yi ngc a us a ls t r uc t u r e . 5 . 2 . 9 D訓11 号Pu モAe Hh eL o甲信棚o O m eL ar geDi a gr am Sho r t ‑ t e r m me mo r yc a nhol d7±2c hunksofi nf o r ma t i ona to nc e・Thi sput sa r a t he rs ha r pl i mi tont hee fe c t i ves i z ea ndc o mpl e x i t yo fac a us a lma p・ Pr e s e nt l ng ac o mpl e xc a us a lma pa l la to nc ema ke si tha r dt os e et he一 oo ps , unde r s t a ndwhi c h ∬ei mpor t a nt ,O runde r s t a ndhowt he yg e n e r a t et hedyna mi c s ・Re s i s tt het e mpt a ‑ t i o nt oputa l lt hel oopsyoua ndyo u rc l i e nt sha vei de nt i f i e di nt oas l ng l ec o mp r e ‑ he ns i vedi a gr a m.Suc hd i a g r a msl ooki mp r e s s i ve ‑My ,wha tal otofwo r kmus t ha vego nei nt oi t ! Howbi ga ndc ompr e he ns i v eyou rmode lmus tbe! ‑buta r eno t e f f e c t i vei nc o mmuni c a t l ngWi t hyo ura ud i e nc e ・ Al a r ge , wa l l ‑ f i l l i ngdi a g r a mma y bepe r f e c t l yc ompr e he ns i bl et ot hepe r s o nwhod r e wi t ,butt ot hepe o pl ewi t h 155 Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms whom t hea ut h o rs e e kst oc o mmuni c a t e ,i ti si ndi s t i ngui s ha bl ef r o m aJ a c ks on Po l l oc ka ndc o n s i d e r a bl yl e s sva l ua bl e, Ho wt h e nd oyo uc o mmuni c a t et her i c hf e e d ba c ks t r u c t u r eo fas ys t e mwi t hout ove r s i mpl i f y i ng?Bui l dupyo urmode li ns t a ge s ,wi t has e r i e sofs ma l l e rc a us a l l oo pd i a g r a ms . Ea c hdi a g r a ms houl dc o r r e s pondt oo nepa r toft hed yna mi cs t or y be i ngt o l d. Fe wpe o pl ec a nunde r s t a ndac o mpl e xc a us a ldi a g r a munl e s st he yha ve ac ha nc et odi g e s tt hepl e C e SOnea tat i me.De ve l o pas e pa r a t edi a gr a mf or e a c hi mpo r t a nt l oo p. The s edi a g r a msc a nha vee n oug hd e t a i li nt he mt os ho whow t hepr oc e s sa c t ua l l yo pe r a t e s .The nc hunkt hed i a g r a msi nt oas i mpl e r ,hi g h l e ve lo ve r v i e wt os ho whowt he yi nt e r a c twi t ho n ea no t he r . I np r e s e nt a t i o ns , bui l d 4a nd5. 6f o r upyou rd i a g r a m pi e c ebypi e c ef r o mt hec hun ks( s e es e c t i o ns5. e xa mpl e s ) . 5且 10 Maket heGoa! SofNegat i veLoopsExpl i ci t Al lne ga t i vef e e d ba c kl oo psha vegoa l s . Goa l sa r et hed e s i r e ds t a t eo ft hes ys t e m, a nda l lne g a t i vel o o psf unc t i onbyc o mpa r l ngt hea c t ua ls t a t et ot hegoa l , t he ni ni ‑ t i a t l ngaC O 汀e C t i vea c t i o ni nr e s po ns et ot hed i s c r e pa nc y. Ma ket hegoa l sofyou r ‑ 1 6s ho wst woe xa mpl e s . Thet o ppa ne ls ho wsa ne ga t i vel o o pse xp l i c i t . Fi gur e5 ne ga t i vel o o pa f f e c t i ngt hequa l i t yo fac o mpa ny' spr od uc t : t hel owe rt heq ua l i t y , t hemo r eq ua l i t yi mpr ov e me ntpr o gr a mswi l lbes t a r t e d,a nd( p r e s u ma bl y)t hede ‑ f i c i e nc i e si nq ua l i t ywi l lbec o r r e c t e d. Ma k i nggoa l se x pl i c i te nc o ur a ge spe o pl et o a s kho wt hego a l sa r ef o r me d.Thegoa l si nmos ts ys t e msa r eno tgi ve ne XOge ‑ no us l ybuta r et h e ms e l v e spa r toft hef e e dba c ks t uc r t u r e . Goa l sc a nva r yo ve rt i me a ndr e s pon dt op r e s s u r e si nt hee nvi r onme nt . I nt hee xa mpl e , wha tde t e r mi ne st he FI GURE5 ‑ 16 Mak et h egoal so f n ega t i v el oops e x pH dt . Humanagen c yor n at ur al pr oces s es c ande t er mi n e goal s ・ T op: Th egoal o f t h el oopI S de t er mi n edb y man agemen t dec i s i on . Bot t om. ・ Th el a wsof t h er mod ynami c s de t er mi n et hegoal o ft h el o op. I ncor r ect r o d u +P O u a l i y c t t 真 土 ( す QuaM t y 日 mpr ovement Pr ogr ams Cor r ect D e s i r e d r o d u c t +P P r o d u c t O u a l i t y i t y Q u a \ 、 . ‑; ̲‑ ‑ ' l i i ( ? 主王 Qual i t y Shor t f aH Qual i t y t f {‑ I mpr ovementT Pr ogr ams + Cof f ee Temper a t ur e Room Temper a t ur e Temper at ur e Di f f er ence 156 P a r t I IT o o l sf o rS y s t e ms Th i n k i n g de s i r e dl e ve lofpr od uc tq ua l i t y?TheCEO' se d i c t ?Be nc h ma r ki ngs t ud i e so fc o m pe t i t o rq ua l i t y?Cus t ome rI npu t ?Thec ompa ny' so wnpa s tq ua l i t yl e ve l s ?Wh e nt he goa li se x pl i c i tt he s eq ue s t i onsa r emo r el i ke l yt obea s ke da ndhypo t he s e sa bo ut l . t h ea ns we r sc a nbeq ui c kl yi nc o r po r a t e di nt h emod e Ma ki ngt hegoa l sofne ga t i vel o o pse x pl i c i ti se s pe c i a l l yi mpor t a ntwhe nt he l o o psc a pt ur ehuma nbe ha v i o r ・ Buto f t e ni ti si mpo r t a ntt or e pr e s e ntgoa l se x pl i c i t l ye ve nwhe nt hel oo pdoe snoti nvol vepe o pl ea ta l l ・ Thes e c o nde xa mpl epo r ‑ t r a yst hene ga t i vef T e e d ba c kbywhi c hac u pofc o f f e ec ool st or oom t e mpe r a t u r e . Ther a t eo fc ool i ng( t her a t ea twhi c hhe a tdi fus e sf r o mt hehotc ofe et ot hes u r ‑ r o und i nga i r )i sr o ug hl ypr o po r t i o na lt ot hed i fe r e nc ebe t we e nt hec ofe et e mpe r ‑ a t ur ea ndr oo mt e mpe r a t ur e ・ Thec oo l i ngp r oc e s ss t o pswhe nt het wot e mpe r a t ur e s a r ee q ua LTh i sba s i cl a wo ft he r mod y na mi c si sma d ec l e a rwhe nt hegoa li ss ho wn e x pl i c i t l y . The r ea r ee xc e pt l OnSt Ot hepr l nC i pl eo fs howi ngt hegoa l sofne ga t i vel o o ps . Co ns i de rt hede a t hr a t el oo pi nFi g ur e5‑ 1 . Thegoa loft hede a t hr a t el oo pl Si m‑ pl i c i t( a nde qua lt oz e r o: i nt hel o ngr u n, wea r ea l lde a d) . Yo urmode l ss ho ul dno t e x pl i c i t l ypo r t r a yt hegoa lo ft hed e a t hl o o po rt hegoa l sofs i mi l a rde c a ypr o c e s s e s . s u c ha st hede pr e c i a t i onofc a pi t a le q ul pme nt ‑ ‑ 5. 2. ll a )i sモ i E l gui shbeモ W・ ?enA・ 7 号 l Jah? nd Per cei vedCondi t i ons Of t e nt he r ea r es i gni f i c a ntdi f f e r e nc e sbe t we e nt het r ues t a t eofa fa i r sa ndt he pe r c e pt i o nOft ha ts t a t ebyt hea c t o r si nt hes ys t e m. The r ema ybede l a ysc a us e dby , r e po r t l nga ndme a s u r e me ntpr oc e s s e s .The r ema ybenoi s e ,me a s ur e me nte r r or bi a s ,a ndd i s t o r t i ons ・I nt heq ua l i t yma na g e me nte xa mpl es howni nFi g ur e5‑ 1 6, t he r ema ybes i gni f i c a ntde l a ysi na s s e s s l ngq ua l i t ya ndi nc ha ngi ngma na g e me n t ' s o pl ni o na boutpr oduc tqua l i t y ・Se pa r a t l ngpe r c e i ve da nda c t ua lc ondi t i onshe l ps pr o mptq ues t i onss uc ha sHowl o ngdoe si tt a ket ome a s ur equa l i t y?Toc ha nge ma na g e me nt ' so pl ni ona bo utqua l i t ye ve na f t e rt heda t aa r ea va i l a bl e ?Toi m‑ pl e me ntaqua l i t yI mpr ove me n tpr og r a m?Tor e a l i z er e s ul t s ?Be s i de st hel o ngt l me de l a ys , t he r ema ybebi a si nt her e po r t i ngS ys t e mC a us i ngr e por t e dqua l i t yt odi fe r s ys t e ma t i c a l l yf r om qua l i ya t se x pe r i e nc e dbyt hec us t o me r . Cus t ome r sdo n' tf i l e wa r r a nt yc l a i msf o ra l lpr o bl e mso rr e po r ta l lde f e c t st ot he i rs a l e sr e pr e s e n t a t i v e . Sa l e sa ndr e pa l rpe r s onne lma yno tr e po r ta l lc us t ome rc o mpl a i nt st ot heho me Of f i c e . The r ema ybebi a si ns e ni o rma na g e me nt ' sq ua l i t ya s s e s s me nt be c a us es u b‑ o r di na t e sf i l t e rt hei nf o r ma t i o nt ha tr e a c he st he m・So mea ut oe xe c ut i ve sa r epr oI v i d e dwi t ht hel a t e s tmode l sf o rt he i rpe r s o na l us e ; t he s ec a r sa r ec a r e f ul l ys e l e c t e d a nd丘. e que nt l ys e r vi c e dbyc o mpa nyme c ha ni c s . The i ri mpr e s s i onoft heq ua l i t yo f he t i rf i r m' sc a r swi l lbeh i g he rt ha nt ha to ft hea v e r a gec us t o me rwhobuysof ft he l o ta ndke e pst hec a rf o r1 0ye a r s .Thed i a g r a m mi g htber e vi s e da ss howni n Fi g ur e5‑ 1 7.Thedi a g r a m now s howsho w ma na ge me nt ,de s pl t egoodi nt e n‑ t i o ns , c a nc omet ohol dag r os s l ye xa g ge r a t e dvi e wofpr od uc tqua l i t y , a ndyoua r e we l lpos i t i one df o radi s c us s i ono fwa yst os ho r t e nt hed e l a ysa nde l i mi na t et he d i s t o r t i o ns . 157 Ch a p t e r 5 C a u s a l Lo o pDi a g r a ms FI GURE5 ‑ 17 Di s t i n gui sh be t weenac t u al andp er c ei ved c ondi t i on s. Bi asi n Repor t i ng Sys t em + / 座 軒 / Pr oduc t QuaH t y ㌔. Repor t ed Pr oduc t Qua日 t y 豆 Qual i t y l mpr ovement pr ogr ams 5. 3 ㌣ Management Bi asTowar d Hi ghQual i t y F + + ' Management Per cept i onof Pr oduc tQuaMy Desi r ed Pr oduc t . i̲ Oual i t y 誓ua! i ̲ t y. J Shor t f al l 車 重 「 PROCESSPoI NT: DEVELOPI NG CAUSALDI AGRAMSFROM r NTERVI EW DATA Muc ho ft heda t aamode l e rus e st od e v e l o pad yna mi chy po t he s i sc ome sf r o mi n‑ t e r vi e wsa ndc o nve r s a t i o nswi t hpe o pl ei no r ga ni z a t i ons ・The r ea r ema nyt e c h‑ , n l q ue Sa va i l a bl et oga t he rda t af r o mme mbe r so fo r ga ni z a t i o ns , i nc l ud i ngs u r ve ys i n t e r v i e ws , pa r t i c l pa ntO bs e r va t i o n, a r c hi v a lda t a , a nds oo n・ Sur ve ysge ne r a l l ydo n o ty i e l dda t ar iC he no ug ht obeus e f uli nde ve l o pl ngS ys t e md yna mi c smod e l s . I n t e r vi e wsa r ea ne f f T e c t i veme t hodt oga t he rda t aus e f uli nf o r mul a t i ngamod e l , e i ‑ t he rc o nc e pt ua lo rf わr ma l . Se mi s t r uc t ur e di nt e r v i e ws( whe r et hemode l e rha sas e t o fpr e d e f i ne dq ue s t i onst oa s kbuti sf r e et od e pa r tf r omt hes c r i ptt OPur s uea V‑ e n ue so fpa r t i c u l a ri nt e r e s t )ha vepr o ve nt obepa r t i c ul a r l ye f f e c t i ve. I nt e r vi e wsa r ea l mos tne ve rs ufi c i e nta l onea ndmus tbes u ppl e me n t e dby , o t he rs o u r c e so fda t a , bo t hq ua l i t a t i vea ndq ua nt i t a t i ve. Pe o pl eha veonl yal oc a l pa r t i a lunde r s t a ndi ngoft hes ys t e m,S oyo umus ti nt e r vi e wa l lr e l e va nta c t o r s ,a t mul t i pl el e ve l s ,i nc l udi ngt hos eo ut s i det heo r ga ni z a t i o n( c us t o me r s ,S uppl i e r s , e t c. ) . I nt e r vi e wda t ai sr i c h, i nc l ud i ngd e s c r i pt i onsofde c i s i o npr oc e s s e s ,i nt e r na l po l i t i c s , a t t r i but i o nsa bo utt hemo t i ve sa ndc ha r a c t e r sofo t he r s , a ndt he o r i e st oe x‑ pl a i ne ve nt s , bu tt he s ed i fe r e ntt ype sofi nf o r ma t i o na r emi xe dt oge t he r .Pe o pl e bo t hk no wmor et ha nt he ywi l lt e l lyo ua ndc a ni nve ntr a t l ona l e sa nde ve ni nc i ‑ d e nt st oj us t i f yt he i rbe l i e f s , pr ovi di ngyo uwi t h" da t a "t he yc a n' tpos s i bl ykno w ( Ni s be t ta ndWi l s o n1 9 77 ) . Themo de l e rmus tt r i a ng ul a t ebyus i nga sma nys o ur c e s o fda t aa spos s i b l et oga i ni ns i g hti nt ot hes t r uc t u r eo ft hep r o b l e ms i t ua t i o na ndt he d e c i s i o npr oc e s s e so ft hea c t o r si ni t . Ane x t e ns i vel i t e r a t ur epr ovi de sg ui da nc ei n t e c hn i q ue sf o rq ua l i t a t i veda t ac ol l e c t i o na nda na l ys i s ; S e e , f o re xa mpl e , Ar g y r l Se t a l .( 1 98 5 ) , Emme r s one ta l .( 1 995) ,Gl a s e ra ndSt r a us s( 1 96 7) ,Kl e i ne ra ndRot h , ( 1 99 7) , Ma r c he ta l .( 1 991 ) , Mo r e c r o f ta ndSt e r ma n( 1 99 4) , Va nMa a ne n( 1 98 8) a ndYi n( 1 9 94) . ‑ 158 Pa r t I I To o l sf o rS y s t e msTh i n k i n g Onc eyou' vedoneyouri nt e r vi e ws ,youmus tbea bl et oe xt r a c tt hec a us a l s t r uc t ur eoft hes ys t e mf r om t hes t a t e me nt soft hei nt e r vi e ws ub j e c t s .Fo r mul a t e va r i a bl ena me ss ot ha tt he yc o r r e s pondc l os e l yt ot hea c t ua lwor dsus e dbyt hepe r ‑ s onyoui nt e r vi e we d, whi l es t i l la dhe r i ngt ot hepr l nC i pl esf orpr ope rva r i a bl ena me s e l e c t i ondes c r i be da bove( nounphr a s e s ,ac l e a ra ndpos i t i ves e ns eofdi r e c t i on) . Ca us a ll i nkss houl dbedi r e c t l ys uppor t e dbyapa s s a gei nt het r a ns c r i pt . Typi c a l l y, pe opl ewi l lnotde s c r i bea l lt hel i nksyouma ys e ea ndwi l lnote xpl i c i t l yc l os e ma nyf e e dba c kl oo ps .Shoul dyoua ddt hes ea ddi t i ona ll i nks ?I tde pe ndsont he pur pos eofyourdi a gr a m。 I fyoua r et r yl ngt Or e pr es e ntape r S On' sme nt a lmode l ,youmus tnoti nc l ude a nyl i nkst ha tc a nnotbegr ounde di nt hepe r s on' sowns t a t e me nt s . Howe ve r ,you ma yc hoos et os howt hei ni t i a ldi a gr a mt ot hepe r s ona ndi nvi t ehi morhe rt oe l a b‑ or a t eo ra dda nymi s s l ngl i nks . Pe opl ewi l lof t e nme nt i ont hemot i va t i onf orade c i s i ont he yma de,Wi t ht hef e e dba c ke f f e c tont hes t a t eoft hes ys t e mi mpl i c i t l y ," Ourma r ke ts ha r ewa ss l i ppi ng,S OWef i r e dt hema r ke t ‑ unde r s t ood. Fore xa mpl e 1 ngVPa ndgotour s e l ve sane wa da ge nc y. HI mpl i c i ti nt hi sdes c r l pt l Oni st hebe ‑ l i e ft ha tane wVPa nda ge nc ywoul dl e a dt obe t t e ra dsa nda ni nc r e a s ei nma r ke t s ha r e,c l os i ngt hene ga t i vel oo p. I ft hepur pos eofyouri nt e r vi e wsi st ode ve l opagoodmode loft hepr obl e m s i t ua t i on,yous houl ds uppl e me ntt hel i nkss ugges t e dbyt hei nt e r vi e wswi t hot he r da t as o ur c e ss uc ha syourowne xpe r i e nc ea ndobs e r va t i ons ,a r c hi va lda t a ,a nds o on.Ⅰ nma nyc a s es ,youwi l lne e dt oa dda ddi t i ona lc a us a ll i nksnotme nt i one di n t hei nt e r vi e wso rot he rda t as o ur c es ・ Whi l es omeoft he s ewi l lr e pr e s e ntba s i cphys ‑ i c a lr e l a ions t hi psa ndbeobvi oust oa l l , ot he r sr e qul r ej us t i f i ca t i ono re xpl a na t i on. Yous houl ddr a w ona l lt heknowl e dgeyouha vef r om youre xpe r i e nc ewi t ht he s ys t e mt oc ompl e t et hedi a gr a m・ 1 ‑ Pr ocess垂 m町OVen 頂門号 Thef ol l owl ngt woquot e sa r ea c t ua li nt e r vi e wt r a ns c r l Pt Sde ve l o pe di nf i e l dwor k ca r r i e douti na na ut omo bi l ec ompa nyi nt heUni t e dSt a t es .Thema na ge r s ,f r om t wodi f f e r e ntc ompone ntpl a nt si nt hes a medi vi s i onoft hec ompa ny, de s c r i bewhy t heyi e l doft he i rl i neswa spe r s i s t e nt l yl owa ndwhyi tha dbe e ns odi f f i c ul tt oge t pr oc es si mpr ove me ntpr og r a msof ft hegr ound( Re pe nni nga ndSt e r ma n1 999) : I nt h emi n dso ft h e[ o pe r a t i o nst e a ml e a d e r s ]t he yha dt oh i t t he i rpa c kc o u n t s[ d a i l y q u o t a s ] ・ Thi sme a n ti fy o uwe r eha v i n gaba dda ya ndyo u ry i e l dha df a l l e n. ‥y o u ha dt or u nl i kec r a z yt oh i ty o u rt a r g e t . Ⅵ) uc o ul ds a y , = Yo ua r ema k i n g2 0% ga r ba g e , s t o pt h el i r l ea n df i xt h ep r o b l e r r l , "a r i dt h e ywo ul ds a y , H Ic a r l ' t h i ti r l y pa c kc o un twi t ho u tr u n n l n gl i k ec r a z y . HThe yc o u l dn e v e rg e ta h e a do ft h ega me . ‑Man a ge ratPl ant A Su pe r v i s o r sne v e rha dt i met oma kei mp r o v e me n t so rd op r e v e n t i v ema i n t e n a n c e o nt h e i rl i n e s‑・ t he yh a dt os pe n da l l t h e i rt i meJ us tt r y l ngt Ok e e pt h el i n eg o l n g , i Bu r c h i l l a n dFi n e( 1 997)i l l u s t r a t eh o wc a u s a l d i a g r a msc a nb ed e v e l o edf p r o mi n t e r v i e wd a t a i nap r o d u c t d e v e l o p me n t c o n t e x t . 159 Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms b u tt h i sme a n t i t wa sa l wa ysi nas t a t eo ff lu x・ Hbe c a us ee v e r y t hi n gwa ss ou n p r e ‑ ・ I twa sak i n do fs n o wba l l e f f e c tt ha t j us t ke p tg e t t l n gwor s e . d i c t a bl e ‑Su pe 7 Vi s orat Pl a nt B De ve l opas l ngl eca us a ldi a gr a mc a pt ur l ngt hedyna mi c sdes c r i be dbyt hei nt e r ‑ vi e ws . Na meyo url oo psus i ngt e m sf r r omt hequot e swhe r epos s i bl e. Expl a i ni na pa r a gr a phort wohowt hel oo psc a pt ur et hedyna mi csdes c r i be d,Bui l dyourdi a l gr a ma r oundt heba s i cphys i c a ls t r uc t ur es howni nFi gur e5‑ 1 8. TheNe tThr ough‑ putofapr oc e s s( t henumbe rofus a bl epa r t spr oduc e dpe rt i mepe r i od, f o re xa mpl e, t henumbe rofus a bl epa r t spr oduc e dpe rda y)e qua l sGr os sThr o ughput( t het ot a l numbe rpr oduc e dpe rt i mepe r i od)mul t i pl i e dbyt hepr oc es sYi e l d( t hef r a c t i onof gr os st hr oughputt ha tpa s s esi ns pe c t i ona ndi sus a bl e ) .Ther e ma i nde r ,Gr os s Thr oughput* ( 1IYi e l d) , a r ede f e c t i ve. + Gr oss Net ‑√ 一 ㊥ Throughput Thr oughput 5. 4 CoNCEPTUAuZATJ ONCASESTUDY: uRW oRKLOAD MANAGI NG Yo Thi ss e c t i oni l l us t r a t es血eus eofc a us a ldi a gr a mst omode la ni s s ue・ Thee xa mpl e s howshowc a us a ldi a g r a mml ngC a nbea na i dt ot hede ve l o pme ntofadyna mi chy‑ pot he s i s ,a l ongwi t hi de nt i f yi ngva r i a bl e sa ndde ve l o pl ngar e f T e r e nc emodes how‑ 1 ngt hedyna mi c so ft heva r i a bl esove rt her e l e va ntt i mehor i z on. 5. 4. 1 Pr obJ em Def i ni t i on Cons i de rt hepr o c e s sofma na gl ngyourWOr kl oa d. Youmi ghtbea ne ngl ne e ri na pr oduc tde ve l opme nto r ga ni z a t i on, ac ons ul t a nt , oraCEO. Toke e pl tC OnC r e t e , f oI c usonas t ude ntma na gi nghi sorhe rwor kl oa d. As t ude nt( i ma g i neyour s e l f )mus t ba l a nc ec l a s s e sa nda s s l gnme nt SWi t ho ut s i dea c t i vi t i es ,ape r s ona ll i f e,a nds l e e p. Dur i ngt hes e me s t e ryoua t t e ndc l a s s e s ,dot her e a di ngs ,a ndha ndi na s s l gnme nt S a st he ya r edue, a tl e a s toc c a s i o na l l y. Yo upr oba bl yt r yt owor kha r de ri fyout hi nk yourgr a desa r el owe rt ha nyoudes i r ea ndt a kemor et imeof fwhe nyoua r es l e e p de pr i ve da ndyo ure ne r gyl e ve lf a l l s . The r ea r et woba s i cpol i c i e syouc a nf ol l ow: ( 1 )Thea nts t r a t egy 一me ve rputof funt i lt omor r ow wha tyouc a ndot oda y;or ( 2)t hegr a s s hoppe rs t r a t e gy‑ne ve rdot oda ywha tc a nbeputof funt i lt omo r r ow. Thea ntwor kss t e a di l yt hr o ughoutt hes e mes t e ra swor ki sa s s i gne da ndne ve r bui l dsupal a r geba c kl ogofa s s l gnme nt S . Asar e s ul t , t hea nta vo i dst hee ndofs e ‑ mes t e rc r unc h,ke e pst hewo r kwe e kunde rc ont r ol ,a ndi sa bl et os t a ywe l lr e s t e d. Be c a us et hea ntge t se noug hs l e e p, pr oduc t i vi t yi shi gh,a ndt hea ntha spl e nt yof ‑ 160 P a r t I IT o o l s f o rS y s t em s Th i n k i n g t i met opa r t l C l pa t ei no ut s i dea c t i vi t i e s . Thea n t ' sg r a d e si mpr ov es t e a di l yt hr o ug h‑ o utt het e r m. Theg r a s s ho p pe r ,i nc ont r a s t ,de f e r st hewo r kunt i lt hel a s tmi nut e.The g r a s s ho p pe r ' swo r kwe e ki sl owa tt hebe g i nnl ngO ft het e r m, pr o vi di ngl o t soft i me f o rpa r ie t sa n do u t s i d ea c t i vi t i e s . Theg r a s s ho ppe rc a ns t a yr e a s ona bl ywe l lr e s t e d de s pl t eahe a vys oc i a ls c he d ul ebe c a us et hewo r kwe e ki sl ow.Butbe c a us et he g r a s s ho p pe rdo e s n' tdot hewo r ka sf a s ta si ti sa s s l g ne d, t hea s s l g nme ntba c kl og s t e a d i l ybu i l dsu pi Eve nt ua l l y , i t ' sc r u nc ht i me ,a ndt hegr a s s ho ppe rs t a r t sput t i ng i nl o ngho ur s , pe r ha pspul l i ngaf e wa l l ‑ ni gh t e r s ・ Un f o r t una t e l y,a ss l e e ps uf f e r s , e ne r g ya ndp r o d uc t i v i t yf a l l . Ther a t ea ndq ua l i t yo fwo r ks uf f e r s ・ Gr a de spl umme t , a ndt het e r me ndsbe f o r et heg r a s s ho ppe rc a nf i ni s ha l lt hewo r k, pe r ha psl e a d i ng t heg r a s s ho ppe rt opl e a df o re xt e ns i onsf r omt hef a c ul t y. 5且2 E dent i 菅 y岳 mgKeyVar i ab暑 es Thede s c r l pt l O na boves ugge s t ss e ve r a lva r i a bl e si mpo r t a nti namode lofs t ude nt wo r kl oa dma na ge me n t( uni t so fme a s ur ea r egi v e ni npa r e nt he s e s ) : As s i gnme ntr at e:t her a t ea twhi c hpr o f e s s o r sa s s l g nWO r kt hr o ug houtt he t e r m( t a s ks / we e k) . Wo r kc o mpl e t i onr a t e:t her a t ea twhi c ht a s ksa r ec o mpl e t e d( t a s ks / we e k) . As s i gnme mtbac kl o g:t henumbe ro ft a s kst ha tha vebe e na s s l g ne dbutnot ye tc ompl e t e d( t a s ks ) . Gr a de s :t heg r a der e c e i ve df o rwo r kha nde di n( 01 1 00s c a l e ) . Wor kwe e k: t henumbe rofho ur ss pe nto na c a d e mi cwo r k, i nc l udi ng c l a s s e s , r e a d i ng, ho me wo r k, p r o j e c t s , e t c. ( ho ur s / we e k) . Ene r g yl e ve l :me a s ur e sho wwe l lr e s t e dt hes t ud e nti s . Ar bi t r a r ys c a l ef r o m O 11 00%whe r el OO% ‑f ul l yr e s t e da nd0‑c o ma t os e ) , Ot he rva r i a bl e sc o ul dbea dde d, butt hi ss e t pr o vi d e sar e a s o na bl es t a r t l ngPO l n tf o r c o nc e pt ua l i z a t i o noft hef e e dba c ks t uc r t ur egove r nl ngt hed yna mi c s . Asyoupr o‑ c e e d, yo uma yf i ndyo un e e dt or e v i s et hel i s t . 5. 4. 3 DeveB opmg昔 heRe骨 er emeeMode Fi g ur e5‑ 1 9t r a ns l a t e st hewr i t t e nde s c r l pt l OnSO ft hea nt ' sbe ha vi o ri nt og r a phi c a l f o r m( Fi g ur e5 ‑ 2 0s ho wst heg r a s s ho ppe rs t r a t e g y) ・ The s eg r a phsc o ns t i t ut et her e f ‑ e r e nc emo dec ha r a c t e r i z l ngt hepr o bl e m. Somei t e mst ono t e : 1 .Thet i meho r i z oni se x pl i c i t l ys t a t e d. He r e , t hes e me s t e ri s1 3we e ksl ong. 2.Se ve r a ld i f f e r e ntg r a phsa r eus e dt oa vo i dc l ut t e r . Thet i mea xe sofe a c h g r a pha r ea l i g ne ds ot ha tt het i mi ngOfe ve nt sc a nbedi r e c t l yc o mpa r e d. 3.Va r i a bl e swi t ht hes a meuni t sa r epl o t t e do nt hes a mea xi s . Fo re xa mpl e , t he a s s l g nme n ta ndc ompl e t i o nr a t e sa r ebo t hme a s u r e di nt a s ks / we e ka nda r e pl o t t e dt oge t he r . 4.Yo udo n' tne e dqua nt i t a t i veda t at oc a pt u r et hed yna mi c si nt her e f e r e nc e mo de s . Whe nnume r i c a lda t aa r euna va i l a bl eyo us ho ul de s t i ma t et he 161 Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms FI GURE5 ‑ 19 qa aき Ref er en c emode f ort hean ts t r at egy a Jds とSe1 Assi gnmentRat e Wor kCompl et i onRat e Ti me( weeksoHhesemest er ) 13 Assi gnmentBack一 og Ti me( weeksoft hesemest er ) ( ooL・ 0)SaPeJ 9 望 ( ㌔ ooTO)l a^a1 ^ 6J auu ( 葛8 mJ S m OLi)竜a き 0き 0 Ti me( weeksoft hesemes t er ) be ha vi o roft heva r i a bl e sf r omt hewr i t t e nde s c r l Pt 1 0na ndot he rq ua l i t a t i ve i nf or ma t i o n. Sc a l esa ndr oug h ma gni t udesa r epr ovi de dwhe r epos s i bl e,a s t he ya r ef o rt hewor kwe e k,g r a des ,a nde ne r gyl e ve l ・ Ofc our s e, whe n qua nt i t a t i veda t aa r ea va i l a bl e,血e ys houl dbeus e d. Butdon' tomi t i mpo r t a ntva r i a bl ess i mpl ybe c a us et he yha ve n' tbe e nme a s ur e dye to r be c a us et heda t aa r e n' tr e a di l ya va i l a bl e. Ani mpo r t a ntgoa loft hemode l i ng 162 Pa r tI IT o o l sf o rS y s t e msTh i n k hg q a qa Jvta Jd sse1 ‡ 5,8舶 脚 ≡ o 1 Ti me( we ek soHhes emes t er ) 1 3 Ti me( week sof的esemest er ) 1 3 aP u 、 、 \ 、 、\ 0 0 \ \ a1 ー \ 0 ) 、‑I Gr ades ( ooL・ S 9 eJ o oL ・ 0)la^ 6 ^ L au o ( ㌔ ( 竜 aNV S JnOu)qaaNtU OJ V L Ener gyLe vel Ti me( week soHhes emes t er ) p r o c e s si st hei d e nt i f i c a t i o nofva r i a bl e st ha ts ho ul dbeme a s ur e ds ot he ne c e s s a r ye mpl r l C a lwo r kc a nbed one . 5.The r es ho ul dbeaba s i si nt heda t a( n ume r i c a lo rwr i t t e n)f o re a c hf e a t u r eo f t her e f e r e nc emode . Fo re xa mpl e , heg t r a pho ft hea nt ' sg r a de sr i s e sbe c a us e t hed e s c r l pt l OnOft hea nts t r a t e g ys t a t e st ha tt hea nt ' sg r a de si mpr o ve s t e a d i l yt hr o ug houtt het e r m. Li ke wi s e , f o rt heg r a s s ho ppe rt he" t e r me nds Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms 1 63 be f or et heg r a s s hoppe rc a nf i ni s ha l lt hewor k"s ot hea s s i gnme ntba c kl og, t houghf a l l i ng, r e ma i nspos i t i vee ve na st het e r me nds . 6.Thema gni t udesa ndt i ml ngOfva r i a bl e ss houl dbec ons i s t e ntwi t hyour n Owl k e dgeoft hes ys t e me ve ni ft hedes c r l Pt l Ona va i l a bl edoe snots pe c i f y t he s ef e a t ur e s . De t a i l sma t t e r . Fore xa mpl e, c ons i de rt hegr a s s ho ppe r s t r a t e gy. Thewor kc ompl e t i onr a t emus tde pe ndont hes t ude nt ' swor k e for t( wor kwe e k) ,s ot he s emovet oge t he r . Howe ve r , be ca us ee ne r gya nd pr oduc t i vl t ya r ef a l l i nga tt hee nd, t hec o mpl e t i onr a t edoesnotr i s ea smuc h a st hewor kwe e kdur i ngt hee ndofs e me s t e rc r unc h. Toma ket hi se ve n mo r eobvi o us ,youmi ghtde f i net heva r i a bl ePr oduc t i vi t ye xpl i c i t l y( t r y s ke t c hi ngi t sdyna mi c s血. omt hede s c r i pt i ona bove ) ・ 7.Ma kes ur eyourgr a phsa r ec ons i s t e ntwi t ha nys t oc ka ndf lowr e l a t i ons hi ps a mongt heva r i a bl e s . Si nc et hea s s l gnme ntba c kl oga c c umul a t est her a t eof a s s l gnme nt Sl e s st her a t eofwor kc ompl e t i on, i tmus tber i s l ngWhe ne ve r t hea s s l gnme ntr a t ee xc e e dst hec o mpl e t i onr a t e,a ndvi c eve r s a. The r e l a t i ons hi pbe t we e nt heba c kl oga ndi t sf lOwsi smos tc l e a r l ys e e ni n t heg r a s s ho ppe rs t r a t e gy. Unt i lwe e k1 0, t hea s s l gnme ntr a t ee xc e e dst he c ompl e t i onr a t e,s ot heba c kl ogbui l dsup. Atwe e k1 0, t heg r a s s hoppe r i sha ndi ngl nWOr kj us ta sf a s ta sne wwo r ki sa s s l gne d, a ndt heba c kl og r e a c he si t spe a k. A洗e rwe e k1 0, t hec ompl e t i o nr a t ee xc ee dst hea s s l gnme nt r a t ea ndt heba c kl ogf a l l s . 5. 4. 4 1 3 eveE opi ngt heCausa=〕i agr ams Ne xtyoumus tus et hede s c r l Pt l OnO ft hes ys t e ma ndr e f e r e nc emode st ode ve l opa c a us a lma poft hef e e dba c kpr oc es s e syoube l i e vea r er e s pons i bl ef o rt hedyna mi c s . Cons i de rFi g u r e51 21 ・ TheAs s i gnme ntRa t ei sa s s ume dt obee xoge nous ' . Onc e as t ude ntha ss l g ne dupf oras e tofc our s es ,t hea s s i gnme ntr a t ei sde t e r mi ne d・ Cl a s s e sc a ns o me t i mesbedr o ppe d, butt hi spos s i bi l i t yl SI gno r e df ornow. TheAs ‑ s l gnme ntBa c kl o gl Si nc r e a s e dbyt heAs s i gnme ntRa t ea ndde c r e a s e dbyt heCom‑ pl e t i o nRa t e.Compl e t i onRa t e( t a s ks / we e k)i sWor kwe e k( hour spe rwe e k)t i me s Pr oduc ivi t t y( t a s ksc ompl e t e dpe rhourofe f f o r t )t i me st heEfor tDe vot e dt oAs ‑ s l gnme nt S ・ E恥 r tDe vot e dt oAs s i gnme nt si st hee 肋r tputi nbyt hes t ude ntc om‑ pa r e dt ot hee fo r tr e qui r e dt oc ompl e t et hea s s l gnme ntWi t hhi ghqua l i t y .I fwo r k pr e s s ur ei shi gh, t hes t ude ntma yc hoos et oc utc or ne r s ,s ki ms omer e a di ng,s ki p c l a s s e s ,o rgl Vel e s sc ompl e t ea ns we r st ot heques t i onsi na s s l gnme nt S . Fo re xa m‑ pl e ,i fas t ude ntwo r ks50hour spe rwe e ka ndc a ndoonet a s kpe rhourwi t hhi gh qua l i t ybutonl ydoe sha l ft hewor kea c ha s s l gnme ntr e qui r esf o ragoodj ob,t he n t hec o mpl e t i onr a t ewoul dbe( 50) ( 1 ) ( . 5)‑25t a s ke qui va l e nt spe rwe e k. Wor kPr es s ur ede t e r mi nest hewor kwe e ka nde for tde vot e dt oa s s l gnme nt S ・ Wo r kpr es s ur ed e pe ndsont heas s i gnme ntba c kl oga ndt heTi meRe ma i nl ngt O c ompl e t et hewo r k:Thebi gge rt heba c kl ogort hel es st i mer e ma i nl ng,t hehi ghe r t hewor kwe e kne e dst obet oc ompl e t et hewor kont i me.Ti mer e ma i nl ngl SOf c our s es i mpl yt hedi fe r e nc ebe t we e nt heDueDa t ea ndt hec ur r e ntCa l e nda rTi me. Thet womos tba s i copt i onsa va i l a bl et oas t ude ntf a c e dwi t hhi ghwor kpr e s s ur e a r et o( 1 )wo r kl o nge rhour s ,t husi nc r e a s i ngt hec ompl e t i onr a t ea ndr e duc i ngt he 164 Pa r tI I Tool sf o l ‑ Sys t e msThi nki ng Fl GURE5‑ 21 Bas i cc on t r ol l oop sf ort h eas s i gn men tb ac k l og ‑\遠 来′ ′一一 \ 二 ▲讐 禁 Comp一 et i on + Assi gnment Ass E gn∑ent a . Ca一 endar Ti me 、< + Time ̲ emai ni ng\ ‑ = 二十 ヽWo l. Back l o r k g Pr essur e = ‑= \‑ 、嬢t 喜 f i o s r ! i 冨 害 v m o e t 喜 T s Pr oduc t i vi t y Wor k week ba c kl og( t heMi dni g htOi ll oo pBl ) ,o r( 2)wo r kf a s t e rbys pe ndi ngl e s st i meo n e a c ht a s k, s pe e di ngt hec o mpl e t i o nr a t ea ndr e duc i ngt heba c k l og( t heCo r ne rCut ‑ t i ngl o o pB2) A Bot ha r ene ga t i vef e e d ba c kswhos egoa li st or e d uc ewo r kpr e s s ur e l . t oat ol e r a bl el e ve Howe ve r ,e a c ho ft he s ene ga t i vef e e d ba c ksha ss i dee f f e c t s I Co ns i de rFi g ur e 5‑ 22. Sus t a i ne dhi g hwo r kwe e ksc uti nt os l e e pa ndt hes a t i s f a c t i o no fo t he rne e ds ) , c a us i ngt hes t ud e nt ' sEne r g yLe ve l ( e a t i ng, e xe r c i s e , h uma nc o mpa ni o ns hi p, e t c・ l s ,s ot oodoc o nc e nt r a t i o na ndf o c us . Er r o r sr i s e . Pr o‑ t of a l l . Ase ne r g yl e ve lf a l d uc t i vi t ydr o ps , r e d uc i ngt hec o mpl e t i o nr a t e ‑at i r e ds t ud e ntmus ts pe ndl o nge r ha t nawel ‑ r e s t e do net oc o mpl e t eat a s kwi t hag l Ve nl e ve lo fq ua l i t y ・ Ast hec o m‑ pl e t i o nr a t ef a l l s , t heba c kl o gr e ma i nshi g he rt ha ni two ul do t he r wi s ebea ndwo r k pr e s s ur ei nt e ns i f i e s , l e a d i ngt os t i l lhi g he rwo r kwe e ksa nds t i l ll owe re ne r gya nd ft hes e l f ‑ r e i nf o r c l ngBur no utl oo p,Rl ,domi na t e st heba l a nc l ng pr od uc t i vi t y・I Mi dni ghtOi ll oo p,a ni nc r e a s ei nwo r kwe e kwo ul da c t ua l l yl owe rt h ec o mpl e t i o n r a t ea st hee xt r aho ur sa r emo r et ha nof f s e tbyt hei nc r e a s ei ne r r o r sa ndr e d uc t i on i npr o duc t i vl t y . Re d uc i ngt hee f f o r tde vot e dt oe a c ha s s l gnme nta l s oha ss i dee f f e c t s ・ Put t i ng l e s se fo r ti nt oe a c ht a s kdoe sa l l o wa s s i g nme nt st Obec o mpl e t e di nl e s st i me butr e d uc e st heQua l i t yo fWo r k, l o we r i ngt hes t ude nt ' sGr a d e s ・ Wh e ng r a d e sf a l l l 165 Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms F【 GURE5 ‑ 22 Th ebur n ou tl oop ‑\立 木′ 一 一 「 s h g a n .∑e nt As n d ar T i me \亘 Cal e + ー ‑二 "Wp. r ̲ 5 Compl et i on + Tj me emai ni ng\ ヽ r D u e D a t e R Pr essur e r k Wo week r e l a t i vet ot hes t ude nt ' sa s pi r a t i o ns ,t he r ei spr e s s ur et oboos tt hee f f o r tpu ti nt o e a c ht a s k・ Thene g a t i veQua l i t yCo nt r o ll oo pB3pr e ve nt se f f or ta ndqua l i t yf r o m f a l l i ngt oof a re v e nwhe nwo r kpr e s s u r ei shi g h( Fi g ur e5‑ 23 ) . Ho we ve r , t hee f f o r t t oma i nt a i nqua l i t ya l s oc r e a t e sa ni ns i d i ouspos i t i vef e e d ba c k・ Aswo r kpr e s s u r e f o r c e st hewo r kwe e kup,e ne r gyl e ve le ve nt ua l l yf a l l s( not et hede l a y) ,r e d uc i ng g r a de s . Thes t ud e n tr e s po ndsbyi nc r e a s l ngt hee f f o r tputi nt oe a c ht a s ki na na t ‑ t e mptt oboos tg r a de sba c ku pt hr o ug ht heq ua l i t yc o nt r oll oo pI Buti nc r e a s l ngt he t i mes pe nto ne a c ht a s kl owe r st hec o mpl e t i o nr a t e 。 Theba c kl ogofwo r kr i s e s , i n‑ t e ns i f y i ngwo r kp r e s s ur ea ndl e a d i ngt os t i l lmo r eove r t i me , s t i l l l owe re n e r g y , a nd s t i l ll owe rg r a de s ・ Whe nt hee x ha us t e ds t ude nti sT わoTi r e dt oThi n k, t hepos i t i ve l o o pR2O pe r a t e sa savi c i o usc yc l e ‑e fo r t st oboos tg r a de sonl ys uc c e e di nc r e a t ‑ e ,l o ng e rho ur s ,e ve nl o we re ne r gy ,a nds t i l ll owe rq ua l i t y 1 ngmo r ewor kp r e s s ur wo r k. Yo uma ywo nd e rwhya nyo newo ldke u e pwo r ki ngwhe nt he i re fo r t sno to nl y yi e l de ddi mi ni s h i n gr e t ur nsbutne ga t i v er e t ums . Woul dn' tt heg r a s s ho ppe r sr e a l ェ i z et he i re f f o r t swe r ea c t ua l l yc o unt e r pr od uc t i ve?I ti spr e c i s e l ywhe npe o pl e a r ee xha us t e dt ha tt he i rj udg me nti smos ti mpa i r e d.Howma nyt i me sha veyo u c o nt i nue dt owo r konapr o j e c tWhe n, a tl e a s ti nr e t r os pe c t , yo us ho ul dha vec a l l e d i tada y? 16 6 Pa r t I IT o o l sf o rS y s t e msTh i n k i n g FI GURE5・ 23 The" t oot i r edt ot hi nk "l oop √ ‑1も As sL g ̲ T ent R a te Cal endar Assi gnment 東 ̲T i m e e m a i n i n 束W l . k l o g o r k P r e s s u r e Ti me \ + \‑ wor k Comp一 et i on + g \ ‑ Bac 巌 ̲ 一 匝 Wor kweek̲ 1 1 .ノ T . . 0 % 二 一 ; . : ; +\ 二言 \ 二 £ G√ a c Q O u n ニ yo〆 号 + E n e r g y L e v e l J f ‑ Wor r I fa l le l s ef a i l s ,t hee xha us t e ds t ude ntca na ppe a lt ot hef a c ul t yf T o rr e l i e f ,ge n‑ e r a t i ngRe que s t sf o rExt e ns i ons( Fi gur e5‑ 24) ・ Us ua l l y,s uc hr e ques t sa r ea c c om‑ pa ni e dbys t or i e sofba dl uc ka ndha r ds hi pbe yondt hes t ude nt ' sc o nt r ol :" Mydog a t emyhome wo r k, 日日 Myha r ddi s kc r a s he d, "H Myr oo mma t eha dane r vousbr e a k down. "I ft hef a c ul t ya r emove dbyt he s et a l esoft r a ge dya ndwoe( abi gi f ) ,t he dueda t ei ss l i ppe d,ma ki ngmor et i mea va i l a bl ea ndr e duc i ngwor kpr e s s ur e. Be ‑ c a us ef a c ul t yr a r e l ygl Vee xt e ns i onsunl es st he r ea r ege nui nee xt e nua t l ngC i r c um s t a nc e s , t hene ga t i veMyDogAt eMyHome wor kl oopB4i squl t eWe a k・ Not et ha t s l i ppl ngt hede a dl i ne,be ca us ei tl owe r swor kpr es s ur e ,ma ya c t ua l l yc a us et he wor kwe e kt of a l la ndt hee for tde vot e dt oe a c ha s s i gnme ntt Or is e , bot hr e duc i ng t hec omt ) 1 e t i onr a t ea ndc a us i ngWOr k1 ) r e S S ur et Obui l dupa ga i n. The s ef e e dba c ks a r er es pons i bl ef orPa r ki ns on' S( 1 957)f a mousl a w:" Wo r ke xpa ndst of i l lt het i me a va i l a bl ef ori t sc ompl e t i on. " Whi l et he r ea r ema nyot he rl oopsyouc oul da ddt ot hef r a me wor k,t he s es i x f e edba c ksj oi nt l ye xpl a i nmos toft hedyna mi c sc r e a t e dbyt hea nta ndgr a s s ho ppe r S t r a t egl e S ・ ‑ ‑ 5. 4. 5 Li mi t at i onsof的eCausa‖〕i agr am Ca us a ldi a gr a msc a nne ve rbec ompr e he ns i ve( a ndyous houl d n' tt r y:mode l i ngi s t hea r tofs i mpl i f i c a t i on) .The ya r ea l s one ve rf i na l ,buta l wa yspr ovi s i ona l .The 167 Ch a p t e r5 Ca u s a l L o o pDi a g r a ms FI GURE5‑ 24 Myd ogat emyh omewor k ‑Par k i n s on' sL a w a 「‑ 左 京′ 一 一、 Assi gnment As s B gn . Tent 一 e n d Ca ar = ‑ Backl og Ti me \ 亘 /競 e:i a Tn e b ng‑ ̲ ; =f i / ' 二 \Wo r k o m ‑ \ 二 M Wp. r A E C p一 e t i on + :ニ Pr essur e R e q u e s t s f o rG E x t n i o n s r a d e s 十 ・ R l 2 M y D o g A t e M y H o m e wo r k \ ‑ ‑ ふ Pr oduc t i vi t y t o Ef i o s r :i 冨:v m o e t :E s す ㌧ Qual i t yof T T i r e d t T h n k o o o A W o r k week ma pse vol vea syo uru nd e r s t a ndi ngI mpr o ve sa nda st hepur pos eo ft hemode l i ng t . e fo r te vol ve s .Thea c c o untofwo r kl oa dma na ge me nta bo vei sf a rf r o mpe r f e c He r ea r es o mei s s ue st oc o ns i de r : r, Fi r s t , t hedi a g r a mdoe sno tdi s t i ng ui s hbe t we e ns t oc ksa ndf lo ws . I npa r t i c la u i t wo ul dbehe l pf u lt os ho wt hes t o c ka ndf lows t uc r t u r eo ft hea s s i g n me n tba c k l og. Wha to t he rva r i a bl e si nt hi smo de la r es t oc ks ? Se c o nd,s o mel o o psc o ul dbes pe c i f i e di nmo r ede t a i l ・ Fo re xa mpl e , t heq ua l l l t yc o nt r oll oo pa s s u me st ha te fo r ti nc r e a s e swhe ng r a de sf a l lr e l a t i vet ot hes t u‑ de nt ' sa s pi r a t i o ns .I twou l dbec l e a r e rt os pe c i f yt hos ea s pl r a t i o nse x pl i c i t l y ,f o r e xa mpl e , byc r e a t i ngava r i a bl eDe s i r e dGr a d ePoi nt Ave r a g e( GP A) . Efo r two ul d t he nbea fe c t e dbyt h es t u de nt ' sSa t i s f a c t i o nwi t hGr a de s , whi c hme a s ur e st hega p be t we e nde s i r e da nda c t ua lg r a de s . Ane x pl i c i tgoa lf o rg r a d e sma ke si te a s i e rt o e x pl o r et hed yna mi c sf o rs t ud e nt swi t hd i fe r e nta s pl r a t i o nsa nda t t i t ud e sa bo utt he i mpo r t a nc eofg r a de s . Ma k i ngt hegoa le x pl i c i ta l s omo t i va t e sq ue s t i onss uc ha s Wha tde t e r mi ne sa s pi r a t i onsf o ra c a d e mi ca c hi e ve me nt ? ‑t ha ti s , wha tf e e d ba c k pr oc e s s e smi ghtc a us et hede s i r e dGPAt ova r yove rt i me ? Ava r i e t yo fpr e s s u r e sf o ra c hi e ve me nt , e xt e ma lt ot hewo r kl oa dma na ge me nt mo de l , Putupwa r dp r e s s u r eo ng r a dea s pi r a t i ons . Suc hpr e s s u r e sa r i s ef r o mo bs e r ‑ va t i o nso ft heg r a d e syo urpe e r sr e c e i ve( o rc l a i mt oha ver e c e i v e d) , f r ompa r e nt s , 168 r t I I ¶〕 o l sf o rS y s t e msTh i n k i n g P a FI GURE5 5 Mak i ngt hegoal of aL oopexpl i ci t Addi n gt hedesi r ed GPAandi t s det er mi nant s. ・ Wor kPr essur e 2 dI S en vot me、 e∩ Dg Sat i sf act i on wi t hGr ades 1.ノ I + Qu a H t yCo n t r ol 〆 Desi r ed GPA k l こ、 Gr ades 普 Pr essur ef or Achi evement ‑L Q豊 吉r y k Of ・\ Ener gyLevee Orf r omt he( pe r c e i ve d)r e qui r e me nt soff ut ur ee mpl oye r so rgr a dua t es c hoola d‑ mi s s i onsofi c e r s .Fi gur e5‑ 25s howsa not he ri mpor t a ntde t e r mi na ntofs t ude nt goa l s :As pi r a t i onsa d j us tt opas ta c t ua la c hi e ve me nt ,f or ml ngt hene ga t i veGoa l Er os i onl oo p.Ma nype o pl ej udgewha ti spos s i bl e ,a tl e a s ti npa r t ,f r om wha tha s be e na c hi e ve d・ Er odi ngyourgoa l si nt hef a c eo fape r s i s t e ntdi s c r e pa nc ybe t we e n a s pi r a t i ona nda c hi e ve me nti sac ommonwa yt or e duc ewha tFes t i nge r( 1 957) c a l l e d" C ognl t i vedi s s ona nc e Ha ndha sbe e na mpl ydoc ume nt e di nma nys i t ua t i ons . Thegoa le r os i onl oopca nbea ni mpor t a ntl e a r nl ngpr oc e s sOrma yC r e a t eaha r m f uls e l f ‑ f ul f i l l i ngpr ophe c y. Fore xa mpl e, mos ts t ude nt sa dmi t t e dt oe l i t euni ve r s i ‑ t i e swe r ea tt het opoft he i rhi ghs c hoolc l a s s .Onc ee nr ol l e di nt hel vyLe a gueo r MI T,howe ve r ,ha l foft he m wi l lbei nt hebot t om ha l foft hei rc l a s s .Thea d j us t 一 me れtofg r a dea s pl r a t i onst oane ws i t ua t i onpr e ve nt spe r pe t ua ldi s a ppol nt me nt , s t r e s s ,a nds e l f ‑ doubt .Ont heot he rha nd,Ove r l yf l e xi bl egoa l sc a nl e a dt ounde r ‑ a c hi e ve me nt ・Somegr a s s hoppe r s ,r e le f c t i ngonhow muc hmi dni ghtoi lt he y bur ne da tt hee ndoft het e r ma ndt hedi s a ppol nt l nggr a dest hos ehour sl e dt o, ma y c onc l udet he ya r e n' t Aore ve nBs t ude nt sa ndl owe rt he i ra s pl r a t i onst or e l i e vet he d i s s ona nc ebe t we e ne xpe c t a t i onsa nda c hi e ve me nt .Sa dl y,t hi sl es s onma ybee n‑ t i r e l ye r r one ous :Fe we rhour sofe f f or t ,i ft he ywe r ewe l lr es t e d,ma ye a s i l yha ve l e dt ohi ghe rg r a de s 。 ‑ Pol i cyAnaJ ys垂 sWi t hCL quSa§D弓 a§r a. P T I S Thebo unda r yoft hes t ude ntwor kl oa dmode lc oul dbee xt e ndedt oi nc l udema ny ot he rf e e d ba c kpr oc es s es .Modi f yt hes t ude ntwo r kl oa ddi a g r a mt oi nc l udet he f ol l owl ngi s s ues : 1 ・ Dr oppl ngC l a s s e si nr e s pons et ohi ghwo r kpr e s s ur e ,l owgr a de s , orl owe ne r gy. 2. Dr i nki ngc of f e eo rt a ki ngs t i mul a nt st os t a ya wa kewhe ne ne r gyl e ve li sl ow. CI l a p t e r5 Ca u s a l Lo o pDi a g r a ms 169 3・Chea t i ngona s s l gnme nt St Oboos tt hec ompl e t i onr a t ea ndr a i s egr a des . . 4・Ot he rl oopsyoube l i e vet obei mpor t a nt Asyoue xpa ndt hebounda r yoft hemode l ,as kyour s el f :Doest hea bi l i t yoft he mode lt oe xpl a i nt hedyna mi csc ha nge?Doest her es pons eoft hemode lt opol i c i es c ha nge?Ar et hec oncl us i onsoft heea r l i e ra na l ys i sr obus tt oc ha ngesi nt hebound a r yoft hemode l ? ‑ 5t 5 ADAM SMI THウ S岳 NV事 S旧しE HANDANDTHE FEEDBACKSTRUCTUREOFMARKETS Ada m Smi t h' si nvi s i bl eha ndi soneoft hemos tf a mousme t a phor si nt heEngl i s h l a ngua ge.Smi t hr ea l i ze dt ha taf r eema r ke tc r ea t espowe r f ulnega t i vef e edba c k l oopst ha tca us epr i c esa ndpr of i t st obes e l f ‑ r e gul a t l ng・ Whi l eSmi t hl a c kedmod‑ e nt r ool ss uc ha sc a us a ldi a gr a msa nds i mul a t i onmode l s , hef t eedba c kl oopsi nhi s des c r i pt i onoft hef unc t i oni ngofma r ke t sa r ec l ea r . I nTh eT V e al t ho fNat i on sSmi t h a r gue dt ha tf ora nyc ommodi t yt he r ewasa" na t ur a l "pr i c eWhi c hi sj us t" s uf f i c i e nt t opa yt her e nto ft hel a nd,t hewa gesoft hel a bou r ,a ndt hepr of i t soft hel ca pi t a l ] s t oc ke mpl oye di nr a i s i ng, pr e pa r i ng,a ndbr i ngi ng[ t hec ommodi t y]t oma r ke t.‥= Att hena t ur a lpr l C e, aH commodi t yi st he ns ol dpr e c i s e l yf わrwha ti ti swor t h, Orf or wha ti tr e a l l ycos t st hepe r s onwhobr i ngsi tt oma r ke t‥ . "Ⅰ ncont r as t ,t hea c t ua l ma r ke tpr l C eH ma ye i t he rbea bove,orbe l ow,ore xa c t l yt hes a mewi t hi t sna t ur a l pr l C eH ‑t ha ti s , ma r ke t sma ya ta nyt l mebeoutofequi l i br i um. Smi t ht he nnot e dhow pr l C eSr es pondt ot heba l a nc ebe t wee nde ma nda nd s uppl y: Thema rke tp r l C eO fe ve r ypa r t i c ul a rc ommod i t yl Sr e gu l a t e dbyt hepr o po r t i o n be t we e nt hequ a n t l t yWhi c hi sa c t ua l l ybr o ug h tt oma r ke t , a ndt hede ma ndo ft hos e whoa r ewi l l i n gt opa yt hena t ur a lpr l C eOft hec ommod i t yI‑Whe nt hequa n t l t yO f a n yc o mmo d i t ywhi c hi sbr o ughtt oma r ke tf a l l ss ho r to ft hee f f e c t ua lde ma nd, a l l t hos ewhoa r ewi l l i ngt opa yt hewho l eva l ue. Hc a n no tbes u ppl i e dwi t ht heq ua n‑ t l t yWh i c ht he ywa n t . Ra t he rt ha nwa nti ta l t o ge t he r , s o meo ft he mwi l lbewi l l i ng t ogl Vemo r e . Ac ompe t i t i o nwi l li mme d i a t e l ybe gi na mo ngt he m, a ndt hema r ke t pr l Ce Wi l lr i s emo r eo rl e s sa bovet hena t u r a lp r l C e . Si mi l a r l y, whe ns uppl ye xc eedsde ma nd,=[ t ] hema r ke tpr i c ewi l ls i nkmor eorl es s be l owt hena t ur a lpr l Ce. H Buts uppl yl nt ur nr es pondst ot hema r ke tpr l C e: I f. . . t hequa n t i t yb r o ug htt oma r ke ts houl da ta nyt i mef a l ls ho r toft hee f f e c t ua l de ma nd, s o meo ft h ec o mpo ne ntpa r t so fi t sp r l C emus tr i s ea bov et he i rna t ur a lr a t e . I fi ti sr e nt , t hei n t e r e s to fa l lo t he rl a ndl o r dswi l lna t u r a l l ypr o mp tt h e mt opr e pa r e mo r el a ndf o rt her a i s l ngO ft hi sc ommod i t y; i fi ti swa g e so rp r o 恥t hei nt e r e s to f a l lo t he rl a bou r e r sa ndd e a l e r swi l ls o onpr omptt he mt oe mpl oymo r el a bo ura n d s t o c ki npr e pa r l n ga ndbr i ng l ngl tt Oma r ke t . Theq ua nt i t yb r o ug htt hi t he rwi l ls oo n bes u f f i c i e n tt os u ppl yt hee f f e c t ua lde ma nd. Al lt hedi f f e r e ntpa r t sofi t sp r l C eWi l l s oo ns i n kt ot he i rna t u r a lr a t e , a ndt hewho l epr i c et Oi t sna t ur a lp r l C e . 170 P a r t I IT o o l sf o rS y s t e msTh i n k i n g 、モ Re V 豆) P r l i c ‑ = ‑ P r e f i t s 束 e ヽ ー ノノ ‑ D e m a n d 二 ㌢ L a t i v e a l u e ーノ Demandr esponds t ot her el a t i ve v al ueoft hecom‑ modi t yc ompar ed t osubs t i t u t es; hi gherr e一 at i ve val uei n cr eases demand,bi ddi ng pr l C eSuPand l owenngr el at i v e val ue.Suppl y expandswhen pr of i t sr i se;pr o f i t dependsonpr l C e r el at i v et opr o‑ duc t i onc os t s i nc一 udi n gt her e‑ qui r edr et ur non c api t al . Gr eat er suppl ybi dspr l C eS down,l ower l ng pr o f i t s. Thepn c e ofsubs t i t u t esand t hecos tofpr odu c‑ t i ondet er mi ne what Adam Smi t h c aH edt he" nat ur al pr 】 c e"oft hec om modi t y ‑t heequ卜 I i br i umpn c eat whi chsuppl yand demandar eequal . Pr i ceof Subst i t ut es ヽ FI GURE5‑ 26 Thei n vi si bl eh an d: t hef eedback s t r uc t ur eof mar k et s Costof Pr oduct i on + Suppl y As i mpl er e pr es e nt a t i onoft hef e e dba c ks t r uc t ur eSmi t hdes c r i be si ss howni nFi g‑ ur e5‑ 26. Whe nt hepr l C eOfac ommodi t yr l S eSa bovet hena t ur a lpr l C e , f e we rbuy‑ e r s" wi l lbewi l l i ngt ogl Vemo r e "a ndmor ewi l lbef or c e dt oH wa nti ta l t oge t he r . H Tha ti s ,a spr l C er i s e sr e l a t i vet ot hepr l CeOfs ubs t i t ut es ,i nc l udi nga l ls ubs t i t ut e us esf ort hef undsa va i l a bl et ot hebuye r ,c ons ume r swi l ls e e ks ubs t i t ut e so rf i nd t he ms e l vess i mpl ypr i c e doutoft hema r ke t . Asde ma ndf a l l spr l C e SWi l lbebi d down, f or ml ngane ga t i vel oo p. Att hes a met i me, hi ghe rpr i c esi nc r e a s et hepr of i t s uppl i e r sc a nr ea l i z e,whi c ha t t r a c t sne we nt r a nt st ot hema r ke ta nde nc our a ges e xi s t l ngpr oduc e r st oi nc r ea s eout put . Ast hes uppl yI nc r ea s e s , pr l C e Sa r ebi ddown‑ wa r ds .Thes et wone ga t i vef e e dba c kl oopsca us epr l C et Oa d j us tunt i l ,i nt hea b‑ s e nc eoff u r t he re xt e r na ls hoc ks ,t hema r ke tr e a c he se qui l i br i um,Wi t hpr oduc t i on e q ua lt oc ons umpt l Ona ndpr l C ee q ua lt oi t sna t ur a ll e ve l . Smi t hc onc l ude s : Th en a t u r a l p r l Ce , t h e r e f o r e , i s , a si twe r e , t h ec e nt r a l p r l Ce , t OWh i c ht hep r l C e SO f a l lc o mmo d i t i e sa r ec o n t i nu a l l yg r a v i t a t i n g. Di f f e r e n ta c c i d e n t sma ys o me t i me s k e e pt h e ms us pe n d e dag o o dd e a la b o v ei t , a n ds o me t i me sf o r c et h e md o wne v e n s o me wha tb e l o wi t . Bu twha t e v e rma ybet heo bs t a c l e swh i c hh i n d e rt h e mf r o m s e t t l i ngi nt h i sc e n t r eo fr e po s ea n dc o n t i n ua n c e , t h e ya r ec o ns t a n t l yt e n d i n g t o wa r dsi t . Smi t h' sgr e a ti ns i ghtwa st or e a l i z et ha twhe npr l C eSr i s ea bovet hena t ur a ll e ve l , pr oduc e r swhos e e kt oma xi mi z et he i rownga l れWi l lc ont i nuet oe nt e rt hema r ke t unt i lt hepr l C ei sbi ddownt ot hepol ntWhe r et her e t ur nont he i rc a pl t a li snohi ghe r ( t oda ywewoul da ddH onar i s ka d j us t e dba s i s M )t ha nt ha ta va i l a bl ee l s e whe r e , r e ‑ s ul t i ngl nc ompe t i t i vepr l C eSa nda ne f f i c i e nta l l oc a t i onofr e s our c e st hr oug ho uts o c i e t y. Hef a mous l yc onc l ude s : ‑ Ev e r yi nd i v i d ua le nd e a v o r st oe mp l o yh i sc a p l t a ls ot ha ti t sp r o d u c ema ybeo f g r e a t e s tv a l u e . Hege n e r a l l yn e i t he ri n t e n dst op r o mo t et hep u b l i ci n t er e s t , n o r kn o wsho wmu c hhei sp r o mo t l n gi t . Hei n t e n dso n l yh i so wns e c u r l t y , O n l yh i s o wnga i n. Andhei si nt h i sl e db ya ni n v i s i b l eha n dt op r o mo t ea ne n dwh i c hwa s n opa r to fh i si n t e n t i o n. Byp u r s u l n gh i so wni nt e r e s thef r e q ue n t l ypr o mo t e st ha to f s o c i e t ymo r ee f f e c t ua l l yt ha nwh e nh er e a l l yI n t e n dst op r o mo t ei t . 171 Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms Smi t hwa st huso neo ft hef i r s ts ys t e mst hi nke r st os howho wt hel o c a l , i nt e nd e d l y r a t i ona ls e l f ‑ i nt e r e s t e dbe ha v i o rofi nd i v i d ua lpe o pl ec oul d, t hr o ug ht hef e e d ba c k pr oc e s s e sc r e a t e dbyt he i ri nt e r a c t i o ns , l e a dt ouna nt l C I Pa t e ds i dee fe c t sf o ra l l 1 0fc o ur s e,Smi t h' Sc onc e ptoft hei nvi s i bl eha ndi sf a rmo r ef a mo usa st he c r e doofmode r nf r e ema r ke tc a pi t a l i s m,I ti st hec o r eoft hef a i t ht ha tma r ke t s knowbe s t .Smi t hhi ms e l f ,howe ve r ,wa sc a r e f u lt onot et hel i mi t soft hema r ke t Thi sa tl e a s t f e e d ba c ksi ne q ui l i br a t l ngde ma nda nds u ppl ya tt hena t ur a lpr l C e・" wo ul dbet hec a s e MSmi t hno t e s , " whe r et he r ewa spe r f e c tl i be r y" t ‑t ha ti s , u nd e r c o nd i t i onso fpe r f e c tc o mpe t i t i o n( f r e ee nt r ya n de xi t , f r e emobi l i y oft t hef a c t o r s o fpr od uc t i o n,a ndf r e ee xc ha ngeo fi nf o r ma t i o nonde ma nd,s uppl y ,c os t s ,a nd pr o f i t s ) . Whe r et he r ea r emo no po l i e s , t r a des e c r e t s , go ve r nme ntr e g ul a t i o ns , ba r r i ‑ e r st ot r a de ,r e s t r i c t i onsoni mml g r a t i o na ndc a pi t a lmo bi l i t y,o ro t he rf e e d ba c ks o ut s i det hes i mpl ene ga t i vel oo psc o u pl i ngs up pl ya ndde ma nd,Smi t hno t e st ha t pr i c e sa ndpr of i t sma yr i s ea bo vet hena t u r a ll e v e lf o rma nyye a r s , e ve nde c a d e s ・ Thef e e d ba c ks t r uc t u r ef o rc o mpe t i t i vema r ke t ss howni nFi gur e5‑ 26i sq u l t e r k, O nec a ndi s a gg r e ga t et os ho wt he us e f ul . Be gl nnl ngWi t ht heg e ne r a lf r a me wo s pe c i f i ca d j us t me ntpr o c e s s e sa two r ki na nypa r t i c ul a rma r ke tf o rbo t hde ma nd a nds uppl y.Ad di t i o na lf e e d ba c ksbe s i de st hede ma nda nds uppl yl oo psc a nbe a dd e d,bot hpos i t i vea ndne ga t i ve ,a ndt he i ri mpl i c a t i o nsa s s e s s e d・Thet i med e ‑ l a ys , i fa ny , i nt h er e a c t i o no fd e ma nda nds u p pl yt oh i g he rpr l C e SC a nbee s t i ma t e d, a ndt hei mpl i c a t i onsf o rt hes t a bi l i t yo ft hema r ke te x pl o r e d・ I fe i t he rt hede ma nd o rs uppl yl oo po pe r a t e ss t r o ngl ya nds wi f t l y( hi g hs ho r t ‑ r une l a s t i c i t i e s ) , t he nt he ,i ft he r ea r el o ng ma r ke twi l lr a pi d l yr e t ur nt oe q ui l i br i umi fpe r t ur be d. Howe ve r de l a yso rwe a kr e s po ns e si nt hel oo ps( l ows hot ‑une l a s t i c i t ya ndhi g hl o ng‑ r u n i t y) , t he nt hema r ke twi l lbepr o n et ope r s i s t e ntdi s e q ui l i br i um a ndi ns t a bi l ‑ e l a s t i c i t y; r a ndo ms ho c ksi nd e ma ndo rpr od uc t i onwi l le xc i t et hel a t e ntos c i l l a t o r ybe ‑ ha v i o roft hema r ke t( s e ec ha pt e r s4a nd2 0) ・ No ta l lma r ke t sc l e a rt hr o ug hpr l C ea l o ne . Fe wpr od uc t sa r epur ec o mmo d i t i e s f o rwhi c hpr l C ei st heonl yc o ns i de r a t i o n:Pr od uc t sa nds e r vi c e sa r ei nc r e a s l ng l y d i f f e r e nt i a t e da ndc o mpa ni e sc ompe t et oo f f e rt hebe s ta va i l a bi l i y,de t l i ve r yr e l i a ‑ t ,a nds oo nL I n bi l i t y ,s e r v i c e ,f u nc t i o na l i t y , t e r mso fpa y me nt , a f t e r ma r ke ts uppor ma nyma r ke t sp r l C e Sdono tc ha ngef a s te no ug ht oe q ui l i br a t es uppl ya ndd e ma nd mpor t a nti nc l e a r l ng a ndo t he rc omp e t i t i veva r i a bl e ss uc ha sa va i l a bi l i t ybe c o mei i on, t hec os t sa n da d一 t h ema r ke t . Pr i c e sma ybes l ugg i s hd uet og ov e mme ntr e g ul a t i onsoff a i r ne s s .Fo r mi ni s t r a t i vebu r de noff r e q ue ntpr i c eC ha nge s ,orc o ns i de r a t e xa mpl e ,mos tpe o pl ec ons i d e ri tunf a i rf o rha r d wa r es t or est or a i s et hepr i c eO f nc r e as e d( s e eKa hne ‑ s no ws hove l sa f t e ras t o r m, e ve nt ho ug hd e ma n dma yha vei ma n, Kne t s c h,a ndTha l e r1 98 6; Tha l e r1 991 ) . r ke t sa ta l l ・Mos t I nma nyI ns t i t ut i ona ls e t t l ngSpr l C edoe snotme di a t ema sf orofi c e s ,pa r ki ng o r ga ni z a t i ons ,f o re xa mpl e ,ha venopr i c e ‑ me d i a t e dma r ke t s pa c e s ,s e ni o rma na ge me nta t t e nt i o n,a ndma nyo t he rs c a r c er es our c e s ・I nt he s e e d ba c ks ,butr e s o u r c e s c a s e s ,s uppl ya ndde ma nda r es t i l lc o u pl e dv i ane ga t i vef e a r ea l l oc a t e do nt heba s i so fa va i l a bi l i t y ,po l i t i c s ,pe r c e i ve df a i r nes s ,l o t t e r y , mpl esofno n‑ p r l C e ‑ o ro t he ra dmi n i s t r a t i vepr oc e d ur e s ・Fi g ur e5‑ 27s howsexa me d i a t e dma r ke t s . I ne a c hc a s et hef e e d ba c ks t r uc t ur ei sas e tofcoupl e dne g a t i ve l oo pswhi c hr e g ul a t et hede ma ndf o ra nds u ppl yofar e s our c e・ Asi nt hec a s eof pr l C e ‑ me d i a t e dma r ke t s , t he r ema ybes u bs t a nt i a lde l a ysi nt hea d j us t me nt s , 1 e a d‑ 1 ngt Ope r s i s t e ntd i s e qui l i br i a . r r 172 P a r t I IT わ o l sf o rS y s t e ms Th i n k i n g FL GURE5‑ 27 Feedbac ks t r u c t ur eofn on ‑ pr i c e ‑ medi a t e dr es our c eaH oc a t i ons y s t ems Lef t :A vai l abi l i t yl Sani mp or t an tc ompe t i t i v ev ar i abl ej nman ypr odu c tmar k e t s, an df i r msr egu l at e pr odu c t i oni nr es p on s et oi n ven t or yadequ ac yan ddel i v er ydel ay . Ri ght : I ns er vi c es e t t i n gs, hi gh ers er vi c equ al i t ys t i mul a t esdeman d, bu tgr ea t erdeman der o dess er vi c e qu al i t yaswai t i ngt i mei n cr eas es, an dac c ur ac y , f r i en dl i n es s, an do t h erex p er i en t i al as p ec t so ft h e s er vi c een c oun t erde t er i or a t e. P r o d u c t A t r ' a c t i v e n e s 豆 Backl ogof Unf ‖e dOr der s e ‑‑ I Pr oduc tJ Avai l abi l i t y v e 二 P r 。 . ) ・ 卑 しP r o d u c t i o n C 尊王 二 D e s i r e d o d u c t i o n + cus t omer Bas e C u s t o m e r S e S a t i s f a c t i o nや 主) R e q u e ノ + ㌧㌻ ‑ ・ ‑ Ser vi ce Resour ces ヽ + r vi c e s t s ヽ + Adequacy ofSer vi ce Ser vi ce i t y ‑ ‑Qual 吋 TheOi lCr i sesoft he1970s I n1 973t hef i r s tOPECo i ls ho c ks t unne dt hei nd us t r i a l wo r l d. Oi l pr l C e Smo r et ha n t r i pl e di nama t t e rofmo n t hsa sma nyAr a boi lpr od uc e r se mba r g oe ds hi pme n t st o we s t e mna t i onst or e t a l i a t ef わrt he i rs up po r to fi s r a e li nt heYo nKi ppu rwa r . Ma ny a na l ys t sbe l i e ve dma r ke tf o r c e swo ul dbr i ngt hepr l C eOfoi lba c kt opr e ‑ e mba r go l e ve l si nama t t e ro fmo nt hs ,o ra tmos taye a rort wo,a sde ma nda nds u ppl yr e ‑ a c t e d。 I ns t e a d, pr l C e Sr e ma i ne dhi g h, t he nr os ee ve nhi g he ra sl r a ni a npr o duc t i on f e l li nt hewa keo ft he1 979r e vol ut i on.Byt hee a r l y1 98 0S ,ma nya na l ys t spr e ‑ di c t e dt ha toi lpr l C e SWe r ehe a de de v e nhi g he ra ndwo ul dne ve rr e t u mt ot hel ow l e ve l soft hee a r l y1 9 70S . Buta f t e rr e a c hi ngne a r l y$ 50pe rba r r e l( i n1 99 0do l l a r s ) , t hepr l C eOfoi lc o l l a ps e di nt hemi d1 98 0S . Ma nyo i le xpl or a t i o na nda l t e r na t i ve e ne r gypr o j e c t sWe r eC a nc e l e d;ba n kr upt c ywa sc ommo n.I nt heUS,ga s ol i ne pr l C e Si nr e a lt e r msf e l lbe l o wt he i rpr e ‑ e mba r gol e ve l ‑ga s o l i nei nt hel a t e1 99 0s wa so f t e none ‑ f o ur t ht hepr l C eOfde s i g ne rwa t e r . St a r t i ngwi t ht heba s i cma r ke tf e e d ba c ks t r uc t ur e( Fi gu r e5‑ 26 ) ,de ve l o pa c a us a ldi a g r a mt oe x pl a i n( 1 )t hef a i l ur eofma r ke tf o r c e st obr i ngpr i c e sba c kt o e q ui l i b r i ums o ona f t e rt hef i r s toi ls ho c k( t ha ti s , Howc o ul dpr i c e sr e ma i ns ohi h g s ol ong? )a nd( 2)whypr i c e sc ol l a ps e di nt hemi d1 98 0sa ndr e ma i ne dbe l owt he e qui l i br iuml e ve lf or s ol o ng( t ha ti s , Whyd i dn' tpr i c e ss t a yhi g h? ) , Tohe l p, Fi g u r e 5‑ l lS howss o meo ft hec a us a ll i nkso nt hede ma nds i deo ft hema r ke t . Fi g u r e3 ‑ 4 s howsUSpe t r ol e umpr od uc t i o n,c o ns umpt l On,a ndr e a lpr l C e SO Ve rt her e l e va nt 173 Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms t i mehor i zon・Ke e pyourdi a gr a ms i mpl ea ndf ol l owt hegui del i nesf orca us a ll oop di a gr a ms . Us eyourdi a gr a mt os ke t c ht hepa t t e r nofbe ha vi oryouwoul de xpec tf ort he r a t eofoi lpr oduc t i ona ndt her a t eofdr i l l i ngofne wwel l sf r om 1 970t o1 990. Al s o pl otc a pa c i t yut i l i za t i onf orbot ha c t i vi t i es( t ha ti s ,wha tf r a c t i onofe xi s t i ngwe l l s a r epumpl ng,a ndwha tf r a ct i onofe xi s t l ngdr i l lr l gSa r eoper a t i ng,a ta nygi ve n t i me ) . Wha tdoesyourdi agr a ms ugges ta boutt hel i ke l ydyna mi csoft hewor l doi l pr i ceOVe rt hene xtf e wdec a des ? Specul at i veBubbl es Nota l lma r ke t sc ons i s tofne ga t i vef e edba c ksa l one.I nma nyma r ke t st hel oca l l y r a t i ona lbe ha vi orofi ndi vi dua le nt r e pr e ne ur sc r ea t espos i t i vef ee dbac ksa st he yI n‑ t e r a c twi t honea not he ra ndwi t ht hephys i c a ls t r uc t ur eoft hes ys t e m. Onecommon e xa mpl ei st hes pec ul a t i vebubbl e. The r eha vebe e nma nydoz ensofma j orS pec u‑ l a t i vebubbl esi nt hepa s tf e wce nt ur i es , f r om t hei nf a moust ul i pma ni aof1 636a nd Sout hSeabubbl eof1 720t ot hema ni a sa ndc r as hesoft hepas tf e w dec a des ,i n‑ ・ 2 c l udi nggol d,s i l ver ,r ea les t a t e,i mpr es s i oni s tpa l nt l ngS ,a ndi nt e r ne ts t oc ks J ohnSt ua r tMi l ldi s il t l edt hees s e nc eoft hedyna mi csofs pec ul a t i oni nt hef ol l owi ngpas s a gef r om hi sf a moust e xtPr i nc i pl e so fPol i t i c alEc onomy ,or i gi na l l y publ i s he di n18 48: ‑ Whe nt he r ei sage ne r a li mpr e s s i o nt ha tt hep r i c eO fs o mec o mmo di t yl Sl i ke l yt o r i s e , f r o ma ne x t r ad e ma nd, as ho r tc r o p, o bs t r uc t i o nst oi mpo r t a t i on, o ra nyo t he r c a us e , t he r ei sadi s pos i t i o na mo ngde a l e r st oi nc r e a s et he i rs t oc ks , i no r d e rt op r o f i t byt hee x pe c t e dr i s e . Thi sdi s pos i t i o nt e ndsi ni t s e l ft opr o duc et hee f f e c twhi c hi t l oo ksf o r wa r dt o, ar i s eo fpr i c e: a ndi ft her i s ei sc o ns i de r a bl ea ndpr o g r e s s i ve , o t he rs pe c ul a t o r sa r ea t t r a c t e d, who, S ol o nga st hepr l C eha sno tbe g unt of a l l , a r e wi 1 1 i ngt obe l i e v et ha ti twi l lc o nt i n uer i s l ng・ The s e , byf ur t he rpu r c ha s e s , p r od u c ea f u r t he ra dva nc e :a ndt husar i s eo fp r l C ef o rwhi c ht he r ewe r eo r l gl na l l ys omer a t i o na lg r o unds , i so f t e nhe i g ht e ne dbyme r e l ys pe c ul a t i vepur c ha s e s , unt i li tg r e a t l y e x c e e dswha tt heo r i gi na lg r o undswi l l j us t i f y . Af t e rat i met hi sbe gi nst obepe r ‑ c e i ve d; t hepr l Ce C e a s e st Or i s e , a ndt hehol d e r s , t hi n ki ngl tt i met or e a l i z et he i r ga l nS , ∬ea nx i o ust os e l l . The nt hepr l C ebe g i nst ode c l i ne: t heho l de r sr us hi n t o ma r ke tt oa vo i das t i l lgr e a t e rl os s , a nd, f e wbe i ngwi l l i ngt obuyl naf a l l i ngma r ‑ ke t , t hepr i c ef a l l smuc hmo r es udd e n l yt ha ni tr os e. ‑ De vel opar ef e r e nc emodef l orM i l ' sdes c r l Pt l OnOfas pe c ul a t i vebubbl e.Be gi n‑ ni ngwi t ht heba s i ct wo‑ l oops t r uc t ur ef orama r ke t( Fi gur e5‑ 26) ,de ve l opaca us a l di a gr a m gr ounde di nMi l l ' st e xtwhi c he xpl a i nst hedyna i cshedes m c r i bes . Expl a i n br i e lyhowt f hef e edba c ks t r uct ur ec or r es pondst oMi l l ' sdes c r l Pt l Ona ndhowi te x‑ pl a i nst hebe ha vi or .Gi vee xa mpl esoft hephe nome non. i 2 pe r h a p st h eb e s t t r e a t me n t o fs p e c u l a t i v eb u b b l e si sCh a r l e sK in d l e b e r g e r ' S( 1 9 78 )Mani as , Pani c s ,andCr as he s .Se ea l s oGa l b r it a h' S( 1 988 )TheGr e atCr as ho nt h e1 9 29s t o c kma r k e t c r a s h. 1 74 Pa r tI I Tool sf orSys t em sTh i nki ng Th eTh or ou gh b r e dHor s eMa r k e t Fi gur e5‑ 28s howst hepr l C eOft o pye a r l i ngt ho r o ug hbr e dsi nt heUSf r o m1 965 t hr o ug h1 990. Fr o m1 9 74t o1 98 4nomi na lpr l C e Sf o rt he s ee l i t eho r s e si nc r e a s e d bya l mos taf a c t o ro f1 0, t oa bout$ 450, 000. Eve na f t e rr e mo vi ngt hee f f e c t sofi n‑ la f t i on,t her e a lpr l C eO fat o pt ho r oug h br e di nc r e a s e dbymo r et ha naf a c t orof4. Pr i c e st he nc o l l a ps e d,f a l l i ngbyne a r l y5 0% i nj us t4y e a r s( i nr e a lt e r ms ) . Ada pt yo urd i a g r a mo fs pe c ul a t i vebub bl e st ot het ho r o ug hbr e dho r s ema r ke t . Adds uf f i ‑ c i e n td e t a i lt os pe c i f yt hepa r t i c ul a rbi o l o g i c a la ndi ns t i t ut i o na lf e a t u r e so ft hema r ‑ ke t . Fo re xa mpl e , wha ta r et hemo t i va t i o nsf o rowni ngat o pr a c eho r s e ?( Yo uc a n c o ns i d e rar a c eho r s et obea ni nve s t me n tl i keac o mmo ns t o c k,Wi t ha nunc e r t a i n f ut ur epa yo f fde pe nd i ngo nt heho r s e' spe r f or ma nc eo nt het r a c k, butt hi si so ly n oneoft her e a s o nspe o pl eownr a c eho r s e s ,a nde x pe c t e dc a s hnowr a r e l yj us t i f i e s s u c har i s kyi nve s t me nt ) . Ho wi st hes u ppl yo fho r s e si nc r e a s e d?Wha tt i mede l a ys a r ei nvol ve d? Us eyou rc a us a ldi a g r a mt oe xpl a i nt hed yna mi c so ft het ho r o ug hbr e dpr i c e dur i ngt he1 9 70sa ndS OS .Whydi dt hema r ke tr i s es od r a ma t i c a l l y?Whydi di t c r a s he ve nf a s t e r ?I n1 9 65a bo ut1 8, 000t ho r o ugh br e dswe r ebo mi nNo r t hAme r ‑ i c a . Us i ngyo u rmo de l , S ke t c ht hel i ke l ybe ha v i oro ft hebi r t hr a t eofNo r t hAme r ‑ i c a nt ho r o ug hbr e dst hr o ug h1 990. 500 400 8 ‑ 3 ( ち300 め ⊃ J 0 = 200 毛 : ≡ 100 0 1965 1970 1975 1980 1985 1990 Sour ce. ' Her mannandLl nk( 1 990) . 5息 確 聞a F 敗 e 竜野 a ̲ 着 目 ur e, 魚釣er S eSe 室 e e を 毒 ⑳閃, a md菅 的 eDe a 抽Spj柑目 Ma nyr e a lwo r l dma r ke t sa r ei mpe r f e c td uet ol i mi t a t i onso fi nf o r ma t i o n, c os t so f e nt r ya nde x i t , a ndi nf le xi bi l i t yo fr e s o ur c e s . The s ei mpe r f e c t i o nsc r e a t ef e e d ba c ks t ha ts o me t i me so ve r whe l mt hene ga t i vel oo psno r ma l l yba l a n c i ngS u ppl ya ndde ‑ ma nd,l e a di ngt oi ne f f i c i e nc yo re ve nt hec o mpl e t ef a i l u r eo ft hema r ke t .One s o ur c eofma r ke tf a i l ur ei sadv e r s es e l e c t i on. Adve r s es e l e c t i o nc a na r i s ewhe ns e l l e r sa ndbuye r si nama r ke t ha ved i f f e r e nt i nf o r ma t i onAc l a s s i ce xa mpl e,f i r s tde ve l o pe dbyAke r l o f( 1 970) ,c o ns i de r st he Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms 175 us e dca rma r ke t .Tbi l l us t r a t ehow a dve r s es e l ec t i onwor ks ,Ake r l ofas s umedt ha t t heowne r sofus edca r sknowt het r uequa l i t yoft he i rca r swhi l epot e nt i a lbuye r s donot . Ata nygl Ve nma r ke tpr l C e,OWne r S ,knowl ngt het r uequa l i t yoft he i rca r s , wi l lof f e rf ors a l eonl yt hos eca r sa c t ua l l ywor t hl es st ha nt hema r ke tpr i c e( t he " l e mons ")whi l eke e pi nga nyca ra c t ua l l ywor t hmor e( t he" pea c hes ") . The r e f or e, t heonl yc a r sof f e r e df ors a l ewi l lbel e mons . Pot e nt ia lbuye r s , r ea l i zi ngt hi s , r e f us e t obuy・Ake r l ofs howe dt ha ti ne qui l i br i um noonewi l lbewi l l i ngt obuyaus e d ca r ‑t hema r ke twi l lnote xi s t , e ve nt hOught he r ea r ebuye r sa nds e l l e r swhowoul d bewi l l i ngt ot r a dei fbot hkne w whi c hwe r el e monsa ndwhi c hwe r epea c hes ・ 3 Ea c hpe r s on,be ha vi ngr a t i ona l l ygl Ve nt hei nf or ma t i ona va i l a bl et ot he m,Ca us es a nout c omeundes i r a bl ef ora l l . Ake r l of ' sr es ul twa sabr ea kt hr oughi ne c onomi cs . Notonl ydi dhi smode lf or mt hef ounda t i onf ort hei mpor t a ntf i e l dofi nf or ma t i on e conomi cs ,af i e l dofi mme ns ei mpor t a nc ei neconomi cst oday, buthea l s ode mon‑ s t r a t e dt ha tt hewor ki ngsoff r eema r ke t swe r enota l wa ysbe ni gn,e ve nwi t hout monopol ypowe rorcol l us i vea gr ee me nt sa mongpr oduce r s .Ada m Smi t hc e l e br a t e dma r ke tf or c esf orc r e a t l nga ni nvi s i bl eha ndl ea di ngi ndi vi dua l st oH pr omot e a ne ndwhi c hwasnopa r tofl t he i r ]i nt e nt i on, "anendwhi c h" f r e que nt l ypr omot es l t hei nt e r es t s ]ofs oci e t y. "Ake r l ofs howedt ha tr a t i ona ls el f ‑ i nt e r es tc oul dl ea d i ndi vi dua l st opr omot e,t houghuni nt e nt i ona l l y,a ne ndha r mf ult ot hei nt e r es t sof s oc i e t y‑ a ndt he ms e l ves . y,l i kemos teconomi cmodel s ,i sa nequi l i br i um Howe ve r ,Ake r l of' st he or mode la nddoe snota ddr es st hedyna mi csoft hepr oces s ・Tbe xa mi net hedyna m‑ i csofa dve r s es e l e c t i oni na ni mpor t a ntpubl i cpol i c yc ont e xt ,c ons i de rt hema r ke t f orhea l t hi ns ur a nc e. ‑ Si nc et he1 950S , hea l t hca r ec os t si nt heUSha vegr ownmuc hf a s t e rt ha nGDP a ndhavel ongbe e nt hehi ghes ti nt hewor l d,bot hi na bs ol ut ee xpe ndi t ur espe r ca pl t aa nda sape r c e ntofna t i ona li ncome. Ascos t sr os e,s ot oodi dhe a l t hi ns ur ‑ a nc epr e mi ums . Fede r a lpr ogr a mss uc ha sMedi ca r e( f ort heel de r l y)a ndMe di ca i d ( f ort hepoor )we r ec r ea t edt opr ovi deas a f et y ne tf ort hes egr oups .Butr i s i ng hea l t hca r ecos t ss oonout s t r l PPedf ede r a lbe ne f i t s ,a ndf or c edt hee l de r l yt os e e k pr l Va t ei ns ur a nc et os uppl e me ntMe di ca r e. Ast hecos t sofpr l Va t ei ns ur a nc er os e, howe ve r ,ma nywe r ef r oze noutoft hema r ke t . Topr e ve nthea l t hca r ef r om ba nk‑ r upt l ngt he m,ma nys t a t esr equi r e dhea l t hi ns ur e r st oofe rs oI Ca l l e dme di ga pI n‑ s ur a nc et os e ni orci t i z e nsi nr et ur nf ort hepr i vi l egeofunde r wr l t l ngOt he rbus i nes s i nt he i rs t a t e.I nMas s a c hus e t t s ,i ns ur e r swe r er eq ui r edt oof t bra tl e as toneme di ‑ ga ppl a npr ovi di ngunl i mi t edcove r agef orpr es c r l pt l Ondr ugs ,Oneoft hehi ghes t c os t sf ort heel d er l y.Atf i r s t , t hepr ogr a m wa sve r ys ucc es sf ul . I nt he1 980S , awi de r a ngeofi ns ur e r so f f e r edme di ga pcove r a gei nMas s a c hus et t s ,ca pt ur l ngal a r ge s ha r eoft het otal s en i orc i t i z enma r ket .Thel a r ges tpr og r a m,Mede x,Of f e r e dby 3 ofc o u r s e , t h e r ei sau s e dc a rma r k e t . Ak e r l o f ' sa s s u mp t i o nt h a t b u y e r sh a v en ok n o wl e d g eo f q u li a t ywa sas i mp l i f y i n ga s s u mp t l O nt Oma k et h ee x a mp l ecl e a r . Th er e lu a s e dc a rma r k e t h a s e v o l v e dv a r i o u sme a n st opr e v e n t ma r k e t f a i l u r e . Bu y e r sc a ng a l nS O mei n f o r ma t i o no nq u a l i t y t h r o u g ht e s t d r i v e sa n db yh a v i n gt h e i ro wnme c h a n i cl o o ka t t h ec a r , a n dr e g u l a t i o n ss u c ha sl e mo n l a wsa n di mp l i e dwa r r a n t yd o c t r i n er e d u c et h eb u y e r ' sr i s k. I n f o r ma t i o no nt h ep a s t q u a l i t yo fc rs a o f f e r e db yu s e dc a rd e a l e r sd e t e r ss o mef r o ms el l i n gl e mo nst ou n wi t t i n gb u y ? r s I Th ec o s t( i nt i me a n dmo n e y )o ft h e s ea c t i v i t i e si same a s ur eo ft h ei mp a c t o ft h ea d v e r s es e l e c t l O nP r o b l e mi nt h e u s e dc a rma r k e t . 176 Pa r t I I n) O l sf わ r S y s t e ms T h i n k i n g Bl ueCr os s / Bl u eShi e l do fMa s s a c hus e t t s , c ove r e da bo u to ne ‑ t hi r dofa l ls e ni o rc i t ‑ i z e nsi nt hes t a t ei n1 98 7. Pr e mi umswe r el o w, a bo ut$ 5 0 / mo nt h. Ⅰ nt hel a t e1 98 0S , he a l t hc a r ec os ti nf la t i o na c c e l e r a t e d,a ndunde r wr i t e r sha dt or a i s epr e mi ums , i n‑ c l udi ngt hepr e mi umsf o rme di ga pa ndMe de x.I nr e s po ns e ,s o meoft hee l de r l y we r ef o r c e dt odr o pt he i rme d i ga pc ove r a ge.Ot he r sf o undt he yc o ul dge tl owe r r a t e swi t ho t he rc a r r i e r so rbys i g ni ngu Pf o rpl a nso f f e r i ngf e we rbe ne f i t so rwhi c h c a ppe dbe ne f i t sf o ri t e mss uc ha spr e s c r l Pt 1 0nS . Ho we ve r ,o nl yt hehe a l t hi e s ts e ‑ l y , t hos e ni o r swe r ee l i ibl g ef o rt he s eo t he r , c he a pe rpl a ns . Thes i c ke s to ft hee l de r s ufe r i ngf r o mc h r on i ci l l ne s s e s ,t hos ewi t hahi s t o r yp ut t i ngt he ma thi ghr i s k‑ t hos ewi t hs oI C a l l e dpr e ‑ e xi s t i ngc ond i t i o ns ‑We r eno te l i g i b l ef o rl e s se xpe ns i ve c o ve r a geo rhe a l t hma i nt e na nc eo r ga ni z a t i o ns( HMOs )a ndha dnoc ho i c ebutt o s t a ywi t hme di g a p. I nma nyc a s e s , t hec os to fpr e s c r l Pt l O nSa l o nef o rt hos ee l de r l y c o ve r e dbyMe de xe xc e e de dt he i rpr e mi umsbyh und r e dso fdo l l a r se a c hye a r . As me d i ga pl os s e smo u nt e d, pr e mi umsgr e w. Buthi g he rp r e mi u msf o r c e ds t i l lmo r e oft hec o mpa r a t i ve l yhe a l t hye l de r l yt oo pto utofme d i g a pa st he yf わu ndc o ve r a ge e l s e whe r eo rs i mpl yd i dwi t ho ut , be a r l ngt her i s ko fi l l ne s st he ms e l ve s ・ Thos er e ‑ ma i ni ngWi ht t hepl a nwe r e ,o na ve r a g e,s i c ke ra ndc os t l i e r , f o r c l ngPr e mi umsup f ur he t r . Fi g u r e51 29s ho wst hee vo l ut i o no ft heMe de xs u bs c r i be rba s ea ndpr e mi ‑ ums . To t a ls u bs c r i be r sf e l lf r o mne a r l y3 00, 000i n1 988t oa bou t1 58 , 000i n1 997, whi l es ubs c r i be r so ft hep r e mi umMe de xGo l do pt l O n, Whi c hpr o vi de dunl i mi t e d c o ve r a gef o rpr e s c r l Pt l OnS ,f e l le ve nf a s t e r ,f r o ma bo ut250, 000i n1 988t oa bout 65, 000i n1 99 7.Ove rt hes a me1 0ye a r spr e mi umsr os ef r o ma bo ut$50 / mo nt ht o $228 / mo nt h,Wi t hf ur t he ri nc r e a s e spr o j e c t e d. Ast hec us t o me rba s es hr a n ka nd l os s e sg r e w, unde r wr i t e r sbe ga nt owi t hd r a w丘. o mt hema r ke t . I nt hee a r l y1 990s ha l fadoz e ni ns ur e r swr o t eme di ga pc o ve r a g ei nMa s s a c h us e t t s ;by1 997Onl y Me d e xr e ma i ne d. Ac o ns u me ra c t i vi s tl a me n t e d,H Ashe a l t hi e rpe o pl ec o nt i n uet o n, pr e mi umsc on t i nuet ogou p,a ndyo uc r e a t ea dr o po uta nds i c ke rpe o pl es t a yl de a t hs pi r a l . "( Bos t onGl obe ,2 0J a nua r y1 998, A1 2) ・ TheMedi gapDea骨 的Spi 相月 1 .De ve l o pac a us a ll oo pdi a g r a mc a pt ur l ngt hede a t hs pi r a la sde pi c t e di n s e c t i o n5. 5. 1 . Yo u rd i a g r a ms ho ul de x pl a i nno to n l yt hedy na mi c soft he s u bs c r i be rba s ea ndpr e mi ums , buta l s ot hepr of i t a bi l i t yoft heme di ga p ma r ke t , t hen umbe ro fc a r r i e r so f f e r i ngc o ve r a ge , a ndt hehe a l t hs t a t usof t hos ei nt h epr o g r a m・ No t ea n yI mpor t a ntde l a ysi nyo u rd i a g r a m・ Us eyour d i a g r a mt oa na l yz et hei mpa c toft hef ol l o wl ngPO l i c i e s : a . Re q ul r l nga l lc a r r i e r sd oi ngbus i ne s si nt hes t a t et oi ns u r ea l lq ua l i f i e d a ppl i c a n t s , r e ga r dl e s sofa geo rhe a l t h. b. Re qu i r i n ga l lme di ga ppl a ns( a l l血eve r s i onso fMe de x)t opr ovi de u nl i mi t e dc o ve r a g ef わrpr e s c r l pt i ond r u gs , Th egoa li st opo olhe a l t hi e r s e n i o r swhog e ne r a l l yus ef e we rd r ugsa ndc hoos et hel e s se x pe ns i v e Me de xpl a nswi t ht hes i c ke rs e ni o r swhous emo r ed r ugsa ndo ptf o r Me de xGo l d. C. Pr o vi deas u bs i d yt ol owe rme d i ga ppr e mi ums , f und e dbyt hes t a t e . 177 Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms d・ Al l owi ngBC/ BSt odr o pMe de x, e f f e c t i ve l ye l i mi na t i nga l lme di ga p c ove r a gei nt hes t a t eofMa s s a c hus e t t s . I na s s es s l ngt hei mpa c toft hepol i c i es , c ons i de rt he i re fe c t sont hei ns ur e r s , on t hee l de r l y( i ns ur e da nduni ns ur e d) ,a ndons oc i e t ya tl a r ge. 2.Wha ta s s umpt l O nSa bouti nf om a t i ona va i l a bi l i t ya ndc ons ume rbe ha vi or unde r l i et het he o r yc a pt ur e di nyourc a us a ll oopdi a gr a moft hehe a l t h i ns ur a nc ema r ke t ?Howmi ghtt heva l i di t yoft hes ea s s umpt l OnSbea l t e r e d, f o re xa mpl e, bya dva nc e si ni nf or ma t i ont e c hnol ogywhi c hmi ghtma kea pe r s on' se nt i r ehe a l t hhi s t or ya va i l a bl et oi ns ur e r s ,ora dva nc esi nge ne t i c s c r e e nl ngWhi c hmi ghtr e ve a lwhi c hpe opl ewe r ea ti nc r e a s e dr i s kf ort he de ve l o pme ntofpa r t i c ul a ri l l nes s e s ? 3.Wha tot he re xa mpl esofa dve r s es e l e c t i onc a nyoui de nt i f y?Ma pt he i r f e e dba c ks t r uc t ur e. deat hs pl r al : sub s cr i ber san dpr emi umsf ormedi gapl nsur anc e nsur an cef ort heel der l yof f er edbyBl ueCr os s / BI ueShi el do fMas s achus et t s. unl i mi t edpr es cr i p t i ondr ugswi t hasmaHc opaymen t . Ot herMedexpl ansl i mi tt ot al f orDecemberio feachy ear . 'i ndj c at espr opos edr at ef or1 998of$278 / mon t h. 0 0 5 0 2 2 q n SP u e S n O L J 1 SJ l aq! ) 3S 1988 1 989 1990 1 9911992 1993 1 994 19951 996 1 997 So u r c e : Bo s t o nGl o b e ,20J a n u a r y1998,Al. 5. 6 250 200 150S e ≡ 0 100蔓 50 0 ExpLAj Ni N1 3野oL! CYRES! STANCE:TRAFF忙 CoNGEST旧N Bys howi ngt hene t wo r koff e e d ba c kl oopsi nwhi c hpol i c i e sa r ee mbe dde d, c a us a l di a gr m Sa a r eo f t e na ne f f e c t i vewa yt os howhowe ve nt 1 0 r i e nt e d,ope n‑ l oo pme n‑ t a lmode l sl e a dt opol i c yr es i s t a nc e.Cons i de rt hepr o bl e m oft r a f f i cc onges t i on. Ame r i ca' sr oa dsa r ec hoke dwi t ht r a f f i c. I n1 995t he r ewe r ene a r l y200mi l l i onve‑ hi c l esr e gl S t e r e di nt heUS. The1 990c e ns usr e po r t e dt ha ta bo ut1 00mi l l i onpe o‑ pl e,87% ofa l lwor ke r s ,t r a ve l e dt owor kbymot orve hi c l e,85% oft he ma l one. Onl y5% us e dpubl i ct r a ns por t a t i on.I n1 96064% c ommut e dbymot orve hi c l e. Si nc e1 970t henumbe rofr e gl S t e r e dve hi c l e sgr e wby70% a nda nnua lve hi c l e mi l esgr e wby90%, bot hmuc hf a s t e rt ha nt hegr owt hi npopul a t i ono rhous e hol ds , 178 Pa r t I IT わ o l sf o rS y s t e msTh i n k i n g whi l epubl i ct r a ns por t a t i ons t a gna t ed( Fi gur e5‑ 30) . Mor ea ndmor eoft hea ve r a ge pe r s on' sda yl SS pe nti ns i deaca r :Thegove r nme ntes t i ma t esAme r i ca nss pend 8bi l l i onhour spe rye a rs t uc ki nt r a f f i c.Thecos tofdr i vi ngi nc l udesa bout$6000 pe rca rpe ryea ri ndi r ec tcos t sa ndupt oa not he r$9400i ni ndi r ec t ,e xt e r na l i zed c os t s .Es t i ma t esofl os tpr oduct i vi t yduet ot r a f f i cc onges t i onr a ngef r om $43t o $1 68bi l l i onpe ryea r . Theec onomya ndc ul t ur eoft heUS( a ndofot he ra ut o‑ r i c h na t i ons )ha vea da pt edt he ms el vest ot hedomi na nc eoft hea ut o,f r om t he$40bi l ‑ l i ons pe nta nnua l l yl nt heUSt oma r keta ut omobi l est ot her i s eofdr i ve‑ t hr ough f as tf oods ,e s pe c i a l l yf oodsyouca nea twi t honeha nd( whi l et heot hers t ee r s ) . Roa dr a gei si nc r eas i ngl yr e cogni z eda sac ommonme nt a ldi s or de r ,a ndf us r t r a t e d dr i ve r sha vet a ke nt os hoot i ngt hos ewhoc utt he m of font hes o‑ ca l l edf r e ewa y. Wha twe ntwr ong? 4 56. 1 Ment alMode一 sott heTr af f i cPr obl em . Thet r a di t i ona ls ol ut i ont ot r a f f i cj a msa ndconges t i onhasbee nr oa dbui l di ng. Fi g ur e5‑ 31s howst heope n‑ l ooppe r s pe c t i veont hepr obl e m: Thepr obl e mi shi ghwa y conges t i on;t hes ol ut i oni st obui l dmor er oa ds . ‑ Tot alVehi c一 eMi l esTr avel ed i nt heUS 2 a UO ≡ !)ト . 1 J I E ! a^JS ニL N aI U! L J a^ FI GURE5‑ 30 Mor er oads, mor et r af f i c 1 920 1 940 1 960 1 9 80 2000 Tot alPassenger son US Publ i cTr ansi tSyst ems 30 0 2 人 U 一 ‑ L t 2 3 とS J a 6 u a s s t 2 du Ou! g 19 20 1 9 40 1 9 60 1 9 80 2000 Sour c es :Hi s t o r i c a 一 St a t i s t i c so f t h eUS; Ku r j a n( 1 9 9 4 ) ・ 4 s o meo ft h e s ed a t aa p p e a ri nKa y( 1 9 9 7 ) , wh o s eb o o kAs phal tNat i ond i s c u s s e sab r o a dr a n g e o fs o c i a l , c u l t u r a l , e c o n o mi c , a n de n v i r o n me n t le a f f e c t so fa u t o mo b i l ea d d i c t i o n . S e ea l s oDo wn s ( 1 9 9 2) , Ha n s e n( 1 9 9 5 ) , a n dGi b bs( 1 9 9 7 ) . 179 Cha pt e r5 Ca us a lLo o pDi a g r a ms FI GURE5 ‑ 31 Open‑ 一 oopvi ewof t r af f i cc onges t i on Congest i on a ndDe l a y s Bui l dNew 匝 ・ Roads Butwha tha ppe nswhe nne wr oa dsa r ebui l t ?Andwhe r es ho ul dyoube gi nt he de ve l opme ntofac a us a ldi a gr a mt os how t hef e e dba c ke f f e c t sofr oa dc ons t r uc ‑ t i on?I t ' sus ua l l ybes tt obe gi nbyc a pt ur l ngt hephys i ca ls t r uc t ur eoft hes ys t e m. Sys t e msc ons i s tofbot haphys i c a ls t r uc t ur ea ndt hede c i s i onr ul e sus e dbyt hepe o‑ r uc t ur ei sof t e ne a s i e r pl ei nt hes ys t e m( t hebe ha vi or a ls t r uc t ur e ) . Thephys i c a lst t ovi s ua l i z ea ndr e pr es e ntt ha nt hede c i s i on‑ ma ki ngs t r uc t ur e・ Addi t i ona l l y,c on‑ c e pt ua l i z a t i oni sof t e npa r tofagr ouppr oc es si nwhi c hpe opl emus ts ha r et he i r sus ua l l y ownme nt a lmo de l sa ndr e a c ha gr e e me ntove ras l ng l er e pr e s e nt a t i onJti e a s i e rt oga l れa gr e e me nta boutt hephys i c a ls t r uc t ur e. Thebe ha vi or a ls t r uc t ur ei s of t e nmor ec on t r ove r s i a l ; i fyous t a r tt he r eyourg r ouppr oc e s sma ygr i ndt oaha l t be f o r eyou' ver e a l l ybe gun. Agoodpl a c et os t a r tf ort het r a f f i cc onges t i onc a s ei sc onge s t i oni t s e l f . Agood mode lr e qul r e SaVa r i a bl et ha tha so pe r a t i ona lme a nl nga ndc a nbeme a s ur e d.One goods umma r yme a s ur eofc onge s t i oni sa ve r a get r a ve lt i me( f ort het ypi c a lt r i pi n apa r t i c ul a rr e g i o n) ・ Wha tde t e r mi nest r a ve lt i me?Tr a ve lt i mede pe ndsont heba h a nc ebe t we e nt hec a pa c i t yOft hehi ghwa yst oha ndl et r a fi ca ndt henumbe rofve ‑ hi c l e sus i ngt her oa ds ,de not e dTr a fi cVol umei nFi gur e5‑ 3 2. Ast henumbe rofve hi c l e sont her oa dsi nc r e a s e s , gl Ve nt hehi ghwa yc a pa c l t y, t hea ve r a get r l pWi l lt a kel onge r . Ashi ghwa yc a pa c l t ynS eS , gl Ve nt heve hi c l evol ‑ ume, t hea ve r a g et r a ve lt i mewi l lf a l l . Hi ghwa yc a pa c i t yl Sa l t e r e dbyc ons t r uc t i on ofne wr oa ds .Roa dc ons t r uc t i onhe r ei nc l ude snotonl yne wr oa dsbuta l s oi m pr ove me nt st oe xi s t l ngr oa dss uc ha sa ddi ngl a ne so ri nc r e a s l ngC a pa c i t ybyc ha ng‑ 1 ngt hef low oft r a f f i c,f ore xa mpl ebyconve r t i ngaf our ‑ wa yI nt e r s e c t i oni nt oa c l ove r l e a f ・Anypr o J e C tt ha ta ugme nt st heca pa c l t yOft her oa dst oc a r r yt r a f f i c woul dbei nc l ud e di nt henot i onofr oa dc ons t r uc t i on, a tl e a s ti nt hi sf i r s tve r s i o nof ‑ FI GURE5 ‑ 32 Road Const r uct i on Det er mi n ant so f t r av el t i me Hi ghway Capaci t y t 、 、 \ ‑壱 / Tr . af f i c Vol ume Tr avel Ti me 180 P a r t I IT o o l s f o rS y s t e ms Th i n k i n g t hemod e l( l a t e ryo uc o ul dd i s a gg r e ga t et hec o ns t uc r t i o no fne wr oa dsf r omwi de n‑ i ngofe xi s t i ngr oa ds ,i ft ha twa sde e me dt obene c e s s a r yf o rt hepur pos e ) .Si nc e hi ghwa ypr o j e c t st a ket i me , t hede l a ybe t we e nt hei ni t i a t i o no fac o ns t r uc t i o npr o j ‑ e c ta ndt hei nc r e a s ei nhi ghwa yc a pa c i t yl Se x pl i c i t l yno t e d. Whe nd e ve l o pi ngaC a us a l ma pl t i she l pf ul t oc ons i de rt heun i t so fme a s u r ef o r t h ec o ns t r uc t si nyo u rd i a gr a m. Ha v i n gc o ns i s t e ntuni t si so f t e nag r e a ta i dt oc l e a r t hi n k i nga bo utt hede f i ni t i onso fa ndr e l a t i o ns hi psa mongt heva r i a bl e s . Spe c i f yi ng uni t sa ndc he c ki ngl brdi me ns i o na lc o ns i s t e nc yl Sus e f u le ve nwhe nyo urmo de li s pu r e l yc o nc e pt ua la ndyo udono ti n t e ndt ode ve l o paf o r ma ls i mul a t i on. Tr a ve l t i mewo ldbeme u a s ur e di nmi nut e spe rt r i p( f o rt hea ve r a get r i pi nt her e g i o n) . ‑ mi l e spe rda y( a Hi g hwa yCa pa c i t ya ndTr a fi cVo l u mea r eme a s ur e di nve hi ce ve hi c l emi l ei so nemi l et r a ve l e dbyo neve hi c l e ) . Ha vi ngs pe c i f i e dt hephys i c a ls t uc r t u r eofr oa dbui l di nga ndhi g hwa yc o nl s t r uc t i o n, ne xta s kwha td r i ve shi g hwa yc o ns t r uc t i o npr og r a ms . Thep r l ma r ymo t i ‑ va t i o ni sc onge s t i o n:a st r a ve lt i mer i s e s ,a st r a f f i cj a msbe c omet henor m,a st he r us hho u re x pa ndsf r o mda wnt hr o ug hd us k, po l i t i c a lpr e s s ur et obui l dwi l lbui l d. Fi g ur e5‑ 33a d dst hel i nkf r o mt r a ve lt i met or oa dc o ns t r uc t i on. Conge s t i onc r e a t e spr e s s ur ef o rne wr oa ds ;a f t e rt hene wc a pa c i t yi sa dde d, t r a ve lt i mef a l l s , r e l i e vi ngt hepr e s s u r e . TheCa pa c i t yEx pa ns i onl oo p( B1 )a c t st o r e duc et r a ve lt i met oa c c e pt a bl el e ve l s . No t et ha t血egoa loft hel oo p, t hede s i r e d t r a v e lt i me ,ha sbe e nma dee x pl i c i t .De s i r e dt r a ve lt i mei st het r a ve lt i med rv e r sc o ns i de ra c c e pt a bl e( ona ve r a ge ) , pe r ha ps20mi nut e sf o rt hec o mmut ef r o m ho met owor k. The1 990c e ns usf o unda ve r a geo ne ‑ wa yc o mmut i ngt i me sf o ra l l mode sa nda l lwor ke r sofa bo ut2 2mi nut e s , t ho ug hmo r et ha n1 7mi l l i o npe o pl e s pe ntmo r et ha n40mi nu t e sge t t l ngt Owo r ka ndne a r l y2mi l l i ons pe ntmo r et ha n 90mi nut e s . l i FJ GURE5 ‑ 33 Cong es t i on l eadst op ol i t i c al pr es s ur et obui l d mor er o ads, r edu c i n gc on一 ges t i onvi at h e n ega t i v eCap ac i t y ヒXPanS i on f eedb ac k d c t i o Roa Co ns t r u n ㌔ Hi ghway Capaci t y \ a p a c i t y X P a n S l 0n C T r . a v e l E T i m e j i . ‑‑ / ‑ ‑ F Tr af f i c Vol ume r e ss ureto Redu c e Co nge P 年少 s t i o n ‑ i‑ : i TTr d Ti me Desi r e ave一 ‑ Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms 1 81 5. 6. 2 Compensa! i ngFeedback: TheResponset oDecr easedCongest i on Sof a rt r a f f i cvol umei sc ons i de r e dt obee xoge no us . Thi sa s s umpt l Oni sa na c c u‑ r a t er e le f c t i ono ft heme nt a lmode l sofma nypol i t i c i a ns ,c l t yPl a nne r s ,a ndt r a ns po r t a t i onofi c i a l s ,f orwhomt r a f f i cvo l umegr owsa st hepopul a t i onoft her e gi on gr owsa nda st hel oc a le c onomyde ve l o ps . The ys e et he i rj oba sbui l di nge nough r oa dst oke e pt r a ve lt i mea tt hea c c e pt a bl el e ve l ,s opol i t i c a lpr e s s ur es t a ysl ow,s o t he yc a nber e e l e c t e d,a nds ot he yc a ns e r ves pe c i a li nt e r es t ss uc ha sc ons t r uc t i on f i r ms ,r e a le s t a t ede ve l ope r s ,a ndt hebus i ne s sc ommuni t yWhobe ne f i tf r omr oa d bui l di nga ndwhoof t e npr ovi del uc r a t i vej obsf o rt he mwhe nt he yl e a veofi c e. I ft hec a pa c i t ye xpa ns i onl oo pwe r et heonl yf e e d ba c kope r a t l ngi nt hes ys t e m, he t nt hepol i c yofr oa dbui l di ngt or e l i e vec onge s t i onwo ldwo u r kwe l l :whe ne ve r t r a f f i cvol umer os e, l e a di ngt oc onge s t i ona ndpr es s ur ef r omt hec ommuni t y , ar oa d bui l di ngpr ogr a m woul dbes t a r t e da ndhi g hwa yc a pa c l t yWOul de xpa ndunt i lt he pr e s s ur ewa sr e l i e ve d. Howe ve r ,t r a f f i cvol umei snote xoge nous . Tof or mul a t et heca us a ls t r uc t ur e de t e r mi nl ngt r a f f i cf lOwi ti sa ga i nhe l pf ult oc ons i de rt hephys i csoft hes ys t e m a ndt heuni t sofme a s ur ef o rt heva r i a bl e s . Wha tde t e r mi nest hevol umeoft r a f f i c? Toha vet r a f f i c , he t r emus tbe.Hc a r s . Noc a r s , not r a f f i c. Sot henumbe rofc a r si n her t e gi onmus tbeade t e r mi na ntoft r a fi cvol ume. Tr a fi cvol umei sme a s ur e di n ve hi c l e ‑ mi l espe rda y.Tot a lt r a f f i cvol umemus tt he r e f or ee qua lt henumbe rof ve hi c l esi nt her e gl Onmul t i pl i e dbyt henumbe rofmi l esea c hve hi c l et r a ve l spe r da y.I nt ur n,t henumbe rofmi l e se a c hve hi c l et r a ve l spe rda yl St hepr oduc tof t henumbe roft r i pse a c hve hi c l ema ke spe rda ya ndt hel e ngt hofea c ht r i p. Thus , a ve r a gl ngove rt heve hi c l epo pul a t i on, ‑ Tr a f f i cVo l u me ‑Ve h i c l e s* Av e r a g eTr i psp e rDa y* Ave r a g eTr i pLe ng t h Tr i pS/ Da y * Mi l e S / Tr i p Ve h i c l eMi l e s / Da y‑Ve hi c l e s* Thenumbe roft r i pspe rda ya ndt hea ve r a get npl e ngt ha r enotc ons t a ntbutde ‑ pe ndont hel e ve lofc onge s t i on. I ft r a f f i ci sl i ght , pe o pl ea r emor el i ke l yt ot a kea d‑ di t i ona la ndl onge rt r l pS .Whe nc onges t i oni shea vy,pe opl ewi l lf or e goo rde f e r t r l pSa ndma kes hor t e rt r l pS ,S ki ppi ngt ha tqui c kr unt ot hevi de os hopa ndbuyi ng wha tt he yne e da tt hec l os e s ts t o r er a t he rgol ngOnt Ot hema l l . Li ke wi s e, t henum‑ be rofca r si nt her e gl Oni snotc o ns t a nt . Thenumbe rofve hi c l e si nt her e g l OnC a n bet houghtofa st hepr oduc toft hepopul a t i onoft her e gl Ona ndt henumbe rofc a r s pe rpe r s on: Themor epe opl ei nt her e g i on( a ndt hemor ebus i ne s s e s ) , t hemo r eve ‑ hi c l est he r ewi l lbe. Thenumbe rofve hi c l e spe rpe r s onorbus i nes si nt ur ni snot c ons t a ntbut( l e pe ndsont hea t t r a c t i ve ne s sofd r i vl ng・1 nea t t r a c t i ve nes sofdr i vl ng de pe ndsont hel e ve lofc onges t i o n( Fi gur e5‑ 3 4) . Addi ngt he s er e l a t i ons hi pst ot hemode lc l os e st hr e ene ga t i vef e e dba c kl oops , a l lofwhi c ha c t t oi nc r e as ec o nge s t i onwhe ne ve rne wr oa dsa r ebui l t . Suppos ene w r oa dsa r ebui l tt or e l i e vec onge s t i on.I nt hes hor tr un,t r a ve lt i mef a l l s ‑t henum‑ be rofca r si nt her e gi onha s n' tc ha nge da ndpe o pl e' sha bi t sha ve n' ta d j us t e dt ot he ne w,s hor t e rt r a ve lt i mes .Aspe opl enot i c et ha tt he yc a nnow ge ta r oundmuc h f a s t e rt ha nbe f o r e,t he ywi l lt a kemor eDi s c r e t i ona r yTr i ps( l oopB2) .The ywi l l 182 Pa r tI IT o o l sf o rS y s t em s Th i n k i n g 34 Tr af f i cvol umedependsonc onges t i on, cl osi ngs ever al negat i vel oopst h atc au s et r af f i c FI GURE5‑ t oi ncr eas ewhenev ern ewr oadsar ebui l t . Road on‑ Const r uc t i 工 、 Hi ghway Capaci t y T r . a f f i c V o l u m e u c e C a p a c i t ye s t i o n ‑ き ‑ Pr essur et o Red ( , !lf D e s i r e d i e B A T : q e u A t r a c t i v e n e s p u b l i c o f D r i v i n g I + acyof Tr ansi t T r i p s Tr i psper Day Popul at i on andEconomi c Act i vi t yof Regi on 痩 E x t r aMi l e s 千 、\ ̲ T a k et h e 'Aver age Bu s ? Tr i pLengt h+ b 千 ‑ 昔 二十 崇 、 、 ‑ Pu Tr an F a r e lic s it Publ i c ,‑ : ‑‑ : 蕊 a l s ot r a ve lExt r aMi l e s( l oo pB3) 。 Ove rt i me,S e e i ngt ha tdr i vi ngi snowmuc hmor e a t t r a c t i vet ha not he rmodesoft r a ns por ts uc ha st hepubl i ct r a ns i ts ys t e m,s ome pe opl ewi l lgi veupt hebuso rs ubwa ya ndbuyac a r t Thenumbe rofc a r spe rpe r ‑ s on( a ndbus i ne s s )r i s e sa spe o pl ea s kwhyt he ys houl dTa ket heBus ?( l oo pB4) . Al lt h r e eoft he s el oo psc ompe ns a t ef わra nyne wr oa dc ons t r u c t i o nbyi nc r e a s ‑ 1 ngt r a f f i cf low.Butr oa dc ons t r uc t i ons t i mul a t esot he rl ong‑ t e r mf e e dba c ks . The popul a t i onoft her e gi oni snote xoge no usbuti sa fe c t e dbyt hea c c e s s i bi l i t yoft he out l yi ngdi s t r i c t s . Ast her oa dne t wor ke xpa nds ,a sne wf r e e wa ysa ndr i ngr oa ds l i nkt hec ount r ys i dewi t ht hec e nt e rc l t y, t hes i z eoft her e gl OnWi t hi nar e a s ona bl e t r a ve lt i megr ows . Ofc o ur s e ,a ve r a get r a ve lt i meha sane ga t i vee fe c tont hes i z e oft hea c c e s s i bl er e gl O n: Thegr e a t e rt hec onges t i on, t hes ma l l e rt her a di usa c c e s s i ‑ bl ewi t hi n,s a y ,a30‑ mi nut edr i veoft hec i t y( Fi gur e5‑ 35) . Thel i nkst ot hepopul a t i onoft her e g1 0nC l os et womo r ef e e dba c ks . Pe o pl ebe ‑ gi nt oMovet ot heSubur bs( B5) . Ast hepopul a t i onoft hes ubur bsg r ows , t hea ut o popul a t i onr i s esa swe l l . Ther oa dsbe gi nt of i l l . Tr a f f i cvol umegr owsf u r t he ra nd 183 Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms FI GURE5‑ 35 Reducedt r avel t l L mean danexpan dedhi gh wayn et wor ki ncr eas et hesi z eoft her egi on ac c es s i bl ef r omt hec en t er , whi chexpandst hepopul a t i onandl eadst os t i Hmor et r af f i c. Road Const r uct i on丈 ‑ 、 C a p a X P n D s i e d T r . a v ‑ ㌔ ̲ ≡ i m 与 垂 ) = : ̲ ‑ : q e u i 7 7i s c r e t i o I A t r a c t i v e n s p u b H c D r i g I + 渚 Hi ghway Capaci t y ( もタ Op e nt h e Hi n t e r l a n d s c i t y er T r a f f i c V o 一 u m e Si zeofRe gi on wi t hi nDesi r e d Tr a ve日Ti me LL :T = Tm ‑ p s of e n e acy.. Tr ansi t Tr i psper Day Mov et o t he Bu一 bs Pop ul ati on ‑ x、 andEc on om ic : ̲三 \\ T a ke u s ? Ac t i vi t yof Re gi on \ Pr essur et o Reduce est i on も th e B 寺 喜 車 重 Publ i c Tr ansl t Far e E x t r aMi l e s ー Ave r age L eng t h+ Tri p … 器霊 . J p a e r r s s S e n r〆 Pu b一 i c R: d r e a r n s S l で p t r a ve lt i mer i s e sunt i lt her es ul ingc t o ng es t i onma ke st hes ubur bss uf f i c i e nt l yuna t ‑ . t r a c t i vet os t o pf u r t he ri nml g r a t i ona ndde ve l opme nt Thec ombi ne de f f e c toft hef o urne ga t i vef e e dba c ksB2t hr oughB5i st oc o m‑ pe ns a t es t r ongl yf ora nyde c r e a s ei nt r a ve lt i mec a us e dbyne wr oa ds . I fne whi gh‑ wa yswe r ebui l ta ndt he na l lc ons t r uc t i ons t o ppe d,t he r ewoul dbea ni mme di a t e dr opl nt r a ve lt i me. Buta spe o pl er es pondt ot he i rne wf ounde a s eoft r a ve l , mo r e , l onge rt r l pSWO ul dbet a ke n. Mor epe o pl ewoul da ba ndont hebusa ndbuyc a r st o c o mmut et owo r k. Thepo pul a t i onoft hes ubur bswoul dgr ow. Thes ea d j us t me nt s c ont i nueunt i lt r a ve lt i mer i s e se nought os t opt hee xpa ns i onoft hes ubur bsbe ‑ c a us et hec ommut er e qui r e di st ool o ng. Thede l a ysi nt he s ene ga t i vel oo psc oul d c a us ec onges t i ont oove r s hoott hede s i r a bl el e ve l . Butr oa dc ons t r uc t i ondoes n' ts t op・ Asne whi ghwa ysOpe nt heHi nt e r l a nds ( l oopRl ) ,i tbe c omespos s i bl et ol i vei nt heco unt r ys i dea ndc ommut et owor ki n t het ownorc i t y.Wha twa sonc er e mot ef a r m co t l nt r yOrWOOdsnowbe c omesa 20mi nut edr i vef r om t hec i t y,wi t hi t sj o bs ,c ul t ur e,a ndni ght l i f e.Whol ene w 184 P a r t I IT o o l sf o rS y s t e ms Th l n k i n g c ommuni t i e ss pr l ngup,C Ommuni t i eswhe r et hepe o pl eha vet odr i venotonl yt o wor kbuta l s ot ot hema r ke t , t os c hool , t ot hehome soft he i rf r i e ndsa ndt he i rc hi 1 ‑ dr e n' sf r i e nds . Thebur ge onl ngpopul a t i onbr i ngsne wde ve l opme nt ,Sho ps ,S t r l p ma l l s ,a ndot he rbus i ne s s ess pr l ngup,t uml ngC Ount r yS i det oc ondode ve l opme nt , pas t ur et opa r ki ngl ot . Al lt hewhi l e,t henumbe rofc a r sont her oa dgr ows . Af t e r s omeye a r s ,t r a f f i cc onges t i oni nt hes ef or me r l yqui e tt ownsbe c ome sat e r r i bl e pr obl e m・ Pol i t i c a lpr e s s ur egr owsa nds t i l lmor er oa dsa r ebui l t . Rout e1 28,ar l ngr oa da r oundBos t onbui l ti nt he1 950st or e l i e vec onge s t i on bydi ve r t i ngl ong‑ ha ult r a f f i ca r o undt hec e nt e rc i t y, r a pi dl ya t t r a c t e dl oc a ldr i ve r s a nds oonpr ove di na de qua t e. Tor e l i e vet hec onge s t i oni twa swi de ne d,f r om f our t oe i ght ,a ndi npl a c e s ,e ve nmor el a nes .I ns t r e t c he st hebr ea kdownl a newa s ope ne dt ot r a f f i cdur i ngr us hhour( notaf e wha pl es smot or i s t sha vebe e nki l l e d whe nt he yha dt het e me r i t yt ous et hebr ea kdownl a nef orabr e a kdown) .Tr a fi c s oonf i l l e dt hes ene wl a nes ,a ndt oda ydur i ngr us hhourt hec a r sc r a wla l ong bumpe rt obumpe rt hr oug hl ongs t r e t c he sofr out e1 28・ As e c ondr i ngr oa d,I nt e r s t a t e495, wa st he nbui l ta not he r1 5t o20mi l e sf a r t he ro ut . Thee xpa nde dne t wor k ma dee ve nmor ec ount r ys i dea c c e s s i bl e ,a nda not he rr oundofpo pul a t i ongr owt h a nde c onomi cde ve l o pme ntbe ga n. Thi ss e l f ‑ r e i nf or c l ngPr oc es sl e a dst omor ea nd mor ene wr oa ds , pus hi nge ve rf a r t he ri nt ot hec ount r ys i de, i nava i na t t e mptt oe a s e c onge s t i on・ Thes t or yl SS i mi l a rf o rot he rc i t i e si nt heUS,i nc l udi ngt hepa r a di gm ca s eofc onges t i on‑Lo§Ange l es ‑a swe l la sLondon,Pa r i s ,I s t a nbul ,Ca i r o, Tokyo, Ba ngkok,a ndc ount l es sot he rc i t i e sa r oundt hewor l d. Themode lc l ea r l ys howst hef ut i l i t yofa t t e mpt st or e duc et r a f f i cc onges t i on t hr oughr oa dbui l di ng.I tma yt a kes omeye a r s ,but ,i na na ut omot i veve r s i onof Pa r ki ns on' sLa w, t r a f f i ca l wa yse xpa ndst of i l lt hehi g hwa ysa va i l a bl ef ori t st r a ve l . Tr a f f i cvol umegr owsunt i lc onge s t i onl SJ us tba de nought ode t e rpe opl ef r omt a kl l ngt ha ta ddi t i ona lt r i p,f r om dr i vi ngt owor ki ns t ea dofr i di ngpubl i ct r a ns i t ,Or f r ommovi ngj us tal i t t l ef a r t he ro uti nt ot hes ubur bs ・ 5T r a f f i ce ngi ne e r sC a l lt hi sr e ‑ a c t i on" r oa dge ne r a t e dt r a f f i c・ "Ha ns e n' S( 1 995)e c onome t r i cs t udyofUSme t r o‑ pol i t a na r e a ss howe dt ha tt hee l a s t l C l t yOft r a f f i cvol umewi t hr e s pe c tt ohi ghwa y ca pa c i t yWa s0. 9a f t e rj us t5ye a r s ,t ha ti s ,al O% i nc r e a s ei nc a pa c l yl t e dt oa9% i nc r ea s ei nt r a f f i cwi t hi n5ye a r s .Ma nyoft hef e e dba c ksi de nt i f i e di nt hemode l ope r a t eove re ve nl o ng e rpe r i ods , f ul l yne ga t l ngt hee f f e c tofr oa dc ons t r uc t i onon c onge s t i on. Somea na l ys t se ve na r guet ha tbyH a ddi ngc a pa c i t yt oac r owde d[ hi gh‑ wa y]ne t wor kyouc o ul da c t ua l l ys l owt hi ngsdown"( Ka y1 997, p.1 5) , aphe nom‑ e nonk n owna sBr a e s s ' La wa f t e rt heo pe r a t i onsr es e a r c ha na l ys twhof i r s tc oi ne d i t . Fore xa mpl e, heM25, t London' sr l ngr oa d, wa sde s i gne dt oc a r r yl ongdi s t a nc e t r a f f i ca r oundLondon. I ns t e a d, i ti sa c t ua l l yus e dpr i ma r i l yf ors hor tt r i psbyl oc a l r e s i de nt sa ndc ommut e r s .I tsoonbeca met hebus i es thl gh wa yl nEur opea ndha s l ongbe e nknowna s̀ t hel ongestpar ki ngl oti nt hewo r l d' ,t houghc ommut e r son t heLongl s l a ndExpr es s wa y,Par i s 'Pe r i phe r i que,a ndt heSa mDi e goFr e e way mi ghtdi s a gr e e.I nr e s pons e,t heM 2 5ha sbe e ns t e a di l y wi de ne d,a l lt onoa vail . St udi e st ypi c a l l yf i nd,a st heLondonTl ' me sr e por t e d( 1 0 No ve mbe r1 997) ,t hat ‑ 5 Th ea n a l o g ywi t hPa r k i n s o n ' sLa w( H wo r ke x p a n d st of i l l t h et i mea v a i l a b l ef o ri t sc o mp l e‑ t i o n " )i smo r et h a nc a . s u l: a P a r k i n s o n ' SLa wa r i s e st h r o u g han e g a t i v ef e e d b a c kl o o ps t r u c t ur eq u i t e s i mi l a rt ot h a t g o v e r n i n gt r a fi cc o n g e s t i o n ・ S e es e c t i o n5. 4. Ch a p t e r5 Ca u s a l Lo o pDi a g r a ms 1 8 5 Tr a fi cc o n g e s t i o no nawi d e n e ds e c t i o no ft heM2 5i sn o wg r e a t e rt h a nbe f o r et he i mp r o ve me n t t o o kpl a c e , amo t o r l n gS u r v e yS u g g e s t s . Th ewi d e ni n go fas t r e t c ho f t h emo t o r wa ya t J u n c t i o n1 5, we s to fLo nd o n, wa si n t e n d e dt oc u r bc o n g e s t i o n, b u t t h es u r v e ys h o we dt h a t j a mso nt hes t r e t c hwe r eno wc o mmo n p l a c e , a l t h o ug hl a s t y e a rt r a f f i cwa sg en e r a l l yf r e e ‑ lo f wl n g. 5 . 6 . 3 Th eMa s sT柑m Si 昔De a 抽Spi F a日 St a nda r de c ono mi ca na l ys ュ sS ugge s t st ha tade c l i nei nt hea t t r a c t i ve nes sofagood ors e r vi c es hou l dl e a dpe opl et os wi t c ht os ubs t i t ut e s ・Why,t he n,a sc onges t i on bui l dsup,don' tpe opl et ur nt oma s st r a ns i t ?Pa r toft hea ns we ri ss howni nFi g‑ ur es‑ 36. Asl owe rt r a ve lt i mec a us e dbyne wr oa dsi nc r e a s e st hea t t r a c t i ve nes sofdr i v 1 ng,r i de r s hi pa ndr e ve nueoft hepubl i ct r a ns i ts ys t e mf a l l ,Cos t sdon' tf a l lve r y muc h,s i nc emos toft hec os t sa r et hef i xe dc os t sofpr ovi di ngs e r vi c e:t hebus es mus tr unwhe t he rt he ya r ef ul lore mpt yJft het r a ns i ta ut hor i t yt r i est oc l os ei t s de f i c i tbyCos tCut t i ng( l oopB6) , s e r vi c ea ndq ua l i t ye r ode. Ro ut e sa r ec l os e da nd t he丘. e que nc yo fs e r vi c ei sc ut . Ther e l a t i vea t t r a c t i ve ne s sofdr i vi ngr l S e Sa ndma s s t r a ns i tr i de r s hi pf a l l ss t i l lmo r e. Thede f i c i twi de ns , l e a di ngt os t i l lmor ec ut si nt he publ i ct r a ns i tne t wo r ka st hes e l f ‑ r e i nf or c i ngRout eExpa ns i onl oo pR2O pe r a t e sa s avi c i ousc yc l eo fde c r e a s i ngr i de r s hi p,g r e a t e rc ut s ,a nds t i l lf e we rr i de r s ・ Ra i s i ngf a r e st oba l a nc et het r a ns i ta ut ho r i t ybudge ti sl i t t l ebe t t e r : Hi ghe rf a r e s i nc r e a s et her e l a t i vea t t r a c t i ve nes sofdr i vi ng,a ndmor epe o pl ea ba ndonma s st r a n‑ s i tf o rc a r s . Ri d e r s hi pf a l l s ,a ndf a r e smus tber a i s e da ga i n, Choki ngof fRi de r s hi p ( l oopR3) . Be c a us ema s st r a ns i ts ys t e msha veahi g hpr o por t i onoff i xe dc os t s , t he y a r ehi ghl yvul ne r a bl et ot hes es e l f ‑ r e i nf or c l ngf e e dba c ks . Asr oa dc ons t uc r t i ona nd a ut ous ea c c e l e r a t e di nAme r i c a ,pa r t i c ul a r l ya f t e rt hel a t e1 940S ,pe opl ea ba n‑ done dt r ol l e ys ,t r a i ns ,a ndbus es .Thes epos i t i vel oo psbe c a meade a t hs pl r a lof hi ghe rf a r es ,r e d uc e ds e r vi c e,a nddec l i nl ngqua l i t yunt i li nma nyc i t i e sonl yt he poor es tpe opl e , t hos ewhoc a nnota f f or dt omovet ot hes ubur bso rownac a r ,a r e l e f tt or i det hepu bl i ct r a ns i ts ys t e m. At t e mpt st obui l dupt hema s st r a ns i tne t wor k t oof f s e tt hepos i t i vel oopst ha te r oder i de r s hi pt hr oughMa s sTr a ns i tCa pa c l t yEx‑ pa ns i on( l oo pB7)of t e nf i ghtal os i ngba t t l ed uet ot he i rl ongde l a ysa ndhi ghc os t s . Onef i na lpos i t i vef e e dba c ki swor t ha ddi ng: Thea de qua c yofapubl i ct r a ns i t s ys t e m de pe ndsnotonl yont hes c opeoft hene t wor ka ndt hef r e q ue nc yofs e r vi c e buta l s oont hes i z ea ndpo pul a t i onde ns i t yoft her e gl O n. Ast hec ount r ys i dei sde ‑ ve l ope d,t hel o c usofa c t i vl t yS hi f t sa wa yf r om t hea r e as e r ve dbye xi s t i ngmas s t r a ns i t . Aspo pu l a t i onde ns i t yf a l l s , f e we ra ndf e we rpe opl el i vene a rabusors ub‑ wa yr o ut e. Publ i ct r a ns i tbe c omesl es sa ndl e s sus e f u lbe c a us eYouCa n' tGe tThe r e ont heBus ,l e a di ngt os t i l lmor edr i vi nga nds t i l ll owe rma s st r a ns i tr i de r s hi p,1 n a not he rvi c i ousc yc l e ,l oopR4( Fi gur e5‑ 3 7) ・ Thes ubur bsg r owa ndt hea de qua c y ofpubl i ct r a ns i tf a l l smuc hf as t e rt ha nmas st r a ns i tc a pa c i t yC a nbea dde d・ Themode la bovei ss t i l li nc ompl e t e( a sa l lmode l sa l wa ysa r e ) . Onec oul da dd ma nymor ef e e d ba c ks . Fore xa mpl e, hes t pr e a dofpopul a t i oni nt ot hel e s sde ns e l y po pul a t e ds ubu r bsi nc r e a s est hea ve r a gel e ngt hoft r i ps ,f or mi nga ddi t i ona lc ha n‑ ne l sbywhi c hc o nges t i onr i s e st oof f s e ta nyga i nsCa us e dbyne whi ghwa ys . The mode ldoe sno te xpl or eot he rs i dee f f e c t soft hea ut omobi l e' sr i s et odomi na nc e, ‑ I . 3! l a凸 l ! Sut 2 ) i ニ qnd 3 J. a n u a ^ a t ] 3! ] qnd 3 巌 o ! u 6 a t ] u ! S J t2 3 L J 1 6uald! J 1 aBt 2 J a^V sd l . ] 1 ^ eo d uO! t OnJ l t SuO3 Pe Ot j へ旦 ^ 1 . 3 t 2 d e 3 J a S a l! ≡ e J I I X 山 師 J ads J e3 ・ uos塵 i T s s u j ⁝ JP lu\ 車 ! l qnd l ! S u 空 1 ザノ d ㍗ Bu! ^! ] 凸1 0 葛 uej ト茎 qnd SSaua^! l Ut 2 J l t l V 1 0^3enbapv‑‑ ・ ・ L「 ! L J S J aP! t J OaqOL J U d l ! Sue J 1 ‑ 0 ニ⊃ q d‑ u o ! s u e d x u a l n O t J ^ A l a N u e A L . q JI0 g i ) t !S i 3 蓋 nd / 軒 + d x uo 叩 S u t 2 u ^l ! 9 e d t 2 0 トM 甲 a3nPat ] 0taJ l nSSa・ l d 了 1 ⅧLu Sq J n ga O l a ^ O ≡ ⑥ F u J p⁝ 緑 Aau^ Iim uo ! 6au‑oaN!S L J t u o EBatJ 0^ l ! ^! ) 3V U OuOOuPut2 u o! l er ndod ・ 9? S U 覧 望﹄ ・ a ^! J polaE doad6u! ^! J pL aL l l J n JL PaS ! P JS a J P JPu Pl n 3aqt S n∈ 93 ! ^ 」 aSE Sニ 空 d! L I S JaP! Jl ! S u t 2 ) 1S S eL uSV J ・ l t 2 ) ! dsL 1 1 t 2 aPt 201Pea二! S u C J tS S t 2 L uOS t S 8P aX1 !L l 6! L I aL l 1 186 pu竺 I . 3! l a凸 ) ! SueJ 1 0 ! I q n d + a nuaa ^ tj t ! SuJ e1 3ニqnd l ! S u I E 2 J n q d U ! l u u o ! s u q d x O l コ 0 ∝ W O き l aN㊨ S t u ! e Jl 1 蓋n 3 J /夢 l ! Su空 ト2蓋 nd + ー 0^Uenbapv ・ ⊥ u o!suedxu A ) . Dede31m d指 摘 F ・ . f tj , .I p l ! S u E u 1 0 ! r qnd ‑ (, 0 6u! ^! 占 V S Saua^! ) 3t 2 J l I I 、 aL u! 1a l^eJ l l PaJ l S !a凸 a3nPat j OlaJ l nSSaL d / ∴ 1 . ut = 3 S n m aL J luO aJ I a LJ1 la9 ⑤ + sd ) !i ノ ‑ト ト .u o ! 6 a t ] u ! S Jl t= 3 uOSJ ad , 臥. S .i . 封 L J t Buald! J 1 aBe J a^v J ad UL t j 圃 S a M ニ e JIIX山 簡 ..: ' : s d! ) i リ ゝ 1 .6e d t = 3 申 t SuO3 .uO芯3nj + PE 2 0t j ¢L unr OA U! l l eJ l 1 SPu a 1 !tO e 0^) ! ^V Pu o O uOU山 uo( t . t 2 1 nd d U! ∈ J 1 ! 1 C la ^ 凸 l Z! Jl! き S LI a u!L a uJ Pa J l ! S uo a ! 6t J Oa Sq J I ngaL 0 ta^OL N e l JI a t u ! H L J I u ¢ d o u: l . 礼 ; A)! D ede3 2 N t L J B! H ^t J . snqau luOaaL l 867 . ueDnO^ ト? S u∝n9 L i . wo J v qaul ! Sut 2 J tUニqndau ouo! Suedxaut 2ut 2L l tJ au t t Z JuOI . ) DnL I SuOU Pt 2 0LaJ OL u≡l S uo! 1 S a6uo3aJ Ou JL 6u! ^! J paJ o∈ S二一 n S a JaL 1 1. Sau! PaPl ! SU空13ニ qndl O^ O CnbopeaL l tE SPu edxa uo一 6aLPatt 2 1 ndo daL l O aZ! Sa u tSV や ・ . 1 187 1 88 Pa r tI I To o l sf o rS ys t em s Th i n k i n g i nc l udi ngt hede a t hs , i n j u r i e sa ndc os t so fa c c i d e nt s , hehe t a l he t f f e c t so fs moga nd o z o nepr oduc t i o n,g r e e nho us ega sge ne r a t i o n,t hes ol i dwa s t epr obl e m pos e dby t hedi s c a r do fmi l l i o nso fv e hi c l e se a c hye a r( s e ec ha pt e r6 ) , a ndt hede pe nd e n c eo f t hehi ghl ya ut omo t i vena t i o nso ni ns e c u r es u ppl i e so fi mpor t e do i l .Wha to t he r f e e d ba c ksa nds i dee f f e c t sdoyous e e ? 5. 6. 4 Pol i cyA. nal ys妻 S:The岩 mpacto守J T echr ! Obgy De s pi t ei t sl i mi t a t i onsa ndo mi s s i o ns , t hemo de l pr ov i de sar i c he x pl a na t i o nf o rt he pe r s i s t e ntf a i l ur eo fr oa d‑ bui l d i ngpr o g r a mst oa l l e vi a t et r a f f i cc o nge s t i o n. Yo uc a n nowus et hemode lt oa s s e s st hel i ke l ye f f e c tofo t he rpol i c i e s . I nt he1 970sa nd1 98 0S ,apo pul a rs o l ut i o nwa sHOVl a ne s( hi gh‑ oc c u pa nc y v e hi c l e , o rc a r pooll a ne s ) . The s el a ne sa r er e s t r i c t e dt oc a r swi t ha tl e a s tt woo c c u‑ pa n t s( s o me t i me sonl yd ur i ngr us hho u r ) . Ther e s ul t ?Tot hee xt e ntd r i ve r sj o i ne d c a r po ol s , t henumbe roft r i pspe rda yf e l l , r e d uc i ngt r a f f i cv o l umes l i g ht l y . Ther e ‑ s ul t i ngr e d uc t i oni nc ong e s t i o n, howe ve r ,s i mpl ye nc o ur a ge dot he r st ot a ket ot he r oa dsi ns t ea dofma s st r a ns i t ,t ot a kea dd i t i o na lt r l pSt he ymi g htot he r wi s eha ve f o r e go ne , a n dt ol e a vef o rwo r kal i t t l el a t e r . Thet o t a lvol umeoft r a f f i cdu r i ngr us h hou r sdi d n' tc ha ngea ndmo r epe o pl ewe r eno wo nt hehi ghwa yst ha nbe f o r e , f ur ‑ t he re r odi ngma s st r a ns i tr i de r s hi p. Ands o mee nt e r pr l S i ngbuti mmo r a lmo t o r i s t s t oo kt or i di ngwi t hi nf la t a bl ed ummi e si nt hepa s s e nge rs e a tt of oolt hepol i c ea nd i l l e ga l l yt a kea dva nt a geo ft heHOVl a n e . De s pl t et hepe r s i s t e ntf a i l u r eo fr oa dbui l d i nga ndi nno va t i onss uc ha sHOV l a ne s ,ma nyt r a ns po r t a t i onpl a n ne r sc o n t i nuet opl 机t he i rho pe sont e c hno l og l C a l s ol ut i onst ot hec onge s t i onpr o bl e m.Thel a t e s toft he s ei ss O‑ c a l l e di nt e l l i ge nt ‑ hi ghwa ys ys t e ms ・ Ma nyc l e ve rt e c hno l og i e sa r eunde rde ve l o pme n t , f r o m v e hi ce s e ns o r st ode t e c tt hed i s t a nc et ot hec a ra h e a da nda ut o ma t i c a l l ya d j us tyo u rc a r ' s s pe e d,t ot r a ns po nde r so rma g ne t se mbe dd e di nt her oa ds ur f a c et oa ut o ma t i c a l l y s t e e ryo u rc a r . Al r e a d ys e ns o r se mbe d de di ns o mehi g hwa yst r a ns mi tr e a l t i met r a f J f i eda t at oc a r se qul PPe dwi t hs pe c i a lr e c e i ve r s ・ Te c hno l og i s t sl oo kf o r wa r dt ot he da ywhe nt hei nt e r ne t ,GPS,a ndr e a lt i meve hi c l ec ont r ol swi l la l l o wyo urc a rt o pi c kt heo pt l ma lr o ut et oyou rde s t i na t i o na ndd r i veyout he r ewhi l eyo ur e l a xo r r e a daboo k.Someo ft he s et e c hnol og i e sa r ede s i gne dt oi nc r e a s ehi g hwa ys a f e t y. Ma nya r emot i va t e dbyt hene e dt oi nc r e a s ehi g hwa yc a pa c i t yl nC i t i e swhe r e bui l d i ngne wr oa dsa nda ddi ngne wl a ne si snol onge rpos s i bl e:unde rc o mput e r ol , t het e c hnol ogi s t spr o mi s e , c a r sc o ul dz i ps a f e l ya l o nga t70mi l e spe rho u r c o n t r o nl yi nc he sa pa r t , g r e a t l ye xpa nd i ngt hec a pa c l t yO fe x i s t i nghi g hwa ys . Themode ls ho ws血ef u t i l i t yo ft he s eho pe s . The r ei snot e c hnol o gl C a ls o l u t i o n t ot hec o nge s t i onp r o bl e l m. Thel mO r ee f f e c t i v e l yt he s et e c hno l og i e si r I T C r e a S ehi g h wa yc a pa c l t y , t hemo r et r l pSWi l lbet a ke n, t hemo r epe o pl ewi l lb uyc a r s , t hel e s s a t t r a c t i vepu bl i ct r a ns i twi l lbe ,a ndt hemo r ec o unt r ys i d ewi l lbede ve l o pe di n t o be d r o o mc ommuni t i e sf o rc o mmut e r s . Thevo l umeoft r a f f i cwi l ls wi f t l yr i s et Oa b s o r ba l lt hene wc a pa c l t yt e c hno l og yc a ny i e l d. Wemi g htz i pa l o ngt hef r e e wa ya t s e v e nt y , butwe' l lbes t uc ki nmuc hl o nge rl i ne sa tt hee nt r a nc er a mpa ndo ns e c o nda r yr out e s . Ont her oa dwa ysoft hef u t ur ewema yr i demor es a f e l ya ndmo r e c o mf o r t a bl y, butwewon' tr i d emo r es wi f t l y . l ‑ l ‑ 189 Ch a p t e r5 C a u s a l Lo o pDi a g r a ms Ec o no mi s t sge ne r a l l ys ugge s tt hes ol ut i oni st oc ha r g et ol l st ha ti nc r e a s ea s c o ng e s t i o nr i s e s( Do wns1 992) , Whi l es o mer e g i o nsa r ee xpe r i me nt i ngwi t ht i me ‑ of ‑ da yt o l l sa ndc o nge s t i on‑ ba s e dpr l C l nguS l ngr e a lt i mes e ns l nge q ul pme nt , t he r e i sc o ns i de r a bl epo l i t i c a lr e s i s t a nc et ot heno t i o no fpa yi ngf o rt hef r e e wa y ,a nd s o mec o nc e r no v e rt her e g r e s s i vei mpa c to ft ol l s , Wo r s e , d r i ve r st e ndt os wi t c ht o s e c o nda r yr o a dsa ndc i t ys t r e e t swhe r et o l l sa r ei nf e a s i bl e . So mena t i o nsha vec o met ounde r s t a ndt he s ed yna mi c sa nda r emovl ngt O r e d uc et r a f f i ca n dt hea t t e nda ntpol l ut i o n,a c c i d e nt s ,a ndde s t r uc t i onofo pe nl a nd nc r e as i ngt r a ve lt i me s ・I nSe pt e mbe r1 997Swe de n' spa r l i a me nt i tc a us e sb yi a do pt e d" Vi s i o nZe r o" ,apo l i c ya i me da te l i mi na t l nga l lt r a f f i cf a t a l i t i e sbype r ‑ mi t t i ngt ownst Or e duc es pe e dl i mi t st o3 0ki l o me t e r spe rhoura ndi ns t a l ls pe e d l l , bumpsa ndo t he rf lowr e s t r i c t i ngde v i c e s . Themod e ls ugg e s t st he s epol i c i e swi i na d di t i o nt os a v l ngl i ve s , e nc o ur a gepe o pl et ous eo t he rmod e ss uc ha sbus , t r a i n, a ndb i c yc l e , t h usr e d uc i ngt hepr e s s u r ef o rr oa dbui l d i nga ndt heg r owt hi nt r a f f i c . 5. 6. 5 Compensat i ngFeedback: TheSour ceofPol j cyResi st ance Thef e e d ba c ksa f f e c t i ngt r a f f i cc l e a r l ys howt ha ta t t e mpt st oc ont r olc onge s t i o n t h r o u g hr o a dbui l d i nga r eva i n, Anyr e d uc t i o ni nc o ng e s t i o nl e a dst omo r et npsa n d mo r ec a r s ,s wi f t l ybui l di ngc onge s t i o nba c kup. Wha tr oa dc ons t r uc t i o na c t ua l l y c on t r o l si st hes i z eoft heme t r o pol i t a na r e aa ndt hen umbe rofc a r so nt her oa d. Roa dc o ns t r u c t i o nc a us e st hedr a ma t i ce x pa ns i o noft heur ba ni z e da nds ubur ba n‑ o r ‑ i z e da r e a , t heg r o wt ho fs t r i pma l l sa ndpa r ki ngl o t s ,a ndt hede c l i neo ff a ,f e s t , a ndf i e l d. Thec a us a ls t uc r t ur eoft het r a f f i cpr o bl e mi l l us t r a t e showpo l i c yr e s i s t a nc e a r i s e si nawi der a ng eo fc ompl e xs ys t e ms ・ Roa d ‑ bui l d i ngpr og r a msa ret y pi c a lof po l i c i e sdi r e c t e da tt hes ympt o m ofdi f f i c ul t y. Pol i c i e sdi r e c t e da ta l l e v i a t l ngt he s y mpt o mso fap r o bl e mus ua l l yf a i lbe c a us et he yt r i g ge rc ompe ns at i ngf e e dbac k s , f e e d ba c kst ha tu n d e r c utt hei nt e nde de fe c t so ft hepo l i c y ・ Thec o mpe ns a t l ngl o o ps a r i s ebe c a us eo t h e ra c t o r s , wi t ht he i ro wngoa l s , r e s po ndt oc ha ng e si nt hes t a t eo f t hes ys t e mi ns uc hawa ya st oo f f s e tt hei nt e nde de f f e c t so ft hepo l i c y. Whi l ee a c h i ndi v i dua ll oo pma ybewe a k,t hec ombi ne de fe c tc a nof t e nc o mpe ns a t ec om‑ pl e t e l yf o ra nyp ol i c yd i r e c t e da tas ympt om o fapr o bl e m.Di r e c t l ngpo l i c i e sa t hes t ympt o mso fapr o bl e mi sl i ket r yl ngt OS q ue e z eaba l l oo nt oma kei ts ma l l e r . Whe ne ve ryous q ue e z e ,t hea i rpr es s ur ei nc r e a s e s ,e x pa nd i ngs o meo t he rpa r to f t heba l l oons oi t svol umer e ma i nsa bo utt hes a me . Whyt h e ndos oma nypo l i c i e sf o c uso na l l e v i a t i ngt hes y mpt o mso fd i f l f i c ul t y? Wef o c uso ns ympt o msbe c a us es omuc ho fo u re xpe r i e nc ei swi t hs i mpl es ys t e ms i nwhi c hc a us ea nde f f e c ta r ec l os e l yr e l a t e di nt i mea nds pa c e , i nwhi c hs ympt o m a ndc a us ea r eo b vi o us . Mos tofo ure xpe r i e nc ei swi t hs ys t e msi nwhi c ht he r ei sa s i ngl e ,do mi na n tne ga t i vef e e d ba c k,a swhe nyo ur e a c ho utt og r a s pa no b j e c tby b j e c ta ndyo urha nd. Wet he ne x‑ a s s e s s l ngt hega pbe t we e nt hepos i t i ono ft heo t r a po l a t et he s ee v e r yda ye x pe r i e nc e swi t hs i mpl es ys t e msi nt ot hema na ge me nto f c o mpl e xs ys t e ms . But , a sJ a yFo 汀e S t e r( 1 969, pp. 9 ‑1 0)no t e s rm 190 P a r t I IT o o l sf o rS y s t e msTh i n k i n g I nt h ec o mpl e xs ys t e mt hec a us eo fad i f f i c u l t yma yl i ef a rba c ki nt i mef r o m , t h es y mpt o ms , o ri nac o mp l e t e l yd i fe r e n ta n dr e mo t epa r to ft hes ys t e m. I nf a c t c a us e sa r eus u a l l yf o u n d, n o ti np r l O re v e n t s , b u ti nt h es t r uc t u r ea n dpo l i c i e so ft h e s ys t e m.‥Co nd i t i o n e dbyo u rt r a i n l n gl nS i mpl es ys t e ms , wea p pl yt hes a mei n t u ‑ i t i o nt oc o mpl e xs ys t e msa n da r el e di n t oe r r o r . Asar e s u l twet r e a ts y mp t o ms , n o t c a us e s . Th eo u t c o meli e sb e t we e ni n e f f e c t i v ea n dd e t r i me n t a l. .. I ft hea t t e mpt e d s o l u t i o ni n t e ns i f i e st h ep r o bl e m, wr o n g l ya t t r i b u t e dt oa n o t h e rs o u r c e , t h eo r g a n i z a ‑ t i o nl i k e l ywi l lr e d o u b l ei t s" c o r r e c t i v e "a c t i o n, p r o d uc i n gmo r ed i f f i c u l t ya n dp r e s S u r ef o rs t i l lmo r er e me d i a la c t i o n. Ad e s t r u c t i v es pl r a l be c o me se s t a b l i s h e d. ‑ i dent i f yi ngt heFeedbackSt r L 氾t ur eO官 PoF 毒 cyRes≠ st ance L Cons i de rt hef a i l e dRoma ni a npopul a t i onpol i c yde s c r i be di nc ha pt e r1 . De ve l o paca us a ll oopdi a gr a me xpl a i nl ngt hef a i l ur eoft hegove r nme nt ' S e f f o r t st oi nc r e a s et hebi r t hr a t e. 2. Ta bl e1 ‑ 1l i s t sanumbe rofc ommone xa mpl e sofpol i c yr e s i s t a nc ei ns oc i a l , bus i ne s s ,a nde c onomi cs ys t e ms . De ve l ops i mpl ec a us a ldi a gr a msf ore a c h. Us eyo urdi a gr a mst oe xpl a i nwhye a c hpol i c yf a i l e d・ 5. 7 SL 糊R . ・ 1 ARY Ca us a ldi a gr a msa reapo we r f ult oolt oma pt hef e e dba c ks t r uc t ur eofc o mpl e xs ys ‑ t e ms . Ca us a ldi a gr a msc a nbehe l pf ult oyoui nt hee a r l ypha s esofapr o j e c t , Whe n youne e dt owor kwi t ht hec l i e ntt e a mt oe l i c i ta ndc a pt ur et he i rme nt a lmode l s ・ The ya r ehe l pf u li npr e s e nt l ngt her e s ul t sofyourmode l i ngwor ki nano nt e c hni c a l f a s hi on. Tobee fe c t i ve, yous houl df ol l owt her ul esf orc a us a ldi a gr a ms , i nc l udi ng s e l e c t i onofva r i a bl ena me s ,l a yout ,a nda s s l gnme ntOfl i nka ndl ooppol a r i t i es Jt i sbe s tt obui l dupdi a gr a msi ns t e ps : r e s i s tt heur get oc r e a t eas l ngl e ,C ompr e he n‑ s i vedi a gr a m. Asi nl e a r nl ngt Or ea dmus i c,pr a c t i c ei se ve r yt hi ng・De ve l opyour s ki l l si nma ppl ngt hef e e dba c ks t uc r t ur eofs ys t e msbys ke t c hi ngc a us a ldi a gr a ms t oc a pt ur et hef e e dba c ksyour e c ognl Z ea Syour ea dt hene ws pa pe rort heg r e a t wor ksofl i t e r a t ur e . St oc ksa ndFl o ws I' mv e7 7goo dati nt e gr alanddl He r e nt i alc al c ul us , Ik nowt hes c i e nt i fi cname so fbe i ngsani mal c ul ous ; I ns hor t ,i nmat t e r sv e ge t abl e ,ani mal ,andmi ne r al , Iamt hev e f Tmode lo famode r nMa j or ‑ Ge ne r al . ‑W. S. Gi l be r t , T h ePi r a t e so fPe n z a n c e ,Ac t1. Th i sc ha pt e ri nt r od uc e st hec onc e pto fs t o c ksa ndmows ,ac e nt r a li d e ai nd yna m‑ i c s . I t pr e s e nt st h ec o nc e pt ua la ndma t h e ma t i c a l de f i n i t i o nsofs t oc ksa ndf lo ws , t he d i a g r a mml ngt oo l sf o rma ppl ngne t WO r ksofs t o c ksa ndf lows ,a ndc a s es t udi e so f t heus eofs t oc ksa ndf lOwsi nmode l i ngpr o j e c t si nc l udi nga ut o mo bi l er e c yc l i ng a ndt hec ons t r uc t i ono fpul pa ndpa pe rmi l l s .De ve l o pl ngf a c i l i t yi ni de nt i f yi ng, ma ppl ng, a ndi nt e r pr e t i ngt hes t oc ka ndf lowne t wo r kso fs ys t e msi sac r i t i c a ls k i l l f o ra n ymode ms ys t e msmode l e r . 6J I S STOC葛 (S,FLOW ,ANDAccuMULATl ON Ca us a ll oo pdi a g r a msa r ewonde r f ll jyt l S e f uli nma nys i t ua t i o ns ,The ya r ewe l J I s ui t e dt or e pr e s e nti nt e r de pe nde nc i e sa ndf e e d ba c kpr o c e s s e s .The ya r eus e de f ‑ f e c t i ve l ya tt hes t a r tofamode l i ngpr o j e c tt OC a pt ur eme nt a lmod e l s ‑bot ht hos e o fac l i e ntg r o u pa ndyo urown. The ya r ea l s ous e dt oc o mmuni c a t et her e s ul t so fa c o mpl e t e dmode l i nge fo r t . Howe ve r ,c a us a ll o o pdi a gr a mss ufe rf r o m anumbe rofl i mi t a t i o nsa ndc a n e a s i l ybea bus e d.So meoft he s ea r ed i s c us s e di nc ha pt e r5.Oneoft hemos ti m po r t a n tl i mi t a t i o nso fc a us a ldi a g r a msi st he i ri na bi l i t yt oc a pt u r et hes t oc ka nd lo f ws t uc r t ur eofs ys t e ms . St oc ksa ndf lo ws , a l o ngwi t hf e e d ba c k, a r et het woc e n‑ t r a lc o nc e pt so fd yna mi cs ys t e mst he o r y . ‑ 191 1 92 P a r t I IT o o l sf o rS y s t e ms Th i n k i n g St oc ksa r ea c c umul a t i ons . The yc ha r a c t e r i z et hes t a t eoft hes ys t e ma ndge ne r ‑ a t et hei nf or ma t i onuponwhi c hde c i s i onsa nda c t i onsa r ebas e d・St oc ksgi veS ys ‑ t e msi ne r t i aa ndpr ovi det he mwi t hme mor y. St oc ksc r e a t ede l a ysbya c c umul a t l ng t hedi f f e r e nc ebe t we e nt hei nf lowt oapr oc e s sa ndi t sout lowI f Byde c oupl i ngr a t es off low,S t oc ksa r et hes ou r c eofdi s e qui l i br i umdyna mi csi ns ys t e ms . St oc ksa ndf lowsa r ef a mi l i a rt oa l lofus .Thei nve nt or yofama nuf a c t ur l ng f i r mi st hes t oc kofpr oduc ti ni t swa r e hous e s . Thenumbe rofpe opl ee mpl oye dby abus i ne s si sas t oc k. Theba l a nc ei nyourc he c ki nga c c ounti sas t oc k.St oc ksa r e a l t e r e dbyi nnowsa ndo ut lo f ws . Af i r m' si nve nt or yl Si nc r e a s edbyt hef lowofpr o‑ duc t i ona ndde c r e a s e dbyt hef lowofs hi pme nt s( a ndpos s i bl yot he rout lowsdue f t os poi l a geors hr i nka ge ) . Thewor kf o r c ei nc r ea s esvi at hehi r i ngr a t ea ndde c r e a s e s vi at her a t eofq ui t s , l a yof f s , a ndr e t i r e me nt s . Yourba nkba l a nc ei nc r e a s e swi t hde ‑ pos i t sa ndde c r e a s e sa syo us pe nd・ Ye tde s pl t ee ve r yda ye xpe r i e nc eofs t oc ksa nd lows f ,a l lt ooof t e npe o pl ef a i lt odi s t i ngui s hc l e a r l ybe t we e nt he m・ I st heUSf e d‑ e r a lde f i c i tas t oc koraf low?Ma nype o pl e,i nc l udi ngpol i t i c i a nsr e s pons i bl ef o r f i s ca lpol i c y,a r eunc l e a r . Fa i l ur et ou n de r s t a ndt hedi fe r e nc ebe t we e ns t oc ksa nd lowsof f t e nl e a dst ounde r e s t i ma t i onoft i mede l a ys , as hor t ‑ t e r mf oc us , a ndpol i c y r es i s t a nc e. 6. 1. i Di agr amm垂 ngNot at i or i苧 orSモ ocksandF一 ows Sys t e m dyna mi c sus e sapa r t i c ul a rdi a gr a mmi ngnot a t i onf ors t oc ksa ndf lows ( Fi gur e6‑ 1 ) . 。 St oc ksa r er e pr e s e nt e dbyr e c t a ngl e s( s ugges t i ngac ont a i ne rhol di ngt he c ont e nt soft hes t oc k) . 。I nf lowsa r er e pr e s e nt e dbyapi pe( a r r ow)poi nt i ngi nt o( a ddi ngt o)t he k. s t oc Out lOwsa f r er e pr e s e nt e dbypi pe spoi nt i ngoutof( s ubt r a c t i ngf r o m) t hes t oc k. o Va l ve sc ont r olt hef lows . ・ Cl oudsr e pr es e ntt hes our c e sa nds i nksf ort hef lows ・ As our c er e pr e s e nt s t hes t oc kf r omwhi c haf lowor l gl na t l ngOut s i det hebounda r yoft hemode l a r i s es ;s i nksr e pr e s e ntt hes t oc ksi nt owhi c hf lOwsl e a vl ngt hemode l bounda r ydr a i n. Sour c e sa nds i nksa r ea s s ume dt oha vei nf i ni t ec a pa c i t ya nd c a nne ve rc ons t r a i nt hef lowst he ys uppor t . Thes t r uc t ur eofa l ls t oc ka ndf lows t r uc t ur esi sc ompos e doft he s ee l e me nt s . Ast hee xa mpl ei nt hef i gur es hows ,af i r m' si nve nt or yl SaS t oc kt ha ta c c umul a t es t hei nf lowofpr od uc t i ona ndi sr e duc e dbyt heout lowofs f hi pme nt s ・ The s ea r et he on lyf lowsc ons i de r e di nt hemode l :unl es se xpl i c i t l ys hown,ot he rpos s i bl ef lows i nt ooroutoft hes t oc k, s uc ha si nve nt or ys hr i nka geo rs poi l a ge, a r ea s s ume dt obe z e r o. Thec l oudsi ndi c a t et ha tt hes t oc kofr a wma t e r i a l sne ve rs t a r ve st hepr oduc ‑ t i onr a t ea ndt hes t oc kofpr oduc ts hi ppe dt oc us t ome r sne ve rgr owss ohi ght ha ti t bl oc kst hes hi pme ntr a t e. 1 93 Cha pt e r6 St oc ksa ndFl o ws FI GURE6 ‑ 1 St oc kan df l ow di agr amml ng n ot a t i on Gener a一St r uct ur e: t E t b LS t o c k て 「 7 ∠ ̲ 二 ゝ = ] st ock Key= > Fr ow X て 「 7 ∠ ⊥ ゝ 由 一 . ー val ve( RowRegul at or ) ○ Sour c eorSi nk ( St ock sout si demode一boundar y) Val v esr egul at eamount \ / t I owmgl nOrOut\ FI owofmat er i al Sour ce fl owofmat er i al Out f 一 ow I nf l ow Outofst ock 〔 3 SI ' nk 争 / \ \ ー Nameo f I ow f / Examp一 e: l n v e n t o r y Pr oduct i on 6且2 Ma的ema昔 i ea自Repr esenせ a抽 mo甘 St ocksandFl ows Thes t oc ka ndf lo wdi a g r a mmi n gc o nve nt i o ns( or i g i na t e dbyFo r r e s t e r1 961 )We r e ba s e donahyd r a ul i cme t a pho r ‑t hef lO wo fwa t e ri nt oa ndo utofr e s e r vo i r s . I nde e d,i ti she l p ult f ot hi n ko fs t oc ksa sba t ht ubsofwa t e r . Theq ua nt l t yO fwa t e r 194 P a r t I IT o o l sf o rS y s t e ms Th i n k i n g i nyourba t ht uba ta nyt l mei st hea c c umul a t i onoft hewa t e rnowl ngl nt hr ought he t a pl es st hewa t e rf lowi ngoutt hr ought hedr a i n( a s s umenos pl a s hi ngore va por a ‑ t i on) . I ne xa c t l yt hes a mewa y , t hequa nt i t yofma t e r i a li na nys t oc ki st hea c c umu‑ l a t i onoft hef lowso fma t e r i a li nl es st hef lowsofma t e r i a lout . Des pi t et hepr os a i c me t a phort hes t oc ka ndf lOwdi a gr a m ha sapr e c i s ea nduna mbi guousma t he ma t i ‑ c a lme a nl ng. St oc ksa c c umul a t eori nt e gr at et he i rf lows ; hene t tf lOwi nt ot hes t oc k i st her a t eofc ha ngeoft hes t oc k.He nc et hes t r uc t ur er e pr es e nt e di nFi gur e6‑ 1 a bovec or r e s pondse xa c t l yt ot hef ol l owl ngI nt e gr a le qua t i on: S t o c k ( t )‑l w( S )IO f low( S ) ] ds+S t o c k( t o ) I n lo f lo t ( 6 ‑ 1 ) ut whe r eI nf low( S )r e pr e s e nt st heva l ueoft hei nf lowa ta nyt i mesbe t we e nt hei ni t i a l t i met oa ndt hec ur r e ntt i met . Equi va l e nt l y ,t hene tr a t eofc ha ngeofa nys t oc k,i t s de r i va t i ve , i st hei nf lowl e s st heout low,de f f i ni ngt hedi fe r e nt i a le qua t i on d( St o c k ) / d t‑I n no w( t )IOu t lo f w( t ) . ( 6 ‑ 2 ) I nge ne r a l , t hef lowswi l lbef unc t i onsoft hes t oc ka ndo t he rs t a t eva r i a bl e sa ndpa ‑ r a me t e r s . Fi gur e6‑ 2S howsf oure qul Va l e ntr e pr e s e nt a t i onsoft hege ne r a ls t oc ka nd nows t uc r t ur e . Theba t ht uba nds t oc ka ndf lOwdi a g r a msma ya ppe a rt obel e s sr 1 g‑ o r o ust ha nt hei nt e g r a lo rdi f f e r e nt i a le qua t i onr e pr es e nt a t i ons ,butt he ya r epr e ‑ c i s e l ye qul Va l e nta ndc ont a i ne xa c t l yt hes a mei nf or ma t i on・Fr om a nys ys t e m of i nt e gr a lo rdi f f e r e nt i a le qua t i onswec a nc ons t r uc tt hec or r e s pondi ngs t oc ka nd lowma f p;f r o ma nys t oc ka ndf lOwma pwec a nge ne r a t et hec or r es pondi ngI nt e ‑ gr a lordi f f e r e nt i a le qua t i ons ys t e m. FI GURE6 ・ 2 Fourequl VaJ en t r epr es en t at i ons ofs t ockand 月ows t r u c t ur e Each r epr es en t at i on con t ai ns pr ec i s el yt he Same i n f or mat i on . Hydr au一 i cMet aphor : l 曹 ノ= St ockandF一 owDi agr am: l nf l ow Out f 一 ow l nt egr alEquat i on: St ock( t )‑ l l nf E ow( S)‑Ou紺ow( S) ] ds+St ock( t o ) tt Di f f er ent i alEquat i on: d( St ock) / dt‑NetChangei nSt ock‑J nf l ow( I )IOut f l ow( I ) Ch a p t e r6 S t o c k sa n dF l o ws 195 Pr o c e s sPo i n t : No t a t i o nf o r Ac c u mu l at i o n Thet r a di t i ona lnot a t i onus e di nc a l c ul usa nds howni nFi gur e6‑ 2i sof t e nc on f us i ngt oma nyp eopl e. I nt hi sbook, Iwi l lge ne r a l l yr e pr e s e ntt hepr oc e s sofa c c u‑ mul a t i onwi t ht heI NTEGRAL( )f unc t i on・ . ‑ St o c k‑I NTEGRAL( I n lo f w Ou t lo f w, St o c k t 。 ) ( 6‑ 3) TheI NTEGRAL( )f unc t i oni se xa c t l ye qui va l e ntt oe qua t i on( 6‑ 1 )a ndr e pr e s e nt s t hec onc e ptt ha t t hes t oc ka c c umul a t e si t si nf lowsl es si t sout lows f , be gi nni ngWi t h kt o ・ a ni ni t i a lva lueo fSt oc 6. 1. 3 TheCont r i but i onofSt ockst oDynami cs St oc ksa rec r i t i c a li nge ne r a t i ngt hedyna mi csofs ys t e msf ort hef ol l owl ngr e a s ons ( Ma s s1 98 0) : 1 . St oc ksC har ac t e r i z et hes t at eoft hes ys t e m andpr ovi det hebas i sf or ae t i ons . Thes t oc ksi nas ys t e mt e l lde c i s i onma ke r swhe r et he ya r e , pr ovi di ngt he m wi t ht hei nf o r ma t i onne e de dt oa c t . Api l otmus tknowt hes t a t eoft hea i r c r a f t i nc l udi ngpos i t i on, he a di ng,a l t i t ude ,a ndf ue ll e ve l ・ Wi t houtk n owl e dgeof t hes es t a t e s , t hepi l oti sf lyi ngbl i nda ndwon' ts ur vi vel ong. Li ke wi s e,a f i r m ca n' ts e ti t spr od uc t i ons c he dul ea ppr opr i a t e l ywi t ho utk no wl e dgeof t heor de rba c kl og, t hes t oc kofi nve nt or y ,t hepa r t ss t oc ks ,t hel a borf or c e , a ndot he rs t oc ks , Aba l a nc es he e tc ha r a c t e r i z e st hef i na nc i a lhe lt a hofa , c or por a t i onbyr e por t l ngt heva l uesofs t oc kss uc ha sc a s h, i nve nt or y pa ya bl es ,a ndde bt . I nf o r ma t i ona boutt hes es t oc ksa f f e c t sde c i s i onss uc ha s i s s ul ngne wde bt , pa yi ngdi vi de nds ,a ndc ont r ol l i nge xpe ns e svi al a yof f s . 2. St oc kspr ov ides ys t e msw it hi ne r t i aandme mor y . St oc ksa c c umul a t epa s te ve nt s . Thec ont e ntofas t oc kc a nonl yc ha nge t hr ougha ni nf lowo rout low. f Wi t houtc ha nge si nt he s ef lows , t hepa s t a c c umul a t i o ni nt ot hes t oc kpe r s i s t s . Thes t oc kofl e a di nt hepa l ntOf Ame r i c a' si nne rc l t yhous l ngr e ma i nshi ght oda ye ve nt houghl e a dpa i ntwa s ba nne di n1 9 78. 0mc et hes t oc kofl ea dpa l nta c c umul a t e d, t heo nl ywa yt o e l i mi na t ei ti st hr o ughe xpe ns i vede l e a di ngo r血ee ve nt ua lde mol i t i onoft he hous l ngI t s e l f . Eve nt he nt hel e a dr e ma i ns , e i t he rs a f e l ys e que s t e r e dormor e l i ke l ydi s pe r s e di nt ot hee nvi r onme nta sdus t ,c hi ps ,o rl e a dl e a c hi ng血・ om l a ndf i l l si nt owa t e rs uppl i es . Li ke wi s e ,t hes t oc kofoz one ‑ de s t r oyi ng c hl or i nege n e r a t e dbyCFCswi l lr e ma i ni nt hea t mos phe r ef わrde c a dese ve n a f t e rt hepr o duc t i onr a t eofCFCsf a l l st oz e r obe c a us et her a t ea twhi c h c hl or i nei ss c r ubbe df r o mt hes t r a t os phe r ei sve r yl ow. St oc ksdon' tha vet o bet a ngi bl e. Me mor i e sa ndbe l i e f sa r es t oc kst ha tc ha r a c t e r i z eyourme nt a l s t a t es . Yourbe l i e f spe r s i s tove rt i me ,ge ne r a t l ngl ne r t i aa ndc ont i nul t yl n youra t t i t ude sa ndbe ha vi or Jfyouha veaba de xpe r i e nc eo na na i r l i nea nd ne ve rf lyont ha tc rr a i e ra ga i n, yourbe l i e fa boutt hel owqua l i t yoft he i r s e r vi c er e ma i nse ve ni ft he y' vei mpr ove d. 196 Pa r tI IT o o l sf o rS y s t em s Th i n k i n g 3. St oc ksa ret hes our c eofde l ays . Al lde l a ysi nvol ves t oc ks ・ Ade l a yl Sapr oc e s sWhos eout putl a gsbe hi ndi t s l nPut . Thedi fe r e nc ebe t we e nt hei nputa ndo ut puta c c umul a t esi nas t oc kof ma t e r i a li npr oc es s . The r ei sal a gbe t we e nt het i meyouma i lal e t t e ra ndt he t i mei ti sr e c e i ve d. Dur i ngt hi si nt e r va l , t hel e t t e rr e s i de si nas t oc kofl e t t e r s i nt r a ns i t . Eve ne ma i la c c umul a t esi ns t oc ksofunde l i ve r e dpa c ke t sa nd me s s a ge sr e s i di ngi nt heme mor yofva r i ousc omput e r sbe t we e nt hes e nde r a ndr e c e i ve r . The r ei sal a gofs e ve r a lye a r sbe t we e nt hede c i s i ont obui l d ne wof f i c ebui l di ngsa ndt het i met he ya r er e a dyf o roc c upa nc y・ Dur i ngt hi s i nt e r va lt he r ei sas uppl yl i neofbui l di ngsunde rde ve l o pme nt ,i nc l udi nga s t oc ko fpr opos e dpr o j e c t sa ndas t oc kofbui l di ngsunde rc ons t uc r t i on・ Byde f i ni t i on,whe nt hei nputt oade l a yc ha nge s , t heout putl a gsbe hi nd a ndc ont i nue sa tt heol dr a t ef ors omet i me. Dur i ngs uc ha d j us t me nt s , t he s t oc ka c c umul a t i ngt hedi f f e r e nc ebe t we e nI nputa ndout putc ha nge s ・ I fyou ma i lwe ddi ngI nvi t a t i onst o1 000ofyourc l os es tf r i e ndsa l la tonc e, whi l et he r a t ea twhi c hot he rma i li sde pos i t e dr e ma i nsc ons t a nt , t hes t oc kofl e t t e r si n t r a ns l t J umpSby1 000a ndr e ma i nsa tt hene wl e ve la st hel e t t e r sma ket he i r wa yt ot he i rde s t i na t i ons . Onl ya st hei nvi t a t i onsbe gi nt oa r ivedoe r st he s t oc kofl e t t e r si nt r a ns i ts t a r tt of a l l . Thede l i ve r yr a t ee xc e e dst hema i l i ng r a t e ,S hr i nki ngt hes t oc kofma i li nt r a ns i t , unt i la l lt hei nvi t a t i onsha vebe e n de l i ve r e d,a twhi c hpoi ntt hede l i ve r yr a t eonc ea ga l ne qua l st her a t ea twhi c h ma i li sde pos i t e da ndt hes t oc kofl e t t e r si nt r a ns i tr e t ur nst oi t sor l gl na ll e ve l ・ Pe r c e pt i onde l a ysa l s oi nvol ves t oc kst hought hes es t oc ksdonoti nvol ve a nyma t e r i a lf lows . Fore xa mpl e, t hebe l i e fofma na ge r si nac ompa ny' S ¶l i wa nhe a dqua r t e r sa bo utt hes hi pme ntr a t ef r o mt he i rSi l i c onVa l l e ypl a nt l a gsbe hi ndt het r ues hi pme ntr a t eduet ome a s ur e me nta ndr e por t i ngde l a ys ・ Me a s ur e me nto far a t es uc ha ss hi pme nt sa l wa ysi nvol vesas t oc k・ Duet o unpr e d i c t a bl eva r i a t i onsi nc us t ome ror de r s , pr od uc ta va i l a bi l i t y,a nd t r a ns por t a t i on,S hi pme nt sc a nva r ys l gni f i c a nt l yf r omhourt ohour ,da yt o da y, orove re ve nl onge rpe r i ods .Shi pme nt smus tbea c c umul a t e df o rs ome pe r i odoft i mes uc ha sada y, we e k, Ormont ht opr ovi deame a nl ngf u l me a s ur e me ntoft her a t e. I fs hi pme nt sa r ehi ghl yvol a t i l e ,t hef i r mwi l lha ve t oa c c umul a t et he m ove rl onge ri nt e r va l st of i l t e routt hes hor Lt e r mnoi s ea nd pr ovi deame a ni ngf ula ve r a gema na ge r sc a nus et oma kede c i s i ons ・ I n a dd i t i ont he r ea r er e por t i ngde l a ysi nvol vi ngas t oc kofs hi pme nti nf or ma t i on wa i t l ngt Obeupl oa de dt oa nddownl oa de df r omt hef i r m' sc omput e rs ys t e m・ The r ema ybef ur t he rde l a ysi nt hea d j us t me ntoft hee xe c ut i ve s ' be l i e f se ve n a 氏e rt he ys e et hel a t e s tda t a. Cha pt e r1 1de s c r i be st hes t r uc t ur ea nddyna mi c s ofde l a ysi nde t a i l . 4. St oc ksde c oupl er at e soff l owandc r e at edi s e qui l i br i um dyna mi c s 。 St oc ksa bs or bt hedi fe r e nc esbe t we e ni nf lowsa ndout l fows , t huspe r mi t t l ng t hei nf lowsa ndout lowst f oapr oc es st odi f f e r . I ne qui l i br i um, t het ot a l i nf lowt oas t oc ke qua l si t st ot a lout lows f ot hel e ve loft hes t oc ki s unc ha ngl ng. Howe ve r , i nf lowsa ndout lowsus f ua l l ydi fe rbe ca us et he ya r e o f t e ngove me dbydi fe r e ntde c i s i onpr oc e s s e s . Di s e qui l i br i um i st her ul e r a t he rt ha nt hee xc e pt l On. Ch a p t e r 6 S t o c k s a n dF l o ws 197 Thepr o d uc t i ono fgr a i nde pe ndso nt heye a r l yc yc l eofpl a nt l nga nd ha r v e s t , a l o ngwi t hunpr e di c t a bl ena t u r a lva r i a t i o nsi nwe a t he r , pe s t po pul a t i o ns , a nds oo n. Cons umpt l OnO fg r a i nde pe ndso nhowma nymo ut hs t he r ea r et of e e d. Thed i f f e r e nc ebe t we e ng r a i np r o d uc t i o na ndc ons umpt i on r a t e sa c c umu l a t e si ng r a i ns t o c ks ,S t o r e dt hr ou g ho utt hed i s t r i but i ons ys t e m f r o mf i e l dt ogr a i ne l e va t o rt opr oc e s s o ri nv e n t o r i e st oma r ke tt oki t c he n c u pboa r d. Wi t ho utas t oc ko fg r a i nt obuf f e rt hedi f f e r e nc esbe t we e n p r od uc t i o na n dc o ns u mpt i on, C O nS umpt l O nWO ul dne c e s s a r i l ye qua l pr o d uc t i o na ta l lt i me sa ndpe o pl ewo u l ds t a r v ebe t we e nha r ve s t s . Thus J os e pha d v i s e dPha r a oht os t o c kpi l eg r a i nd ur i ngt he7goodye a r si n a n t i c l pa t i o no ft he7l e a nye a r sd u r i ngwhi c hc o ns umpt l O nWO ul de xc e e d ha r v e s t s . Whi l eo na ve r a get hepr o duc t i o no fg r a i nba l a nc e sc o ns umpt l O n ( a n dl os s e s )a sf a r me r sr e s po ndt oma r ke tp r i c e sa ndi nve nt o r yc ondi t i ons i nde t e r mi n i ngho wmuc ht opl a nt , a nda sc o ns ume r sa d j us tc o ns umpt i on i nr e s pons et opr l C e Sa nda va i l a bi l i t y , p r od uc t i o na ndc o ns umpt l O na r e r a r e l ye q ua l . Whe ne v e rt woc o upl e da c t i v i t i e sa r ec o nt r o l l e dbyd i fe r e ntde c i s i o n ma ke r s , i nv o l vedi f f e r e ntr e s o ur c e s , a nda r es u b j e c tt odi f f e r e ntr a ndo m s ho c ks ,ab u fe ro rs t oc kbe t we e nt he mmus te x i s t , a c c u mul a t i ngt he d i f f e r e nc e . Ast he s es t oc ksva r y , i nf o r ma t i o na bo utt hes i z eoft hebuf f e r wi l lf e e dba c ki nva r i o uswa yst oi n lue f nc et hei nf lo wsa ndo ut lows f . Of t e n, butno ta l wa ys , t he s ef e e d ba c kswi l lo pe r a t et obr i ngt hes t o c ki nt oba l a nc e・ Whe t he ra ndho we q ui l i br i umi sa c hi e ve dc a n no tbea s s ume dbuti sa n e me r ge ntpr o pe r t yo ft hewho l es ys t e ma si t sma nyf e e d ba c kl oo psi nt e r a c t s i mul t a ne o us l y. Unde r s t a nd i ngt hena t u r ea nds t a bi l i t yo ft he s edyna mi c s l . i so f t e nt hepu r pos eo fas ys t e md yna mi c smod e 6d 2 日 der 酬 y百 mgSt ocksand『日 ⑳ws Thedi s t i nc t i onbe t we e ns t oc ksa ndf lowsi sr e c o gni z e di nma nydi s c i pl i ne s . Ta bl e61 ls howss o mec o mmo nt e r msus e dt od i s t i ng ui s hbe t we e ns t oc ksa nd lowsi f nva r i o usf i e l ds . I nma t he ma t i c s ,s ys t e md y na ic m s , c o nt r o lt he o r y ,a ndr e l a t e de ng l ne e r i n gd i s c i pl i ne s , s t oc ksa r ea l s ok nO wna si nt e gr al so rs t at ev ar i abl e s ・ Fl o wsa r ea l s oknowna sr at e so rder i v at i v e s .Che mi s t ss pe a ko f7 1 e aC t ant Sa nd r e ac t i onpr oduc t s( t hes t oc ks )a ndr e ac t i onr at e s( t hemows ) .I nma nuf a c t u r i ng He r sa ndt hr ough put .I ne c onomi c s , s e t ings t ,s t oc ksa n df lowsa r ea l s oc a l l e dbu s t o c ksa r ea l s ok no wna sl e v e l sa ndf lOwsa sr at e s .Fo re xa mpl e ,t hec a pi t a ls t oc k o fa ne c o no myi si t sl e ve lofwe a l t h( me a s ur e di n,s a y ,do l l a r s )whi l et heGDPi s t hea gg r e ga t er a t eo fna t i ona lout put( me a s u r e di nS / ye a r ) . I na c c o unt i ng, ba l a nc e s he e ti t e msa r es t o c ks ,s uc ha sc a s h,t hebo o kva l ueo fi nve nt o r y , l o ng‑ t e r mde bt , a nds ha r e hol d e re q ui t y( a l lme a s u r e di n,e . g・ ,do l l a r s ) . I t e msa ppe a r i ngont hei n‑ c o mes t a t e me nto rno wo ff undsr e po r ta r ef lOwswhi c ha l t e rt hec o r r e s po ndi ng s t oc kso nt heba l a n c es he e t , s uc ha sne tr e c e l pt S , t hec os tofgo o dss ol d, l o ng‑ t e r m bo r r owi ng,a ndt h ec ha ngei nr e t a i ne de a r nl ngS .The s ef lowsa r eme a s u r e di n S / y e a r . Phys i o l o g i c a lmo de l so f t e nl umpdi fe r e nts t oc ksi nt oas ma l lnumbe ro f c ompar t me nt so rb oxe sc o nne c t e dbydi f f us i o nr a t e s( t hef l ows ) . Fo re xa mpl e ,t he s t o c ko fgl uc os ei nahuma nc a nber e pr e s e nt e dbyat hr e ec o mpa r t me ntmode l : ‑ 198 I IT わ o l sf o rS y s t e msTh i n k i n g P a r t TABLE6 ・ l Fi el d Ter mi nol ogyu s ed t odi s t i ngui sh bet weens t ock s andf 一 owsi n di f f er en t di s cI PI E neS m Ma t h e atic s,p St ocks h y s i cs an de n l n e erl n g Chemistry g M anu f a c t u rl ng Eco nomi cs Ac c oun t i ng Bi ol og y , p hy Medi c i n e, epi d emi ol o si l o o gy gy l n t egr al s, s t at es, s t at e v ar i abl es, s t ock s Reac t an t sandr eac t i on p「 oduc t s Bu f f er s,i n ven t or i es L ev el s St ock s,bal anc esheet i t ems Compar t men t s Pr e val en c e,r es er voi r s Fl ows De r i vai v e s , r a t es of c ha g e,f l o ws ac t nr a t e s Re t n io Thr oughpu t Rat es FE ows, c ashf i owor i ncomes t at emen t i t ems Di f f usi onr at es, f l ows I nci den c e,i n f ec t i on, mor bi di t yand mor t al i t yr a t es gl uc os ei nt hedi ges t i ves ys t e m, gl uc os ei nt hebl oods t r e a m,a ndgl uc os ei nt hei n‑ , pr e v al e nc eme a s ur e st henumbe rors t oc kof t r a c e l l ul a rma t r i x・I ne pi de mi ol ogy pe o pl ewhoha veapa r t i c ul a rc ondi t i ona ta nygi ve nt i me,whi l ei nc i de nc ei st he r a t ea twhi c hpe o pl ec omedownwi t ht hedi s e a s eorc ondi t i on. I nDe c e mbe r1 998 t hepr e va l e nc eofHI V/ AI DSwor l dwi dewa ses t i ma t e dbyt heUni t e dNa t i ons AI DSpr ogr a mt obe33. 4mi l l i ona ndt hei nc i de nc eofHI Vi nf T e c t i onwa se s t i ma t e d t obe5. 8mi l l i oI Vye a r . Tha ti s ,at ot a lof33. 4mi l l i onpe o pl ewe r ee s t i ma t e dt obe HI Vpos i t i veo rt oha veAI DS;t her a t eofa ddi t i ont ot hi ss t oc kwa s5. 8mi l l i on pe o pl epe rye a r( 1 6, 000ne wi nf e c t i onspe rda y) I Thene tc ha ngei nt hepo pul a t i on ofHI Vpos i t i vei ndi vi dua l swa se s t i ma t e dt obe3. 3mi l l i onpe opl epe rye a rduet o t hedea t hr a t ef r omA l Ds, es t i ma t e dt obe2・ 5mi l l i onpe opl epe rye a ri n1 998. Howc a nyout e l lwhi c hc onc e pt sa r es t oc ksa ndwhi c ha r ef lows ?St oc ksa r e qua nt i t i esofma t e r i a lorot he ra c c umul a t i ons .The ya r et hes t a t e soft hes ys t e m. Thef lOwsa r et her a t e sa twhi c ht he s es ys t e ms t a t esc ha nge. I ma gl near i ve rf low i ngi nt oar es e r voi r . Thequa nt i t yofwa t e ri nt her e s e r voi ri sas t oc k( me a s ur e di n, s a y,c ubi cme t e r s ) .I fyoudr e wa ni ma g i na r yl i nea c r os st hepoi ntwhe r et her i ve r e nt e r st her es e r voi r , t hef lOwi st her a t ea twhi c hwa t e rpa s s e st hel i ne ‑t her a t eof lowi f nc ubi cme t e r spe rs e c o nd. ‑ 6 . 2. 1 Uni t sofMeasur ei nSt ockandFl ow Net wor ks Theuni t sofme a s ur ec a nhe l pyo udi s t i ngui s hs t oc ksf r om f l ows .St oc ksa r e us ua l l yaqua nt l t yS uc haswi dge t sofi nve nt or y,pe opl ee mpl oye d,orYe ni na n a c c ount . Thea s s oc i a t e df lOwsmus tbeme a s ur e di nt hes a meuni t s pert i mepe r i od, f o re xa mpl e, t her a t ea twhi c hwi dge t sa r ea dde dpe rwe e kt oi nve nt or y , t hehi r i ng r a t ei npe opl epe rmont h, o rt her a t eofe x pe ndi t ur ef r oma na c c ounti n¥ ノ ho u r . No t e t ha tt hec hoi c eoft i mepe r i odi sa r bi t r a r y・ Youa r e氏. e et os e l e c ta nyme a s ur e me nt s ys t e myoul i kea sl onga syour e ma i nc ons i s t e nt . Youc a nme a s ur et hef lowofpr o‑ duc t i oni nt oi nve nt or ya swi dge t spe rwe e k,wi dge t spe rda y,orwi dge t spe rhour . Thes t a t e me ntHThec ur r e ntr a t eofpr od uc t i oni s1 200wi dge t spe rda yHi se xa c t l y 199 Cha pt e r6 St o c k sa ndFl o ws e q ul Va l e ntt o山es t a t e me ntt ha tpr od uc t i o ni spr oc e e di nga tar a t eo f8 400wi d ge t s ur , 5 / 6wi d ge t spe rmi n ut e , o re ve n43, 8 00, 000wi d ge t s pe rwe e k, 50wi d ge t spe rho pe rc e nt u r y. Al la r es t a t e me nt sa bo uth owma nywi dg e t sa r ebe i ngpr od uc e dr i g ht now‑att hi si n s t ant . Whe t he rt hec u mul a t i venu mbe ro fwi dge t spr o duc e di na ny g l Ve ni nt e Ⅳa ls uc ha sada y , we e k, o rc e nt u r yl Se q ua lt o1 20 0,8 400, o r43 , 8 0 0, 0 00 de pe ndso nwhe t he rt hec ur r e ntr a t es t a ysc o ns t a ntove rt ha ti nt e r va l( o ra v e r a ge s t . o utt ot hec ur r e ntr a t e ) . Mos tl i ke l yi two n' 6. 2. 2 Tht T tSnapshotTest St oc ksc ha r a c t e r i z et hes t a t eoft hes ys t e m.Toi d e nt i f yke ys t oc ksi nas ys t e m, i ma gi nef r e e z i n gt hes c e newi t has na ps hot .St o c kswo ul dbet hos et hi ngsyo u c o ul dc ounto rme a s u r ei nt hepi c t ur e, i nc l ud i ngps yc ho l og l C a ls t a t e sa ndo t he ri n‑ t a ngi bl eva r i a b l e s . Youc a ne s t i ma t et hes t oc ko fwa t e ri nar e s e r voi rf r o m as e t o fs a t e l l i t ei ma ge sa ndt o po g r a ph i cda t a ,butyouc a nnotde t e r mi newhe t he rt he wa t e rl e ve li sr i s i ngO rf a l l i ng. Yo u rba nks t a t e me ntt e l l syo uhowmuc hmo ne yl S i nyo u ra c c o untb utnott her a t ea twhi c hy o ua r es pe ndi ngl tnow. I ft i mes t o ppe d, i two ul dbepos s i bl et ode t e r mi neho wmu c hi nv e nt or yac o mpa nyha so rt hep r i c e o fma t e r i a l sbutno tt hene tr a t eo fc ha ngei ni nve nt o r yo rt her a t eo fi nf la t i o ni n ma t e r i a l spr l C e S . Thes na ps hott e s ta p pl i e sa l s ot ol e s st a ngi bl es t oc ks ・ Thepl a nt ma na ge r ' Se x pe c t a t i ono ft hec us t o me ro r d e rr a t ea ta nyI ns t a ntO rpe r C e p t l O nO ft he s i z eo fi nve nt o r ya r es t o c ks , e ve nt ho ug ht he ya r eme nt a la ndnotphys i c a ls t o c ks . As na ps ho to fpe o pl e' sme nt a ls t a t e s , ho we ve r , d oe snoti ndi c a t eho wf a s tt h e ya r e r e v I S l ngt he i rbe l i e f s . , Fi g ur e61 3l i s t ss o mec o mmo nc o nc e pt sa ndi de nt i f i e st he ma ss t oc kso rf l o ws s ho wi ngt he i rs t oc ka ndf lows t r uc t u r ea ndun i t so fme a s ur e ・ Po pul a t i o n, Empl oy‑ e e s ,a ndDe bta r es t r a i g ht f o r wa r d. Whyi st hepr l C eOfapr oduc tas t oc k?Pr i c e s t . c ha r a c t e r i z et hes t a t eoft hes ys t e m, i nt hi sc a s ehowmuc hyo umus tpa ype ru ni Ap r i c epos t e do na ni t e mr e ma i nsi ne fe c tu nt i li ti sc ha nge d, j us ta st henu mbe r o fwi d ge t si na ni nve nt o r yr e ma i nsc o ns t a ntunt i li ti sc ha nge dbyaf lo wo fpr o‑ d uc t i o no rs hi pme nt s .Eve nt hebi dsa ndo fe r sc a l l e do uti nat r a d i ngpl ta taf i ‑ do ne s ・ .abi do rof f e rr e ma i nsi ne fe c t na n c i a lma r ke ta r es t oc ks ,a l be i ts ho ve l t e r si tbyc r y i ngO uta nOt he r ・ u nt i lt het r a de rwi 山d r a wso ra Whyi st hee xpe c t e dc us t ome ro r d e rr a t ef o rapr od uc tas t oc k?Cl e a r l y , hea t c ‑ t ua lc us t ome ro r de rr a t ei sanow. Thef lO wo fc us t ome ro r de r sa c c umul a t e si na ba c kl ogo rs t oc ko funf i l l e do r de r sun t i lt hepr o d uc tc a nbed e l i ve r e d. Ho we ve r , a ma na ge r ' sbe l i e fa bo utt her a t ea twhi c hc us t o me ro r de r sa r eboo ke di sas t o c k‑1 t i sas t a t eo ft hes ys t e m,i nt hi sc a s eame nt a ls t a t e. Noo nek nowst het r uec u r r e nt o rf ut u r eo r de rr a t e. Tl hema na ge r ' sbe l i e fa bo uto r d e r sc a n,a ndus ua l l yC L O e S , d i f ‑ f e rf r o mt het r ueo r d e rr a t e( t hebe l i e fc a nbewr o ng) . Ma na ge r s ' be l i e f sa bo utt he c us t ome ro r de rr a t ewi l lt e ndt or e ma i nt hes a meun t i lt he ybe c o mea wa r eo fne w i nf o r ma t i o na ndu pda t et he i rbe l i e f s .TheCha ngei nEx pe c t e dOr de rRa t ei st he r a t ea twhi c ht heb e l i e fi su pda t e d. Not et heuni t sofme a s u r ef o rt hee x pe c t e do r ‑ de rr a t e. Li ket hea c t ua lo r de rr a t e , t hee xp e c t e do r de rr a t ei sme a s ur e di nwi d ge t s pe rt i mepe r i od( s a ywe e ks ) . Theuni t so fme a s u r ef b∫t her a t ea twhi c ht heb e l i e f a bo utc us t o me ro r d e r si su pda t e da r e( wi d ge t s / we e k) / we e k r t ‑ l i 200 Ft GURE6‑ 3 Exampl esof s t ock sandf l ows wi t ht hei runi t sof measur e Thech oi ceoft i me uni tf ort hef l ows ( e. g. , days, week s, year s)i sar bi t r ar y bu tmu s tbe c onsi s t en twi t hi na . sl ngl emodel Pa r tH To ol sf o rSys t e msTh i n k i ng て 「 7 由一 . ー Popu 一 at i on て 「 7 血 , . . ̲ ( peopl e / year ) Repayment ( S / year ) Bor r owi ng ( S / ye ar ) Rat eofPr i ce Change ( S / uni t ) ( S / unWyear ) Changei n Expect ed Or derRat e Expect ed Cust omer 1 0r der s ( wi dget s / week ) ( wI ' dget s / weeJ dweek ) Not et ha tt her a t eofpr l C eC ha ngea ndt hec ha ngei nt hee xpe c t e do r de rr a t ec a n bepos i t i veorne ga t i ve( pr ic esa ndde ma ndf or e c a s t sc a nr i s eorf a l l ) A Anyf lowi nt o oroutofas t oc kc a nbee i t he rpos i t i veorne ga t i ve。Thedi r e c t i onoft hea r r ow ( poi nt i ngi nt oo ro uto fas t oc k)de f i nest hes i gnc onve nt i onf o rt hef low. Ani nf low a ddst ot hes t oc kwhe nt hef lowi spos i t i ve; i ft hef lowi sne ga t i vei ts ubt r a c t sf r om t hes t oc k. Whe nt heo ut lowi f spos i t i ve, t hef lows ubt r a c t sf r o mt hes t oc k. Ch a p t e r6 S t o c k sa n dF l o ws 201 ! dent i f yi ngSt ocksandF! ows Ar et hef ol l owi ngc o nc e pt sS t oc kso rf lows ?Dr a was t oc ka ndf lowma pf ore a c h a ndgi vet he i ru ni t so fme a s ur e. 1 .I nt e r e s tr a t e( e. g. , t hepr i mei nt e r es tr a t eorr a t eont he30‑ ye a rUSTr e a s ur y bond) . 2.Une mpl oy me ntr a t e. Hi nt :Wha tdoe st hewo r d" r a t e "me a ni nt hes es e t t i ngs ? 6. 2. 3 Conser vat i onofMat er i a一i n St ockandFl owNet wor ks Ama j orS t r e ngt hoft hes t oc ka ndnowr e pr es e nt a t i oni st hec l e a rdi s t i nc t i onbe ‑ t we e nt hephys i c a lf lowst hr oug ht hes t oc ka ndf lOwne t wor ka ndt hei nf or ma t i on f e e dba c kst ha tc ou pl et hes t oc kst ot hemowsa ndc l os et hel oo psi nt hes ys t e m. The c ont e nt soft hes t oc ka ndf lOwne t wo r ksa r ec o ns e r v e di nt hes e ns et ha ti t e mse n‑ t e r l ngaS t oc kr e ma int he r eunt i lt he yf lowout . Whe na ni t e mf lowsf r omones t oc k t oa not he rt hef i r s ts t oc kl os e spr e c i s e l ya smuc ha st hes e c ondga i ns . Cons i de rt he s t oc ka ndf lOws t r uc t ur er e pr e s e nt i ngt hea c c ount sr e c e i va bl eofaf i r m( Fi gur e 6‑ 4) ・ Thes t oc ko fr e c e i va bl e si si nc r e a s e dbybi l l i ngsa ndde c r e a s e dbypa yme nt s r e c e i ve da ndbyde f a ul t s . Thef lOwofbi l l i ngsi sc ons e r ve di nt hes e ns et ha tonc ea c us t ome ri sbi l l e d, t hei nvo i c er e ma i I I Si nt hes t oc kofr e c e i va bl e sunt i li te xpl i c i t l y lowsoutwhe f nt her e c e i va bl e sde pa r t me ntr e c or dst hec us t o me r ' spa yme ntora c ‑ knowl e dgest ha t t hec us t ome rha sde f a ul t e da ndwr i t e sof ft hea c c ount . I nc o nt r a s t , i nf わr ma t i ona bo utt hes t oc kofr e c e i va bl esi snotc ons e r ve d.Thec or po r a t ea c ‑ C ount l ngS ys t e m ma kest heva l ueof也er e c e i va bl e ss t oc ka va i l a bl et oma ny hr t oughoutt heo r ga ni z a t i on. Ac c e s s l nga ndus i ngt hi si nf or ma t i ondoe snotus ei t upo rma kei tuna va i l a bl et oot he r s . Not ea l s ot ha twhi l et heuni t sofa c count spa ya bl ea r edol l a r sa nd也ebュ l l i ng, pa yme nt ,a ndde f a ul tmowsa r eme a s ur e di ndol l a r spe rt i mepe r i od, t hec ont e nt sof 血es t oc ka r enota c t ua l l ydo l l a r s . Ra t he r , t hec ont e ntoft her e c e i va bl ess t oc ki si n‑ f o r ma t i on,s pe c i f i c a l l y ,al e dge ro rda t a ba s ec ons i s t l ngOfr e c o r dso fi nvoi c e sout ‑ s t a ndi ng. Tos e ewhy , i ma gi net r yi ngt Oe xc ha ngeyourf i r m' ss t oc kofr e c e i va bl es f orc a s h‑youc a ns e l lt he mt oac ol l e c t i ona ge nc y, butonl yf o rmuc hl e s st ha n1 00 c e r l t SOn払edol l a r . Thought hec ont e nt soft hes t oc kofr e c e i va bl esi si nf or ma t i on a ndnotama t e r i a lqua nt i t y,l ti sne ve r t he l es sc ons e r ve d‑youc a nnots e l lagl Ve n s t oc kofr e c e i va bl e smo r et ha no nc e( notl e ga l l y, a nywa y) . St oc ksc a nr e pr e s e nti n‑ f or ma t i ona swe l la smor et a ng ibl equa nt i t i ess uc ha spe o pl e, mone y ,a ndma t e r i ‑ a l s .St oc ksc a na l s or e pr es e nti nt a ngi bl eva r i a bl esi nc l udi ngps yc hol ogi c a ls t a t es , pe r c e pt l OnS , a nde xpe c t a t i onss uc ha se mpl oye emo r a l e ,t hee x pe c t e dr a t eofi nf la ‑ t i on,orpe r c e i ve di nve nt or y. 202 I IT o o l sf o rS y s t em s Th i n k i n g Pa r t Fl GURE6‑ 4 St ockandf l ow s t r u c t ur eof ac c oun t s r ec ei vabl e Thema t er i al f F ow‑ l ngt hr ought he net wor ki sac t u aH y i nf or mat i onabou t cus t omer sandt he amoun t st he yowe, Thi si n f or mat i oni s c on ser ved ‑t he onl ywayar ecei v abl e, Onc ebi l l ed, i sr emovedf r om t hes t ocki si ft he cus t omerpaysor def aul t sJn f or ma‑ t i onabou tt hesi z e andcomposi t i onof acc oun t spayab一 e, howev er , canbe madeavai l abl e t hr oughou tt he s ys t eman di s notdepl et edb y u Sa ge・ ‑ 6. 2. 堵 S竜 aモ e‑ Deモ er mi medSysを ems Thet he or yofdyna mi cs ys t e mst a kesas t a t e ‑ d e t e r mi ne ds ys t e m ors t a t eva r i a bl e a ppr oa c h. Theonl ywa yas t oc kc a nc ha ngei svi ai t si nf lowsa ndout lows f . I nt um, hes t t oc ksde t e r mi net hef lows( Fi g ur e6‑ 5) . Sys t e mst he r e f or eco ns i s tofne t wor ksofs t oc ksa ndf lowsl i nke dbyi nf o r ma ‑ t i onf e e dba c ksf r omt hes t oc kst ot her a t e s( Fi g ur e6‑ 6) . Ass howni nt hef i g ur e, t he de t e mi na nt sofr a t e si nc l udea nyc ons t a nt sa nde xoge no usva r i a bl es ・ Thes et ooa r e s t oc ks .Cons t a nt sa r es t a t eva r i a bl e st ha tc ha nges os l owl yt he ya r ec ons i de r e dt o bec ons t a ntove rt het i mehor i z onofi nt e r e s ti nt hemode l . Exoge nousva r i a bl esa r e s t oc ksyouha vec hos e nnott omode le xpl i c i t l ya nda r et he r e f or eout s i det hemode l bounda r y. Fo re xa mpl e,i namode loft hede ma ndf orane wvi de oga me,t hes i z e oft hepot e nt i a lma r ke tmi ghtde pe ndont hepo pul a t i onbe t we e n,s a y,a ge s4a nd 20・ Thepr oduc tl i f ec yc l ewi l ll a s taf e wye a r sa tmos t . Ove rt hi st i mehor i z ont he popul a t i onbe t we e n4a nd20ye rsofa a gei snotl i ke l yt oc ha nges i gni f i c a nt l ya nd c a nr e a s ona bl ybea s s ume dc ons t a nt . Al t e r na t i ve l y,youc oul dmode lt hes t oc kof c hi l dr e ni nt het a r ge ta gegr oupasa ne xoge no usva r i a bl e,us l ngC e ns usda t aa nd pr qe c t i onst oes t i ma t ei t sva l ues . Ma ki ngpo pul a t i onc ons t a ntore xoge nousi sa c ‑ c e pt a bl ei nt hi sc a s es i nc et he r ea r enos i gni f i c a ntf e e d ba c ksbe t we e ns a l esofvi de o ga me sa ndbi r t h,de a t h,ormi gr a t i onr a t e s . 6. 2, 5 Aux百 日 岳 aF yVar i ab日 es Asi l l us t r a t e di nFi gur e6ェ 6, ma t he ma t i c a lde s c r l pt l OnOfas ys t e mr e qul r e SOnl yt he s t oc ksa ndt he i rr a t esofc ha nge. Fore a s eofc ommuni c a t i ona ndc l a r i t y, howe ve r , i ti sof t e nhe l pf ult ode f i nei nt e r me di a t eorau xi l i ar yV ar i abl e s . Auxi l i a r i e sc ons i s t off u nc t i onsofs t oc ks( a ndco ns t a nt sore xoge nousi nput s ) ・ Fore xa mpl e, apopul a ‑ t i onmode lmi ghtr e pr es e ntt hene tbi r t hr a t ea sde pe ndi ngonpopul a t i ona ndt he f r a c t i ona lbi r t hr a t e;f r a c t i ona lbi r t hr a t ei nt ur nc a nbemode l e da saf unc t i onof f oodpe rc a pl t a. Thel e f ts i deofFi gur e61 7S howst hes t r uc t ur ea nde qua t i onsf or 20 3 Ch a p t e r6 S t o c k s a n dF l o ws FI GURE6 ‑ 5 St a t e‑ det er mi n ed s ys t ems Sys t emse vol v e b yf eedbac ko f i n f or ma t i onf r om t h es t a t eo ft h e s y s t emt ot he f l owst h atal t er t hes t a t es . Lef t : Cau s aHoop 賢 √ ‑ / l 畢 iS璽『璽5 ⊥ \\ ‑ / l ̲ r epr es en t a t i oni n L. whi cht hes t oc k andf l o w St at eott heSy s t em≡l NTEGRAL( NetRa t eofChange・ St a t eoft heSyst emt 。 ) s t r u c t ur ei sno t NetRa t eofChange= i( St a t eof的eSys t em) e xpH dt . Ri ght :Ex pl l Ci t s t oc kan df 一 ow s t r u c t ur ef ort h e s amef eedbac k t hemode l . TheNe tBi r t hRa t ea c c umul a t e si nt hePo pul a t i o ns t o c k. Thea uxi l i a r y l oop. va r i a bl e sFr a c t i o na lBi r t hRa t ea ndFoodpe rCa pi t aa r ene i t he rs t oc ksno rf lows . Theequ a t i on s The ya r ef u nc t i o nso ft hes t o c ks( a nde xoge no usi n put s , i nt hi sc a s eFood ) . Po pu‑ c or r es p on dt ot h e l a t i o npa r t i c i pa t e si nt wof e e d ba c kl oo ps :apos i t i vel oo p( mo r epe o pl e ,mo r e s t oc kan df l ow bi r t hs , mo r epe o pl e )a ndane ga t i vel oo p( mo r epe o pl e , l e s sf oo dpe rpe r s on, l owe r map. Then et f r a c t i o na lne tbi r t hr a t e , f e we rbi r t hs ) . Thei nc l us i o noft hea u xi l i a r yva r i a bl e sdi s ‑ r a t eo fc h ange t l n g u i s h e s t h e t w o l o o p s a n d a l l o w s u n a m b i g u o u s a s s l g n me n t O f l i n ka n d l o o p p o o ft h es t oc ki sa 1 a r i t i e s . f un c t i ono ft he Thea ux i l i a r i e sc a na l wa ysbee l i mi na t e da ndt hemod e lr e d uc e dt oas e tof s t oc ki t s el f , e q ua t i o nsc o ns i s t i ngO n lyofs t oc ksa ndt he i rf lows ・ Bys ubs t i t ut i ngt hee qua t i on c l os l n gt h e f o rFoodpe rCa p i t ai n t ot hee q ua t i o nf o rFr a c t i o na lBi r t hRa t ea ndt he ns ubs it t ut l f eedba c kl oop. , l ngt her e s ul ti n t ot hee q ua t i o nf o rNe tBi r h Ra t t e , yo uc a ne l i mi na t et hea u xi l i a r i e s r e d uc i ngt hemo d e lt oo newi t ho nl yNe tBi r t hRa t ea ndPo pul a t i o n. Ther i ghts i de o fFi gu r e6‑ 7s h o wst hi smode la ndi t se q ua t i ons . Tho ug ht hemo d e li sma t he ma t ‑ i c a l l ye q ul Va l e n tt ot hemode lwi t ha uxi l i a r i e s , i ti sha r d e rt oe x pl a i n, und e r s t a nd, a ndmodi f y . No t et ha ti nt her e duc e df o r mmode l po pul a t i o ne n t e r st hee q ua t i o nf o r t her a t eo fc ha n g eo fpo pul a t i o ni nbo t ht henume r a t o ra ndde no mi na t o r .The , po l a r l t yO ft hec a us a ll i n kbe t we e nPo pul a t i o na ndNe tBi r t hsi snowa mbi g uous a ndi ti snotpos s i bl et odi s t i ngui s ht het wof e e dba c kl oo psi nvo l vi ngpo pul a t i on a ndbi r t hs . Thepr o c e s so fc r e a t l ngt her e duc e df o r mmode lbys u bs t i t ut i ono fi nt e r me d i ‑ l . a t eva r i a bl e si n t ot he i rr a t e si sage ne r a lo nea ndc a nbec a 血e do uto na nymode Ho we ve r ,t heus eofa uxi l i a r yva r i a bl e si sc r i t i c a lt oe f f e c t i vemode l i ng.I de a l l y , e a c he q ua t i o ni nyo u rmode l ss houl dr e pr e s e nto nema i ni de a . Do n' tt r yt oe c o no‑ mi z eo nt henumbe rofe q ua t i onsbywr l t l ngl o ngo ne st ha te mbe dmul t i pl ec on‑ c e pt s ・ The s el o n ge q ua t i o nswi l lbeha r dl bro t he r st or e a da ndu nde r s t a nd. The y wi l lbeha r df oryout ounde r s t a nd.Fi na l l y ,e qua t i o nswi t hmul t i pl ec ompone nt s a ndi de a sa r eha r dt oc ha ngei fyo urc l i e ntdi s a g r e e swi t ho neo ft hei d e a s . ‑ 204 P a r t I IT o o l sf o rS y s t e msTh i n k i n g F】 GURE6 ‑ 6 Ne t wor k sofs t ock sandf l owsar ec oupl edb yi n f or ma t i onf eedback St ock sac cumul at et hei rr at esoff l ow;i n f or mat i onabou tt h es t ock sf eedsbackt oal t ert her at es, cl osl ngt hel oopsi nt hes y s t em. Cons t an t sar es t ock schangl n gt oosl owl yt obemodel edexpl l Ci t l y; ex ogenousvar i abl esar es t oc k sou t si det hemodel boundar y( sh ownbyt h er ec t angl ewi t hr ounded c or ner s ) . Equat i onr epr es en t at i on: Th eder i vat i vesoft hes t ock si ndyn ami cs y s t emsar e,i ngener al ,nonl i n ear f un c t i onsoft hes t oc k s, t heex ogenousvar i abl es,andanyc on s t an t s.l nmat r i xn ot at i on, t her at esof dtar eaf un c t i onf ( )oHhes t at evec t orS, t heexogenou sv ar i abl esUandt hecon s t an t sC: changedS/ . dS/ dt‑i ( S,U,C) ( 6‑ 4) Fort hedi agr amb el ow, t h eequat i onf ort her at eofchangeo fS4i s dS4 / dt‑f 4 ( S3 , S4 ,U3 , C3 ) ( 6‑ 5) Exogenous l nput l Ex og enous put2 l n n o Ex og e u s put 3 l n 62. 6 St ocksChangeOn! yThr 軌唱h■ r i l ei rRat es . St oc ksc ha ngeonl yt hr ought he i rr a t e soff low・ The r ec a nbenoca us a ll i nkdi r e c t l y i nt oas t oc k. Cons i de ramode lf o rc us t ome rs e r vi c e. Cus t ome r sa 汀i vea ts omer a t e a nda c c umul a t ei naque ueofCus t ome r sAwa i t i ngSe r vi c e. Theque uec oul dbea l i nea taf a s tf oodr es t a ur a nt , C a r sa wa i t l ngr e pa l ra tabodys hop, Orpe o pl eonhol d c a l l i ngf ora i r l i ner es e r va t i ons ,Whe nt hes e r vi c ei sc ompl e t e dc us t ome r sde pa r t f r omt heque ue,de c r ea s l ngt hes t oc kofc us t ome r swa i t i ngf o rs e r vi c e・ Ther a t ea t whi c hc us t ome r sc a nbepr oc es s e dde pe ndsont henumbe rofs e r vi c epe r s onne l , t he i rpr oduc t i vi t y( i nc us t ome r spr oc es s e dpe rhourpe rpe r s on) , a ndt henumbe rof hour st he ywor k( t hewor kwe e k) .I ft henumbe rofpe o pl ewa i t i ngf o rs e r vi c e i nc r ea s e s ,e mpl oye e si nc r ea s et he i rwor kwe e ka st he ys t a ya ne xt r as hi f t ,s ki p l unc h,o rc utdownonbr e a ks . 205 Ch a p t e r6 S t o c k s a n dF l o ws FI GURE6‑ 7 Auxi l i ar yv ar i abl es Lef t : Asi mpl epopul at i onmodel wi t hau xi l f ar yV ar i abl es.Fr ac t i on al Bi r t hRat eandFoodperCapi t aar e nei t hers t ock snorf l ows,bu ti n t er medi at ec onc ept saddedt ot h emodel t oai dcl ar i t y . F 7 i ght : Thesamemodel wi t ht h eau xi l i ar yvar i abl esel i mi nat edbysubs t i t u t i oni n t ot her at eequat i on. TheJ i nkf r om Popul at i ont oNe tBi r t hRat enowhasanambi guoussF gn, apoorPr ac t i c e. Cor r ect l ncor r ect ・ もし / / 5 ' ‑ Food Pop u l a t i on‑I NTEGRAL ( Ne tBl r t hRa t e, Pop u l a t i on t 。 ) Ne tBi r t hRa t e‑Pop u l a t i on'Fr a c t i on a=∋ i r t hRa t e Fr a c t i o n a l Bi r t hRa t e‑i ( Foodp e rCap i t a ) F o o dp erCapi t a‑F o o d / Po p u 一 a t i o n Po pu 一 a t i on‑l NTEGRAL ( Ne tBi r t hRa t e,Pop u l a t i on t 。 ) Ne tBi r t hRa t e‑Po p u l a t i on'f ( F o o d / Popu l a t i o n ) Iha veof t e ns e e npe o pl ei nwor ks hopsdr a wt hedi a gr a ms howni nt het opof Fi gur e6‑ 8. The yc oI Te C t l yr e c ognl Z et ha tt her a t ea twhi c hc us t ome r sa r epr oc e s s e d i st hepr oduc tofSe r vi c eSt a f f , Pr oduc t i vl t y, a ndWo r kwe e ka ndt ha thi ghe rque ues ofwa i t l ngC us t o me r sl e a dt ol onge rhour sa ndhi r i ngofa ddi t i ona ls t a f f ,f or ml ng t woba l a nc l ngf e e dba c ks .Butof t e npe opl edr a wi nf or ma t i onf e e dba c ksdi r e c t l y f r om t hewo r kwe e ka nds e r vi c es t a ft ot hes t oc kofCus t ome r sAwa i t l ngSe r vi c e, a s s l gnl ngt he m ane ga t i vepol a r i t y. The yr e a s ont ha ta ni nc r e as ei nt hewor kwe e k ors t a f fl e ve lde c r e a s est henumbe rofc us t o me r sr e ma i nl ngi nt heque ue, t husc l os ‑ i ngt hene ga t i vef e e dba c kl oops . Thec or r e c tdi a gr a mi ss howni nt hel owe rpa ne lofFi gur e6% Theonl ywa y c us t ome r sc a ne xi tt hes t oc ki svi at hede pa r t ur er a t e.Thede pa r t ur er a t ei st he pr oduc toft henu mbe rofs t a f f , he t i rwor kwe e k, a ndt he i rpr oduc t i vi t y. Ani nc r e a s e i na nyoft he s eI n put sboos t st her a t ea twhi c hc us t ome r sa r epr oc es s e da ndl e a ve t heq ue ue.Theba l a nc l ngf e e dba c ksa r es t i l lpr es e nt :Al onge rque ueofwa i t l ng c us t ome r sl e a dst ol onge rhour sa ndmor es t a f fa nda ni nc r e a s ei nt hepr oc es s l ng r a t e. Theva l vec ont r ol l i ngt heout lowf f r omt hes t oc kofwa i t i ngC us t ome r sope ns wi de r ,a ndc us t o me r sde pa r tt heque uea tahi ghe rr a t e. Thepol a r i t i e soft hei nf or na t i onl i nksi nt hef e e dba c kl oo pa r ea l lPos i t i ve, buta ni nc r e a s ei nt hec us t ome r de pa r t ur er a t ec a us e sar e duc t i oni nt hes t oc kofwa i t l ngC us t ome r sbe c a us et hede‑ pa r t ur er a t ei sa nout lowf f r om t hes t oc k. 一 20 6 FI GURE6‑ 8 St ock schange onl yt hr ough t hei rr at es. Pa r t I IT o o l sf o rS y s t e msTh i n k i n g l ncor r ect T op:l nc or r ect s t oc kan df l ow mapofas er vi c e oper at i on. Wor k ‑ week,Ser vi ce St af f , an do t her var i abl esc anno t di r ec t l yal t ert he s t oc kofCus‑ t omer sAwai t i ng Ser vi c e. Bot t om:Cor r ec t ed di agr am. The , Wor k week numberofSer vi c e St af f , andPr odu c ‑ t i vi t ydr i vet he Cus t omerDepa卜 l ur eRat e, whi ch decr eas est he s t ockofCus‑ t omer sAwai t i n g Ser vi c e. 6. 2. 7 Cont i nuousTi meandl nst ant aneousFl ows Thes t oc ka ndf lowpe r s pe c t i ve( a ndi t se qui va l e nti nt e gr a lordi f f e r e nt i a le q ua t i on s t r uc t ur e )r e pr es e nt st i mea sunf ol di ngc ont i nuous l y.Tha ti s ,a soure xpe r i e nc e s ugges t s ,t i mepr og r e s s e ss moot hl ya ndc ont i nuous l y.I ns ys t e m dyna mi c swe a l mos ta l wa ysr e pr es e ntt i l Tl ea SC Or i t i nuous .Eve nt sc a nha ppe na ta l n l yt i l T T i e; c ha ngeca noc c urc ont i nuous l y;a ndt i mec a nbedi vi de di nt oi nt e r va l sa sf i nea s onedes i r e s . 1 i I nn u me r i c a l s i mu l a t i o nt i mei sd i v i d e di n t od i s c r e t ei n t e r v a l s . Ho we v e r , t h es ei n t e r v a l smu s t b es ma l l e n o u g ht h a t t h en u me r i c a l s o l u t i o ni sag o o da p p r o x i ma t i o no ft h eu n d e r l y i n gc o n t i n u o u s d y n a mi c s , a n dmo d e l d y n a mi c sc a n n o t d e p e n do nt h el e n g ho t ft h es o l u t i o ni n t e r v a l ( c u t t i n gi t i n h lf a , e ・ g ・ , s h o u l dn o t a f f e c t a n yo fy o u rc ? n c l u s i o n s ) ・ I nd i s c r e t et i meo rd i f f e r e n c ee q u a t i o ns y s ‑ t e mst h et i mei n t e r v a l i sa ni rr e d u c i b l eml n i ml l mt i med e l a yl ne v e r yf e e d b a c kl o o pa n do f t e nh a s al a r g ei mp a c t o nt h ed y n a mi c s . Ap p e n d i xAd i s c u s s e sn u me r i c a l i n t e g r a t i o na n dt h es e l e c t i o no fa n a p p r o p r i a t et i mes t e pf o ry o u rs i mu l a t i o n s . Ch a p t e r6 S t o c k sa n dF l o ws 2 07 Af lO wa ta n yt l mei sd e f i ne dt obei t si ns t a nt a ne o usva l ue ‑t her a t ea twhi c h i ghtnow.Ma t he ma t i c a l l y ,t hene tf lO wt oa wa t e ri sf lowl ngi nt oyo u rba t ht u br s t oc k( i nf lo wsl e s so ut lo f ws )i st h ei ns t a nt a ne o usr a t eo fc ha ng eo ft hes t oc k ‑i t s d e r i va t i ve( t hi si st heme a ni ngo fe q ua t i on6‑ 2) , Noonec a nme a s ur et hei ns t a n t a ‑ ne o usva l ueofa nyf low. Th ego ve r n me ntdoe snota ndc a nnotr e po r tt heGDPa ta pa r t i c ul a rmome ntbuti ns t e a dr e po r t st hea ve r a ger a t eo fpr od uc t i ono ve rs o me pr i o r , f i ni t ei nt e r va lo ft i me( t y pi c a l l yaq ua r t e ro faye a r ) 。 Li ke wi s e , q ua r t e r l yr e ‑ po r t so faf i r m' ss a l e sa r et h ec u mul a t i ves a l e sd ur i ngt heq ua r t e r , nott hei ns t a nt a ‑ ne o uss a l e sr a t ea tt hee ndoft heq ua r t e r .Dur i ngt heq ua r t e rs a l e sl i ke l yva r i e d s ubs t a nt i a l l y .Sa l e sr e po r t sa tmo r ef r e que nti nt e r va l ss uc ha smo nt hl yo re ve n d a i l ya r ebe t t e ra pp r o x i ma t i o nso ft hei ns t a n t a ne o uss a l e sr a t ebu ts t i l l r e pr e s e n ta v‑ a r l y ,t hes pe e dome t e ro fac a r e r a g est a ke no ve rs omepr i o r ,f i ni t ei nt e r va l .Si mi l doe sno tme a s u r ei t si ns t a nt a ne o usve l oc i t y . Be c a us et hec o mpo ne nt so ft hev e l oc 1 t yS e ns o ra ndi ns t r ume nt a t i o nha v ei ne r t i a ,t hes pe e dome t e ri ndi c a t e sa na ve r a g e o ft heve l oc i t yo ve ra( s ho r t )pr i o ri nt e r va l . Ast hel e n gt hoft heme a s ur e me nti nt e r va ls hr i nks ,t her e po r t e da v e r a ger a t e be c o me sabe t t e ra ppr o xi ma t i o no ft hei ns t a nt a ne ousr a t e , Mos ts pe e do me t e r sr e ‑ s po ndq ui c kl yr e l a t i vet ot her a t eo fc ha ngeo ft hec a r ' st r ueve l o c i t y , s of o rpr a c t i ‑ c a lpur pos e st h ea ve r a g eve l o c i t yr e po r t e dont hei ns t r ume ntpa ne li st hes a mea s t hea c t ua l , c u r r e ntve l o c i t y . Ont heo t he rha nd, t hede l a ysi nr e po r t i ngt hes t a t eo f t hee c o nomyo rt hep r o f i t so fac o mpa nya r eof t e nl o ngr e l a t i vet ot he i rr a t e so f c ha ngea ndd r a ma t i c a l l yi nf lue nc et hes t a bi l i t yoft hes ys t e m. Thoug hwemi g ht d e ve l o pl nS t r u me nt Sf o ro urphys i c a la nds oc i a ls ys t e mst ha ts hr i n kt hed e l a ysi n me a s ur i nga ndr e por t i ngr a t e sO ff lo w,Wec a nne ve rme a s ur et hei ns t a nt a ne ous va l ueo ft hef lo wsa f f e c inga t nys t o c k. ‑ 6 . 2 。 8 e⑳ m 菅 岳 mu ⑳u S B yDj vi s 岳 b日 ev e帽u S Qu a n t i z e dFl ows J us ta st i mec a nber e pr e s e nt e da sunf ol d i ngc ont i n uo us l yo ri ndi s c r e t ei n t e r va l s , s ot oot heun i t sf lOwl ngI nt oa ndo utofs t oc ksc a nbet houghto fe i t he ra sc o n t i n u‑ o us l ydi vi s i bl eo ra sadi s c r e t enu mbe r sofi t e ms .Mos tf l owsa r ea c t ua l l yq ua n‑ t i z e d,me a nl ngt he yc o ns i s tofc o l l e c t i o nso fi ndi vi dua li t e mswhi c hc a n no tbe d i vi de di nt oa r bi t r a r i l ys ma l luni t s . Oi lt a n ke r sa r ec o mmi s s i o ne do nea tat i me ‑ i ti sno tme a ni ng f u lt os pe a ko fl a unc hi ngha l fat a nke r . Compa n yhi r i ngc o ns i s t s ofawhol enumb e ro fpe o pl e. Eve nt hef lo wi nar i ve rc o ns i s t sofa n( a s t r o no mi ‑ c a l l yl a r ge )i nt e g e rn umbe rofwa t e rmo l e c ul e s . Thes t oc ka ndf lOwc o nc e pta nd t hef o ure qui va l e ntno t a t i onss howni nFi g ur e61 2a ppl ywhe t he rt hef lo wi sc on‑ c e i ve dt obei n f i ni t e l yd i v i s i bl eo rq ua nt i z e d. Theme t a pho ro ft hef lO wo fwa t e r i n t oaba t ht ube mpha s i z e so ure ve r y da ye x pe r i e nc eofwa t e ra sac o n t i n uo us l ydi ‑ vi s i bl es ubs t a n c e ‑wea r e n' tc o nc e r ne dwi t ht hei de nt i t yOft hei nd i vi d ua lwa t e r mo l e c ul e s ・ Ho we ve r , i fi twe r ei mpo r t a ntt oo urpur pos e ,wec o ul dj us ta se a s i l y i ma g i net ha tt h et ubi sf i l l e dbyal u mpyf lo wo fi ndi v i d ua l i c ec ube s . h e W he t rc o n‑ t i n uo uso rq ua n t i z e d, t heq ua nt l t yi nt hes t o c ki sa l wa yst hea c c umul a t i o no ft h ei n‑ lowst f ot hes t o c kl e s si t so ut lows f . I nma nymod e l si ti sa pp r o p r l a t ea ndus e f ult oa ppr o xi ma t et hef lo wo fi nd i v i d ‑ ua li t e msa sac on t i nuo uss t r e a m. I nmode l i ngt hec a s hf lowofal a r geo r ga n i z a t i o n 208 Pa r t I IT o o l sf わ rS y s t em s Th i n k i n g youus ua l l ydonotne e dt ot r a c ki ndi vi dua lpa yme nt s ;i ti sape r f e c t l ya c c e pt a bl e a ppr oxi ma t i ont oc ons i de rt hef l owofr e ve nuea nde xpe ndi t ur esa sc ont i nuousi n t i mea ndc ont i nuous l ydi vi s i bl e( t houghofc our s et hea c c o unt i ngde pa r t me ntmus t t r a c ki ndi vi d ua lpa yme nt s ) . Si mi l a r l y, t ho ughor ga ni z a t i onshi r edi s c r e t e , whol ei n‑ di vi dua l s ,i ti sus ua l l ya c c e pt a bl et oa s s umet hef lOwsofpe o pl ea r ec ont i nuous l y di vi s i bl e.Somec l i e nt sa r et r oubl e dbyt hef r a c t i ona lpe o pl eyourmode lwi l lge n‑ e r a t e, buta l mos ta l wa yst hee r r ori si ns i g ni f i c a ntc ompa r e dt ot heme a s ur e me nte r ‑ r ori npa r a me t e r si nc l udi ngt henumbe rofe mpl oye e st hef i r ma c t ua l l yha s .Si nc e pe opl ec a nbehi r e dpa r tt i me,wor ki nj ob‑ s ha r i ngs i t ua t i ons ,orbea s s l gne dt o mul t i pl epr o j e c t s , i ti squi t eme a ni ngf ult os pe a koff r a c t i ona le mpl oye e s , me a s ur e d i nFTE( Ful トTi meEqui va l e nt )pe opl e. Whe nt hepur pos eoft hemode lr e qui r est r a C ki ngt hei ndi vi dua lpe opl e, f ore x‑ a mpl emode l i ngt hebe ha vi orofpe opl ee nt e r l ngt hel i nea tt hes upe r ma r ke tt ode ‑ t e r mi net heo pt l ma lnumbe rofc he c koutc ount e r s ,t he npe o pl ec a nbemode l e da s di s c r e t ei ndi vi d ua l sa r r i vl nga tdi s c r e t epol nt S ; t hi si sac l a s s i cmode l i ngpa r a di gm i nque ui ngt he or y( Pr a bhu1 997;Gr os sa ndHa r r i s1 998; Pa pa dopoul os1 993) , Ye t e ve ni nma nyq ue ul nga ppl i c a t i ons , t hec ont i nuoust i me, c ont i nuousf lowa ppr ox‑ i ma t i onwor kse xt r e me l ywe l la ndt hee r r or si ti nt r oduc e sa r eof t e ns ma l lc ompa r e d t ome a s ur e me nte r r o ra ndpa r a me t e runc e r t a i nt yi nt her e a ls ys t e m. Thede c i s i ont o r e pr es e nts t oc ksa ndf lOwsa sc ont i nuousordi s c r e t ea l wa ysde pe ndsont hepur ‑ pos eoft hemode l . Fore xa mpl e,i fyourpur pos ei st ounde r s t a ndt hedyna mi csof pr i c ea ndt heo r i gi nofc yc l esi nt heoi lt a nke rma r ke t( S e ec ha pt e r20) , i ti sf i net o a s s umet ha tt her a t e soft a nke ror de r i ng,c ons t r uc t i on,a nds c r a ppa gea r ec ont i nu‑ ousi nt i mea ndc ont i nuous l ydi vi s i bl e. Ⅰ nc ont r a s t ,i fyourpu r pos ewe r et omode l t hea r r i va la ndomoa di ngoft a nke r st oo pt l mi z epo r tf a c i l i t i e syo uwoul dha vet o mode lt hes hi psa sdi s c r e t ee nt i t i e s . 6. 2. 9 Whi ehM⑳東e軸 gApp相aehSh⑳u日 e E Youuse? Thec hoi c eofmode l i ngt e c hni quea nds of t wa r ewi l lde pe ndonwhi c ha s s umpt 1 0nS a boutt hes t oc ksa ndf lOwsi nyours ys t e ma r ea ppr opr i a t et OyourPur pos e. I na l l c a s e sma kes ur eyourmode l i ngs of t wa r ea ndme t hodc a ni nc l udet hef e e dba c k pr oc e s s esyo uc ons i de ri mpor t a nt . I nmode l i ngt hebe ha vi o ro fpe opl ei nl i nea tt he s upe r ma r ke t , f ore xa mpl e, youmi ghtc hoos et ous eadi s c r e t et i me, qua nt i z e df low r e pr es e nt a t i ona nds e l e c tas t oc ha s t i cmode l i ngpa c ka ge, o re ve nus eas pr e a ds he e t . Bes ur e,howe ve r , t ha tyourt ool sa l l owyout oc a pt ur ebe ha vi or a lf e e dba c kss uc h a st hef e e dba c kf r omt hel e ngt hoft hel i net ot her a t ea twhi c hpe opl eJ Ol nt hel i ne. Somemode l sa ndag r e a tma nyoft het he or e msi nque ul ngt he o r ya s s umet ha tt he r a t eofa r r i va l st oaq ue ues uc ha st hec he c koutl i nei se xoge nous . Pe opl ea c t ua l l y c hoos et oe nt e ral i neba s e doni t sl e ngt h( mor epr e c i s e l y ,t he i re s t i ma t eofe x‑ pe c t e dwa i t i ngt i me ) . Al o ngl i newi l lc a us epe opl et os wi t c ht oa not he r , de f e rt he i r s hoppi ngt Oal e s sc r owde dt i meofda y ,ore ve ngot oadi fe r e nts t or e. Suc hb al k ‑ mgc r e a t e sapowe r f ulne ga t i vef e e d ba c kl oo p: Thel onge rt hel i ne, hes t ma l l e rt he a r r i va lr a t e. Omi t t l ngS uc hf e e dba c kpr oc es s e sf r omyo urmode li nt hei nt e r e s t sof a na l yt i c a lt r a c t a bi l i t yorpr ogr a mml ngC OnVe ni e nc ewi l lof t e nl e a dt oaf a t a lma w i nyoura na l ys t sa ndpol i c yc onc l us i ons . Ch a p t e r6 S t o c k sa n dF l o ws 209 6. 2. 10 Pr ocessPoi nt : Por t r ay岳 ngSt ocksandFF owsi nPr act i ce Ea c hoft hes t o c ka ndf lowr e pr e s e nt a t i onsi nFi gur e6‑ 2( t heba t ht ub,s t oc ka nd lowdi f a gr a m,i nt e gr a le qua t i on,a nddi fe r e nt i a le qua ion)cont t a i nspr e c i s e l yt he s a mei nf or ma t i o n. The ya r ee xa c t l ye qul Va l e nt . Whi c hs houl dyouus et ode ve l op a ndpr es e ntyo u rmode l s , e s pe c i a l l ywhe nyoua r ewo r ki ngl nat e a m? Thea ns we rde pe ndso nt hec ont e xtoft hemode l i ngpr qJ e c tyo ua r edoi nga nd t heba c kgr oundofyourc l i e ntt ea m.Whi l ema nyma t he ma t i c a l l ys ophi s t i c a t e d mode l e r ss c of Fa tt hei de aofe xpl a i nl ngaC Ompl e xmode lus i ngba t ht ubsa ndpi pe s , Iha vema nyt i me sS e e nOt he r wi s ebr i l l i a ntmode l i nge fo r t sf ounde rbe c a us et he a na l ys tt ie r dt oe xpl a i namode lus i ngdi fe r e nt i a le qua t i onsa ndma t he ma t i c a lno‑ t a t i on‑ort hes i mul a t i onc ode ‑t oac l i e ntt e a mwi t hl i t t l et e c hni c a lba c kg r ound. Oneoft hewor s tt hi ngsac ons ul t a ntc a ndoi shumi l i a t et hec l i e nt .Showi ngo f f yourma t he ma t i c a lkno wl e dgebyus i ngdi f f e r e nt i le a qua t i o ns , l ot sofGr e e kl e t t e r s , a ndot he rnot a t i ont hec l i e ntne ve rs t udi e dorf or gotal ongt l mea goi sas ur e ‑ f i r e wa yt oc onvi nc eyourc l i e nt syouc a r emo r ef o rt hee l e ga nc eofyo ure qua t i o nst ha n f orhe l pi ngt he ms ol vet he i rpr o bl e m. St oc ka ndf lowd i a gr a msc ont a i nt hes a mei nf or ma t i ona st hemo r ema t he ma t ‑ i c a l l yf or ma lno t a t i o nbuta r ee a s i e rt ounde r s t a nda ndt omodi f yont hef ly.St i l l , S omet e a mme mbe r sc o ns i de re ve nt hes t oc ka ndf lowdi a gr a mf o r ma tt obet ooa b s t r a c t .iha veo f t e ns e e nc l e ve rgr a phi c soft a nks , pi pe s ,a ndva l ve sus e dt oe xc e l ‑ l e nte f f e c twi hc t l i e ntt e a ms . Fore xa mpl e, ac ons ul t i ngpr o j e c tWi t hamul t i na t i ona l c he mi ca l sf i r mr e pr e s e nt e dt hef lowsofpr oduc t i on,i nve nt or i e s ,s hi pme nt s ,a nd c us t ome rs t oc ks ‑a l ongwi t hc a pa c l t y , C a s h, a nde ve ne qui pme ntde f e c t s ‑a sas e ‑ r i esofpi pes ,va l ve s ,a ndt a nks .Thet ea m me mbe r swe r ea bl et ogr a s pt hes t oc k a ndf lows t r uc t u r er e a d i l ys i nc et he ywe r ea l1f a mi l i a rwi t ht het a nksa ndpi pescr r yi ngma t e r i a l si nt he i rpl a nt s . I nf a c t ,mos toft hec l i e ntt e a m we r ee ngl ne e r Sby t r a i nl nga ndha dpl e nt yofba c kg r oundi nma t he ma t i c s ・ Ye ts e ve r a lc o mme nt e dt ha t t he yne ve rr e a l l yunde r s t oodhowt hebus i nes swo r ke dunt i lt he ys a wt hec ha r t s howl ngl t SS t oc ka ndf l ows t r uc t ur ea st a nksa ndpi pes ・ Wha ti fyou rc l i e nt sha vee ve nl e s st e c hni c a lt r a i nl ngt ha nt he s ec he mi c a lc om‑ pa nye xe c ut i ve s ?Theba t ht ubme t a phori sof t e nus e dt ogoode fe c t ,a si l l us t r a t e d byt hec a s eofa ut o mobi l el e a s i ng( s e eFi gur e2. 4) A Wha ti ft hes t o c ksa ndf lowsi n yourmode lare n' ta st a ngi bl ea sba r r e l sofoi lora ut omobi l e s ?Ge tc r e a t l veJna ma na ge me ntf li gh ts i mul a t o rofi ns ur a nc ec l a i mspr oc es s i ng( Ki m1 98 9;Di e hl 1 994) ,af low ofle t t e r sa r r i vi ngt oa ni nboxr e pr es e nt e dt hea ddi t i o no fne wc l a i ms t ot hes t oc k ofunre s ol ve dc l a i ms . Le t t e r sc ont a i ni ngC he c ksf lo we do u tt ot hec us ‑ t ome r sa sclaim sw e res e t t l e d. I c onsofpe o pl er e pr e s e nt e dt hes t o c ka ndf lows t uc r ‑ t ur eofc l a i m sadjus t e r s( Fi gur e61 9) .Pa r t i c i pa nt si nwor ks ho psus i ngt hemode l we r ea bl eto unde rs t andt hes ys t e ms t r uc t ur emuc hbe t t e rt ha ni ft h emo r ea bs t r a c t s ymbol shad be e n us e d. Ia m notre com m e nd i ngt ha tyouke e pt hee qua t i onsors t o c ka n df l owdi a l gr a mshi dde nf rom yourc l i e nt ・ Ne ve rhi deyourmode lf r omac u r i o uscl i e nt ・ You s houl da l wayslook forandc r e a t eo ppor t uni t i esf orc l i e ntt e a mme mb e r st ol ea n r mor ea boutthem ode l i ng p r oc e s s ;yous houl da l wa ysbepr e pa r e dt oe x p l a i nt he wor ki ngsofyourm ode l. ‑ a ‑ 210 I IT o o l s f o rS y s t e msTh i n k i n g P a r t FI GURE6 ‑ 9 St o ck san df l o ws o fc J ai msand c l ai msad j u s t er s l nanl n Sur an C e c omp an y 撃薄 ≡ ミ Ad j u s t e r s 轟 CI ai ms Re c e i v e d Cl a i ms Ou t s t a n di n g T u r n o v e r ≡ 牽 Cl ai ms Se t t 日 e d Sour ce. I Ki m 1989. Andwhi l elc a ut i o nt hema t he ma t i c a l l ys o phi s t i c a t e dmode l e ra ga l nS tOve r l y t e c hni c a lpr e s e nt a t i on,t heoppos i t epr o bl e mc a na l s oa r i s e:s omec l i e nt sa r eof ‑ f e nd e dbywha tt he yc ons i de rt obes i mpl i s t i cc a r t oo nd i a g r a msa ndpr e f e rwha t t he yv i e wa st hemor epr o f e s s i o na lpr e s e nt a t i ono fs t oc ka ndf low di a g r a mso r e v e ne q ua t i o ns ・ Asa l wa ys , yo umus tge tt okno wyo urc l i e ntde e pl ya nde a r l yl n t hemo d e l i ngpr o c e s s . Fi na l l y , ac a ut i o nf b∫t hos ewi t hl e s st e c hn i c a lt r a i ni nga ndma t he ma t i c a l ba c k一 g r o u nd:Cl i e nt sma yno tne e dt ounde r s t a ndt hed e e pr e l a t i ons hi pbe t we e nt he i r ba t h t u ba ndt hema t he ma t i c sunde r l yi ngs t oc ksa ndf lows , b utyo udo. Whi l eyo u do n' tn e e dt obea bl et os o l vedi fe r e nt i a le qua t i o nst obeas uc c e s s f ul mod e l e r , you done e dt ou nd e r s t a ndt hes t r uc t ur ea nddyna mi c so fs t oc ksa ndf lowst ho r o ug hl y a ndr i go r o us l y 。 6。 3 MApp日 NG STOeKSAND FLOWS 63. 1 WhenSh⑳uはPea L uSaは oopD岳 agr amsSh㊤w St ockandFl ow St r uct ur e? コ Ca us a ld i a g r a msc a nbed r a wnwi t houts howi ngt hes t oc ka ndf lo ws t r uc t ur eo fa s ys t e m芋 Or , a ss h owni nFi g ur e6‑ 8ー he yc a ni nc l u det hes t o c ka ndf l o ws t r l J p C t lr e e ,a ndwhe nc a n e x pl i c i t l y. Whe ns houl dyo ui nc l udet hes t o c ka ndf lows t r uc t ur yo uomi ti t ?Ge n e r a l l y , yous houl di nc l udes t o c ka ndf lo ws t uc r t ur e sr e p r e s e nt l ng ph ys i c a lpr o c e s s e s , de l a ys , Ors t oc kswhos ebe ha vi o ri si mpo r t a nti nt hed yna mi c s yo us e e kt oe xpl a i n・ Fo re xa mpl e , c o ns i de rt hef lowo fapr o d uc tt hr o ug has u p pl y c ha i nf r o mp r o duc e rt oc o ns ume r . Thepr odu c tt r a ve l st hr o ug hane t wo r ko fs t oc ks ( i nv e n t o r i e s )a ndf lows( s hi pme nta ndd e l i ve r yr a t e s ) . Thes t o c ka ndf lowr e pr e ‑ s e n t a t i o nf o rt hi spr oc e s si ss howni nt het o ppa ne lo fFi g ur e6‑ 1 0. Pr od uc t i ons t a r t sa ddt ot hes t oc kofwo r ki npr oc e s s( WI P)I nve nt o r y .The Pr o duc t i o nCo mpl e t i onRa t er e duc e st hes t o c ko fWI Pa ndi nc r e a s e st hes t oc kof ラ 211 Ch a p t e r6 S t o c k sa n dF l o ws FI GURE6・ 10 St oc kan df l o wv s . C a u s al di agr amr epr es en t at i on s St ockandRowRepr esent at i onofaManuf act ur i ngPr ocess Wor . ki n Pr oc e ss l nv ent or y Pr oduct i on St ar tRa t e Fi ni shed l nv ent or y Pr oduc t i on Compl et i on Rat e Shi pment Ra t e CausalLoopDi agr am Repr esent at i onoft heManuf act ur i ngPr ocess /一一 1 ‑ 、 T' AL Pr oduc t i on St ar tRa t e ふ Wor ki n Pr ocess l nvent or y 一 ‑‑‑‑ 、 . /一 一 一 ・ ‑ 五 Pr oduc t i on Compl et i on Ra t e 二 g Fi ni shed hvent or y 一一 ・ 一 \ー Shi pment Ra t e Fi ni s he dI nv e n t o r y .Shi pme nt st oc us t o me r sde pl e t eFi ni s he dI nve nt o r y. Eq ula 1 e nt l y ,t hes t oc kofWI Pa c c umul a t e spr od uc t i ons t a r t sl e s sc o mpl e t i ons ,a ndt he s t oc ko ff i n i s he di n ve n t o r ya c c umul a t e spr od uc t i onc o mpl e t i o nsl e s ss hi pme n t s . Thec a us a ld i a g r a mr e pr e s e nt a ioni t ss howni nt hebo t t om pa ne lofFi g ur e 6‑ 1 0・ Whi l et e c h ni c a l l yc o r r e c t , t hec a us a ldi a g r a mma ke si tha r dt os e et hephys i ‑ c a lf low o fpr o d uc tt h r o ug ht hes ys t e ma ndt hec o ns e r va t i o nofma t e r i a li nt he s t oc ka ndf lo wc ha i n. I ti so f t e nc o nf us i ngt oi nt e r p r e tt hepo l a r i t i e so ft hec a us a l l i n kswhe nt he yI nvo l ves t oc ksa ndf lo ws . Ani nc r e a s ei nt hePr od uc t i onCo mpl e ‑ t i onRa t ec a us e sFi ni s he dl nve nt o r yt or i s ea bov ewha ti two u l dha v ebe e no t he r ‑ wi s e( i tr i s e sa taf a s t e rr a t e ) , he nc et hepol a r i t yo ft hel i n ki spos i t i ve. Ad e c r e a s e . i npr od uc t i o nc o mpl e t i o ns ,howe ve r ,do e sno tc a us ef i ni s he di nve nt o r yt of a l l Ra t he r ,ade c r e a s ei nt hepr od uc t i o nc ompl e t i o nr a t ec a us e sf i ni s he di nve nt o r yt o bel e s st ha ni two ul dha vebe e n. Yo uc a nno ts a ywhe t he rf i ni s he di n ve n t o r ywi l l be r i s l ngO rf a l l i ngba s e dont hebe ha vi o ro ft hepr od uc t i o nr a t ea l o ne . I nve nt o r ywi l l r i s eo nl ywhe np r o d uc t i o nc o mpl e t i o nse xc e e dt hes hi pme n tr a t e; t ha ti s , i nve nt or y r i s e sonl ywhe nwea ddt oi tf a s t e rt ha nwer e mo veun i t sf r o mi t . Yo une e dt ok no w t heva l ue so fa l lt hef lo wsa fe c ingas t t o c kt ode t e r mi nei t sbe ha vi o r . Ri c ha r ds o n ( 1 98 6a ,1 9 97 )c a r e f ul l ydo c ume nt st hepi t f a l l so fc a us a ld i a g r a ms ,mos tofwhi c h i nvo l vet hef a i l u r eo fc a us a ldi a g r a mst os ho wt hes t o c k / lo f wd i s t i nc t i o n. V ‑ Add的 1 gSt ockP . ndFl owSt r uct ur et oCausalD妻 agr ams Cons i de rt hec a us a ll oo pdi a g r a msi nc ha pt e r5・Fore a c h,r e dr a wt hedi a g r a m s howi ngt hei mp o r t a nts t o c ka ndf lO ws t r uc t ur ea l o ngwi t ht hef e e d ba c ks t uc r t ur e s howni nt hed i a g r a m. I npa r t i c ul a r , i de n t i f yt hema i ns t oc ksa ndf lOwsi nt hef oi l l owl ngC O nC e p t ua l i z a t i o nc a s es t udi e spr e s e n t e di nc ha pt e r5: 21 2 P a r t I IT b o l sf わ rS y s t e ms Th i n k i n g 1 .Thewo r kl oa dma na ge me n te xa mpl e. 2.Theo i li nd us t r ya ndho r s er a c l nge xa mpl e s . 3.Thet r a f f i cc onge s t i o ne xa mpl e . he a c hc a s e ,c o ns i de rwhe t he rt hee x pl i c i tr e pr e s e nt a t i ono ft hema i ns t oc ksa nd lo f wse n ha nc e syo ura bi l i t yt ounde r s t a ndt hedyna mi c so ft hes ys t e mo rme r e l y c l ut t e r s血ed i a g r a m. Li nkさ ngSt et : 汰andFl owS号 r uct ur ey ・ ^ / 軸 Fee軸 t lCk Of t e nu nde r s t a ndi ngt hed yna mi c sofas ys t e mr e qul r e Sl i nk i ngt hef e e d ba c kl o o p s t r uc t ur ewi t ht hes t oc ka ndf lows t r u c t u r e . Asa ne xa mpl e , c o ns i de rt hega s ol i ne s ho r t a ge so ft he1 970s Jn1 979t heUni t e dSt a t e s( a nds omeot he ri nd us t r i a l i z e d na t i o ns )e x pe r i e nc e das e ve r ega s ol i nes ho r t a g e.I r a n' se x po r t so fo i ld r o ppe di n t hewa keo ft her e vol ut i ont he r e ,a ndpe t r o l e um pr l C e SO nt hewor l dma r ke ti n‑ c r e a s e ds ha r p l y. Wi t hi nwe e ks , as ho r t a g eo fga s o l i nebe ga n・ Somes e r v i c es t a t i o ns f o undt he i rt a nkse mpt i e dbe f o r et hen e xtd e l i ve r y . Dr i ve r s , r e me mbe r i ngt hef i r s t o i l e mba r goi n1 973a ndwo r r i e dt ha t t he ywo ul d n' t bea bl et oge tg a s , be ga nt ot o p o f ft he i rt a nks ,i ns t e a doff i l l i ngupo nl ywhe nt hega sga ugef e l lt owa r de mpt y・ Soo n, l o ngl i ne sofc a r swe r es e e ni dl i ngi nf r o ntofga ss t a t i ons ,a ndH So r r y ‑No Ga s "S i g nss pr out e da l o ngt hehi g hwa ysofAme r i c aa ss t a t i o na f t e rs t a t i o nf o und i t sunde r g r o undt a nkspumpe dd r y. Thes ho r t a gewa st het o ps t o r yo nt hee ve nl ng ne ws ‑a e r i a lf oot a geofc a r sl i ne du pa r o undt hebl oc k,c l os e ‑ upso f" NoGa s " , s l g nS ,a ndi nt e r vi e wswi t ha nxi ousd r i ve r sd omi na t e dt hene ws ・I ns omes t a t e s ma nda t o r yr a t i o nl ngWa si mpos e d, i nc l ud i ngl i ml t l ngPur c ha s e st o, f o re xa mpl e , no mo r et ha n$1 0wor t hofga s . Ca l i f o r n i ai mpos e do dd / e ve npu r c ha s er ul e s : Dr i ve r s we r ea l l o we dt obuyga so nl ye ve r yo t he rda y , ba s e do nwhe t he rt he i rl i c e ns epl a t e numbe rwa soddo re ve n. I ts e e me d血a tt hes u p pl yo fga s ol i neha dbe e ns l a s he d・ Cur i o us l y , t hei mpa c to ft heI r a ni a nr e vo l ut i o no nt hef lowo fo i lt ot heUSwa s s ma l l . Tr ue, USoi li mpo r t sf r o mt hePe r s i a nGul f( i nc l udi ngI r a n)f e l lby50 0, 00 0 o ns umpt i o n, but i mpo r t s ba r r e l spe rda ybe t we e n1 978a nd1 9 79, a bo ut3% ofUSc f r o mot he rna t i o nsi nc r e a s e dby6 40, 0 00ba r r e l spe rda y ,s oi mpo r t si n1 9 79a c t u‑ a l l yl nCr e aS e dby1 40, 000ba r r e l spe rda y・Dome s t i cpr oduc t i onf e l lby1 50, 000 ba r r e l spe rda y , s ot o t a ls up pl ywa se s s e n t i a l l yc o ns t a nt , whi l ec o ns umpt i o nf e l l by a bo ut33 0, 000ba r r e l spe rda y,ad r o pof2% f r o m1 978. Pl a i nl y , f o rt heye a ra sa whol e ,t he r ewa snos ho r t a ge.Buti ft heI lo wofoi li nt ot heUSwa se s s e nt i a l l y c o ns t a nt , wha tc a us e dt hes ho r t a ge ?Whe r edi dt hega sgo? Fi r s t ,de ve l o pas t oc ka ndf lowma pf o rt hega s ol i nedi s t r i but i ons ys t e m・ Yo u ne e dno tc o ns i de rt hee nt i r es u ppl yc ha i nf o rga s ol i nebutc a nf oc uso nr e t a i ld i s ‑ t r i but i o n. Yo urdi a g r a ms ho ul dbe g i nwi t ht hef lOwofga s ol i net os e r vi c es t a t i o ns , t he nr e pr e s e ntt hes t oc ka ndf lOw s t r uc t ur ef o ri t ss ubs e que nts t o r a ge ,s a l e ,a nd e ve nt ua lc ombus t i o n. Onc eyo u' vema ppe dt hes t o c ka ndf lows t r u c t ur e , i de nt i f yt hei nf o ma r t i o ni n‑ pu t st ot her a t e soff lo wi nyo urdi a g r a m・ As s umet ha tt her a t ea twhi c hga s ol i nei s de l i ve r e dt os e r vi c es t a t i o nsi se xo ge no us . Byi de nt i f yi ngt hei nf o r ma t i o ni n pu t st O Ch a p t e r 6 S t o c k sa n dF l o ws 213 tef h lo wsi nyo u rs t oc ka ndf lowma p,yo uwi l lbec l os l ngs omef e e d ba c kl oo ps , l o o pswhi c hs h o ul dhe l pe xpl a i nwh yt hes ho r t a g eo c c ur r e da nda ns we rt heq ue s ‑ t i o n,Whe r edi dt hega sg o?Bes ur et oa s kho wi nd i vi d ua ldr i ve r swoul dl e a r n a bo utt hes ho r t a gea ndwha tt he i rbe ha vi o rwo ul dt he nbe. Fi na l l y,us l ngyo urdi a g r a m,a s s e s st hel i ke l ye fe c t i ve ne s soft hema xi mum p ur c ha s ea ndo d d / e ve npol i c i e s . Dopol i c i e soft hi st y pehe l pe a s et hes ho r t a geo r ma kei two r s e ?Why?Wha tpol i c ywoul dyo ur e c o mme ndt oe a s et hes ho r t a g e? Ex pl a i nwhyyo ut hi nkyourpol i c ywoul dbee fe c t i vei nt e r msoft hes t oc k / lo f w a ndf e e d ba c ks t r u c t u r eo ft hes ys t e m. 6. 3. 2 Aggr egat i Qn喜 nSt ockandFl ow Mappi r ! g Thea bi l i t yt oma pt hes t oc ksa ndf lowsi nas ys t e mi sc r i t i c a lt oe fe c t i vemod e l ‑ i ng. Us ua l l yi ti swi s et oi de nt i f yt hema i ns t oc ksi nas ys t e ma ndt he nt hef lo ws t ha ta l t e rt hos es t oc ks .Yo umus ts e l e c ta na ppr o p r l a t el e ve lofa gg r e ga t i ona nd bo unda r yf o rt he s es t oc ka ndf lowma ps .Thel e ve lo fa gg r e ga t i onr e f e r st ot he n umbe ro fi nt e r na lc a t e go r i e so rs t oc ksr e pr e s e nt e d. Thebounda r yr e f e r st ohow f a ru ps t r e a ma nddowns t r e a mo nec ho os e st or e pr e s e ntt hef lOwso fma t e r i a l sa nd l . o t he rq ua nt i t i e si nt hemode Toi l l us t r a t e ,c ons i d e rt hema nu f a c t u r i ngPr o c e s sdi s c us s e da bovei nwhi c h ma t e r i a lf lOwsf r ompr od uc t i o ns t a r t st hr o ug hWI Pi nve nt o r yt of i ni s he di nve nt o r y a ndf i na l l ys hi p me ntt ot hec us t ome r . Al lt heva r i o uspa r t s ,c ompo ne nt s ,a nds ub‑ a s s e mbl i e sa r ea gg r e ga t e dt o ge t he ri nt oas i ng l es t oc ko fWI P・ Andt ho ug ht hef i r m ma yc a r r yt e nso ft ho us a ndso fSKUs( s t oc kk e e pi nguni t s ) , t he s ei ndi v i dua li t e ms a r ea l la gg r e ga t e di nt oas i ngl es t oc ko ff i n i s h e di nve nt or y. Forma nypur pos e st he a g g r e ga t epi c t u r ei ss uf f i c i e nt . Ho we ve r , t hemod e l pur pos emi g htr e q ui r emo r ed e ‑ t a i l . I ft hepu r pos ei nvol ve dac l os e rl oo ka tt hema nuf a c t ur l ngpr o c e s s , yo uC O ul d , d i s a gg r e ga t et h es t oc kofwo r ki npr oc e s ss e r i a l l yt or e pr e s e ntt hedi fe r e nts t a g e s s uc ha spa r tf a b r i c a t i on, a s s e mbl y , a ndt e s t i ng( Fi g ur e6‑ 1 1 ) ・ Thes umo ft het hr e ei nt e r me d i a t es t o c ksi st het ot a lwo r ki npr oc e s si nve n t o r y, bu tno wt hemo d e lt r a c kst hr o ug h puta taf i ne rl e v e lofr e s ol ut i o na ndc a nr e p r e s e nt mo r epo t e nt i a l bo t t l e ne c ksi nt hepr o d uc t i o npr o c e s s . No t et ha ti nbo t ht heo r l g l na l , a g g r e ga t edi a g r a ma ndi nt hi smo r ed e t a i l e dd i a g r a mt he r ei snopr o vi s i onf o rr e ‑ wo r ko rs c r a p. Al luni t ss t a r t e da r ee ve nt ua l l yc o mpl e t e d ‑t hef low ofwi dge t s t hr o ug ht hes ys t e mi sc o ns e r ve d. No t ea l s ot ha ta sma t e r i a lf lo wst hr o ug ht hes ys t e mi ti st r a ns f o r me df r o mpa r t st of i ni s he dp r o d uc t . Toma i nt a i nc ons i s t e ntuni t s ofme a s ur ewemi ghtme a s ur epa r t si nwi dge te qul Va l e nt s ‑t ha ti s ,awi dge t ' s wo r t ho fpa r t s . I fne c e s s a r yf o rt hepu r pos e , yo uc a nf ur t he rd i s a gg r e ga t et hes t oc k a n df lows t r u c t u r e. ‑ Modi f yi ngSt ockandFI ow Maps 1 .Mod i f yt h edi a g r a mi nFi g ur e6‑ l lt or e pr e s e ntt hec a s ewhe r euni t st ha tf a i l t e s t l nga r eS C r a ppe d. 2.Mo di f yyo urdi a g r a mt or e pr e s e ntt hec a s ewhe r ei t e msf a i l i ngt e s t l nga r e r e t u r ne dt oa s s e mbl yf o rr e wor k. 21 4 Fl GURE61 11 Di saggr egat ed st ockandf f ow mapf ora manuf ac t ur i ng Pr ocess Pa r tI I To ol sf o rSys t em s Thi n k i ng Ch a p t e r6 S t o c k sa n dF l o ws 215 a tt hepl a ntyoua r emode l i nga c t ua l l yr e qui r e sS e ve r a lope r a t i ons : we l di ng,g r i nd‑ 1 ng,a ndpa i nt l ng.Obs e r va t i onoft heg r i ndi ngope r a ionr t e ve a l st ha twor ke r sdr a w pa r t sr e a dyf org r i ndi ngf r om abuf f e rge ne r a t e dbyt hewe l di ngo pe r a t i on. Whe n gr i ndi ngl SC Ompl e t e d, t hepa r t sa r epl a c e di nabi nwhi c ht hengoe sont ot hene xt ope r a t i on( pa i n t i ng) ・ Thewe l di nga ndpa i nts hopsa r es i mi l a r . Dr a wt hedi s a ggr e 一 ga t e ds t oc ka ndf lOwma pf ort hepa r tf a br i c a t i ons t e pt os howt hewe l di ng, gr i nd‑ 1 ng,a ndpa l nt l ngope r a t i onse xpl i c i t l y. Upt onowt hedi s c us s i onha sf oc us e dons e r i aldi s a ggr ega t i on:howf i ne l yt o br e a kdownt hes t a ge sofpr oc es s l ng.Thr o ughout ,t hema nydi f f e r e ntpa r t sa nd pr oduc t spr oduc e dbyat ypl C a lf i r ma r ea ggr e ga t e di nt oas l ngl ec ha i nofs t oc ks a ndf l ows .I nma nys i t ua t i onst hepr oc e s soc c ur snotonl yi ns e r i e sbuta l s oi n‑ vol vespa r a l l e la c t i vi t i e s .Youc oul dofc our s er e pl i ca t et hema i ns t oc ka ndf low c ha i nf ore a c hpr oduc t( ma nys i mul a t i ons of t wa r epa c ka gess uppor ta r r a ys t rc t ur e sf わrt hi spu r pos e ) 。 Whe nt he r ea r emul t i pl e, pa r a l l e la c t i vi t i esyoumus tma ke ade c i s i onnoto nl ya boutt henumbe rofs t a ge soft hepr oc es st or e pr e s e ntbuta l s o howmuc ht oa gg r e ga t et hedi f f e r e ntpa r a l l e lpr oc e s s e st oge t he r . Fore xa mpl e ,t he a s s e mbl ypr oc es sf ora ut omobi l e si nvol vesi nt egr a t l ngt hec ha s s i sa nde ngl ne. Ea c hs uba s s e mbl yi sbui l tonas e pa r a t el i ne ,of t e ni npl a nt sf a rf r om t hef i na la s ‑ s e mbl ypol nt ・Suppos et hec l i e nta r gue st ha tyouca n' ta ggr e ga t ea l ls ubc ompo‑ ne nt si nt oas l ngl ef lowofpa r t s , butmus ts e pa r a t ec ha s s i sa nde ngi nef a br i c a t i on ( omi tt hebodyf o rs i mpl i c i t y) . Thes t oc ka ndf lOwma pf ort hea s s e mbl ypr oc e s s mi ghtbes howna si nFi g ur e6‑ 1 2. The r ea r enowt hr e edi s t i nc ts t oc ka ndf lowc ha i ns , onee a c hf o re ngl ne S , C ha s I s i s ,a nda s s e mbl e dca r s . Be c a us et het hr e ec ha i nsa r es e pa r a t e,e a c hc a nbemea‑ s ur e di ndi f f e r e ntuni t s :e ngl ne S ,C ha s s i s ,a ndc a r s .Thet hr e ec ha i nsa r el i nke d be c a us ee a c hc a rbe gi nnl ngt hef i na la s s e mbl ypr oc es sr e qul r eSOnee ngi nef r om t hes t oc kofc ompl e t e de ngl ne Sa ndonec ha s s i sf r om t hes t oc kofc ompl e t e dc ha s ‑ s i s . Thei nf or ma t i ona r r owsf r o mt hea s s e mbl yr a t et ot hee ngi nea ndc ha s s i sus e r a t e ss howt he s el i nks . Thenumbe rofe ngl ne Sa ndc ha s s i sa va i l a bl ea l s ode t e mi ne t hema xi mum a s s e mbl ys t a r tr a t e,whi c hi nt ur nco ns t r a i nsa c t ua la s s e mbl ys t a r t s : I fe i t he rc ompone ntbuf f e rf a l l st oz e r o,a s s e mbl ymus tc e as e. 2Thes el i nks( not s hown)de f i net woba l a nc i ngf e e d ba c kst ha tr e gul a t et heout f l owsf r omt hes t oc ks ofc ompone nt sa ndc oupl et hes t oc ka ndf lOwne t wor ks ・ Thedi a gr a mdoe snotr e p r e s e ntma nyot he ri nf or ma t i onf lowst ha tmus te xi s ti nt hes ys t e m( s uc ha st hede ‑ t e r mi na nt soft hec ha s s i ss t a r ta ndc ompl e t i o nr a t es ) ; t r ya ddi ngt he s et ot hema p. Yo uc oul dofc our s ec ont i nuet odi s a gg r e ga t e. Thepr oc e s sc a nbebr o ke ndown i nt omor es t e ps :Thepa i ntpr oc e s s ,f ore xa mpl e,a c t ua l l yc ons i s t sofmul t i pl e a c t i vi t i ess e pa r a t e dbybufe r ss uc ha spa r tpr e pa r a t i on( s ol ve ntba t h) ,dr yi ng, s pr a yl ngt hef i r s tc oa t ,dr yi ngi nt heove n,s pr a yi ngt hes e c ondc oa t ,dr yi ng,a nd s oon, wi t hva r i ousi ns pe c t i onsa l ongt hewa y・ Youc oul da l s oc ont i nuet hepa r a l l e l di s a ggr e ga t i onbys pl i t t l ngt hee ngl neOrC ha s s i sa s s e mbl ypr oc es s e si nt ot he i r u ‑ ‑ On e n t Sl a t e r ・ Wh e na 2 F i r msc nS a o me t i me sb u i l di n c o mp l e t eu n i t sa n da d dt h emi s s l n gC O mP 1 997S t r i k es h u t d o wnac r i t i c a l s u p p l i e r , Fo r dc o n t i n u e dt oa s s e mb l ei t sp o p u l a r Ex p l o r e r , s t o r l n g t h en e a r l yc o mp l e t e dc a r su n t i l t h emi s s i n gp a r t sb e c a mea v a i l a b l ea ndc o u l db er e t r o f i t t e d( t r y mo d i f y i n gt h ed i a g r a mi nFi g ure 6 ‑ 1 2t oa c c o mmo d a t es u c hr e t r o f i t t i n g ) . 21 6 Fl GUR E Pa r t I IT o o l sf o rS y s t e ms Th i n k i n g 6 ‑ 12 Di s agg re g ating p ar a ‖ e l ac ti vi t i es E n gi nesi n Pr oces s e t ed Comp一 Engi nes mbE i es i nPr oc ess A sse Ass embl y Compl e t l r on Ra t e C h a s s i s i n P r o c e s s C omp一 et Chassi s Comp一 e t i on Ra t e e d Chassi s Chassi s Us e Ra t e s uba s s e mbl i e s . I nt hel i mi te a c ha nde ve r ypa r ta ndo pe r a t i o nwo ul dber e pr e s e nt e d s e pa r a t e l y. Obv i o us l ys uc hamode lwo ul dbej us ta sc o mpl e xa st her e a ls ys t e m, a t l e a s ta sha r dt ound e r s t a nd,a ndq ui t eus e l e s s . Whe r es ho ul dyo us t o p?Howmuc hde t a i li sne c e s s a r y?Thi si sa l wa ysama t t e ro fj udg me n tt obema debyc o ns i de r i ngt hemod e l pu r pos ea ndt hene e dsoft he c l i e n t . I ft hepur pos ei sr e pr e s e nt l ngt hel a gl nt her e s pons eoft hema nuf a c t ur l ng s ys t e mt oc ha ng e si nde ma nda spa r to fal a r ge rmo de lo ff i r ms t r a t e g y , t hes i mpl e r r e pr e s e nt a t i o ni spr o ba bl yf i ne.I fyous e e kt or e e ngl ne e rt hef lOw ofma t e r i a l t hr ou g ht hep r od uc t i o nl i ne ,amo r ed e t a i l e dr e pr e s e nt a t i o ni sr e q ui r e d. I ti sbe t t e r t os t a r twi t hahi g h‑ l e ve l ,a gg r e ga t er e pr e s e n t a t i o na nda d dd e t a i li fne e d e dt oa d‑ d r e s st hepur pos e . Be g i nnl ngWi t hde t a i l e dpr oc e s sma pso 氏e nl e a dst opa r a l ys i s duet ot he i rc o mpl e x i t y ,da t ar e q ul r e me nt S ,a ndr a pi do bs o l e s c e nc er a t e s . Thea g一 t s , WI P , pr o d uc t i o n, a ndf i ni s he di nve n‑ g r e ga t ema ps ho wi ngo nl ypr od uc t i ons t a r t or yl Squl t eS t a bl ea ndr e ma i nsa ppr o pr l a t ee ve na St hede t a i l so ft hepr od uc t i on pr oc e s sc ha nge , whi l ead e t a i l e dma pma ybe c omeo bs o l e t ea sne wp r od uc t s , t oo レ l ag, O rpr oc e s st e c hno l og i e sa r ei nt r od uc e d. ‑ 6. 乱3 Gui de日 i nes菅 orAgg帽ga抽 m Whe ni si ta pp r o pr i a t et Oa gg r e ga t ed i fe r e nta c t i vi t i e st o ge t he r ?Tode t e r mi ne whe t he ra c t i vi t i e st a ki ngpl a c es e r i a l l yc a nbea gg r e ga t e d,c o ns i de rt hea ve r a ge r e s i d e nc et i meofi t e msi ne a c hs t oc k( t hea ve r a get i mebe t we e ne nt e r i nga nde xi t ‑ i ngt hes t oc k) .St oc kswi t hs ho r tr e s i d e nc et i me sr e l a t i vet ot het i mes c a l ef o rt he Ch a p t e r6 S t o c k sa n dF l o ws 21 7 dyna mi c sofi n t e r e s tge ne r a l l ydonotne e dt ober e pr e s e nt e de xpl i c i t l ya ndca ne t he rbeo mi t t e do rl umpe di nt oa d j a c e nts t oc ks . Fore xa mpl e , i nt hel o ng‑ t e m pl r a n‑ nl ngmode l soft heUSe ne r gys ys t e m de ve l ope dbyt heUSDe pa r t me ntofEne r gy ( Na i l l1 992) ,va r i ouss t oc ksofundi s c ove r e dpe t r ol e um a ndknownr e s e r vesa r e e xpl i c i t l yr e pr e s e nt e dbe c a us et he i rl i f e t i mesr a ngef r om ye a r st ode c a de s( a tc ur ‑ r e nt pr oduc t i onr a t e s ) . Howe ve r , s t oc ksofc udeoi r la ndr e f i ne dpr oduc t si nt hepe ‑ t r ol e um s uppl yc ha i nr e pr e s e ntonl yaf e wmont hsofc ons umpt l On. I nal ong‑ t e r m mode lt he s es t o c ksa r et oos ho r t ‑ l i ve dt or e qul r ee xpl i c i tt r e a t me nt . The yf luc t ua t e a r oundt he i re q ui l i br i um va l uesa spr oduc e r s ,r e f i ne r s ,a nddi s t r i but or sr e a c tt o c ha ngesi ni nv e nt or y.I namode lofs hor t ‑ t e r m move me nt si ns potpe t r ol e um pr i c es , howe ve r , he t s es t oc ksa r ec r i t i ca l l yi mpor t a nt . Agoo dmode lwoul dr e pr e ‑ s e ntt heke ys t o c ksi nt hepe t r ol e um s uppl yc ha i ne xpl i c i t l y ,pe r ha pse ve ni nc l ud‑ 1 ngaS e pa r a t eS t oc kf ort hei nve nt o r yofga s ol i nea tr e t a i ls e r vi c es t a t i onsa ndt he i nve nt or yofga s ol i nei nt het a nksofc a r sont her oa d. Ont heot he rha nd,as hor t ‑ t e r ms potpr l C emode lne e dnoti nc l udepe t r ol e um r es e r ve sorundi s c ove r e dr e ‑ s our c es , a st hes es t oc ksc ha nget oos l owl yt oi nf lue nc et hes potma r ke tove rat i me hor i z onofaye a r . Pa r a l l e la c t i vi t i esc a nl e gl t i ma t e l ybea ggr e ga t e dt oge t he ri ft hei ndi vi dua l lowsa f r egove r ne dbys i mi l a rde c i s i onr ul esa ndi ft het i met hedi f f e r e nti t e ms s pe ndi nt hei nd i vi dua ls t oc ksi ss i mi l a r . Fore xa mpl e, i ti sof t e na ppr o pr l a t et Oa g一 g r e ga t et hema n ypa r t sr e qui r e dt oma nuf a c t ur eapr oduc ti nt oas ma l lnumbe rof c a t e gor i e ss i nc et he ya r eus ua l l yor de r e dus i ngt hes a mepr oc e dur e sa ndt he i rde‑ l i ve r yl e a dt i me sa ndr es i de nc et i me si npa r t si nve nt or i e sge ne r a l l ydon' tdi fe rt oo muc h.I nc ont r a s t ,pl a nta nde qul Pme nts ome t i mesmus tbedi s a ggr e ga t e d.The i r l i f e t i me sa r eve r ydi f f e r e nt , a ndt hede c i s i onr ul esf o rne wg r e e n‑ f i e l df a c i l i t i esdi f ‑ f e rs ubs t a nt i a l l yf r om t hos eus e dt c ・ or de re qul Pme ntf ore xi s t i ngf a c i l i t i e sduet o d i f f e r e nc esi nl e a dt i me s , c os t s , f i na nc l ng, Pe r mi t t l ng,a ndr e gul a t or yI s s ue s . Asar ul eo ft humb,C l i e nt sge ne r a l l ywa ntt os e emor ede t a i li namode lt ha n t hemode l e rt hi n ksi sne e de d, a ndmode l e r s , i nt ur n, ge ne r a l l yove r es t i ma t et hede‑ t a i lne c es s a r yt oc a pt u r et hedyna mi csofi nt e r es t ・Ofc our s e ,t hea mountofde t a i l l i e nt ' spur pos ea nd也ea mountof ne e de dt oca pt u r et hedyna mi c sr e l e va ntt ot hec de t a i lne e de dt ogi vet hec l i e ntc onf i de nc ei nt her e s ul t sa r et wodi f f e r e ntt hi ngs . Ro be r t s( 1 977 / 1 9 78 )e s t i ma t e dt ha tc l i e nt so f t e nr e q ui r et wi c ea smuc hde t a i la st he mode l e rf e e l si sne e de dt of e e lc o mf or t a bl ewi t ha nda c c e ptamode la saba s i sf or a c ion,a t ndi nmye xpe r i e nc et hi si sof t e na nunde r e s t i ma t e・Suc c e s sr e qul r e Syou t oi nc l udet hed e t a i lne c es s a r yt os a t i s f yt hec l i e nt .Butt hi sdoe snotme a nyou s houl da c qul e S C et Oa l lc l i e ntde ma ndsf ormor ede t a i l ‑ youwi l le ndupwi t ha n e xpe ns i vea ndus e l e s sbl a c kbox, Youmus twor kwi t ht hec l i e ntt ounde r s t a ndwhy e xc es s i vede t a i li sof t e nunne c es s a r y.Of t e n,mode l se ndupwi ht t oomuc hde t a i l , buta st hec l i e ntga l nSC Onf i de nc ea ndunde r s t a ndi ngoft hei mpo r t a ntf e e dba c ks d r i vl ngt hedyna mi c s , t hee xc e s ss t r uc t ur ec a nbee l i mi na t e d, r e s ul t i ngl naS i mpl e r , mor ee as i l yma i nt a i ne d,a ndmor eus e f ulmode l( Ra n°e r s1 98 0) .St i l l ,Robe r t si s c or r e c t . A" Youmus tpr ovi det hel e ve lofde t a i lt ha tc a us e sl t hec l i e nt ]t obepe r ‑ s ua de dt ha tyouha vepr o pe r l yt a ke ni nt oa c c ounthi si s s ue s , hi sque s t i ons , hi sl e ve l ofc onc e r ns . Ot h e r wi s ehewi l lnotbe l i e vet hemode lyouha veb ui l t , hewi l lnota c‑ c e pti t ,a ndhewi l lnotus ei t "( p・ 80) ・ L 218 P a r t I IT o o l sf o rS y s t em s Th i n k i n g 6. 3. 4 Syst em L lynar ni cs岳 nAct 喜 on: Mode抽 gLar ge‑ Sca! eConst r uct i onPr oj ec官 s Ag g r e ga t i o nofmul t i pl es e r i a la ndpa r a l l e la c t i v i t i e si swe l li l l us t r a t e di namode l o fl a r gec o ns t r uc t i o npr qj e c t sde ve l o pe dbyJ a c kHo me r( Ho me re ta l .1 993 ) . The c l i e ntwa samul t i na t i ona lf o r e s t pr o duc t sc o mpa n y , S pe c i f i c a l l yt hed i v i s i o no ft he c o mpa n yt ha td e s i gnsa ndbui l dspul pa ndpa pe rmi l l s . Co mpe t i t i onf o rt hes ma l l n umbe ro fmi l l sbui l te a c hye a rwa si nt e ns i f y i nga st hei nd us t r yg l o ba l i z e d, a ndt he f i r m,a l r e a d yal e a de r ,s a wt ha tt or e ma i ns t r o ngt he yha dt odr a ma t i c a l l yr e d uc e t het i mer e q ui r e dt ode s i g na ndbui l dmi l l s . The i rgoa lwa st or e duc es i gni f i c a nt l y t het o t a lc yc l et i me , f r o mt heha nds ha kewi t hac us t o me rt ot heha ndof fofawo r k‑ l l , wi t hout i nc r e a s i ngc os t s . The yk ne wt r a d i t i o na l pr o j e c tma na ge me n tt e C h‑ 1 ngmi nl q ue SWe r eno ta de qua t e:t hede s i gna ndc ons t r uc t i o npr oc e s si se xc e e di ngl y c o mpl e x, wi t ht i g htc o upl i ngsa mongt hepha s e s , a ndt he yha da l r e a d ydo nea l lt he e a s yt hi ngs . The yde c i de dt od e ve l o pas ys t e md y na mi c smode lo ft hee nt i r ee ng i ‑ ne e r i ng, pr oc ur e me nt ,a ndc o ns t r u c t i on( EPC)pr o c e s s ・ Ea r l yme e t i ngsO ft hep r o j e c tt e a mf o c us e do nt hemode lbounda r ya nda gg r e ‑ ga t i o n, i npa r t i c ul a r ,de s c r l Pt l OnSO ft hes t o c ka n df lo ws t r uc t ur eofat y pi c a lpr o‑ j e c t .Ma nyI s s ue sWe r er a i s e d:I st he r eat y pi c a lpr o j e c t ?How muc hde t a i li s ne e de d?Wha ta c t i vi t i e sc o ul dbea gg r e g a t e dt og e t he r ?Oneme mbe roft hec l i e nt t e a ma r g ue dt ha tt hemod e lc o ul d n' t beus e f u li fi td i d nフ t r e pr e s e nte ve r ye ng l ne e r ‑ 1 ngd r a wl ng, e ve r ypur c ha s eo r d e r ,a nde v e r yc o mpo ne nti ns t a l l e da tt hes i t e. Ob‑ v i o us l y ,s uc hamode lc o ul dne ve rbebui l to rma d eus e f u l .Ot he rme mbe r so ft he c l i e ntt e a ma r gue df o ras i mpl e ra ppr oa c h. The ya l r e a d yha dhi ghl yd i s a gg r e ga t e s c he d u l i nga ndpl a nnl ngmod e l sba s e do nt r a d i t i o na lpr o j e c tma na ge me ntt oo l st o ma na get hede t a i lc o mpl e xi t yo ft hepr o j e c t s . The yl a c ke dat oolt oma na get hed y‑ na mi cc ompl e xl t ya ndi n t e r de pe nde nc i e sa mongt hepha s e sa nda c t i vi t i e soft he Pr O J e C t S ・ Af t e re xt e ns i vedi s c us s i o n, a ni ni t i a lmo de lbo unda r ya ndl e ve lo fa gg r e ga t i o n we r es e t( Fi g ur e6 1 1 3) . Thef i g ur ei sahi g h‑ l e v e ls u bs ys t e md i a g r a ms howi ngho w pr o j e c t sWe r ea gg r e ga t e di n t oar e a s ona bl en umbe rofpha s e s . Theove r a l lpr o j e c t wa sdi vi de di nt ot woma i ns t oc ka ndf lo wc ha i nsr e pr e s e nt i ngP&E( pr oc e s sa nd e q ui pme nt )a ndc o ns t r uc t i on. Ea c ha c t i vi t ygoe st hr o ug hde s i gnpr e pa r a t i o n,r e ‑ sa r ei s ‑ vi e w, a ndd e s i gnr e vi s i o ns . Ne xts u ppl i e r sa r es e l e c t e da ndpur c ha s eo r de r s ue d.Thes uppl i e r st he nf a br i c a t et hema t e r i a l sne e d e df o re a c ha c t i vl t y・Ont he c ons t r uc t i o ns i de , hec t l i e ntf e l ti twa sa c c e pt a bl et oa gg r e ga t ea l lc o ns t r uct i o nma ‑ t e r i a l s( e . 蛋. ,s t r uc t ur a ls t e e l ,c onc r e t ef o r ms ,r e ba r )i nt oas i ng l ec a t e go r y.The pr oce s sa nde qul pme ntS i de ,howe ve r ,wa sd i vi de di nt ot hr e ec a t e go r i es:r eact o r ve s s e l s ,ma j o re qui pme n t( e. g. ,l a r get a n ks , pi pe l i ne s ,a ndc o nve yor s ) ,andmi no r qui pme nt( e. 蛋. ,pumps ,mo t o r s ,va l ve s ,a ndi ns t r u me nt a t i o n) .Thedesi gn,pr o‑ e cur e me nt ,a ndc ons t r uc t i o no ft he s et ype so fe q ui pme n ta r eS uf f i c i e nt l ydi f f e r e nti n s cope ,dur a t i on,a ndc os tt ha tt he yc o ul dno tr e a s o na bl ybel umpe dt oget he r .The r e a c t orve s s e l s ,i npa r t i c ul a r ,ha dt obemod e l e di nmo r ede t a i la st heyar et he l a r ge s ts uba s s e mbl y ,a l mos ta l wa ysf a l lo nt hec r i t i c a lpa t h,a nda r ef r equen t l ya bot t l e ne c kc o ns t r a i nl ngC OnS t r uC t i onpr og r e s s .Dur i ngc ons t r uc t i o n,r eact o rves‑ s e l s ,ot he re qul pme nt ,a nds i t epr e pa r a t i o ns uc ha sf ounda t i o nsa ndgr adi ngal l Cha p t e r6 S t o c ksa n dFl o ws 219 FI GURE6 ‑ 13 Bui l di ngapul pandpapermi l l Subsys t em di agr am showr ngf l owsofengl neenng,Pr ocur ement ,andcons t r uct i onwor ki namodelof apul pm‖const r uct i onpr oj ect .Thedi agr am i H ust r at est hesect orboundar i esandl evelofaggr egat i on wi t houtshowl ngal l det ai l s.Eachbl ockr epr esent sapr oJ eCtPhase,model edwi t hagener i cmodul ewi t h r oughl yt hesamest r uc t ur e. Ani nt er nal gat ecapt ur est heconst r ai nt sonwor kavai l abl ewi t hi naphase asaf unct i onoft hewor kcompl et ed.Forexampl e,f oundat i onscannotbecompl et edunt i lsur veyl ng andsi t epr epar at i onar edone;Seesec t i on14. 5. Sour ce: Homere t a l .( 1993) . mus tcomet oge t he r ,f ol l owedbyaf unc t i onal i t ychec kout ,s t rt a ‑ upa nd,f i nal l y, ha ndof Ft ot hec us t omer . Ea chbl oc ki nFi gur e6 ‑ 1 3r epr es ent sapr o j ectPhas e・Themodelcons i s t edof agene r i cpr o j e c tPhas emodul e,r epl i ca t edf oreachbl ocka ndl i nkedass hown・ Ea chmodul econt ai nedas t ockandf low s t r uct ur ei ncl udi ngt hef lowsoft as ks wi t hi nt hephas ea l ongwi t hs chedul eddea dl i nes ,t hel a borf or cededi cat edt ot he 22 0 P a r t I IT o o l sf o rS y s t e ms Th i n k i n g pha s e ,wor ke rpr oduc t i v l y,f t a t i g uel e ve l s ,e l TO rr a t e s ,a ndc os t s .Thes t o c ka nd lo f ws t uc r t u r ef o rt a s kswi t hi napha s emo d e l st hepr og r e s s i o noft a s ksf r o mba s e ‑ wo r kt hr o ug hc ompl e t i o n( Fi g ur e6‑ 1 4) Jnge ne r a lt het a s kst obec ompl e t e di na pha s ec a no nl ybedonea su ps t r e a mt a s ksu po nwhi c ht he yde pe nda r ec o mpl e t e d ( t her a t ea twhi c hba s e wo r kt a s ksbe c o mea va i l a bl e ) . Fore xa mpl e , t her e a c t o rve s I s e l sc a n no tbee r e c t e do ns i t eunt i lt he i rf o u nda t i o nsa r ec o mpl e t e d. Li ke wi s e , no t a l lt a s kswi t hi nag l Ve npha s ec a nbedo n ec o nc u r r e nt l y. Fo re xa mpl e , t hed e t a i l e d d e s i g no fc onve yo r sa ndpi pe l i ne sbe t we e nt hec 血i p pe r s , r e a c t o rve s s e l s , a n dpa pe r ma c hi ne sc a nno tbedo neunt i lt hehi g h‑ l e v e lphys i c a lde s i g noft hepl a n ti sc o m‑ pl e t e d・ The s ewi t hi n‑a ndbe t we e n‑ pha s ede pe nde nc i e swe r emode l e de x pl i c i t l y ・ Thef lowo fwor kf r o mt hes t oc ko ft a s ksa wa l t l ngc o mpl e t i o nt ot hes t oc ko ft a s ks r e q u l nngr e WOr kr e pr e s e nt st hos et a s ksc o mpl e t e di nc o r r e c t l yo rr e nde r e do bs ol e t e l y , e r r o r sa r eno tde t e c t e di ‑ e d i a t e l ya nd byc ha nge si not he rs ubs ys t e ms ・ Ge ne r a l t hede l a yi nt hedi s c ove r yo fr e wo r kc a nbes u bs t a nt i a l ,a swhe nade s i gne r r o ri s no tde t e c t e dunt i lc ons t r uc t i oni nt hef i e l di sunde r wa y. Thedi s c o ve r yo fr e wo r k mov e st a s kst ho ug htt obec o mpl e t eba c ki n t ot hes t o c koft a s ksa wa l t l ngC O mpl e ‑ t i o n( s e eFo r da ndSt e r ma n1 998 bf o rade t a i l e da ndf u l l ydo c ume nt e dmod e lo fa mul t i pha s epr qe c ts i mi l a rt ot heoneus e dhe r e;s e ea l s ot hes hi pbui l di ngpr q】 e c t mo de lde s c r i be di ns e c t i on2. 3 ) . Themode lwa ss ubs t a nt i a l l ys i mpl e rt ha nt hec l i e ntf i r m' sde t a i l e dpr o j e c t pl a nni ngmod e l ,whi c hi nc l ude dl i t e r a l l yt ho us a ndso fi ndi v i d ua la c t i vi t i e s( hi g h d e t a i lc o mpl e xi t y)butnof e e d ba c kl oo ps( nod yna mi cc o mpl e xi t y) . I twa sd i s a g‑ g r e ga t e de no ught oc a pt ur ei mpo r t a nti nt e r d e pe nde nc i e sa mongde s i gn, pr o c u r e ‑ me n t , a ndc ons t r uc t i o na c t i v i t i e sa ndbe t we e nc o ns t r u c t i o na ndt heva r i o ust y pe so f F] GURE6‑ 14 St oc kan df l o w s t r uc t ur eo ft as k s i napr o j e c tph as e Si mpl i f i edr epr e ‑ s en t a t i ono ft h e s t o ckand刊 Ow s t r u c t ur eo fa ph as ei nt h epu l p mi l l pr o j e c tmodel De t er mi n an t so f t hef l owsandcou‑ pl l n gSamongt he di f f er en tph as e s ar en o ts h o wn. 221 Ch a p t e r6 S t o c k sa n dFl o ws e qul pme nt .Themode lc oul dc a pt ur es hi f t si nt hec r i t i c a lpa t ht ha tmi ghtr e s ul t f r ompol i c i e sa c c e l e r a t i ngt hef a br i c a t i ono ft her e a c t o rve s s e l s , apol i c yf a vor e dby s omec l i e ntt e a mme mbe r s . I ti si mpor t a ntt onot et ha tt hepr oc e s sofde ve l opl ngt hef i na ll e ve lofa ggr e ga t i oni nvol ve danumbe rofi t e r a t i onsa ndr e vi s i o ns . Andt hought hemode lr e pr e ‑ s e nt st hepr o j e c ta tahi ghl e ve lofa gg r e ga t i on, t hemode l i ngt ea mde ve l ope dma ny mor ede t a i l e dd i a gr a ms . Thes emor ede t a i l e dma pshe l pe dt hemode l e ra ndc l i e nt t e a mdi s c ove rf la wsi nt he i rt hi nki ng, e s t i ma t epa r a me t e r sbe t t e r ,a ndde e pe nt he i r unde r s t a ndi ngo ft hepr oc e s s . Andt he yde ve l o pe dc onf i de nc et ha tt hemor ea gg r e ‑ ga t er e pr e s e nt a t i oni nt hes i mul a t i onmode lwa sa c c e pt a bl ef わrt he i rpur pos es o t he s emo r ede t a i l e ds t oc ka ndf lOws t r uc t ur e sdi dnotha vet obei nc or por a t e di nt o t hemode l . Thel e ve lofde t a i ls e l e c t e da l s ope r mi t t e dt hemode lt obec a l i br a t e da ga l nS ta wi der a ngeofda t ac ol l e c t e dononeoft hec ompa ny' sc ur r e ntEPCpr o j e c t s . The mode ls uc c es s f u l l y( t ha ti s , t ot hes a t i s f a c t i onoft hec l i e nt )r e pr oduc e da l lr e l e va nt pr o j e c ta c t i vi t i e s ,i nc l udi ngt heva r i ouswo r kf or c e sa ndl a borhour s ,ove r t i mea nd r e wo r kr a t e s , pu r c ha s eor de rvol umesa ndr e vi s i o nr a t e s , ve ndors hi pme nt s , a ndt he pr og r e s sofve s s e le r e c t i ona ndc ons t r uc t i on( Fi gur e6‑ 1 5s howsa ne xa mpl e ) . Whi l et hec l i e nt spr e f e rnott odi s c l os et hede t a i l sofpol i c yr e c omme nda t i ons , t he yvi e we dt hemode la sc r e di bl ea ndus e f ula ndde ve l ope dc onf i de nc e,s ha r e d a mongt het e a m, t ha tt hemode ldi dagoodj obofr e pr e s e nt i ngt he i rEPCpr o j e c t s . The yus e dt hemode lt oa na l yz ema nypol i c i e sa ndi de nt i f i e ds e ve r a lwhi c h, whi l e pr e vi o us l ya ppe a r l ngt Obedes i r a bl e,i nf a c tge ne r a t e dha r mf uls i dee f f e c t s .The mode la l s ohe l pe di de nt i f ypol i c i est ha tr e duc e dpr o j e c tde l i ve r yt l meSbya tl e a s t 3 0%wi t hi naf e wye a r s . Se ve r a loft hepol i c i e swe r enota ppa r e ntt ot hec l i e ntt e a m o rwe r ehot l yde ba t e dpr i ort ot hemode l i nge fo r t . Themode l i ngpr oc e s she l pe d bui l dunde r s t a ndi ngofa ndc ons e ns usa r o undt he s ec ont r ove r s i a li ni t i a t i ve s , he l p‑ l ngt hef i r ms uc c e s s f u l l yi mpl e me ntma nyoft her e c omme nda t i ons . ‑ o r H o u r s 一 一 一 ● 一 一 F日 GURE6 ‑ 15 Sampl ec ompar i s ono fhi s t or i c al andsi mul at edbeh avi oroft hepul pmi Hmodel P&E‑pr oces sandequl Pmen t . Cu m.P良EDesi gn Lab 0 20 40 Gum.Const r uct i onLaborHour s ̲̲̲̲ Act ual ̲̲̲̲Act L J al ゝ 孤‑ 60 Si mul at ed 8 0 1 00 0 Si mul at ed . ♂ 20 Ti meuni t s No t e : T i meF Se x p r e s s e da st i meu n i t st op r o t e c t c l i e n t c o n f i d e n t i a l i n f o r ma t i o n . Sour ce:H o me r e t a l .( 1993) . 40 60 Ti meuni t s 80 1 00 222 P a r t I IT わ o l s f o rS y s t e ms Th i n k i n g S. 3. 5 Set t i ngt heMode一Boundar y: " ChaHengi r f gt heC萱 ouds" Ma ppl ngt hes t o c ka ndf lOw s t r uc t ur eo fas ys t e mi nvol ve si mpo r t a ntd e c i s i ons a boutt hebo und a r yoft hemo de l ・ I nr e a l i t y , lo f wso fma t e r i a l , pe o pl e , a ndmo ne y i nt oas t oc kha vet oc o mef r o ms ome whe r e;t hef lowso utha vet ogos ome whe r e. Toke e pyourmode l sma na ge a bl e,yo umus tt r unc a t et he s ec ha i nsus i ngS ou r c e s 1 . a nds i nks ,r e pr e s e nt e di nt hes t oc ka ndf lowma psby" c l o uds " ;s e eFi g ur e61 So ur c e sa nds i nksr e pr e s e ntt hes t oc kss uppl yi ngma t e r i a lt oora bs o r bi ngma t e r i a l f r o mt hemo de l e ds ys t e m・ So ur c e sa nds i nksa r ea s s ume dt oha v ei nf i ni t ec a pa c i t y t . I nt her e a lwo r l d, hes t t o c kss u p‑ a ndc a nne ve rc ons t r a i nt hef lowst he ys uppor pl yi ngo ra bs o r bi ngmowsha vef i ni t ec a pa c l t ya nddoi nf lue nc et hef lo ws . Whe n yo ut r unc a t eas t oc ka ndf lOwc ha i nwi t hac l o udyo ua r es e t t i ngt hebo unda r yof t hemod e l ‑s t oc ksa ndf lowsbe yo ndt hi spo l nta r eI g no r e d; yo ue xc l udea l lpos s i ‑ bl ef e e d ba c ksf r o mo ri nt e r a c t i o nswi t ht hes t o c ksout s i det hebo u nda r y . Asamode l e ryo umus tc r i t i c a l l ye xa mi net he s ebounda r ya s s umpt l OnS ;yo u mus t , i nt hewor dso fBa n' yRi c hmo nd( 1 9 93, p.1 3 2) , " c ha l l e nget hec l o uds . "I si t a ppr o pr l a t ef o ryo urpur pos et oe xc l udet hes t oc kso ut s i det hebou nda r yoft he mode l ?Wha tf e e d ba c ksi g no r e dbyyo urmo de lm ig hte xi s ti nt her e a lwo r l d,a nd mi g htt he ya f f e c tyo urpo l i c yr e c o mme nda t i ons ?Ca nt hes o ur c e sf o rt hef lO wsbe , d e pl e t e da ndc ons t r a i nt hei nf low?Ca nt hes i n ksbef i l l e da ndbl o c kt heo ut lows f ba c ki ngu pt hes ys t e ml i keac l o gge dd r a i n? Cons i de rt hea ut o mo bi l ei nd us t r y ・ As t oc ka ndf lowma pf o ra ut o mo bi l epr o d uc io t nmi g ht be g i nwi t hpr o d uc t i o ns t a r t s , WI Pi nve nt o r y , p r od uc t i o n, f i ni s he di n‑ ve nt o r y ,a nds hi pme n t s( Fi g ur e6‑ 1 6) .Dr a wi ngt hema pwi t has o ur c ef o rt he pr oduc t i o ns t a r tf lOwpr e s ume st ha tt hes uppl yo fpa r t si sun li mi t e da ndc a nne ve r c o ns t r a i nt hep r o d uc t i o ns t a r tr a t e . Li ke wi s e , be c a us es hi pme nt sf l owt oas i nk, t he mode l e rha sa s s ume ds t o c ksofpr od uc ti nt heha ndso fde a l e r sa ndc us t o me r sha ve noe f f e c to ns hi pme nt s ・ I nc ha ll e ng i ngt hec l o udsyo ua s kwhe t he rt he s ea s s ump‑ t i onsa r er e a s o na bl e . Fo rt hea ut oi nd us t r yt he ya r enot . Pr oduc t i ons t a r t sr e q ul r e t hea ut o ma ke rt oha vea na d e q ua t es t oc ko fpa r t s . Ye tpa r t ss t oc ksma ye a s i l ybe de pl e t e d.Suppl i e r sc a nnotr e s po ndi ns t a nt l yt oc ha nge si npa r t so r d e r s . La r geor ‑ de r sma yo ut s t r i pS uppl i e rc a pa c l t y, l e a di ngt os ho r t a g e s ・ As t r i kea tas u ppl i e rma y i nt e r r uptt hef l owofpa r t st ot hef i r m. Att heo t he re nd,S hi pme nt so fne wc a r st o r a l l yt r yt oma i n t a i na bo ut de a l e r sde pe ndo nt hes i z eo fde a l e rs t oc ks . De a l e r sgene opr o v i deg oo ds e l e c t i o nf o r 40t o60da yso fi n ve nt o r yo nt he i rl o t s ; t hi si se no ught c o ns ume r swi t ho utc a r r y l nge xc e s s i vea ndc os t l yI nve n t or y . I fs t o c ksa r el o wr e l a ‑ n uf a c t u r e r s ; i fs t o c ksa r ehi g h, t i vet ot he i rt a r ge t s , de a l e r so r d e rmo r ef r omt hema he t yc utba c k. Fi g ur e6‑ 1 7e xpa ndst hemode lbounda r yt oc a pt u r et he s ee fe c t s . t i ona le nt i t i e s ‑S up pl i e r s , ma n u‑ Themode lnowr e pr e s e n t st hr e ed i s t i nc to r ga ni z a hema nuf a c t ur e ri sno we x‑ f a c t ur e r s , a ndde a l e r s . Thei n ve nt o r yo fpa r t she l dbyt ea st hea ut oma ke r :as t oc kof pl i c i t .Thes uppl i e rha st hes a meba s i cs t r uc t ur f i ni s he di nve nt or ya ndas t oc ko fwo r ki npr oc e s s . Att hes hi pme nte nd, ma nuf a c ‑ lowi n t od e a l e rs t o c ks , a l l o wl t u r e rs hi pme nt snol o nge rd i s a ppe a ri n t oas i nkbutf hed e a l e ri nv e nt o r ya nds a l e s l ngyo ut Omode lt hepur c ha s er a t ea saf u nc t i onoft t oc us t ome r s . ‑ 223 t o c k sa n dF l o ws Ch a p t e r6 S Fl GURE6 ・ 16 I ni t i al s t ockand f l owmapf or t heau t omobi 一 e i ndus t r y , showl n g t hemodel boundar y Thes our cesan d si nk sf ort he f l owst hr ough t hes y s t emar e assumedt obe i nf i ni t eandcan havenoi mpac ton t hed yn ami cs・ Sour ce. ・ Unl i mi t ed suppl yof ヽ Absor pt i on Capaci t y J Youc oul da nds houl dc ont i nuet oc ha l l e nget hebounda r yoft hemode l . The mode lnowa l l owsyout or e pr e s e nts uppl i e ror de rpr oc e s s l ng,I nve nt or yma na ge ‑ me nt , a ndde l i ve r y , i nc l udi ngt hepos s i bi l i t yt ha ts uppl i e r sc a nbe c omeabot t l e ne c k a nds t a r vea ut omo bi l epr od uc t i on・ Butnowt hes uppl i e r sa r eas s ume dt oha veun‑ l i mi t e dpa r t sa ndr a wma t e r i a l sa va i l a bi l i t y.I st hi sa ppr o pr i a t e?I tde pe ndsont he mode lpur pos e. Yo uc oul dc ont i nuet oe xpa ndt hemode lbounda r ybya ddi ngt he s uppl i e r st ot hes uppl i e r s , a ndt he i rs uppl i e r s , a nds oo n, unt i lyour e a c he dt hepoi nt whe r ei ti sa c c e pt a bl et oa s s umet ha tt hes uppl yofma t e r i a l st ot hef a r t hes tup‑ s t r e a ms uppl i e ri sunl i mi t e d. Al t e ma t i ve l y, yot l C Oul dr e pr es e ntt hee nt i r eups t r e a m s uppl yc ha i nbyas l ngl ea ggr e ga t es uppl i e rs t a ge. Thema ps ho wni nFi gur e61 1 7a l s oa s s ume st ha tde a l e rs a l e sf lOwi nt oas i nk s ot he r ei snof e e dba c kf r omt hes t oc kofc a r sont her oa dt opur c ha s e sofne wc a r s . Thi si sobvi ous l yaba da s s umpt l On:Sa l esofne wc a r sde pe ndont henumbe ra nd a geoft hec a r spe o pl ea l r e a dyha ver e l a t i vet ot he i rne e ds ・ Pe o pl ewhoha vej us ta c ‑ qui r e dane wc a ra reunl i ke l yt obuya not he rf ors e ve r a lye a r s ,unt ilt he i rl oa ni s pa i dof f , t he i rl e a s ee xpi r e s , Ort he i rc a ri si nvol ve di na na c c i de nta ndmus tber e ‑ pl a c e d( S e es e c t i o n2. 2) . Fi gur e6‑ 1 8e xpa ndst hedowns t r e a me ndoft hes t oc ka nd lowma f pt oi nc l ud et hes t oc kofc a r sont her oa d. Youc a nc ont i nuet oc ha l l e nget hemode lbounda r y.Wha tha ppe nst ot he ca r swhe nt he ya r es c r a ppe d?I nt hec ur r e ntma p, t he ys i mpl ydi s a ppe a r . I nr e a l i t y, t he ydon' t .I nNor t hAme r i c as ome1 0t o1 2mi l l i onve hi c l e sa r es c r a ppe dpe r yea r .Roughl y9 4% a r es hr e dde da ndt hes t e e la nds omenonf e r r ousme t a l sa r e 224 r tI I¶) o l sf o rS y s t e msTh l n k i n g P a Fd GURE6 ‑ 17 Chal l engmgt he c一 ouds Addi ngasuppl l er an ddea一 ers ec t or t ot hes t ockand f l owchai nf or au t omobi l epr o‑ du c t i on.Rec t an一 g】 eswi t hr ounded c or ner sdenot e t heboundar i es bet weendi f f er en t or gani z at i onal en‑ t i t i esanddeci si on‑ mak i nguni t s. Suppl i er Seet or Manuf act ur er Sect or Deal er Seet or r e c ove r e d,O neoft hehi ghes tr e c yc l i ngf r a c t i onsofa nyi ndus t ry・ Howe ve r ,s ome c a r se ndupa ba ndone da sda nge r ouse ye s or e sont hes i deoft her oa d・ Andmuc hof t hepl a s t i c,gl a s s ,a ndot he rnonme t a lma t e r i a l se ndupi nl a ndf i l l s ,c ons t i t ut l nga s i gni f i c a nts o ur c eofpol l ut ion( mor et ha nt wobi l l i ondi s c a r de dt i r e s ,mos ts i t t i ng i nhugepi l e sa c r os st hec ount r y, ha vea l r e a dya c c umul a t e di nt heUS) ・ 225 Cha pt e r6 St o c ksa n dFl o ws FI GURE6 ‑ 18 Expanded au t omobi l emodel Theboundar ynow i ncl u dest hes t ock ofc ar sont he r oad, whi chf eeds backt oi n f . uenc e s al esofnewcar s. peaJ er Seet or Househol d Sect or 6ど 3, 6 Sys t em Dynami csi nAct i on二 ! j 咽 Aut omobHeReeye I Byt hemi d1 990S ,a sl a ndf i l l sf i l l e da nde nvi r onme nt a la wa r e nes sgr e w,pr e s s ur e bui l tt or e c yc l emo r eoft hema t e r i a li nc a r s . Ge r ma nyde ba t e dal a wt ha twoul dr e ‑ qui r ea ut oma nu f a c t ur e r st ot a keba c kt he i rol dc a r swhe npe opl ede r e gl S t e r e d t he m. Pus he dbyt he s ef o r c es , t hea ut oi ndus t r y , f i r s ti nEur opea ndt he ni nt heUS, be ga nt os t udywa yst oi nc r e a s et her e c ove r yofpa r t sa ndt her e c yc l i ngofma t e r i ‑ a l sf r omc a r s . Pa ve lZa mud i o‑ Ra mi r e z( 1 996)mode l e dpa r tr e c ove r ya ndt hema t e r i a l sr e c y‑ c l i ngl nt heUSa u t oi ndus t r yt ohe l pt hei ndus t r yt hi nka boutaf u t ur eofe nha nc e d a ut or e c yc l i ng.Fi gur e6‑ 1 9S howsas i mpl i f i e ds t oc ka ndnows t r uc t ur ea da pt e d f r omt hemode l . Ol dorwr e c ke dc a r sc a ne i he t rbes c r a ppe dl e ga l l y( s ol dt oaj unk‑ ya rdo rdi s ma nt l e r )o ri l l e ga l l ya ba ndone d. Thes t oc kofa ba ndone d, of t e nbur ne d out , c a r si sabl i g h tont hel a nds ca pea nds i g ni f i c a nts our c eofpo l l ut i on. The r ea r e t woout lowsf f r o mt hes t oc kofi l l e ga l l ya ba ndone dc a r s : Di s ma nt l e r swi l lpr oc es s t he mi ft heva l ueoft her e c ove r a bl epa r t sa ndma t e r i a l si shi ghe nough. Al t e r na ‑ t i ve l y , i l l e ga l l yd u mpe dc a r sc a nbec ol l e c t e d( s a ybyl oc a lgov e mme nt s )a ndt a ke n t os hr e dde r sf o rp r o pe rdi s pos a l . Bot ht hes ef l owsa r er e l a t i ve l ys ma l l ,s ot hes t oc k ofa ba ndone dc a r sc a nbui l dupt ohi ghl e ve l se ve ni ft hea ba ndonme ntr a t ei sl ow. Ca r she l di nt hedi s ma nt l e r s 'i nve nt o r i esa r es t r l ppe doft hos epa r t swhos e va l uee xc e e ds血ec os tofr e c ove r y.Thes epa r t se nt e raus e dpa r t ss t oc ka nda r e t he ns ol dt or e pa i rs hopsa ndus e dt or e pl a c ewo no rda ma ge dpa r t sono pe r a t l ng c a r s ・ I nt hi sma p, t hepa r tus a ger a t ef lowsi nt oas i nk・ I na c t ua l i t y, t he s epa r t sa r e i ns t a l l e di nc a r ss t i l lont her oa da nde ve nt ua l l yf lowa ga i nt hr o ught hes c r a por a ba ndonme ntr a t e . Si nc et henumbe rofr e c ove r e dpa r t si sve r ys ma l lr e l a t i vet ot he t ot lf a lowo fma t e r i a l st hr ought hes ys t e m,t hi somi s s i oni spr o ba bl yr ea s ona bl e・ ‑ 226 FI GURE6 ・ 19 Pa r t I I To o l sf o rSys t e msTl l i n k i n g St ockandf l owmapf oramodel ofau t omobi l er ec ycl i ng Thes t ockandf l ows t r uc t ur ef ort hedevel opmentofnewvehi cl ep一 at f or ms,def i nl ngt hemassand mat er i al scomposi t i onofcar sanc Hevel ofdesi gnf ordi sas sembl y ,[ Snotshown. Themodeli ncl udesa par a" els t ockandf l ows t r uc t ur e( co‑ f l ow)t r ack i ngeachoft hes epr oper t i esasvehi cl esageandar e even t ual l yr et i r ed,di sman t l ed,andshr edded.Seechapt er12. Cha pt e r6 St oc ksa n dFl o ws 227 Af t e ra l l pa r t swor t hr e c ove r i nga r er e move d, t hegut t e dc a r , nowca l l e dahul k, i ss ol dt oas hr e dde r .I nt hemi d1 990st he r ewe r ea bout200S hr e dde r si nt heUS whopr oc e s s e dr oughl y94%ofa l lde r e gl S t e r e dc a r s ・ Af t e rs hr eddi ng,t heva l ua bl e ma t e r i a l s( pr i nc i pa l l ys t e e la nds omeno nf e r r ousme t a l s )a r es e pa r a t e doutf orr e ‑ c yc l i ng. I ft hepr l C eSOft her e c ove r e dma t e ia r l sdon' t j us t i f yt hec os t ,S hr e dde r sc a n t a kehul ksdi r e c t l yt oal a nd丘l la ndc utt he i rpu r c ha s e sf r omdi s ma nt l e r s . Wha tr e 一 ma i nsa f t e rs hr e d di nga nds e pa r a t i oni sami xt ur eofpl a s ics t , gl a s s , e l a s t ome r s , a nd s omeunr e cove r e dme t a lca l l e da ut omot i ves hr e dde rr es i due( ASR)or"f luf f , " whi c hi st he nl a ndf me d. ASRi soneoft hema j o re nvi r onme nt a lc onc e r nsge ne r ‑ a t e dbyt hedi s pos a lofol dc a r s . Ther e c yc l a bl ema t e r i a l sa c c umul a t ei na ni nve nt or ya nda r ee ve nt ua l l ys ol dt o ma t e r i a l spr oc e s s or ss uc ha ss t e e lmi l l s .Thei nve nt or yofr a wma t e r i a l si st he n us e dt oma nuf a c t ur ene wpr oduc t s , i nc l udi nga ut omobi l e s , t hushe l pi ngt oc r e a t ea c l os e dma t e r i lf a lOwa ndc ut t i ngt heus eofnonr e ne wa bl er es our c es . Asi nt hec a s e ofpa r t s ,t hema t e r i a l sus a ger a t ef lowsi nt oas i nks i nc et hef lowofr e c ove r e dma ‑ t e r i a l sr e l a t i vet ot het ot a lf lowofvi r gi nma t e r i a l si ss ma l l . Za mudi o‑ Ra mi r e z' smode li nc l ude dar i c hf e e dba c ks t r uc t ur er e pr e s e nt l ngt he be ha vi oroft hev a r i ousa c t o r si nt hes ys t e m, i nc l udi ngt hea ut oma ke r s , c a rowne r s , di s ma nt l e r s ,a nds hr e dde r s .Ma r ke t sf o rr e c ove r e dma t e r i a l swe r ee xpl i c i t .The s t oc ka ndf lOws t r uc t ur ef ora ut osbe ga na tt hedes i gns t a gef orne wmode l sa nd pl a t f or msa ndt r a c ke dke ypr ope r t i esoft hec a r si nc l udi ngt he i rma s s ,ma t e r i a l s c o mpos i t i on( f e r r ous , nonf e r r o us , pl a s t i c s ) , a ndt hel e ve lofde s i gnf ordi s a s s e mbl y bui l ti nt ot hede s i gn.The s ea t t r i but e swe r et r a c ke da st hec a r se mbodyi ngt he m move df r omt hede s i gns t a get oma r ke t ,a ge,a nda r et he nr e t i r e d,di s ma nt l e d,a nd s hr e dde d. Tbga t he rt her e qui r e dda t a , Za mudi o‑ Ra mi r e zc onduc t e di nt e r vi e wswi t hva r ‑ i ousa c t or s , i nc l udi ngc a r ma ke r s , di s ma nt l e r s ,s hr e dde r s , a ndi ndus t r ya na l ys t sa nd ma dee xt e ns i veus eofva r i ousa ut oa ndr e c yc l i ngi ndus t r yda t a ba s e s .Someoft he da t ar e qui r e d,s u c ha sa ge‑ de pe nde nts c r a pr a t esf o rca r s ,we r er e l a t i ve l ye a s yt o ga t he r .Ot he rke ypa r a me t e r swe r enot . Twoc r i t i c a lr e l a t i ons hi psi nt hemode la r e t hes uppl yc ur ve sf o rr e c ove r e dpa r t sa ndr e c ove r e dma t e r i a l s ・ Tha ti s , howwi l lt he numbe rofpa r t sr e c ove r e dbydi s ma nt l e r sva r ya st hepr l C et he yc a nge ta nd也e c os t so fr e c ove r yv∬y? Es t i ma t l ngt h epa r t ss uppl yc ur vei sada unt l ngpr obl e m. Thepr l nC l pa lc os tof r e c ove r yl St hel a bort i mer e qui r e dt or e moveapa r t ・Butt het i mer e qui r e dt or e ‑ moveagl Ve npa r tde pe ndsonhowma nyot he rpa r t smus tber e move df i r s t . Thes e pr e c e de nc er e l a t i ons hi psde pe ndont hede s i gnof血ec a ra ndt heva l ueo ft hei n‑ t e r ve ni ngpa r t s( C a nt hes e a tber i ppe doutq ui c kl yt oge ta tava l ua bl epa r tunde ri t o rmus ti tber e move dc a r e f ul l y?Shoul dwor ke r sge ta tapa r tf r om i nf r ontorbe ‑ hi nd? ) .Tbes t i ma t et hes er e l a t i ons hi psZa mudi o‑ Ra mi r e zwo r ke da tt heVe hi c l e Re c yc l i ngPa r t ne r s hi p, ac ons o r t i umoft hel i i gThr e eUSa ut oma ke r s , di s ma nt l e r s , a ndt her e c yc l i ngi ndus t r y. TheVe hi c l eRe c yc l i ngPa r t ne r s hi pas s e mbl e dac om‑ pr e he ns i veda t a ba s eofpa r tr e mova lt i me sbyc ompl e t e l ydi s a s s e mbl i ngava r i e t y ofl a t emode lc a r s .Za mudi o‑ Ra mi r e za ndhi sc ol l e a gueAndr e w Spi c e rt he nde ‑ ve l o pe da nopt i mi z a t i onmode lt oe s t i ma t et hes uppl yc ur vef orpa r t sr e c ove r ya s f unc t i onsofpa r ta ndma t e r i a l spr l C eS ,l a bo rc os t s ,a ndt hede s i gnoft heve hi c l es ・ Theo pt l mi z a t i onmode lde t e r mi ne dt henumbe rofpa r t swor t hr e c ove r l nga nd也e 228 P a r t I IT わ o l sf o rS y s t e ms T h i n k i n g e ‑ o pt l ma ld i s ma nt l i n go r d e rf o ra nys e tofpr i c e s ,l a bo rc os t s ,a ndde s i gnpa r a m t e r s ‑t hes uppl yc u r v ef o rr e c o ve r e dpa r t s . Ther e s ul t so ft heo pt l mi z a t i o nmode l we r et he ne mbe dde di nt hes i mul a t i onmode l . Ast hede s i g npa r a me t e r sf o rc a r s l s ,t hee s t i ma t e ds uppl yc ur ver e ‑ c ha ngea ndt her e mo va lt i mef o rke ypa r t sf a l s po ndsbyr e a l i s t i c a l l yi nc r e a s l ngt henumbe ra ndt y pe so fpa r t sr e c o ve r e d. Tho ug ht hes t o c ka ndf lo ws t r uc t u r ei nFi g ur e61 1 9i ss i mpl i f i e da nddo e snot s howa nyo ft hef e e d ba c ks t r u c t ur ed e t e r mi nl ngt heva r i o usf lowsf r om t hef ul l mo de l , i ti l l us t r a t e st her e s po ns eo ft hea ut o mo bi l ea ndma t e r i a l sma r ke t st opo l i ‑ c i e sd e s i g ne dt oi nc r e a s er e c yc l i ngo fc a r s . Fi r s tc o ns i de rt hee f f e c to fade s i g nf o rdi s a s s e mbl y( DFD)pr og r a md e s i gne d t oi nc r e a s et hepa r t r e c o ve r yr a t ea ndr e d uc et hea mo unto ff luf fe n di ngu pl nl a nd‑ f i 1 1 S ・ DFDc a nr e d uc et hel a bo rc os tofpa r tr e c ove r yt hr o ug hbe t t e rde s i g n, d i f f e r ‑ e n tc ho i c eo fpa r tf a s t e n e r s , i mp r o ve ds e l e c t i o na ndl a be l i ngo fma t e r i a l s , a ndo t he r t e c hni q ue s . Th ef i r s te fe c ti s ". no t h i ng. The r ei sal a gofa tl e a s ts e ve r a lye a r sbe ‑ t we e nt het i mea na ut o ma ke rs t a r t saDFDpr og r a ma ndt het i met hef i r s tc a r sde ‑ s l gne dt ot hos es pe c sr ol lo f ft hea s s e mbl yl i ne.Thea ve r a gec a ri nt heUni t e d St a t e ss t a yso nt her oa df o ra bo utade c a de , a ndne wc a r sha veve r yl o ws c r a pr a t e s ( mos to ft he s ea r ewr e c ksde c l a r e dt ot a ll os s e sbyi ns ur a nc ec o mpa ni e s ) . Onl ya f ‑ t e rade l a yofma n yye a r swi l lt hes t oc ko fr e c yc l i ng‑ r e a dyc a r sbel a r g ee noug h a ndo l de noug hf o rt he mt oc o ns t i t ut eas i gni f i c a ntf r a c t i o noft hes c r a ppe dc a r s pur c ha s e dbydi s ma nt l e r s . Wha tt he nha p pe ns ?Ma nuf a c t ur e r se x pe c t e dDFD wo ul de ve nt ua l l yc a us e pa r ta ndma t e r i a lr e c o ve r yt or i s e , pe r ma ne nt l yr e d uc i ngt henowofma t e r i a l st o l a ndf i l l s . I ns t e a d, t hemo d e ls ug ge s t st hene xte f f e c twi l l beagl uto fus e dpa r t s , a s t hepa r tr e c ove r yr a t er i s e sa bovet heus e dpa r t sus a ger a t e. Aspa r t si nve nt o r i e s bui l d,t hepr i c edi s ma nt l e r sc a nge tf o rus e dpa r t sf a l l s . Thenumbe rofpa r t st ha t c a nbee c o no mi c a l l yr e c o ve r e dd r o ps , a ndt hedi s ma nt l i ngr a t ed r o psba c k. Pr i c e s c ont i n uet of a l lun t i lt henumbe rofpa r t sr e c ove r e df a l l se nou g ht oba l a nc et he S e , S t i mul a t e dbyl owe rpr l C e S , but us e dpa r t sus a ger a t e. Thepa r tus a g er a t ema yr l i c , t hepa r tr e c o ve r yr a t ewi l l unl e s st hede ma ndf o rus e dpa r t si shi g hl ypr i c ee l a s t dr o pba c kc l os et oi t so r l g l na lr a t epr i o rt ODFD・Thede ma ndf o rus e dpa r t si s l i ke l yt ober a t he ri ns e ns i t i vet op r l C e. Aut oma ke r sa ndt hi r d‑ pa r t ypr od uc e r sofr e ‑ pl a c e me n tpa r t swi l l ber e l uc t a nt t ol os et hel uc r a t i vepa r t sma rke ta ndma ybea bl e t opr o hi bi tt heus eofr e c o ve r e dpa r t sbya ut ho r i z e ds e r vi c ec e nt e r so rf o rwa r r a n t y r e pa l r SO rC O mpe t eO npr l C e Jft hede ma ndf o rus e dpa r t si si ne l a s t i c , t hep r l nC l pa l e f f e c to fDFDmi g hts i mpl ybet ode pr e s st hepr i c eOfus e dpa r t s ,O f f s e t t l ngmos t o ft hebe ne f i tofi mpr o ve dd e s i g n. Nowc o ns i de rt hee f f e c tofat r e ndt o wa r ds ma l l e r ,l i g ht e rc a r swi t hs i gni f i ‑ c a nt l yhi g he rpl a s t i cc o n t e nta ndl e s ss t e e la ndme t a l .Suc hc ha nge sa r epr o mo t e d t oi mpr oveal e le c o no my , 1 nC r e a S epa r tr e C OVe r a bi l i t y , a ndde c r e a s et heq ua n t l t yOf luf f fe ndi ngupl nl a nd f i l l s . Howe ve r , t hes t oc ka ndf lOws t r uc t ur ema yc a us et he i mpa c to fs u c hpol i c i e st obec o unt e rt ot he i ri nt e nt . Thea ut oi nd us t r yl SaS i gni f i ‑ c a ntc ons ume ro fs t e e l . Whe nne wc a r sbe g i nt ous el e s s , t her e c o v e r yo fs t e e l丘. o m s h r e dd i ngofo l dhu l ksc o nt i nue sa t t hepr i o rr a t e ・ Thepr i c eO fs c r a pme t a lwi l lf a l l , r e d uc i ngs hr e dde rpr o f i t a bi l i t y. Thenu mbe rofhul kss hr e dd e da ndt heq ua nt l t yOf Ch a p t e r6 S t o c k s a n dF l o ws 229 me t a l sr e c ove r e dma yf a l l , a ndt hevo l umeo ff lufd i s pos e di nl a nd f i l l sma ya c t u‑ a l l yr i s e・ Fur t he r , onc et hes c r a pr a t eo fc a r swi t hr e d uc e ds t e e lc o n t e nti nc r e a s e s , s hr e d de rpr of i tc a nf a l lf u r t he r . Wi hl t e s ss t e e la ndnonf e r r o usc o nt e nt ,s h r e dde r r e ve nuepe rhul kf a l l s , whi l et hef i xe dc os t so fs hr e ddi ngr e ma i nt hes a me . Za mu‑ di o‑ Ra mi r e zf わu ndt ha tas us t a i ne di nc r e a s ei nt hepl a s t i cc ont e ntofc a r s ,a se x‑ pe c t e d, Woul di n c r e a s et hef r a c t i o no fma t e r i a l sr e c ove r e dbydi s ma nt l e r s . But c a r s wi t hl e s sr e c yc l a bl eme t a lc o ul da l s ode pr e s shul kpr i c e se nought oc uts h r e dde r c r e a s et hes h r e dd i ngr a t e , a nda c t ua l l yi nc r e a s et hen umbe ro fa ba nd one d pr o恥 de c rsa a ndt hea mo u nto ff luf fbu r i e di nl a nd f i l l s . Thes t oc ka ndf lOwma phe l psi l l us t r a t et hel o ngde l a ysbe t we e nac ha ngei n t hede s i g no fc a r sa ndt hef lowso fo l dc a r st ol a nd f i l l s , Byma ki ngt hes t o c kso fr e ‑ C ove r e dpa r t sa n dma t e r i a l se x pl i c i t , i ti se a s i e rt os e et ha tt he r ei si mpe r f e c tc oo r ‑ di na t i o nbe t we e ni nf lo wsa ndo ut lows f ,l e a di ngt opot e nt i a li mba l a nc e sa nd c ha nge si npr l C e S也a ti nva l i da t e血ea s s umpt l OnSbe hi ndr e c yc l i ngpr og r a ms ・ I n‑ s t i t ut i o na ls t r u c t u r e ss uc ha sr e q u l r e me nt St ha ts e r vi c ec e nt e r sus en e wr e pl a c e me nt pa r t sc a nove r wh e l mt hel o g i coft hema r ke t . Ma r ke tme c ha ni s ms , e ve nwhe np r e ‑ s e nt ,a r enotl i ke l yt owo r ks moo t hl y ,pos s i bl yl e a di ngt oi ns t a bi l i t ya ndi ne f f i ‑ c i e nc y .Si mi l a rd y na ic m sha v ea l r e a dybe e no bs e r ve di nt hema r ke tf o rr e c yc l e d pa pe r( Ta yl o r1 9 9 9 ) . Su ppl ys i des t e pst oi nc r e a s er e c yc l a bi l i t ya l o nea r eno tl i ke l y t obee fe c t i veu nl e s sma t c he dbypol i c i e st oi nc r e a s et heus a geofr e c o ve r e dpa r t s er i a l sa ndt hea c t ua lr e c yc l i ngof a ndma t e r i a l s ・Thec ol l e c t i o nofr e c yc l a bl ema t t hos ema t e r i a l sa r e n' t血es a me仙i ng. 6. 4 SL B MMARY Thi sc ha pt e ri nt r o d uc e dt hes t oc ka ndf lowc onc e pt .St oc ksa c c umul a t et he i ri n‑ lo f wsl e s st he i ro u t lows f . St oc ksa r et hes t a t e so ft hes ys t e mu po nwhi c hde c i s i o ns a nda c t i o nsa r eba s e d, a r et hes ou r c eo fi ne r t i aa ndme mo r yl nS ys t e ms , C r e a t ede ‑ 1 a ys ,a ndge ne r a t ed i s e q ui l i b r i umd yna mi c sbyde c o upl i ngr a t e so ff lo w. Thed i a ‑ g r a mml ngnot a t i o nf o rs t o c ksa ndf lOwsc a nbeus e dwi t hawi d er a ngeof a ud i e nc e sa ndma ke si te a s i e rt or e l a t eac a us a ld i a g r a mt ot hed y na mi c so ft hes ys ‑ , t e m・St oc ksa c c u mul a t e( i n t e g r a t e )t he i ri nf lowsl e s st he i ro ut lows f . Equ i va l e nt l y her t a t eo fc ha ng eofas t o c ki st het ot a li nf lowl e s st het ot a lo ut lo f w. Thusas t o c k a ndf lo wma pc o r r e s po ndse xa c t l yt oas ys t e mofi nt e g r a lo rdi fe r e nt i a le q ua t i o ns . Ho we ve r , s t oc ka n df lO wma psa r emuc he a s i e rt owo r kwi t ha nde x pl a i n. The r ea r es e v e r a lwa yst oi de nt i f yt hes t oc ksi ns ys t e ms . I nt hes na ps hott e s t youi ma gl nef r e e z i ngt hes ys t e ma tamome ntoft i me ‑t heme a s u r a bl eq ua nt i t i e s ( phys i c a l , i nf o r ma t i o na l , a ndps yc ho l og i c a l )a r et hes t oc ks , whi l ef lowsa r eno ti n‑ s t a nt a ne ous l yobs e r va bl eo rme a s ur a bl e. Uni t sofme a s ur ec a na l s ohe l pi de nt i f y s t oc ksa ndf lows .I fas t oc ki sme a s ur e di nuni t s ,i t sf lOwsmus tbeme a s u r e di n u ni t spe rt i mepe r i od. St oc kse xi s t l ngl nS e r i e si nane t wo r kc a nbea ggr e ga t e dt o ge t he ri ft he ya r e s ho r t ‑ l i ve dr e l a t i v et ot het i meho r i z o na nddyna mi c so fi nt e r e s t , Mul t i pl epa r a l l e l a c t i vi t i e sc a nbea g g r e ga t e di nt oas i ngl es t oc ka ndf lowne t wo r ki ft hea c t i vi t i e s a r ego ve r ne dbys i mi l a rde c i s i o npr oc e s s e sa ndut i l i z es i mi l a rr e s o ur c e sa ndi ft he 2 30 Pa r t I I To o l sf o rS ys t e msTh i n ki n g r e s i de nc et i me so ft hei t e msi nt hes t o c ksi ss i mi l a re no ug hf o rt hepur pos eofyo ur l . mod e So ur c e sa nds i nksf ort hef lO wsi nas ys t e m ha vei nf i ni t ec a pa c i t y ,unl i ke s t o c ksi nt her e a lwo r l d,a ndt husr e pr e s e ntt hebo un da r yo ft hemode l . Mode l e r s s ho ul da l wa ysc ha l l e nget he s ebo unda r ya s s umpt l O nS ,a s ki ngi ft hea s s umpt i onOf i nf i ni t es up pl yf o rs o ur c e sa ndi nf i ni t ea bs o r pt 1 0 nC a pa c i t yf o rs i n ksi sa ppr o pr l a t e r e l a t i vet ot hemo de lpur pos e. i 3 i { i 3 ̲ 畠 主 賓毒 ぐ §! = : 3 ぎS極∈ 立至表 現頭首呈 t i 笥享 Nat u r el au g h satt h edl Hi c ul t i e so fi nt e gr at i o n. ‑」)i e r r e ‑ S i mo nd eLa p l a c e(1749‑1827) Thes u c c e s s e so ft hedl He r e nt i ale qu at i onpar adi gm we r ei mpr e s s i v eand e xt e ns i v e .Man ypr o bl e ms ,i nc l u di ng bas i ca nd i mpor t anto ne s ,l e dt o e qu at i o nst h atc oul db es ol v e d.Apy 1 0C e S SO fs e l f ‑ s e l e c t i ons e ti n ,whe r e b y e qu at i o nst h atc oul dnotbes ol v e dwe r eaut o mat i c al l yo fl e s si nt e r e s tt h an t hos et hatc o u l d. ‑I anS t e wa r t( 1 989, p.39) . Cha pt e r6i nt r o d u c e dt hes t oc ka ndf lOwc o nc e pta ndt e c hni q ue sf o rma ppl ngt he s t oc ka ndf lo wn e t wo r kso fs ys t e ms . Thi sc ha pt e re x pl o r e st hebe ha v i o rofs t oc ks a ndf lows .Gi ve nt hed yna mi c soft hef lows ,wha ti st hebe ha vi o ro ft hes t oc k? Fr omt hedyna mi c so ft hes t oc k,c a nyo ui nf T e rt hebe ha vi o ro ft hef lows ?The s e t a s ksa r ee q ul Va l e ntt oi nt e g r a t i ngt hef lowst oy i e l dt hes t oc ka nddi fe r e nt i a t i ng t hes t o c kt oyi e l di t sne tr a t eo fc ha ng e. Fo rpe opl ewhoha vene ve rs t udi e dc a l c u‑ T √ 、 i us , t he s ec o nc e p t sc a ns e e mda unt i ng. l nf a c t , r e l a t i ngt hed y na mi c so fs t oc ksa nd lowsi f sa c t ua l l yq ui t ei nt ui t i ve ;l ti st heus eofunf a mi l i a rno t a t i o na ndaf oc uso n a na l yt i cs ol ut i o n st ha tde t e r sma nype o pl ef r o ms t ud yo fc a l c ul us . Wha ti fyo uha veas t r o ngba c kg r oundi nc a l c ul usa ndd i f f e r e n t i a le q ua t i ons ? I ti sge ne r a l l yno t pos s i bl et os o l vee v e ns ma l lmod e l sa na l yt i c a l l yd uet ot he i rhi g h o r de ra ndno nl i n e a r i t i e s ,s ot hema t he ma t i c a lt ool sma nype o pl eha ves t udi e da r e ofl i t t l edi r e c tus e . I fyouha vemo r ema t he ma t i c a lba c kg r o undyo uwi l lf i ndt hi s c ha pt e rs t r a i g ht f o r wa r dbuts ho ul ds t i l ldot heg r a phi c a li nt e g r a t i o ne xa mpl e sa nd c ha l l e nge st obes ur eyo uri nt ui t i veunde r s t a nd i ngl Sa SS Ol i da syo urt e c hni c a l 231 232 P a r tI IT o o l sf o rS y s t e msTh i n k i n g , knowl e dge。 Mode l e r s ,noma t t e rhowgr e a tors ma l lt he i rt r a i nl ngl nma t he ma t i c s ne e dt obea bl et or e l a t et hebe ha vi oro fs t oc ksa ndf lowsi nt ui t i ve l y, us l nggr a Phi C a la ndot he rnonma t he ma t i ca lt e c hni q ue s . Thec ha pt e ra l s oi l l us t r a t eshows t oc k a ndf lOwdyna mi c sgi vei ns i ghti nt ot woi mpor t a ntpol i c yi s s ue s :gl oba lwa r ml ng a ndt hewa rondr ugs . ‑ 7. 1 RELAT1 0NS川PBETWEEN STOCKSAND FLOWS Re c a l lt heba s i cde f i ni t i onsofs t oc ksa ndf lows : t hene tr a t eofc ha ngeofas t oc ki s t hes umofa l li t si nf lowsl es st hes umofa l li t so ut lows f . St oc ksa c c umul a t et hene t r a t eofc ha nge. Ma he t ma t i c a l l y,s t oc ksi nt e gr a t et he i rne tf lows ; t hene tf lowi st he de r i va t i veoft hes t oc k. ' l. . 虹1 S竜 甜 CandDynami cEqus t S ! t bF ! ' um As t oc ki si ne qui l i br i um whe ni ti sunc ha ngi ng( as ys t e mi si ne qui l i br i um whe n al li t ss t oc ksa r eunc ha ngi ng) .Foras t oc kt obei ne qui l i br i um t hene tr a t eof c ha ngemus tbez e r o, i mpl yi ngt het ot a li nf lowI SJ us tba l a nc e dbyt het ot a lout low. f I fwa t e rdr a i nsoutofyourt uba te xa c t l yt her a t ei tf lowsi n,t hequa nt l t yOfwa t e r i nt het ubwi l lr e ma i nc ons t a nta ndt het ubi si ne qui l i br i um. Suc has t a t ei st e r me d ad ynami ce qui l i br i um s i nc et hewa t e ri nt het ubi sa l wa ysc ha ngi ng.St at i ce qul ‑ l i br i um a r i s e swhe na l lf lowsi nt oa ndo utofas t oc ka r ez e r o. He r enotonl yi st he t ot a lvol umeofwa t e ri nt het ubc o ns t a nt , butt het ubc ont a i nst hes a mewa t e r , hour a f t e rhour . Thenumbe rofme mbe r soft heUSs e na t eha sbe e ni ndyna mi ce qui l i b r i um s i nc e1 959whe nHa wa l lJ Ol ne dt heuni on:t het ot a lnumbe rofs e na t or sr e 一 ma i nsc ons t a nta t1 00e ve na st heme mbe r s h i pt ur nsove r( a l be i ts l owl y) . Thes t oc k ofknownBa c hca nt a t a si si ns t a t i ce qui l i br i um s i nc ewea r eunl i ke l yt ol os et he one sweknowof , t heoddsofdi s c ove r l ngPr e vi ous l yunk n ownc a nt a t a sa r er e mot e , a ndBa c hc a n' twr i t ea nyne wone s . ‑ 7. 1. 2 Cal cul uswi t houtMat hemat i cs Tbunde r s t a nddyna mi c s , youmus tbea bl et or e l a t et hebe ha vi oroft hes t oc ksa nd lowsi f nas ys t e m.Gi ve nt hef lowsi nt oas t oc k,wha tmus tt hebe ha vi oroft he s t oc kbe?Gi ve nt hebe ha vi oroft hes t oc k,wha tmus tt hene tr a t eofc ha ngeha ve be e n?Thes eques t i onsa r et hedoma i noft hec a l c ul us .Ca l c ul uspr ovi desr ul est o a ns we rt hes eques t i onsma t he ma t i c a l l ypr ovi de dyouc a nc ha r a c t e r i z et hebe ha vi or oft hes t oc kso rf lowsa sma t he ma t i c a lf unc t i ons . Ca l c ul usi soneoft hemos tbe a u‑ t i f ula ndus e f ulbr a nc hesofma t he ma t i c sbutonef a rt oof e wha ves t l J I di e dH f i a ppiy t hei nt ui t i onbe hi ndt her e l a t i ons hi pbe t we e ns t oc ksa ndf lOwsi ss t r a i ght f or wa r d a nddoe snotr e qul r ea nyma t he ma t i cs Jfyoua r es hownagr a phoft hebe ha vi orof t hef lowsove rt i me, youc a na l wa ysi nf e rt hebe ha vi o roft hes t oc kThi spr oc e s si s n owna k sgr a phi c ali nt e gr at i on. Li ke wi s e, f r omt het r a j e c t or yOft hes t oc kyouc a n a l wa ysi nf e ri t sne tr a t eofc ha nge ,apr oc e s sknowna sgr a phi c aldl He r e nt i at i on. I nt e gr a t i ona nddi f f e r e nt ia t i ona r et het wof unda me nt a lope r a t i onsi nt hec a l c ul us . Ta bl e71 1pr ovi de st hede f i ni t i onsgr a phi c a l l ya ndi npl a i nl a ngua ge. Thea mounta dde dt oas t oc kdur i nga nyt l mei nt e r va li st hea r e abounde dby t hec ur vede f i ni ngI t sne tr a t eOfc ha nge.Why?Cons i de rt heba ht t ubme t a phor l ラ 233 Ch a p t e r7 Dy n a mi c so fS t o c k sa n dFl o ws TABL E7‑ 1 日 n t egr at i onan ddi f f er en t i at i on: def i ni t i onsandex ampl es I nt egr at i on Di f f er ent i at i on nt egr at et hei rnetf l ow. St ock sac cumul at eori Thequan t i t yaddedt oas t ocko veran yi n t eⅣal i st hear eaboundedbyt hegr aphoft henetr at e bet weent hes t ar tandendoft hei n t eⅣal . The f i nal v al ueoft hes t ocki st h ei ni t i al v al uepl u st he ar eaundert hene tr at ecur vebe t weent hei ni t i a一 andf i n a=j mes. l nt heexampl ebel ow, t hev a山eo Hh es t ockat t i met l‑S . Addi ngt h ear eaundert henetr at e cur vebet weent i mest lan dt 2i ncr eas est he s t ockt oS2 . l Thesl opeofal i net angen tt oan ypoi ntoft he t r a j ec t or yOft h es t ockequal st henetr at eof chan9ef ort hes t ockatt hatpoi nt . Thesl opeof t h es t ockt r aj ec t or yi st heden' V at i v eo ft hes t ockl h lt heexampl ebel ow, t hes l opeoft hes t ock t r a j ec t or yatt i met li sRl , S Ot henetr at eatt Rl . Att i met 2 , t h es l opeoft hes t ocki sl ar ger , s o t henetr at eatt 2‑R2i sgr eat ert hanR . The s t ockr i s esatani ncr easmgr a t e,S ot henetr at e i sposi t i veandi n cr easl ng. l ‑ l 2 R (a ∈ Ju a jN l e la s l! n) 1 R t !t 0 ( a u ! J l J S l! un) a t t 2 t ]laN ( s l ! un)羊U OI S 2 S ・ ー S ( s l ! u n)q30 1 S t l モ 2 a ga i n・ Howmuc hwa t e ri sa dde dt ot het ubi na nyt l mei nt e r va l ,s uc ha sbe t we e n t i met la ndt 2i nTa bl e7‑ 1 ?Di vi det hee nt i r ei nt e r va li nt oanumbe rofs ma l l e rs e g‑ me nt s ,e a c hs ma l le nought ha tt hene tnowofwa t e ri snotc ha ngl ngS l gni f i c a nt l y 1 ) .Thel e ngt hofe a c hs e gme nti sc a l l e dH dt Hf or dur i ngt hes e gme nt( Fi gur e7‑ " de l t at i me. "Howmuc hwa t e rf lOwsi ndur i nge a c hs ma l li nt e r va lofdur a t i ondt ? 11 Thequa r l t i t ya dde di st i l ene tnow dur i ngt hei r l t e r Va l ,s a yR,mui t i pl i e c LD y t hel e ngt hoft hei nt e r va l ,t ha ti s ,t hea r eaoft her e c t a ngl edtpe r i odswi dea nd 良uni t s / pe r i odhi g h: R * dt Qua n t i t ya d d e dd u r i n gi n t e r va lo fl e n g t hd t‑ ( Un i t s ) ‑( Un i t s / Ti me )( Ti me ) ( 7‑ 1 ) Not et heuni t sofme as ur e: Thef lowi nuni t spe rt i me,a c c umul a t e df orape r i odof t i meyi e l dst heq ua nt l t ya dde dt ot hes t oc k・ nut ea ndt 2‑2mi nut es .The Tous eac onc r e t ee xa mpl e,s uppos et 1‑ 1mi ques ioni t show muc hwa t e rf lowsi nt ot het ubdur i ngt ha tmi nut e.Di vi det he 234 P a r t I IT わ o l sf o rS y s t e msTh i n k i n g ( a∈! t J s l ! un) a l t 2 t J l aN 0 FI GURE71 1 Gr aphi c al i nt egr at i on Di vi d et i mei n t o smal l i n t er val sof 一 engt hdt ・Each r ec t ang一 er epr e s ent st heamoun t addeddur i ngt he i n t er v al dt ,as s um‑ l ngt hene tr at eR. att ha tt i mer e mai n sc ons t an t . dur i ngt hei nt er val Thear eaofeach dt . r ec t angl ei sR, Thet ot al addedt o t hes t ockbet ween t landt 21 St hent he sumoft hear eas oft her ec t ang一 es. Di vi di ngt i mei n t o s mal l eri n cr emen t s i ncr eas est he accur ac yoft he appr oxi mat i on・ ‑ 2 S 1 S I l n)q U OS (s ! u ‑ 昔 1 t 2 mi nut eupi nt oS i xl OI S e C Ondi nt e r va l sa nda s s umet hef lOwi sc ons t a ntt hr oughout ea c hoft he s ei nt e r va l s .I fa tt hes t a r toft hef i r s ti nt e r va lt hef lowwa s6l i t e r spe r mi nut e( t ha ti s ,0. 1l i t e r s / s e c ond) , t he nt hea mounta dde dwoul dbe( 0. 1l i t e r s / s e c ‑ ( 1 0s e c onds )‑ ll i t e r . Att hes t a r toft hes e c ondl OI S e C Ondi nt e r va l ,t hef low ond) ha si nc r e a s e d, pe r ha pst o7l i t e r s / mi nut e ,ora bout0. 1 1 7l i t e r s / s e c ond. Thea r e aof t hes e c ondr e c t a ngl ei st he n1 . 1 7l i t e r s .Ca l c ul a t i ngt hea r e aofa l ls i xr e c t a ngl es a nda ddi ngt he mt oge t he rgl Ve Sa na ppr oxi ma t i onoft het ot a lvol umeofwa t e r a dde ddur i ngt hemi nut e.Thea ppr oxi ma t i oni s n' tpe r f e c tbe c a us et hene tf lOwi s a c t ua l l yc ha ngi ngdur i ngea c h6‑ s e c ondi nt e r va l ・ I nFi gur e7‑ 1 , t hef lowi sa c t ua l l y r i s l ng,S Ot hec a l c ul a t e dva l ueoft hes t oc kwi l lbet oos ma l l . Toi nc r e a s et hea c c u‑ r a c yoft hea ppr oxi ma t i on,s i mpl ydi vi det i mei nt oe ve nf i ne ri nt e r va l s , i nc r e a s l ng t henumbe rofr e c t a ngl es .Comput e rs i mul a t i onsi nt e gr a t et hes t oc ksi nt hemode l i npr e c i s e l yt hi sf a s hi on;t hemode l e rmus tc hoos et het i mes t e pdts ot ha tt hea p‑ pr oxi ma t i oni sa c c e pt a bl ef o rt hepur pos e・ 1Ⅰ nt hel i mi t ,a st het i mei nt e r va lbe ‑ c omesi nf i ni t es i ma l , t hes umoft hea r e a sofa l lt her e c t a ngl e sbe c o me se qua lt ot he t ot a la r eaunde rt hene tr a t ec ur ve.Ca l c ul uspr ovi desf or mul a st ha tgl Vet hee xa c t a r e aunde rt hene tr a t e ‑pr ovi de dt hene tr a t eca nbee xpr es s e da sac e r t a i nt ypeof ma t he ma t i ca lf unc t i on.Butwhe t he rt hene tr a t ec a nbei nt e gr a t e da na l yt l C a l l yo r not , t hea mounta dde dt oas t oc ki sa l wa yst hea r e aunde rt hene tr a t e. Gr a phi c a li n‑ t e gr a t i oni st hepr oc e s so fe s t i ma t l ngt ha ta r e af r om agr a phoft hene tr a t e. 7. 1. 3 Gr aphi caHnt egr at i on Toi l l us t r a t egr a phi ca li nt e gr a t i on,c ons i de rt hemos tba s i cs t oc ka ndf lows ys t e m: as l ngl es t oc kwi h onei t nf lowa ndoneo ut low・ f As s umet hef lowsa r ee xoge no us ‑ t he r ea r enof e e dba c ksf r omt hes t oc kt oe i t he rf low. Suppos et heo ut lowf f r omt he oc e d u r ed e s c r i b e da b o v ei sk n o wna sEu l e ri n t e g r a t i o na n di st h emo s t c o mmo n l yu s e d l Th ep r me t h o df o rn u me r i c a ls i mu l a t i o n . Ot h e rme t h o d ss u c ha sRu n g e ‑ Ku t t ai n t e g r a t i o nu s emo r es o p h i s t i c a t e dme t h o d st oe s t i ma t et h ea r e aa n ds e l e c t t h et i mes t e p. S e eAp p e n d i xA. ‑ Ch a p t e r 7 D y n a mi c so fS t o c k sa n dF l o ws 柿 0 2 0 1 l a N き 0] L 0 . ( pu o uas s J l ! un) FJ GURE7‑ 2 Gr aphi c al i n t egr a t i on: examp一 e Whi l et her a t e s t epsu pan ds t ep s down, t hes t oc k r i s esandr emai n s atahi gh erl e v eL Not et h edi f f er en t uni t so fmeasu r e f ort h er a t ean d s t oc k 235 400 竜宮 300 き 桟 20 0 1 00 蓮 0 0 華∃ 1 0 20 30 Ti me( seconds ) s t oc ki sz e r o・Su ppos ea l s ot ha tt hei nf lo wt ot hes t oc kf o l l o wst hepa t t e ns r hown i nFi g ur e7‑ 21 Thei nnowbe g i nsa tz e r o・ Att i me1 0t hei nf lo ws ud de nl yl nC r e a S e S t o20uni t s / s e c o nd, r e ma i nsa tt ha tl e ve lf わr1 0s e c o nds ,t he ns t e psba c kd ownt o z e r oJft hei ni t i a ll e ve lo ft hes t o c ki s1 00uni t s , howmuc hi si nt hes t oc ka tt i me 3 0,a ndwha ti st hebe ha v i o ro ft hes t oc kove rt i me? Ta bl e7‑ 2S howst hes t e psi nvol ve di ng r a phi c a li nt e g r a t i on. Appl yi ngt he s e 2, f i r s tma keas e to fa xe sf o rt hes t oc k, l i ne du punde rt heg r a ph s t e pst oFi gu r e71 f o rt hef lows . Ne xtc a l c u l a t et hene tr a t e .Si nc et he r ei so nl yonei nf lo wa ndone o ut low,a f nds i n c et heo ut lo f wi sz e r oa ta l lt i me s ,t hene tr a t eo fc ha ngeo ft he s t oc k( To t a lI nf lo wITo t a lOut low)s f i mpl ye q ua l st hei n lo f w. I ni t i a l l y , t hes t oc k ha sava l ueo fl oou ni t s . Be t we e nt i me0a ndt i me1 0,t hene tf lowi sz e r ouni t s / 0,t hene tr a t e s e c o nd,s ot hes t o c kr e ma i nsc ons t a nta ti t si ni t i a lva l ue. Att i me1 J umpst O20uni t s / S e c o nda ndr e ma i nst he r ef o r1 0s e c o nds . Thea mo unta dd e di s t hea r e aunde rt hene tr a t ec ur ve( be t we e nt hene tr a t ec ur vea ndt hez e r ol i ne ) . Si nc et her a t ei sc o ns t a nt , t hea r e ai sar e c t a ngl e20uni t s / s e c ondhi g ha nd1 0s e c ‑ ondsl ong,s ot h es t o c kr i s e sby2 00u ni t s , g l Vl ngat o t a ll e ve lof3 0 0un i t sbyt i me 20・ Be c a us et hene t r a t el Spos i t i vea ndc o ns t a ntd u r i ngt hi si nt e r va l , t hes t oc kr i s e s l i ne a r l ya tar a t e2 0uni t s / s e c o nd( t hes l o peoft hes t o c ki s2 0uni t s / s e c o nd) . Att i me20, t hei nf lows udd e nl yc e a s e s . Thene tr a t eofc ha ng ei sno wz e r oa nd r e ma i nsc ons t a n t ,a ndt hes t o c ki sa ga i nunC ha ngl ng,t 壬 1 0 ug hno wa tt hel e ve lof 300u ni t s . No t ehowt h epr oc e s sofa c c umul a t i o nc r e a t e si ne r t i a : t ho ug ht her a t er i s e sa nd f a l l sba c kt oi t so r l gl na ll e v e l , hes t t o c kdo e snot r e t ur nt oi t so r l gl na ll e v e l . I ns t e a d, i tr e ma i nsa ti t sma xi mum whe nt hene tr a t ef a l l sba c kt oz e r o.I nt hi sf a s hi o n, S t oc kspr ovi deame mo r yofa l lt hepa s te ve n t si nas ys t e m. Theo nl ywa yf o rt he s t oc kt of a l li sf o rt hen e tr a t et obe c o mene ga t i ve( f o rt heo ut lo f wt oe xc e e dt hei n low) f A No t ea l s ohowt hepr oc e s so fa c c umul a t i onc ha ng e dt hes ha peo ft hei n put . Thei nputi sar e c t a ng ul a rpul s ewi t ht wod i s c ont i nuo usJ umps ;t heout puti sa s moo t h, c ont i n uo usc u r v e . ‑ 2 36 TABLE7 ‑ 2 St epsi ngr aphi cal i nt egr at i on Pa r tI I To ol sf o rSys t e msThi nk i ng 1.Cal cul at eandgr apht het ot alr at eofi nf l owt ot hes t ock( t hesum ofal l i nf l ows ) .Cal cul at eandgr apht het ot alr at eofou t 刊owf r om t hes t ock( t he sum ofa"ou t f l ows ) . 2,Cal cul at eandgr apht henetr at eofchangeoft hes t ock( t het ot aHnf l owl ess t het ot a一 out f l ow) . 3.Mak easetofaxest ogr apht hes t ock.St ock sandt hei rf l owshavedi f f er ent uni t sofmeasur e( i fas t ocki smeasur edi nuni t si t sf l owsar emeasur edi n uni t spert i meper i od) . Ther ef or es t ock sandt hei rf l owsmustbegr aphedon separ at es cal es.Mak easepar at egr aphf or帥es t ockundert hegr aphf or t hef l ows, wi t ht het i meaxesl i nedup. 4.Pl ott hei ni t i al val ueoft hes t ockont hes t ockgr aph. Thei ni t i al val uemus t bespeci f i ed;i tcannotbei nf er r edf r omt henetr at e, 5lBr eakt henetf J owi nt oi nt er val swi t ht hesamebehavi orandcal cul at et he amoun taddedt ot hes t ockdur i ngt hei n t er valSegmen t smi ghtbei nt er val s i nwhi cht henetr at ei scons t ant , changl ngl l near F y,Orf oI I owI ngsomeOt her pat t er n. Theamountaddedt oorsubt r ac t edf r omt hes t ockdur i nga segmen ti st hear eaundert henetr at ecur vedur i ngt hatsegmen t ・For exampF e,doest henetf l owr emai ncons t antf r omt i met lt Ot i met 2?E fso, t her at eofchangeoft hes t ockdur i ngt hats egmenti scons t ant ,andt he quan t i t yaddedt ot hes t ocki st hear eaoHher ec t angl edef i nedbyt henet r at ebet weent landt 2.1 日henetr at er i sesl i near l yl nasegment , t hent he amountaddedi st hear eaoft het r i angl e.Es t i mat et hear eaundert henet r at ecur vef ort hesegmentandaddi tt ot heval ueoft hest ockatt hes t ar tof t hesegment . Thet ot ali st heval ueoft hes t ockatt heendoft hesegment . Pl ott hi spoi n tont hegr aphoft hes t ock. 6.Sk et cht het r a j ec t or yoft hes t ockbet weent hes t ar tandendofeach . segmen t .Fi ndt heva山eoft henetr at eatt hebegl nnl ngOft hesegment f si tposi t i v eornegat i ve?l ft henetf l owi sposi t i ve,t hes t ockwi nbe i ncr easl ngatt hatt i me.l ft henetf l owi snegat i ve,t hes t ockwH lbe deer easmg. Thenaskwhet herj ti sr i sl ngOrf al l l ngatani ncr easl ngOr decr easl ngr at e,andsk et cht hepat t er nyoui n f eront hegr aph. l ft henetr at ei sposi t i veandi nc r easl ng,t hes t ocki ncr easesatan i ncr easl ' ngr at e( t hes t ockaccel er at esupwar d) . l ft henetr at ei sposi t i veanddecr easl ng,t hes t ocki ncr easesata decr easi ngr at e( t hes t ocki sdecel er at i ngbuts t i l lmovi ngupwar d) . l ft henetr at ei snegat i veandi t smagni t udei s/ I ncr easi ng( t henetr at ei s ' ncr easi ngr at e, becomi ngmor enegat i ve) , t hes t ockdecr easesatan/ l ft henetr at ei snegat i veandi t smagnl J t udei sdecr easi ng( becomi ngl ess negat i ve) . t hes t ockdecr easesatadecr easi ngr at e1 7.Whenevert henetr at ei szer o, t hes t ocki sunchangl ng.Mak esur et hat nt hes t ockever ywher et henet yourgr aphoft hes t ockshowsnochangei r at ei szer o.l ft henetr at er emai nszer of orsomei nt er val , t hes t ock r emai nscons t an tatwhat everval uei thadwhent henetr at ebecamezer o. Atpoi nt swher et henetr at echangesf r om posi t i vet onegat i ve, t hes t ock r eachesamaxi mum asi tceasest or i seands t ar t st of a川 . Atpoi nt swher e r om negat i vet oposi t i ve, t hes t ockr eachesa t henetr at echangesf mi ni mum asi tceasest of al l ands t ar t st or i se. i l done. 8.Repeats t eps5t hr ough7unt 237 Ch a p t e r7 Dy n a mi c so fS t o c k sa n dF l o ws FI GURE7・ 3 Theac cumul at i onpr oc es scr ea t esdel ay s. Not et heone‑ quar t erc y cl el agbet we ent hepeak soft henetf l owandt hepeak so ft hes t ock. 00 2 50 1 Out f t o Y 50 n )SきOlj \Sl! u 00 1 ( L J tuO ∈ l nt l ow ㌔ W‑‑ ) 『雨 \ 0 3 … 己 ㌔ ̲ メ 6 9 1 2 ㍉ 24 Ti me( mont hs) j ㌔ ̲ i 36 48 Nowc ons i d e rt hef lOwss pe c i f i e di nt het oppa ne lofFi g ur e71 3. Theout low f i sc ons t a nta t1 0 0uni t s / mont h, 1 D utt hei nf l owF l uc t ua t esa r ounda na ve r a geofl oo wi t hape r i odo f1 2mont hsa nda na mpl i t udeof±50uni t s / mont h. Att hes t a r t , t he i nf lowi sa ti t sma xi mum. As s umet hei ni t i a lva l ueoft hes t o c ki s500uni t s . Si nc et heo ut low i f sc ons t a nt ,t hene ti nf l ow i saf luc t ua t i onwi t ha mpl i t ude ±50uni t s / mont ha ndame a nofz e r o. Thes t oc kbe gi nsa ti t si ni t i a lva l ueof500 uni t s ,buts i nc et hei nf lowi sa ti t sma xi mum,t hes t oc ki ni t i a l l yr i s eswi h as t l ope of50uni t s / mon t h. Howe ve r , t hene tf lowf a l l sove rt hef i r s t3mont hs , s ot hes t oc k i nc r e a s e sa tade c r e a s i ngr a t e. Atmont h3t hene tf lowr e a c he sz e r o, t he ngoesne g‑ a t i ve. Thes t oc kmus tt he r e f わr er ea c hama xi mum a tmont h3. Thea mounta dde d t ot hes t oc ki nt hef i r s t3mont hsi st hea r e aunde rt hene tr a t ec ur ve. I ti snotea s y 2 3 8 I IT わ o l s f o rS y s t em s Th i n k i n g P a r t t oe s t i ma t et hea r e af r omt heg r a p hbe c a us et hen e tr a t ec ur vei sc o ns t a nt l yc ha ng 1 ng. Yo uc o ul de s t i ma t ei tbya ppr oxi ma t l n gt hea r e aa sas e tofr e c t a ngl e s ,a sde ‑ s c r i be da bo ve,t ho ug ht hi swo ul dt a ket i me .Us i ngs i mul a t i ont oc a r r youtt he a c c umul a t i o ns howst ha tal i t t l el e s st ha n1 00u ni t sa r ea dde dt ot hes t oc kbyt he t i met hene tr a t ef a l l st oz e r oa tmo nt h3. Fr o m mont h3t omo nt h6,t hene tr a t ei sne ga t i ve .Thes t oc ki st he r e f o r e f a l l i ng. J us ta f t e rmont h3, t hene t r a t el S J us t ba r e l yne ga t i ve , S ot her a t eofde c l i ne o ft hes t o c ki ss l i g ht . Butt hema gni t udeo ft hene tr a t ei nc r e a s e s ,S ot hes t oc kf a l l s a ta ni nc r e a s i ngr a t e. At6mo nt hs , t hene t r a t eha sr e a c he di t sm i ni mum( mos tne g‑ a t i v e )va l ueof‑50uni t s / mo nt h. Thes t oc ki sde c l i ni nga ti t sma xi mumr a t e; t he r e i sa ni n le f c t i o npo l nti nt het r a j e c t o r yO ft hes t oc ka tmo nt h6. Howmuc hd i dt hes t oc kl os ebe t we e nmo nt h3a ndmont h6?As s umi ngt he luc f t ua t i o ni nt hene tr a t ei ss ymme t r i c a l , t hel os sJ us t ba l a nc e dwha twa sga i ne di n t hef i r s t3mo nt hs , r e duc i ngt hes t oc kba c kt oi t si ni t i a ll e ve lo f50 0uni t s . Fr o mmo nt h6t omon t h9, t hene tf lo wr e ma i nsne ga t i ve ,s ot hes t oc kc o nt i n ue st of a l l , butnowa tade c r e a s l ngr a t e.Bymo nt h9t hene tf lowa ga l nr e a c he s r o, s ot hes t o c kc e a s e st of a l la ndr e a c he si t smi ni mum. Aga i nus i ngt hea s s u mp‑ z e t i ono fs y mme t r y , t hequa nt l t yl os tf r o mmo n t hs6t o9i se q ua lt ot hequa nt l t yl os t f r o mmo n t hs3t o6,S ot hes t o c kf a l l st oal e ve l j us ta bo ve400uni t s . Fr o mmo nt hs9t o1 2t hene tf lowi spos i t i ve , s ot hes t oc ki sr i s i ng. Dur i ngt hi s t i met hene tr a t er i s e s ,s ot hes t oc ki nc r e a s e sa ta ni nc r e a s i ngr a t e ,e ndi ngwi t ha s l o p eo f5 0uni t s / mo nt ha st hene t r a t er e a c he si t sma x i mum. Aga i n, t hes t oc kg a l nS t hes a mea mo unt , r e c ove r l ngI t si ni t i a ll e v e lo f5 00uni t se xa c t l ya tmo nt h1 2. Be ‑ y on dmo n t h1 2t hec yc l er e pe a t s . Thee xa mpl ei l l us t r a t e st hewa yl nWh i c ht hepr o c e s so fa c c umul a t i o nc r e a t e s d e l a ys , Thei nputt ot hes ys t e mi saf luc t ua t i o nwi t ha1 2 ‑ mo nt hpe r i odr e a c hi ngI t s pe a ka tt i me‑0,1 2, 24,... mo nt hs . Thes t o c k, o ro ut puto ft hes ys t e m, a l s of luc t ua t e swi t ha1 21 mOnt hpe r i odbutl a gsbe hi ndt hene ti nf lo wr a t e ,r e a c hi ngI t s pe a ksa tt‑3,1 5,2 7,‥ . mo nt hs . Thel a gl Spr e c i s e l yo ne ‑ q ua r t e rc yc l e. Thel a g a r i s e sbe c a us et hes t oc kc a no nl yde c r e a s ewhe nt hene tf lo wi sne ga t i ve. I ft hene t lowi f spos i t i vea ndf a l l st oz eo, t hes t o c ki nc r e a s e sa ndr e a c he si t sma xi mum. ‑ ‑ ‑ r Anal yt i c alI nt egr at i onofaFl uct uat l r On Thee xa mpl ei nFi gur e7‑ 3c a nbema depr e c i s eus l ngal i t t l eba s i cc a l c ul us . The s t oc kSi st hei nt e gr a loft hene tr a t eR. As s umi ngt hen e tf lo wi sac os i newi t hpe ‑ r i od1 2mo nt hsa nda mpl i t ude50uni t s / mo n t h, R=5 0c os ( 2T r t / 1 2) , t he n ‑l 5 0c o s2 Tu1 2 ) d t‑50( 1 2 / 2T) s i n( 2 Tu 1 2 )+S t s‑lRd t ( D ( 7 ‑ 2 ) Thes t o c kf o l l o wsas i newa vewi t ht hes a mepe r i o da nda mpl i t ud e( 1 2 / 2¶ )t i me s t ha toft hene tf low. Thede l a yc a us e dbyt hea c c umul a t i o npr oc e s si se a s i l ys e e n s i nc es i n( 0 )=c os ( 0‑¶/ 2) : 汀t / 1 2‑¶/ 2 )+S t 。 S‑5 0 ( 1 2 / ユ ′ 汀) c o s ( 2 ′ ( 7 ‑ 3 ) Thes t o c kf ol l owst hes a met r a j e c t o r ya St hene tf lo wbutwi t hapha s el a go f7 T / 2 ( one ‑ qua r t e rc yc l e ) . Equa t i on( 7‑ 2)a l s os howst ha tt hea mpl i t udeo ft hes t oc ki s ( 50uni t s / mont h)*( 1 2mont hs / 2T r )‑ 96uni t s ,S ot hes t oc kf luc t ua t e sbe t we e n a bo ut40 4a nd5 96, a ss e e ni nt hef i g ur e . 239 Ch a p t e r7 Dy n a mi c so fS t o c k sa n dFl o ws Gr aphi c a Hn t e gr a t i on Cons i de ras t o c kwi t has i ngl ei nf lowr a t eRla nds i ngl eo ut nowr a t eR2・ Dr a wt he be ha vi oroft hes t oc kgi ve nt her a t e sRla ndR2S howni ne a c hpa ne lofFi gur e7‑ 4. Thei ni t i a lva l u eoft hes t oc ki s1 00uni t si nbot hc a s es . Donotus eac omput e r . The pol nti st ode v e l o pyo uri nt ui t i ona bouts t oc ksa ndRowsa ndyoura bi l i t yt or e l a t e t he i rbe ha vi o r . Us i ngs i mul a t i onde f e a t st ha tpur pos ea ndwi l lt a kel onge ra swe l l . ♂l nf l ow O〆 ut f 一 ow 1 5 肋 j g 4 9 4 t 減 Ou紺ow Tjk ‑ ∴ こ . : . / . :㌔ 匡 「 ‑ 一 ■ ̀ ■ 5 20 ‑ 10 ‑ ‑ ■‑ ′ 1 5 20 7. 1 . 4 Gr a phi c al Di f f er en t i a t i on Thei nve r s eofi nt e gr a t i oni sdi fe r e nt i a t i on,t heca l c ul a t i onoft hene tr a t eof c ha ngeofas t o c kf r o mi t st r a j e c t ory.Gi ve nagr a phofas t oc k, i ti sa l wa yspos s i ‑ bl et oi nf e rt hene tr a t eofc ha ngea ndpl oti t . Asi nt hec a s eofi nt e gr a t i on, t he r ea r e a na l yt i cme t ho dst oc a l c ul a t et hene tr a t eofas t oc kl ft hef u nc t i ondes c r i bi ngt he s t oc k' spa t hi sknown. Howe ve r , i nmos tdyna mi cmode l snoa na l yt i cf u nc t i onf or t hes t oc ksi skn own,S oyoumus tde ve l opt hes ki l lofg r a phi c a ldi f f e r e nt i a t i on・ Gr a phi c a ld i fe r e nt i a t i oni ss t r a i ght f or wa r d・Si mpl ye s t i ma t et hes l opeoft he s t oc ka te a c hpo l nti nt i mea ndpl o ti tonagr a phoft hene tr a t e. Fi g ur e7‑ 5pr ovi des a ne xa mpl e. 2 4 0 0 0 0 2 0 5 7 1 l! s un)qU ( FI GURE7 ‑ 5 Gr aphi c a一 di f f er en t i at i on Pa r tI I To o l sf わrSys t e msThi nk i ng 疏 ' .t J 1 Q + 0 0 5 1 O ‑ ● ● . 、 令 0 5 2 1 S I ち 〃 〜 Q′ / I ¢ ea, , / .i \ l. 0 ■ ■ コ \ ≠ ⊂ く O ⊂ ▼ つ ー ) ▼ ⊂ ⊂■ > I l ⊂ \ 0 ⑳ 忠 y) : コ ご u) 巴 ・ 、 萎由I 0 0 0 1 5weeks 0 0 2 0 0 1 0 0 1 ( 日石a^ A J St l. un)atet ]a lN 0 0 2 1 0 2 0 Ti me( week s ) 30 40 Thei ni t i a ls t oc ki s2000uni t s .Fo rt hef i r s t1 0we e kst hes t oc kde c l i ne sl i n e a r l y ,S ot hene tr a t edur i ngt hi si nt e r va li sne ga t i v ea ndc ons t a nt . Thes t o c kf a l l s f r o m2 000t o1 000uni t si n1 0we e ks ,s ot hene tr a t e( t hes l o peo ft hes t oc k)i s ‑1 0 0uni t s / we e k. Atwe e k1 0t hes t oc ks ud de n l ys t a r t si nc r e a s l ng. Dr a wl ngal i n e t a nge n tt ot hes t oc kc ur vea tt i me1 0g i ve sa ne s t i ma t eoft hes l o peof200uni t s / we e k. Thene tr a t et he r e f o r es t e psup丘・ o m ‑1 0 0uni t s / we e kt hei ns t a ntbe f わr et he t s / we e kj us ta f t e ri ts t a r t s . Fr om we e ks1 0t o2 0t he s t a r to fwe e k1 0t o+200uni s t o c ki nc r e a s e sa tade c r e a s i ngr a t e ,S Ot hene tr a t ei spos i t i v ebutf a l l i ng. Att i me 20t hes t o c kr e a c he sama xi mum s ot hene tr a t ei sz e r o.The r ea r enoki n kso r bumpsi nt hes t oc kt r a j e c t or y , i mpl yi ngas t e a d y , l i ne a rde c l i nei nt hene tr a t ef r o m 20 0un i t s / we e ki nwe e k1 0t oz e r oi nwe e k2 0. Fr o mwe e k20t owe e k3 0t hes t o c k i sf a l l i ng. Bywe e k3 0i ti sf a l l i ngr a pi dl y;t hes l o peofal i net a nge ntt ot hes t oc k t r a j e c t o r ya tWe e k3 0ha sas l o peo f‑20 0uni t s / we e k. Aga i n, t he r ea r enok i n ksi n t het r a j e c t o r y , S Ot hene tr a t ed e c l i ne sl i ne a r l yf r o mz e r oi nwe e k2 0t o12 00un i t s / We e ki nwe e k3 0. Atwe e k3 0t hes t oc ks udd e nl ys t o psc ha ng l nga ndr e ma i nsc o n‑ s t a nta 氏e r wa r ds . Thene t r a t es udd e nl ys t e psupf r o m ‑200t oz e r ou ni t s / We e ka nd r e ma i nsa tz e r ot he r e a f t e r . Gr a phi c a ld i f f e r e nt i a t i o nofas t oc kr e ve a l sonl yI t sne tr a t eOfc ha nge . I ft he s t o c kha smul t i pl ei nf lowsa ndout lowsi f ti snotpos s i bl et ode t e r mi net he i r ‑ 2 41 Ch a p t e r7 Dy n a mi c so f S t o c k sa n dF l o ws i ndi vi dua lva l u e sf r o mt hene tr a t ea l o ne:af i r m' ss t oc kofc a s hr e ma i nsc o ns t a nt whe t he rr e ve n ue sa nde x pe ndi t ur e sbot he qua l$1mi l l i onpe rye a ro r$1bi l l i on pe rye a r ・ Gr aphi ca一Di f f er ent i at i on Thet r a j e c t o r yO fas t o c ki ss howni nFi g ur e7‑ 6. De t e r mi net hebe ha vi oro fi t sne t r a t ebyg r a phi c a ld i f f e r e nt i a t i o n. Donotus eac o mput e r . 0 7. 2 5 1 0 1 5 20 SYsTEM r 3yh ! AMi CSJ NAcT1 0N:GLOBALW ARM州G Muc hoft hepo we ro ft hes ys t e md yna mi c spe r s pe c t i vec o me s血. omunde r s t a nd‑ 1 ngho wt hepr o c e s sofa c c umul a t i o nc r e a t e sd yna mi c s ,e ve nbe f o r ec ons i de r i ng t hef e e d ba c ksc o upl i ngt hes t oc ksa ndt he i rf lows . Toi l l us t r a t e ,c ons i de rg l o ba l Wa r ml ng・ I st hee rt a hwa r ml ng?I st hewa mi r ngC a us e db ye mi s s i o nso fg r e e nho us ega s e s ( GHGs )c a us e dbyhuma na c t i vi t y?Ho wmuc hwa r mi ngi sl i ke l yove rt hene xt c e nt ur y?Wha tc ha ng esi nc l i ma t epa t t e r ns ,r a i n f a l l ,g r o wi ngS e a s o n,S t o r mi nc i ‑ d e nc ea n ds e ve r l t y , a nds e al e ve lmi ghte ns ue , a ndhowmuc hda ma g ewo ul dt he s e c ha nge sc a us et oh uma ni t ya ndt oo t he rs pe c i e s ?The s eq ue s t i o nsa r edi f f i c ul tt o a ns we r , a ndl e g l t l ma t es c i e nt i f i cde ba t e sa bo utt hei mpa c to fa nt hr o po ge ni cGHG e mi s s i onsc o nt i n ue . De s pi t et hes c i e nt i f i cunc e r t a i nt y , s e ve r a lf a c t sa r eno ti nd i s put e . Thet e mpe r ‑ a t ur ea tt hee a r t h' ss ur f a c e ‑t hel a nd, l o we ra t mos phe r e ,a n ds ur f a c el a ye roft he oc e a n( t hes o ‑ c a l l e dmi xe dl a ye r , t het o p50t o1 00me t e r s , whe r emos ts e al i f ee x‑ i s t s ) ‑i spr i ma r i l yde t e r mi ne dbyt heba l a nc eoft hei nc o mi ngs ol a rr a di a t i o na nd t heo ut g o l ngr e r a d i a t e de ne r gy. Thee a r t hi sawa r mma s ss ur r o unde dbyt hec o l d o fs pa c ea ndl i k ea l ls uc hma s s e se mi t ss o ‑ C a l l e dbl a c kbo d yr a di a t i o nwhos ef r e ‑ q ue nc yd i s t r i bu t i ona ndi n t e ns i t yde pe ndso ni t ss ur f a c et e mpe r a t u r e . Thewa r me r t hema s s , t hemo r ee ne r g yl tr a d i a t e s Jnc o ml ngS O l a re ne r g ywa r mst hee a r t h・ Asi t wa r ms ,mo r ee n e r g yl Sr a d i a t e dba c ki nt os pa c e . Thet e mpe r a t ur er i s e sunt i lt he e a r t hi sJ us tWa r me noug hf ort hee ne r gyr a di a t e dba c kt os pa c et oba l a nc et hei n‑ c o ml ngs o 一 a re ne r g y. 242 P a r tI IT o o l sf o rS y s t e ms Th i n k i n g Thea mo unto fe ne r g yr a di a t e dba c ki nt os pa c ede pe ndso nt hec o mpos i t i o nof t hea t mos phe r e . GHGss uc ha sc a r bo nd i o x i dea ndme t ha net r a ps o meo ft hee n‑ e r g yr a d i a t e dbyt hee a r t h, i ns t e a do fa l l owl ngl tt Oe s c a pei n t os pa c e ・ Thusa ni n c r e a s ei nGHGsc a us e st hee a r t ht owa r m.Thee a r t hhe a t supunt i lt hee ne r gy e s c a pl ngt hr o ught hea t mos phe r et os pa c er i s e se no ught oa ga i nba l a nc et hei n‑ c oml ngs o一 a re ne r gy.Gr e e l l hous ega s e sr e d uc et hee mi s s i vl t yO ft hea t mos phe r e e no ug ht owa r mt hes ur f a c eoft hee a r t h( i nc l ud i ngt heoc e a ns )t oal i f e ‑ s us t a i ni ng a ve r a geo fa bout1 5o C( 59o F) . Wi t ho utGHGsi nt hea t mos phe r e , t heme a ng l o ba l t e mpe r a t ur ewo ul dbea bout‑1 7o C( l o p)a ndabl a nke tofi c ewo ul dpe r pe t ua l l y c ov e rt hee a r t h. n Na t ur a lpr oc e s s e sha vec a us e dt hec o nc e nt r a t i o nofc a r bond i ox i de( CO 2)i t hea t mos phe r et of luc t ua t es i gn i f i c a nt l yov e rge o l og i c a lt i me , a nds u r f a c et e mpe r ‑ a t u r e sha vef l uc t ua t e dwi t hi LHu ma na c t i v i t yha sno wr e a c he das c a l ewhe r ei tc a n a fe c tt he s epr oc e s s e s . Ass howni nFi g ur e7‑ 7,t her a t eo fa nt hr o po ge ni cGHG e mi s s i o nsha sbe e ng r owl nge XPO ne nt i a l l ys i nc et hebe gl nn l ngO ft hei ndus t r i a l ndo t he rGHGsi nc l ud i ngni t r o uso x i d e a ge . At mos phe r i cc onc e nt r a t i onso fCO2a , me t ha ne( CH4),C hl or o luo f r o c a r bo ns( CFCs ) , hyd r of luo r oc a r bo ns( HFCs ) , ( N20) pe r luo f r i na t e dc a r bo ns( PFCs ) , a ndo t he r sha vebe e ng r owi nge x po ne nt i a l l y , wi t h c o nc e l l t r a t i o nso fCO2, N20, a ndCH4upby3 0,1 5, a nd1 45%, r e s pe c t i v e l y ,s i nc e 1 8 00. Me a ng l o ba ls ur f a c et e mpe r a t u r eha sbe e nr i s i ng, ho t ug hno ti nas t e a d ypa t ‑ t e r n. Co mpa r e dt ot hel a t e1 8 00S , a ve r a g egl o ba lt e mpe r a t ur e sa r ea bo ut0. 5t ol o C , wa me rt o da y . Byc o mpa r i s o n, t heme a ngl o ba lt e mpe r a t u r ed ur i ngt hel a s t i c ea ge whe ns he e t sofi c e1 000f e e tt hi c kc o v e r e dmuc hoft heno r t he r nhe mi s phe r e , wa s a bo ut50 cc o l de rt ha nt oda y . De ba t ec o nt i n ue sa bo utt hed y na mi c so ft heg l o ba lc l i ma t es ys t e m, i t sr e s po ns e t of o r c i ngbyhuma na c t i v l t y ,a ndt hec o ns e q ue nc e so far i s ei ng l o ba lme a nt e m‑ pe r a t ur e.Thepu bl i cdi s c us s i onha sbe e npol a r i z e dbywe l l ‑ f i na nc e dc a mpa i g ns t odi s c o untt hes c i e nc e.Ne ve r t he l e s s ,c o ns e ns usi se me r gi ng.I n1 9 95,t heUN s po ns o r e dl nt e r gove r nme nt a lPa ne lo nCl i ma t eCha nge( I PCC)c o nc l ude dt ha t e, gl o ba lwa ml ngWa si nde e doc c u r r l ng,a ndt ha thuma na c t i v l t yWa sr e s pons i bl s t a t l ng" Theba l a nc eofe vi d e nc es ugge s t sadi s c e r ni bl ehuma ni nf lue nc eo nc l i ‑ ma t e "( I PCC1 996) . Thr o ug ht heUNFr a me wo r kConve nt i o no nCl i ma t eCha nge ( UNFCCC)va r i o usna t i o nsa r ene g o t i a t i ngl i mi t st oGHGe mi s s i ons , t ho ug hc o m‑ pl i a nc er e ma i nse l us i ve. Si mul a t i o nmode l so fva r i o ust y pe sa r et hepr l ma r yr e s e a r c ht oo lt oe x pl o r e t he s ei s s ue s . Thee no r mo us l yd e t a i l e dge ne r a lc i r c ul a t i onmode l s( GCMs )c a l c u‑ l a t ec l i ma t ea tf i ne l ys pa c e di nt e r va l sc o ve r l ngt hee nt i r es ur f a c eo ft hee a r t h, but t a keGHGe mi s s i onsa se xoge no usI nput s . Att heot he re xt r e me ,s o‑ C a l l e di nt e ‑ g r a t e dc l i ma t e ‑e c ono mymode l sc l os es o meoft hef e e d ba c ksa mo ngt heh uma n e c o no my , c a r bo ne mi s s i o ns ,a ndg l o ba lc l i ma t ebutt r e a tt hec a r bo nc yc l ea ndc l i 一 ma t ea sgl o ba la gg r e ga t e swi t has ma l ln umbe ro fs t o c ks ・ TわmFi dda ma n( 1 99 7) a na l yz e dma nyo ft hemos twi de l yus e dc l i ma t e ‑e c ono mymode l s ,i d e nt i f yi nga numbe ro fpr o bl e msa ndi nc ons i s t e nc i e si nt he m.Fo re xa mpl e ,t hewi d e l yc i t e d DI CEmo de l( No r d ha us1 992a ,1 992 b)v i o l a t e st hel a wofc o ns e r va t i o nofma s sby a s s umi ngt ha tas i g ni f i c a ntf r a c t i o no fc a r bo ne mi s s i o nss i mpl yd i s a ppe a r( No r d‑ ha usa s s ume dt he yf lOwi nt oas i nko ut s i d et hemod e l bo unda r y) . Fi dda ma n( 1 9 9 7) ‑ 243 Cha pt e r7 Dyna mi csofSt oc ksa ndFl ows andgl obalmean t emper at ur e 0g L u uO!H! g) s ! L uuo N3 u a6odoJL J l uV GHG emi ssi ons, concent r at i on, ( )。 a^ J SuO13! ) t a Suo ! s Fl GURE7 ‑ 7 1900 2000 1950 2000 J J o N 3U EaL I do s∈l V uo ID!ta u JO u M! g (s 1950 ) 1800 1900 1850 1900 5 0 0 0 ( UON . 0 ‑0 ト・096 L) ^l eL uOu V 巴n e l J ad u J l a a3 t ? l J nS u t=a M lq t 2O 一 9 1850 1800 Sour ces:Da t af r omt heCar bonDi oxi del n f or mat i onAnal ysi sCent er( CDI AC) ,OakRl dgeNat i onal Labor at or y( ht t p: / / cdE aC. eS d. or nI . gov / t r ends / t r ends. ht m) lEmi ssi ons:Keel i ng( 1 997) .Emi ssi onsi n‑ cl udecar bonf r ombur nl ngf ossi l f uel sonl yandexcl udesot herGHGsandchangesi ncar bonf l ux f r om,e; g. ,def or es t a t i on CO2 i r lat mospher e:Si pl eSt at 1 0nl CeCOr edat ar Nef t el etal .1 9941 .Mauna Loagasr ec or derda t a( Keel i ngetal .1 997) ; concent r at E Oni nppmvconver t edt obi l l i ont onsl nt ot al at mospher e.Gl obal meansur f acet emper at ur eanomal y:Jones, Wi gl ey ,andWr l gh t( 1997)andAnge" ( 1 997) ,r es ca‡ edso1960‑ 70, E0, 2o C. devel oped a modelt hatcor r ect st h ese and ot herdef ect si n comm on cl i m at e‑ economymodel sandl i nkedi tt oamodeloft heeconomyandener gys yst em ・The models ect orswer ebasedont her el evants ci ent if i cknowl edgeoft hegl obalcar bon cycl eandcl i m at es ys t em andcar eful l ycal i brat edt ot heavai l abl edat a. 244 P a r t I IT o o l sf o rS y s t e ms Th i n k i n g De s pl t et hedi f f e r e nc e sa mo ngt hemod e l s , a l ls howt hec l i ma t es ys t e mt opos I s e s se no r mo usi ne r t i a . Cha ng e si nGHGe mi s s i o nso nl ys l o wl ys ho wu pl nC ha ng e s i ngl o ba lt e mpe r a t ur ea ndc l i ma t e ,a ndt hec ha nge spe r s i s tf orma nyde c a d e s . To i l l us t r a t e, Fi g ur e7‑ 8S ho wsa ne xt r e mec o nd i t i o nst e s tus i ngFi dda ma n' smo d e l . I n mi s s i o nsf o l l owt he i rhi s t o r i c a lpa t ht hr o ugh t hes i mul a t i o n,a nt hr o po ge ni cCO2e t hemi d1 990S , r e ma i nc ons t a n tunt i l2 000,a ndt he nf a l lt oz e r oa f t e r2 000.Su r ‑ pr l S l ng l y,t ho ug ht her a t eofCO2e mi s s i o nsf a l l st oz e r oi nt heye a r2 00 0,me a n g l o ba lt e mpe r a t ur ec o nt i nue st or i s ef o ra bo utt hr e emor ede c a de s .I tt he nf a l l s ve r ys l o wl y. Thes t oc ka ndf lOws t r uc t u r er e s po ns i bl ef o rt hec o unt e r i nt ui t i ver e s ul tt ha t t e mpe r a t ur er i s e se ve nt ho ug he mi s s i o nsf a l lt oz e r oi ss howni nFi g ur e7‑ 9. The l e f ts i deo ft hef i g ur epo r t r a yst heg l o ba lc a r bo nc yc l e;t her i h ts g i depo r t r a yst he Ot hea t mos phe r e. The r ea r e gl o ba lhe a tba l a nc e.Bur nl ngf os s i lf u e l sa ddsCO2t s e v e r a lo ut lo f wsf r o mt hes t o c ko fa t mos phe r i cC0 2・ Hi g he ra t mos p he r i cCO2c o n‑ c e n t r a t i oni nc r e a s e st her a t ea twhi c hCO2 i sc ons ume dbya q ua t i cl i f eo rd i s s ol ve s a ke nupbyt hes u r f a c el a ye r i nt ot hemi xe dl a ye roft heoc e a n. Eve nt ua l l y ,CO2 t di f f us e st ode e pe rwa t e r s , bo t ht hr o ug hoc e a nc ur r e nt sa nda sde t r i t usf r o ma qua t i c l i f es i n ks . Thet r a ns f e ro fc a r bo nt ot hed e pt hsi ss l ow, a ndmi xi ngbe t we e nt hes ur ‑ f a c ea nda bys s a lwa t e r si swe a k,s oma nyc a r bonc yc l emode l sdi s a g g r e ga t et he wa t e rc ol umni nt oanumbe ro fdi s t i nc ts t a t e sa ndmod e lt het r a ns f e ro fc a r bo n be t we e na d j a c e ntl a ye r se x pl i c i t l y. Fi d da ma n' smo de lut i l i z e s1 0l a ye r s , e no ug ht o o nc e nt r a t i onst oc ha ng e si nCO2i n c a pt u r et hes l o wa d j us t me ntofa bys s a lCO2 c t hemi xe dl a ye r . On C e nt r a t i o na l s os t i mul a t e supt a keo fc a r bo nby I nc r e a s e da t mos phe r i cCO2 C t e r r e s t r i a lpl a nt s( t hef l uxo fCo ∑t Obi o ma s s ) . Ca r bo ni nbi o ma s sc a nber e l e a s e d ba c ki nt ot hea t mos phe r et hr o ug hr e s pl r a t i o na ndme t a bo l i ca c t i vl t yO fa ni ma la nd ba c t e r i a ll i f ea ndbyf i r e( na t ur a la ndhu ma n‑ c a us e d) ・ Asbi o ma s sd e c a ys , t hes t o c k ofc a r bo ns t o r e di ns oi li nc r e a s e s( t hef luxo fc a r bo nf r o mbi oma s st os o i lhumus ) . Thec a r bo ni nhumusc a nbet a ke nupd i r e c t l yi nt obi o ma s sa spl a nt sg r o wo rc a n ber e l e a s e di nt ot hea t mos p he r et h r o ug hde c a y . No t et ha tt hemod e lr e pr e s e nt st hei nf lo wofCO2 t Ot hea t mos phe r ef r o mt he bur ni ngOff os s i lf ue l sa sf lOwi ngf r oma nu nl i mi t e ds o ur c ewhe ni nf a c tt hef low dr a wsdownt hec a I もO ns e q ue s t e r e di ng l o ba ls t oc kso ff os s i lf ue l s . Si mi l a r l y , 血e mode ldoe snotc a pt u r et hec o nve r s i o no fc a r boni nhumuso rt hea bys s a ll a y e rof t heoc e a ni nt one ws t oc kso ff os s i lf u e l s . Al t ho ught hed yna mi c so fgl o ba lwa r m‑ 1 ngWi l lpl a yo utove rt hene xts e v e r a lc e nt u r i e s , t hi st i meho r i z o ni ss os ho r tr e l a ‑ t i vet ot hemi l l i onsofye a r sr e q ui r e dt of o r mo i l ,ga s ,a ndc oa lt ha tt he s ec a r bon lowsc f a nbes a f e l yi gno r e d. Ther i g hts i deofFi g ur e7‑ 9s howst hes t oc ka ndf lows t r uc t ur ef o rt hehe a t ba l a nc eoft hee a r t h' ss ur f a c e ,a t mos phe r e ,a ndoc e a ns .Thes u r f a c ea nda t mos ‑ phe r e , i nc l udi ngt hes u r f a c el a ye ro ft heoc e a n,a bs o r bi nc o ml ngS O l a re ne r g ya nd r a di a t ehe a tba c ki nt os pa c e . He a ti sa l s ot r a ns f e r r e dbe t we e nt hes u r f a c el a y e ra nd t hede e poc e a n, t ho ugha ts l o wr a t e s . Th er a t eo fhe a tt r a ns f e rbe t we e ns ur f a c ea nd de e poc e a nde pe ndsont het e mpe r a t u r edi f f e r e nt i a lbe t we e nt hed i fe r e ntl a ye r s , c r e a t l ngt wone ga t i vef e e d ba c kswh i c hs e e kt oe qui l i br a t et het e mpe r a t u r e so ft he d i fe r e ntl a ye r s .Si mi l a r l y ,ne tr a d i a t i vef o r c i ngi st hedi fe r e nc ebe t we e nt hei n‑ C o ml ngS Ol a re ne r gya ndt hee ne r g yr a di a t e df r o mt hewa r me a r t hba c ki n t os pa c e . Cha pt e r7 Dy n a mi c so fS t o c k sa n dF l o ws 245 s ( Lt 20^JS suos ! ! u U eO3 3! d O≡ L uu !g) u 3 6OJ o L I I u uO}UT la FI GURE7‑ 8 Gl obal t emper a‑ t ur er i s eswel l af t er GHGemi s si ons f al l t oz er o. Si mul at edemi s ‑ si onsf a‖t oz er o i n2000.Mean sur f ac et emper a‑ t ur econ t i nuest o r i sef orr oughl y 20year s・ V 2025 2050 ■ ー■ ■ ‑■ ■ ‑ ■ ‑ ■ ‑ ■ 一 一■ 1975 2000 2025 2050 e0 ∈a l qO1 9 ‑ t 2 2050 6 0 ut 23 m 2025 8 0 a3 t =‑ ・ ] nS ( pu no6 Jq oq E2 a ^Oq 3) ^I 2 tuJ O u V 巴n lt2Jad 2000 1950 Sour ce. I F i d d a ma n(1997) . Thewa r me rt hes ur f a c e,t hemor ee ne r gyl Sr a di a t e dba c ki nt os pa c e,C ool i ngt he e a r t ha ndf or ml nga not he rne ga t i vel oop.Thec onc e nt r a t i onofC0 2 a ndot he r GHGsi nc r e a s e sne tr a di a t i vef or c i ngbyr e d uc i ngt her a t ea twhi c he ne r gyl Sr a di a t e dba c ki nt os pa c ef ora nygl Ve nS ur f a c et e mpe r a t ur e. Thedi a gr a m( t houghnott hef ul lmode l )de l i be r a t e l yo mi t sma nya ddi t i ona l f e e dba c ksa f f e c t i ngt her a t esofc a r bonf low a ndhe a te xc ha ngea swe l la sc ou‑ pl i ngst oot he rbi ogeoc he mi c a lc yc l es .Knowl e dgeoft hena t ur ea nds t r e ngt hof t hema nyf e e dba c ksc oupl i ngc l i ma t e,c a r bonc yc l e,a ndhuma na c t i vi t yl SS t i l l e vol vi ng. Someoft he s ef e e dba c ksa r ene ga t i vea ndma yo f f s e tGHGe mi s s i o nso r ‑ 246 Pa r tI I Tわol sf o rSys t em s Thi nki ng FI GURE7‑ 9 St ockandf l owdi agr amofgt obal car boncycl eandheatba一 ance Bur nl ngf ossi l f uel saddsCO2t Ot heat mospher e,i ncr easmgnetr adi at i vef or cl ngunt i l t het emper at ur e oft her and,oceansur f ace,andat mospher er i sesenought obal ancer er adi at i onofener gyi nt ospace wi t hi ncoml ngl nSOl at i on, Thedi agr amdel i ber at el yomi t smanyoft hef eedback s,bot hposi t i veand negat i ve,amongt hecar bons t ock sandgl obalmeant emper at ur e.Fl owswi t har r owheadsatbot hends canbeposi t i veornegat i ve( e. g. ,NetRadi at i veFor ci ngcanbeani nf l owofheatt ot heat mospher eor anout f l ow) . Thesol i dar r owheadi ndi c at est heposi t i vedi r ec t i onoft wo‑ wayf l ows, Sour ce: Adap t edf r omFi ddaman( 1 997) . Ch a p t e r7 Dy n a mi c so fS t o c k sa n dF l o ws 2 47 wa r ml ng・ The s ei nc l udei nc r e a s e dc a r bo nupt a kebybi oma s s ,s t i mul a t e dbyhi ghe r CO2 c onc e nt r a t i ons ,a ndi nc r e a s e dc l oudc ove rf r om e nha nce de va por a t i on,r e ‑ le f c t l ngmor ei nc oml ngS unl i ghtt os pa c e. Pa r t i c ul a t ea e r os ol sf r omf os s i lf ue lc on s umpt i on( a i rpol l ut i ona nds mog)a l s oi nc r ea s er e le f c t i onofi nc omi ngs ol a r r a di a t i ona ndma ya c c o untf o rt hes l owe rt ha ne xpe c t e dr a t eoft e mpe r a t ur er is eo b‑ s e r ve di nt heNo r t he r nHe mi s phe r e. Amongt hepos i t i vef e e d ba c ksdr i vi ngc l i ma t ec ha ngea r ec ha nge si ns ur f a c e a l be do: Wa r ml ngr e duc e st hewi nt e rs nowc ove ra nds hr i nkst hehi ghl yr e le f c t i ve pol a ri c ec a ps , t husi nc r e as i nghe a ta bs o r pt l Ona ndl e a di ngt of u r t he rme l t i ng, l es s s nowc ove r ,a nds t i l lg r e a t e ra bs or pt l On・Sc i e nt i s t se xpe c tt hi spos i t i vel oo pwi l l c a us emuc hgr e a t e rwa r ml nga tt hepol e st ha ni nt het r opl CSa ndmor ewa ml ngl n wi nt e rt ha ns umme r ・Tha wi ngofpe r ma f r os tma yr e l e a s el a r gequa nt i t i e sof me t ha nef r omd e c a yofo r ga ni cma t t e r ,i nc r e a s l ngt hec onc e nt r a t i onofGHGsa nd l e a di ngt of ur t he rwa r mi ngl na not he rpos i t i vel oop.I nc r ea s e de va por a t i o nf r om wa r me rl a nda nds ur f a c ewa t e r sma ybes e l f ‑ r e i nf or c l ngS i nc ewa t e rva po ri sa powe r f ulGHG・ Atpr e s e nti ti snotknownwhe t he rt hene ga t i veo rpos i t i vef e e d‑ ba c ksdomi na t et hedyna mi c sno rhowt hedo mi na nc eo ft hel oopsmi ghtc ha ngea s va r i ousnonl i ne a r i t i e sc omei nt opl a y. Howe ve r ,Goul de ne ta l .( 1 998)s t udi e dt he nor t he r nbor e a lf or es tofCa na daa ndf o undt ha twa r mi ngha sr e s ul t edi nne t c a r bon luxt f ot hea t mos phe r easC0 2r e l e a s e df r omde c a yoft ha we dbi oma s sout we i ghe d i nc r e a s e dca r bo nupt a kebypl a nt s . Fo rt ha tbi ome,a tl e a s t , t hepos i t i vef e e dba c ks a ppe a rt odomi na t et hene ga t i vel oo pofi nc r e a s e dbi ot i ca c t i vi t y. Thei mpa c tofwa r ml ngOnS e al e ve lma ya l s obed r i ve nbypos i t i vef e e d ba c k. ThehugeWe s t Ant a r c t i cI c eShe e t( WAI S)c ons i s t sofaf lOa t i ngt onguea t t a c he d t oal a r ge ri c emas ss ohe a vyl tr e s t sOnbe dr oc kbe l ows e al e ve l . TheWAI Shol ds al otofwa t e r : " I fi tme l t e da wa yl nagr e e nhous e ‑ wa r me dwor l d, i twoul dr a i s ea l l t hewor l d' soc e a nsby5me t e r s "( 拡e r r1 998, p.1 7) . I fwa r me rs e a sc a us et heWAI S t ot hi n,i twi l lr i s ef a r t he rof ft hes e abe d,e xpos l ngmor eOft hei c et ome l t i nga nd a c c e l e r a t i ngt hi nni ngl napos i t i vel oop. Ast hee dget hi ns ,t hehi ghe ri c eont he Ant a r c t i cl a ndma s sf lowsf a s t e ri nt ot hes e a , whe r ei ti se x pos e dt ot hewa r me rwa ‑ t e r s ,f ur t he rs pe e di ngme l t i ngi na not he rpos i t i vef e e d ba c k.Ri gnot( 1 998)not e s t h a tagl a c i e rwi t hH[ t ] hi sc onf i gur a t i oni st he or e t i ca l l yuns t a bl ebe ca us ear e t r e a t o fi t sgr oundi ngl i ne( whe r et hegl a c i e rs t a r t st of loa t )woul dbes e l f ‑ pe r pe t ua t i ng a ndi r r e ve r s i bl e "a nds howst ha tt heg r oundi ngl i neoft hePi neI s l a ndgl a c i e rf e e d‑ 1 n gt h eWAI Si sr e t r e a t i nga t1. 2±0. 3ki l ome t e r spe rye a r .I c ec or e ss howt ha t wi t h i nt hepa s tl ・ 3mi l l i onye a r s ,‖ a tat i mepe r ha psnotmuc hwa r me rt ha nt oda y, t h eWAI Swa s t e da wa yt oas c r a pa ndf loode dt hewor l d' sc oa s t s "( Ke r r1 998, p・1 7 ) II c ec or eda t af r om Gr e e nl a nda l s os ugges tt hepa l e oc l i ma t er e pe a t e dl y wa r me da ndc ool e d,Wi t hc or r e s pondl ngC ha nge si ns nowf a l l ,ove rt i mes c a l esof o n l yd e c a des ・The s er a pi dc ha ngess ugge s tpos i t i vef e e dba c ksma yha vedomi ‑ na t e dc l i ma t edy na mi c si nge ol ogi c a l l yr e c e ntt i mes . I t wi l lt a key ea r sofr e s e a r c ht odi s c ove ra l lt hef e e dba c kst ha tdr i vet hec l i ma t e a ndd e t e r mi net hel i ke l ye f f e c t sofgr e e nhous ewa r ml ng.Ne ve r he t l e s s ,t hes t oc k a n dl fO ws t r uc t u r eoft hegl oba lc a r bonc yc l ea ndhe a tbudge te xpl a i nss omeba s i c f e a t u r e soft hed yna mi cs . Thes t oc ka ndf lOws t r uc t ur es howshowi ti spos s i bl ef o r ‑ 2 48 P a r t I IT o o l sf o rS y s t e ms Th i n k i n g t heg l o ba lt e mpe r a t u r et or i s ee ve na f t e rhu ma nGHGe mi s s i o nsf a l lt oz e r o. Whe n e mi s s i o nsf a l l t oz e r ot hei nf lo wst ot hes t o c kofa t mos phe r i cc a r bo nf a l l be l owt he out nows . The r e f o r et hes t o c kofCO2i nt hea t mos phe r epe a ksa ndbe gi nst of ll a . Thec onc e nt r a t i o no fC0 21 nt hea t mos phe r ef a l l so n l ys l o wl y , ho we ve r 。 Fi r s t ,血e nt hea t mos phe r e upt a keo fc a r bonbybi o ma s sf a l l sa st hec o nc e nt r a t i o no fCO2i de c l i ne s , whi l eCO2c o nt i nue st of lO wi nt ot hea i rf r o mbur nl nga ndde c a yo fbi 0‑ ma s sa ndh umuss t o c ks . Se c ond, a sa t mos phe r i cCO2f a l l s , hef t luxo fc a r bo nf r o m t hea i rt ot hemi x e dl a y e ro ft heo c e a nf a l l s , whi l et hef lu xo fc a r bo nf r o mt heoc e a n t ot hea i ri nc r e a s e s ・ The s ec o mpe ns a t o r yr e s po ns e ss l o wt hede c l i n eo fa t mos phe r i c ha t5 0y e a r sa f t e rh uma ne mi s s i o nss t o pc ompl e t e l y , t hec onc e nt r a t i ono f CO2SO t nt hemo de la t mos phe r eha sf a l l e nba c ko nl yt oi t s1 990l e ve l . C0 2i Thehe a tc o nt e nto ft hes ur f a c el a ye rr i s e sa sl o nga si nc o ml ngr a di a t i one x‑ c e e dst hehe a tr a di a t e dba c kt os pa c eo rt r a ns f e r r e dt ot hede e poc e a n.Though O nC e nt r a t i o nsr e ma i nhi gh f a l l i nga f t e rt heye a r2000,g l o ba la t mos phe r i cCO2C e noug ht or e d uc et hee ne r g yr a d i a t e dba c kt os pa c ebe l owi nc o ml ngl nS Ol a t i on. f t e r2000me a nsg l o ba lme a nt e mpe r a t ur eg r owsa ta De c l i ni nga t mos p he r i cCO2a d i mi ni s hi ngr a t e . Bya bo ut203 0t hes ur f a c eha swa r me de no ug ha ndt hec o nc e n‑ t r a t i o nofCO2i nt hea t mos phe r eha sf a l l e ne noug hf o ri ns o l a t i o nt obeba l a nc e d a ga i nbyt hee a r t h' sbl a c k‑ bodyr a di a t i o na ndt her a t eo fhe a tt r a ns f e rt ot hede e p oc e a n. No t et ha tgl o ba lme a nt e mpe r a t ur ef a l l so nl ys l owl ya f t e r203 0, Fi r s t ,t he s l ow de c l i neo fGHGc o nc e nt r a t i o nsa f t e r2000s l o wst hei nc r e a s ei nr a di a t i ve ur f a c et e mpe r a t ur ee x‑ e mi s s i v i t y . Se c o n d, d u r i ngt hewa r me s tde c a de swhe nt hes c e e de dt het e mpe r a t u r eoft hed e e po c e a n, he a tf lowe df r o mt hes u r f a c el a ye rt ot he d e e p. Ast hes u r f a c el a ye rc oo l s , he a ts t o r e di nt hede e poc e a nnowf lo wsba c kt o t hes ur f a c e , s l o wi nga t mos phe r i cc oo l i ng. Thes t oc ka ndf lO ws t r u c t ur eoft hec a r bo nc yc l ea ndhe a t ba l a nc ee xpl a i nst he s e e ml ng l ypa r a do xi c a lr e s ul tt ha tt e mpe r a t ur e sc a nr i s ee ve nwh e ne mi s s i o nsf a l l . The r ea r es e ve r a ll e s s o ns . Fi r s t , gl o ba lwa r mi ngC a nno tbepr ov e no rd i s pr ove nby c o r r e l a t l nge mi s s i onsa ndt e mpe r a t u r e:t hedyna mi c sa r et ooc o mpl e xf o rs uc h na i vec o mmo ns e ns ea p pr oa c he s . Se c o nd, t hef u l li mpa c to fpa s te mi s s i onsha snot ye tbe e no bs e r ve d. Theoc e a nsa ndt e r r e s t r i a lc a r bons t oc ksha vebe e na bs o r bi ng c a r bo no uto ft hea t mos phe r ea thi ghe rr a t e s ,S uppr e s s l ngt her i s ei na t mos phe r i c CO2C O nC e n t r a t i o ns . Anda st he s es t oc ksi nc r e a s e , t he i ra bs o r pt l O nC a pa C l t yd i mi n‑ i s he s . Thei mpa c toff u t ur ee mi s s i onsona t mos phe r i cCO2ma yWe l l bel a r g e rt ha n t ha to bs e r ve di nt hepa s t . Thi r d,t hei ne r t i ao ft hes ys t e mme a nsf u r t he rwa r ml ng a ndc l i ma t ec ha ngea r ea l r e a d yunde r wa y . Ac t i ont oha l twa r ml ngmus tbet a ke n de c a d e sbe f o r ewec a nk no wwha tt hec o ns e que nc e so fwa r mi ngWi l l bea ndbe f or e s c i e nt i f i cc e r t a i nt ya bo utt hed yna mi c so ft hegl o ba lc l i ma t ec a nbega i ne d. Mos ti mpo r t a nt , t nes t oc ka ndF l owS t r uc t ur eO ft heg l ob a lC l i ma t eme a nsS t a ‑ bi l i z l nge mi s s i onsne a rc ur r e ntr a t e swi l lnots t a bi l i z et hec l i ma t e.Fi g ur e7‑ 1 0 s howsas i mul a t i o ni nwhi c he mi s s i o nsa r es t a bi l i z e di n1 9 95. Thec o n c e nt r a t i ono f a t mos phe r i cCO2C On t i nue st or i s e , mo r et ha nd ou bl i ngby23 00. Gl o ba lme a ns ur ‑ f a c et e mpe r a t u r er i s e sbya bo ut3o C. Ma nyi ndus t r i a l i z e dna t i o nsa g r e e da tt heRi o c onf e r e nc eont hee nvi r o nme ntt os t a bi l i z et he i rGHGe mi s s i o nsa t1 990l e ve l s , a nd38i nd us t r i a l i z e dna t i o nsa g r e e da tt he1 997Kyo t oc o n f e r e nc eo ft heUNFCCC t or e d uc ee mi s s i o nsby201 2t oa bo ut95% of1 99 0r a t e s . Bu tt heUSSe na t ede ‑ c l a r e dt het r e a t yd e a do na r r i va l . I mpl e me nt a t i o nr e ma i nse l us i ve; s l g nl ngat r e a t y 249 Ch a p t e r7 Dy n a mi c so fS t o c k sa n dF l o ws o Z St abi l i zl ngGHG emi s si onsat1 995 1 evel sc ausesaト mos pher i cCO2 con c en t r at i on st o doubl eby2300, whH emeangl ob al sur f ac et emper a t ur ei ncr eases abou t3o C.Ev en undert hepr o‑ pos edKy ot o agr eement ,gl ob al eml S S 1 0nSar e l i k el yt oi ncr eas e subs t an t i a" yo ver t hene x ts ever a一 dec ades. ( J eo^J su 13! J l a∈ uO≡苗) u so !sE s uu o3 0Eu亀odoJLJtuV FI GURE7 ‑ 10 St abi l i zl ngGHG emi s si onsdoes nots t abi 一 i zet he cl i mat e. 1950 2000 2050 2100 2150 2200 2250 2300 2000 2050 2100 2150 2200 2250 2300 2000 2050 2100 2150 2200 2250 2300 ‑ N oo H l q dsoEV 3] }a 0 0 0 0 0 0 5 2 9 ■ ll ■ l g) ( suoI U苫a∈ uO!! 1950 ( pu o しぎ o2 tq a^ ^L eL u OuV aJnlt2 3 2 n O q e30 ) J a d ∈a l t 2 i J mSu d ¢ ≡ lq t !O1 9 a3 1950 Sour ce:F I ‑ d d a ma n(1997) . i sonet hi ng,a c t ua l l yr e d uc i nge mi s s i onsa not he r . Mos tt r oubl i ng, t hee mi s s i onsof r a pi dl yde ve l o pl ngna t i onss uc ha sChi nac ont i nuet ogr ow a thi g he xpone nt i a l r a t e s . TheUSEne r g yl nf or ma t i o nAdmi ni s t r a t i onf or e c a s ti n1 997t ha tGHGe mi s ‑ s i onsf r om de ve l o pi ngna t i onswo ul dne a r l ydoubl eby201 5,a c c ount l ngf ort he l a r gema j or i t yoft hewor l dt ot a l( Ma l a kof r1 997) . Whi l edi fe r e ntc l i ma t emode l sdi fe ri nt he i rde t a i l sa ndi nt he i re s t i ma t esof ut f ur ewa r mi ng, a l la gr e et ha ts t a bi l i z i nge mi s s i onsne a rc ur r e ntl e ve l swi l lnots t a ‑ bi l i z et hec l i ma t e・ Mi t i ga t i ngt her i s kofc l i ma t ec ha ngef r om gl oba lwa r ml ngr e qul r eSaS ubs t a nt i a lde c l i nei nt her a t eo fGHGe mi s s i ons ・ Thewor l dha sye tt of a c e upt ot hei ne xo r a bl el ogi cOft hes t oc ksa ndf lowsoft hegl o ba lc l i ma t es ys t e m. ‑ 250 7. 3 Pa r tI IT o o l sf o rS y s t e ms Th i n k i n g SYsTEM DYNAM! CSI NAcT1 0N:Tt lEW ARON DRUGS I nt he1 98 0st heus eofc oc a i nei nc r e a s e ddr a ma t i c a l l y. Asc oc a i nes pr e a d,c r i me, vi ol e nc e ,a ndhe a l t hpr obl e msgr e we xpone nt i a l l y. TheUni t edSt a t esde c l a r e da wa rondr ugs . Ane wf e de r la a ge nc y,t heWhi t eHo us eOfi c eofNa t i ona lDr ug "wa sa ppoi nt e dt oove r s e e也e Cont r oIPol i c y( ONDCP) , he a de dbyt heH d r ugc z a r , c a mpa l gn. Pe na l t i e sf o rpos s es s i o n,s a l ea ndus eofd r ugswe r es t i f f e ne d・Bi l l i ons we r es pe ntt oi nc r e a s ee nf or c e me nt ,e s pe c i a l l yt or e duc et henowofc oc a i nei nt o t heUS,e s t i ma t e dbyt heONDCPt obe550t o660me t r i ct onsi n1 98 9。 Thef oc us o ft hewa rondr ugswa spr i ma r i l yt hes uppl ys i de:s l a s hi ngt hepr oduc t i onofco‑ c a i ne,c ho ki ngof fs muggl i ngI nt ot heUS,a nds t i f f e ni ngpe na l t i esf o rpos s es s i on a nds a l e, Ont hede ma nds i de, ki dswe r et ol dt o" J us ts a yNO. H Somedr ugda t a Di di two r k?I nt hel a t e1 980st heda t at ol dac o nf li c t i ngs t ory. s howe di mpr ove me nt .Thr ought heH Na t i ona lHous e hol dSur ve yH( NHS)a nd H Hl ghSc hoo lSe ni o rSur ve yH( HSSS) , t hegove r nme nt r e g ul a r l ya s kspe opl ea bout t he i rus eo fa l c ohola nddr ugs .Tba s s es st r e ndsi ni nc i de nc ea ndpr e va l e nc e,也e s ur ve ysa s kwhe t he rpe opl eha vee ve rus edc oc a i ne, whe t he rt he y' veus e di ti nt he l as tye a r ,a ndwhe t he r血e y' veus e di ti nt hel a s tmont h・Fi gur e7‑ l ls howsNHS da t af o rt he虫. a c t i o nofpe opl er es pondi ngt ha tt he yha veus e dc oc a i nei nt hepas t mont h. Ac c or di ngt ot hes ur ve ys ,c oc a i neus ewa sf a l l i ngs ha r pl y,wi t hl e s st ha n 1 % oft hepo pul a t i o nr e po r t l ngpa s tmont hc oc a i neus ei n1 990,downf r om 3% i n 1 985. Thedr o pl nr e po r t e dus ec oi nc i de dwi t has ha r pl nC r e a S ei nt hes e i z ur er a t e, t omor et ha n75me t r i ct onspe rye a r( Fi gur e7‑ 11 ) . Thewa rondr ugss e e me dt obe wo r ki ng. , c i t i ngt he s eda t a, t hea dmi ni s t r a t i onc a l l e df o re ve nmo r emone yt of i ni s h t hej ob. Howe ve r ,ot he ri ndi c a t o r ss howe dt hepr obl e mwa sge t t l ngWOr S e・ Ar r e s t sf or pos s es s i ona nds a l eofc oc a i ne,t henumbe rofe me r ge nc yr oom vi s i t sa s s oc i a t e d wi t hc oc a i ne, a ndt henumbe rofc oc a i ne ‑ r e l a t e dde a t hsa l ls howe de x pone nt i a li n c r e a s es ,whi l et hepur l t yOfc oca i neont hes t r e e twa sg r owl nga ndt hes t r e e tpr l C e wa sf a l l i ng( Fi gur e7‑ ll ) .Byt hes eme as ur e s ,c oc a i neus ewa sups ha r pl ya nd a va i l a bi l i t ywa sg r owl ng. Cr i t i cs ,C i t l ngt hef a i l ur eofpr ohi bi t i oni nt he1 920sa nd 1 930S ,a r gue dt ha ti nt e r di c t i onc oul dne ve rwor ka ndc ll a e df ors t r onge rde ma nd‑ s i deme a s ur e s( Ma c Co una ndRe ut e r1 997r e vi e w血ede ba t e ) .Ot he r sa r gue dt ha t ob l e mc a us e dbyus eofi l l e ga l de c r i mi na l i z a t i onwoul de l i mi na t et hec r i mepr d r ugsa nda l l owt hegove r nme ntt or e gul a t epur l t yt Opr e ve nta c c i de nt a love r dos es ・ Muc hoft hede ba t ef oc us e donwhi c hda t as e r i eswe r er i ghta ndwhi c hwe r e wr ong.Thes t a ke swe r ehi gh:Bes i dest hei s s uesofpubl i chea lt ha nds a f e t y,t he d r ugwa rwa spr os e c ut e da ndda t as e r i eswe r ec ol l e c t e dbya na l pha be ts oupof f e de r a la nds t a t ea ge nc i e s , i nc l t l di ngt heFBI , DEA, SAMHSA, NI J , NI DA, DEPB, A・ 2Ea c ha r gue df ort hepr l ma C ya ndc or r e c t nes sofi t sda t aa nd ONDCP,a nd CI ‑ 2 Fe d e r a l Bur e a uo f I n v e s t i g a t i o n , Dr ugEn f o r c e me n t Ag e n c y , S u b s t a n c eAb u s ea n dMe n t a l He a l t hS e r v i c e s Ad mi n i s t r a t i o no ft h eDe p a r t me n t o fHe a l t ha n dHu ma nS e r v i c e s , Na t i o n a l I n s t i t u t eo f J u s t i c e , Na t i o n a l I n s t i t u t eo nDr ugAb u s e , Dr u gEn f o r c e me n t P o l i c yBo a r d , Ofi c eo f Na t i o n lDr a ugCo n t r o l P o l i c y , a n dCe n t r a l I n t e l l i g e n c eAg e n c y ・ L . N9 6 L . 086 L I eト 6 L l‑ 0 9L6 L nd ;・ ′ ∧ % 066 L 996 の86 \ L L \ 996 9 00 6 ‑ .; , ;・ :" ,M ・/I. ..∵ \ L L L L 寸の6 L 寸86 ∵ 寸86 N9 6 L L Ⅲ L L 1 ' Cト 6 二 8ト6 T 9 ト6 L 9ト : aDJ nOS 9ト 6 L . 9ト6 L 009 6L . ( ト66LL c66L)LO ∈OH L . '' ' 'I O ¢ 6 L1 086 0 9 6 LI : . , , .. . Ne 6 小 86L 1 N LL・ト N 寸 0N o寸 09 00 L 09 L D t D J 亡 L N96 L N96 L J L 1 10!u aP!da au!?。03 aLlト 6LL 4 6no ■ ■ ■ ■ 寸96 t 78 6 LI L I 6 8 t O ( O C) 996 L 996 寸96 ■ : ‑ L L 1 996 L ⊂〉 主己 07 886 99 6 L . G O ト■ 066 L L 996 CO トー O) O ) ▼■ 9L m t ] n u ( u別6/ So66L)的 ! J d J e e ^ pl do∂ dpu t 2 Sn OL 比 ( uo! 1 e l n dod1 0u O! l 〇 t 叫)a 〇u 判e ^a J d N N 昌i ⊂) O . p ‑ OJ ⊂〉 O O く り 0 く つ 0 寸 ⊂ 〉 寸 L L ) L L ) 066 066 ( . C O 亡 O C h く ⊃ t D O J 開^ / a l doa dput 2 Sn OL l ⊥ ( J 閃^ / 6〉 toooL )s a J n Z ! aS ( つ L O ( =l CO 0) Y‑ ▼■ ■ ■ 卜・ C1 L CI ト a) ▼ ■ ■ ■ ト、 く つ C O O) L ‑ 251 252 Pa r t I IT o o l sf o rS y s t e msTh i n k i n g dr ug‑ e nf o r c e me ntpr ogr a msa st he ys t r uggl e dt oga l nal a r gers ha r eofmor et ha n $1 0bi l l i o npe rye a rde vot e dt ot hewa rondr ugs . Suppor t e r soft hei nt e r di c t i ons t r a t e gya r gue dt ha tt hes ur ve yda t adi r e c t l y me a s ur e dwha tc ount s ‑t heus eofdr ugs ‑whi l eot he ri ndi c a t or swe r ei ndi r e c t . The ya r g ue dt ha tr i s i nga r r e s tr a t esa nds e i z ur e sr e le f c t e dgr e a t e re nf or c e me nt , not g r e a t e rdr ugus e ,a ndwe r et he r e f or eas l gnOfs uc c e s s ;f a l l i ngpr i c es , r l S l ngPur i t y , a ndt hes ur gei nme di c a le me r ge nc i e sa ndde a t hss i mpl yr e le f c t e dt hes ubs t i t ut i on ofmo r epot e ntc r a c kf ort hel es spur epowde rf o r m. Cr i t i c sofi nt e r di c t i ona ndt he s ur ve yda t aa r g ue dt ha td r ugus e r sa r el es sl i ke l yt ha nl a w‑ a bi di ngc i t i z e nst obes e ‑ l e c t e df o rorpa r t i c i pa t ei nt hes ur ve ys ・ Ma nyc oc a i neus e r sa r el i ke l yt ode nyt he y us edr ugswhe nt hegove r nme nta s ks . De f e nde r soft hes ur ve yspoi nt e dt ot hes o‑ phi s t i c a t e ds a mpl i ngme t hodst he yus e dt oa c c ountf orpos s i bl eunde r r e pr es e nt a ‑ t i onofc e r t a i ns ubpopul a t i ons ・ The ygua r a nt e e da nonyml t yt OS ur ve yr e s ponde nt s a ndc l a i me dt ha twhi l eH[ t ] heva l ueofs e l f ‑ r e po r t sobvi ous l yde pe ndsont hehon‑ e s t ya ndme mor yofs a mpl e dr es ponde nt s [ , r ] e s e a r c hha ss uppor t e dt heva l i di t yof s e l f ‑ r e po r tda t ai ns i mi l a rc ont e xt s "( SAMHSA1 99 4) . I nt hel a t e1 98 0S血eNa t i ona ll ns t i t ut eofJ us t i c ec ommi s s i one das t udyt or e ‑ s ol vet hea ppa r e ntpa r a doxofde c l i ni ngmea s ur e sofc oc a i neus ea ndr i s l ngC On‑ s umpt l On,C r i me,a r r e s t s ,a ndde a t hs .Aspa r toft hes t udy,as ys t e m dyna mi c s mode lwa sde ve l o pe dt oi nt e gr a t et hede ma nda nds uppl ys i de soft hema r ke t ( Home r1 993,1 997) .Thef ul lmode lc ons i s t e dofs e ve r a lhundr e de qua t i onsa nd i nc l ude dade t a i l e dr e pr e s e nt a t i onoft hes t oc ka ndf lows t r uc t ur eofus e r s ,a l ong wi ht t hef e e d ba c ksa mo ngdi fe r e ntma r ke ta c t o r s , t hema r ke t , a ndt hec r i mi na l j us ‑ t i c es ys t e m. Fi gur e71 1 2S howsas i mpl i f i e dr e pr e s e nt a t i onoft hes t oc ka ndf lows t r uc t ur e f ort hedi fe r e ntc a t e gor i e sofdr ugus e r sr e pr es e nt e di nt hemode l . TheNHSc on‑ s i de r sa l lpe r s onsa ge1 2a ndove rt obepot e nt i a ldr ugus e r s ・ Aspe opl ei nt hi sa ge g r oupf i r s te x pe r i me ntwi t hc oc a i net he ymovef r omt he" ne ve rus e d"popul a t i on t ot hes t oc ko fa c t i vec as ua lus e r s( t hos ewhoha veus e dc oc a i nei nt hepa s tmont h buta r enota ddi c t e d) . Somec a s ua lus e r sf i ndt he yc a nnotc ont r olt he i rc oc a i nec on‑ s umpt l Ona ndbe c omec ompul s i veus e r s . Ac t i veus e r s , bo t hc a s ua la ndc ompul s i ve, c a ns t o p,be c omi ng" t r a ns i t i ona lus e r s "( t hos ewhoha veus e dc oc a i nei nt hepas t ye a r , butno ti nt hepa s tmont h) , Tr a ns i t i ona lus e r sca nr e l a ps e,be c omi nga c t i ve us e r sa ga i n. Af t e raye a rwi t houta nyc oca i neus e , t r a ns i t i ona lus e r sa r er e c l a s s i f i e d a se x‑ us e r s ・Somee x‑ us e r sr e l a ps e ,be c omi nga c t i veus e r sa ga i n・Ot he r squl tpe r ‑ ma ne nt l y.The r ea r e,ofc our s e,de a t hr a t esoutofea c hs t oc k,bot hf r om dr ug‑ r e l a t e dc a us e sa nda l lot he rs our c es 。 Thef u l lmode lha samor ec ompl e xs t oc ka ndf l ow s t r uc t ur et ha ns hown i nFi gur e7‑ 1 2,e xpl i c i t l ydi s t i ngui s hi ngbe t we e nc a s ua la ndc ompul s i vet r a ns i ‑ t i ona la nde x‑ us e r sa ndbe t we e nus e r sofpowde ra ndc r a c kc oc a i ne.Themode l a c c ount e df ore s c a l a t i onf r omc a s ua lt oc ompul s i veus ea ndf ors wi t c hi ngbe t we e n powde ra ndc r a c k.Thi sdi s a ggr e ga t i onwa sne c es s a r ybe c a us et hepr oba bi l i t i e s ofmovi ngf r om ones t a t et oa not he rde pe ndont hef or ma ndi nt e ns l t yOfus e. s i veus e r sa r el es sl i ke l yt oqui ta ndmor el i ke l yt or e l a ps e, a ndc r a c kus e r s Compul a r emo r el i ke l yt oes c a l a t ef r om c as ua lt oc ompul s i veus ea nds uf f e rhi ghe rr e ‑ ps er a t e s . l a Ch a p t e r 7 Dy n a ic m so fS t o c k sa n dF l o ws 253 Fl GURE7 ‑ 12 Cocai n eus e: s t ock sandf 一 ows Sour c e: Ad a p t e df r o mHo me r ( 1993) . Not et ha tt hec a t e go r i e sofus ei nt hemode lc a nbedi r e c t l yc o mpa r e dt ot hos e us e di nt hes ur ve ys . Thet ot a lnumbe rofa c t i veus e r s , bot hc a s ua la ndc ompul s i ve, f orbot hpowde ra ndc r a c k, i st henumbe rofpe o pl ewhoha vea c t ua l l yus e dc oc a i ne i nt hepa s tmont h. Thes umoft hea c t i veus e r sa ndt het r a ns i t i ona lus e r si st het ot a l numbe rwhoa c t ua l l yus e dc oc a i nei nt hepa s tyea r . Fi na l l y, t hes umofa c t i ve , t r a n‑ s i t i ona l ,a nde x‑ us e r si st het ot a lnumbe rwhoha vee ve rus e dc oc a i ne. Wha ta r et hede t e r mi na nt soft hei ni t i a t i onr a t e ‑wha tc a us e spe o pl et ous ec o‑ c a i nef ort hef i r s tt i me?St udi e ss howmos tpe opl ebe gi nus i ngdr ugst hr oughpe e r i nf lue nc e ‑byo bs e r vl ngOt he r sus l ngdr ugsa ndt hr ought he i rme mbe r s hi pi ns o‑ c i a lne t wor ksi nwhi c hot he r sus edr ugs( t ha ti s ,byha ngi ngwi t ht hewr ong c r owd) ・ Asmor epe opl es t a r tus i ngc oc a i ne ,t hes oc i a lne t wo r ksofus e r se xpa nd, br i ngi ngS t i l lmo r enonus e r si nt oc ont a c twi t ht hedr ug,i napos i t i vef e e dba c k pr oc es sa na l ogo ust ot hes pr ea dofa ni nf e c t i ousdi s e a s e( c ha pt e r9) ・ Thes t r e ngt h oft hes oc i le a xpos ur ef e e dba c kde pe ndsont hes oc i a la ur aoft hedr ug:howc hi c c oca i nei spe r c e i ve dt obe( i st hi st hed r ugt heopi ni onl e a de r s ,t hebe a ut if ulpe o‑ pl e,a r eus i ngt hi sye a r ? ) . Thepos i t i vef e e dba c ka l s ode pe ndso nwhe t he rc ur r e nt 254 P rt a I IT o o l s f o rS y s t e msT h i n k i n g a ndpot e n t i a lus e r svi e wt hedr uga sbe ni g n ‑i sl tPe r c e i ve dt oo f f e ragoodhi g h wi ho t utne ga t i vee fe c t ss uc ha sa ddi c t i o n, ba dt r i pso rt her i s ko fs udde nd e a t h? , Pr i c eha sac o mpa r a t i ve l ymode s te f f e c t , a tl e a s ti nhi ghe rs oc i oe c o no mi cg r o u ps be c a us ehi h pr g i c ea nds c a r c l t yC O nf e rs o c i a ls t a t uso nt hos ewhoc a npr o vi d et he d r ugf わrf r i e ndsa tpa r t i e so ri nt hewo r k pl a c e.I nt hemi d1 970S ,a st hec o c a i ne e pi de mi cbe ga n,c oc a i newa svi e we da sabe ni g n,no na ddi c t i ved r ugpos l ngl i t t l e he a l hr t i s k.I tbe c a met hei n‑ g r ou pd r ugo fc ho i c ea mongc e r t a i npr of e s s i o na l e l i t e s ・ Thee nt e r t a i nme n ti nd us t r yr e i nf わr c e dt hec hi ci ma geoft hedr ug・ Al lt he s e s e l f ‑ r e i nf o r c i ngpr oc es s e sa r ec a pt ur e dbyt heWo r dofMout hl oo pRli nFi g‑ u r e7‑ 1 3. Thed yna mi c so ft hema r ke tr e i n f o r c e dt heg r owt hoft hee pi de mi c. Asc o n‑ . s umpt i o ni nc r e a s e d,t hes uppl ys i deo ft hema r ke tbe c a memuc hmo r ee fi c i e nt Pr i c ede c l i ne da ndpu r l t yl nC r e a S e d. Theg r owl n gs c a l eoft hei nd us t r yc r e a t e dhuge i nc e nt i ve sf o rt e c hno l og l C a la ndo r g a n i z a t i o na l i n nova t i o nbypr od uc e r sa nds mug‑ g l e r s ・ Thei nt r oduc t i onofc r a c kc o c a i nei n1 98lwa st hemos ti mpo r t a nt , bu tf a r f r o mt heo nl y , t e c hni c a l i nno va t i o ni nt hema r ke tAsi nma nyl e g l t l ma t ei nd us t r i e s , g r owt hl e dt opr od uc t i o na nde s pe c i a l l yd i s t r i but i o ns c a l ee c onomi e s . Ho r i z o nt a l a ndve r t i c a lma r ke ti nt e g r a t i ont hr oug ht hec oc a i nec a r t e l sc utc os t sa ndl e dt o mo r ec o ns i s t e ntpr od uc tq ua l i t y . Gr owl nge x pe r i e nc el e dt oas ubs t a nt i a ll e a r nl ng c u r vea sha r ve s t l ng,Pr oduc t i o n,s muggl i ng,di s t r i but i o n,a ndmone yl a unde r i ng o pe r a t i o nswe r ei mpr ove d・ The s es c a l ea ndl e a r nl nge f f e c t sc r e a t e da ddi t i o na l pos ‑ i t i vef e e d ba c ksl e a di ngt owi de ra va i l a bi l i t y , g r e a t e rpu r l y, t a ndl owe rpr l C e S , ma k‑ l l( l oo pR2) ・ i ngc o c a i nea 耽) r da bl ea nda c c e s s i bl et oa Asl onga spe o pl epe r c e i ve dt hehe a l t ha ndl e ga lr i s ksofc oc a i net obes ma l l , t he s epos i t i v ef e e d ba c ksdomi na t e dt hes ys t e m. Co c a i neus emus hr oo me d, s pr e a d‑ 1 ngg r a d ua l l y血. o mmi ddl ea ndu ppe ri nc o me ,t r e nd‑ c o ns c i o uspo pul a t i onsont he e a s ta ndwe s tc oa s t st oe ve r ys oc i a la ndi n c o mel e ve li ne ve r ys t a t eoft hec ou nt r y . Whyt he nd i dt heda t as hows uc hal a r g ed r o pl nt hei nc i de nc eofc ur r e n tc o‑ c a i neus ea f t e r1 98 5?Su ppo r t e r soft hei n t e r d i c t i o ns t r a t e gyc r e di t e dt hea d mi n i s ‑ t r a t i o n' ss u ppl y‑ s i depo l i c y. The ya r g ue dt ha te nha nc e de nf o r c e me nti nc r e a s e dt he f r a c t i o no fc oc a i nes e i z e d,c ut t i ngt hea va i l a bi l i t yo ft hedr ug( t heba l a nc i ngSu p‑ )a ndt ha ta gg r e s s i ve l ya r r e s t i nga ndi nc a r c e r a t i ngpus he r s pl yDi s r u pt i o nl oo pB1 heSt r e e t s( t heba l a nc i ngl o o pB2) ・ Bo t ht he s ene ga t i ve a ndus e r she l psc l e a nupt utd r ugus e , a si nd i c a t e dbyt hes u r ve yda t a . l oo ps , i twa sa r g ue d, c ndf low s t r uc t ur ef o rd ugus r e r ss howe dt ha tt hes ur ve yda t a Howe ve r ,s t oc ka c oul dnotbec or r e c ta ndwe r es ubs t a nt i a l l yunde r s t a t i ngt hepr e va l e nc eo fd ug r s ki nga bou tpa s tmo nt hus e , t heNHSa s ksr e s po nd e nt si ft h e y us e ・ I na dd i t i o nt oa ha veus e dc o c a i nei nt hepa s tye a ra ndi ft he yha v ee ve rus e dc oc a i ne . Home rc a r e ‑ f ui i ydi s a gg r e ga t e dt heus e rpo pul a t i oni nt os t oc ksc o r r e s pond i ngt ot he s ec a t e ‑ oul dbedi r e c t l yc o mpa r e dt ot heda t a . g o r i e ss ot hemode lc Fi g ur e7‑ 1 4s howst heNHSda t af o rt hef r a c t i o noft hepo pul a ionwhor t e ‑ s po nd e da f f i r ma t i ve l ywhe na s ke di ft he yha de ve rus e dc oc a i ne.Not et ha tt he c oc a i nepo pul a t i o npe a ksi n1 98 2a ta bout1 2% a ndf a l l st o r e po r t e de ve r ‑ us e d‑ a bo utl o啄by1 988. Thel i f e t i mec oc a i nepr e va l e nc eda t ai nFi g ur e71 1 4i st her a t i ooft hee ve r ‑ ot het ot a lpo pul a t i o n( t hos ewhone ve rus e dpl ust hos ewhoe v e r us e dpo pul a t i ont us e d) A Thei nf lowt ot het ot a ls t oc kofpe o pl ewhoha vea c t ua l l yus e dc oc a i nei st he ^)! J ^ aa sauuat uas l u ua∈a3'0‑ uu 川ゝ l!Sua ∴ a LLJ!J I 3 Pal el at ] ・ au! E 2 3 00 3 , J tS ut 2al ^ lP t .l. q JOL N ^l ! l etOM Pue +I Pat el at J ・ au! eOOU 帯 S 簡 ! a Sq St ] L Jte l H Pa^! a 3J l a S a J JIV I O JI t= a L l ・ ; g T (6 t 2 I U aEul t 2 ! 3 0S Pu L J t lE2aHa^!lt26aN , ・ asn‑ o^ouauau asn‑ o^) ! sual uI L L J J I 0‑PaJ ua‑ aJ l d・ ^qpal e6聖 66es! Q uo! l el ndodJ aSnau!e300 L J l n O LN IO P J 0 ≧ r ・ i . u y au! t 2 003 otaJ nsodxj l e! 00S u I. ^ 1 a 6 d . ( C 6 6 !t e JL S 一 e !30 ト Uun9 正 L u OHL uOJiPatdt2PVJ aO L J nOS L)] a ) ㍉ ^ ! I.t n U u CL ・ ^) ! [ ! q ed ta uov s qsjJt2a 6l PaaUa J l d a o! L uaP! daau1[ t 2 303eL l 1ち eJ n1 0nJ t S宅 eqPOaj SJaS⊃I OuO S ⊃ au! t 2 003 1 0 u ! t JodaJ Lp と 。 , ・ uo! t d∈nsu03 st J odul Sal eSl ! et at ]・ ^l ! J nd, aul. J dl I. E ! t at j l aqJ I t 2 m au! t 2 303 aS nau! e303 1 0a 3ual e^aJ d pauodat J ノ 二/ 0 . 掌 255 256 ( uo 0. 1 5 0. 1 0 O dd1 0u ] no !tt ? FJ GURE7 ‑ 14 Sur veyest i mat es oHi f et i mecocai ne pr eva一 ence Pa r t I I To o l sf o rS y s t e msTh i n k i n g 2 ' i )33ua [e^J ¢d !13 t 0. 05 0. 00 1 976 1 980 1 98 4 1 9 88 1 992 1 99 6 Sour c e: Na t i o n a l Ho u s e h o l dSu r v e y , Ho me r ( 1 9 9 3 , 1 9 9 7 ) i ni t i a t i onr a t e.Theonl yout low i f sdea t h.Theonl ywa yt hes t ockofpeopl ewho ha vee ve rus edcoca i neca nde c l i nei sf ort hede a hr t a t eofc ur r enta ndpas tus e r st o e xc ee dt hei ni t i a t i onr a t eofne w us e r s ・ 3Ye tt hes ur ve yda t ar e por t e da3・ 2% dr op i nt henumbe rofpeopl ewhoha veeve rus edc oca i nef r om 1 982t o1 988.Eve ni f t her a t ea twhi c hpe opl et r i edc oca i nef ort hef i r s tt i mef e l lt oze r oi n1 985‑ e ve n i fe ve r yma n,woma n,a ndc hi l di nt heUSwhoha dneve rus edc oca i neJ us ts a i d NO! ,s omet hi ngnoteve nt hea dmi ni s t r a t i onbe l i e ved‑ mor t al i t yr a t esoft hee ve r ‑ us e dpopul a t i ona r et oos ma l lt oca us et her e por t e dde cl i nei nt henumbe rofpe o‑ pl ewhohaveeve rt r i edcoca i ne.Eve nwi t ht hemos topt l mi s t i ces t i ma t esf ort he de c l i nei nt hei ni t i a t i onr a t e, i ti sphys i c a l l yi mpos s i bl ef ort hes t oc kofpe opl ewho ha vee ve rus edcoca i net of a l la squi c kl ya st hes ur ve yss ugges t ed・ 4 W hyt hendi dt her e por t edi nc i de nceofus ef a l ls odr a ma t i ca l l ya 氏e r1 985? The r ea r et woma i nr eas ons . Fi r s t , t hes ur ve yspr es umet ha tt he i rs a mpl esa r epr op‑ e r l ys t r a t i f i e d,t ha ti s ,t ha tt her e pr e s e nt a t i ona ndr es pons er a t esofs ubpopul a t i ons ( s uc ha sdi f f e r entgeogr a phi c,e t hni c,r a c i a l ,a nds oc i oeconomi cgr oups )a r ea d j us t edt oma t c ht hepr opor t i onoft hes egr oupsi nt heove r a l lpopul a t i ona ndt ha t a nyunde r r e pr es e nt a t i oni sc ons t a ntt hr ought i me.Hea vydr ugus e r s ,howe ve r ,a r e muc hl es sl i ke l yt obei nt e r vi e wedf ort hes ur ve y. Thought heNHSme t hodol ogy a t t e mpt e dt oa d j us tf ort hi sunde r r e pr es e nt a t i on,t he yc a ut i onedt ha t ‑ Pr e va l e nc ee s t i ma t e sf o rs pe c i f i cs u bg r o u psa r es ome t i me sba s e do nmod e s tt o s ma l ls a mpl es i z e s , whi c hma yl e a dt os u bs t a n t i a ls a mpl i nge r r o r‥.[ T] hi sr e po r t do e snotpr e s e nte s t i ma t e sf o rs o mes e g me nt so ft heUSpo pul a t i o nt ha tma yc o n‑ t a i nas u bs t a nt i a lpr o po r t i ono fdr ugus e r s , s uc ha st r a ns i e nt sno tr e s i di ngl nS he l t e r s 3 I np r l n C I Pl e , t h el i f e t i mep r e v le a n c ef r a c t i o nc o u l df a ni ft h o s ei nt heev e r ‑ us e dp o p u l a t i o ne mi ‑ g r a t e df r o mt h eUSt oo t h e rc o u n t r l e Sa t ar a t emu c hh i g h e rt h nt a ha t o ft h o s ewh oh a v en e v e ru s e d c o c a i n e . Th e s er a t e s , h o we v e r , ren a e li g ib g l e . Fo rt h es u r v e yt ob ec o r r e c t t h er e q u i r e do u t ml g r a t i o n o fd r u gu s e r swo u l dg r e a t l ye x c e e da ll o u t ml g r a t i o nf r o mt h eUS. 4 Th ep r o b l e mi nt h es u rv e yd a t ai swo r s e . Th eNHSr e p o rt e dad r o pi nt hefr ac t i o no ft h ep o p u l l a t i o nt h a t h a se v e ru s e dc o c a i n e . Th ed e c l i n ei nr e l a t i v el i f e t i mep r e v a l e n c ewo u l dr e q u l r et he d e a t hr a t eo ff o r me rc o c a i n eu s e r st og r e a t l ye x c e e dt h ed e a t hr a t eo ft h o s ewh oh a v en e v e ru s e d c o c in a e , Th ed i fe r e n c ei nd e a t hr a t e s , h o we v e r , i sv e r ys ma l l , p a r t l yd u et ot h el o we x c e s smo r t a l l l t yO fa c t i v eus e r sa n dl a r g e l yb e c a us emo s t me mb e r so ft h ee v e r ‑ u s e dp o p u l a t i o nn ol o n g e ru s e c o c a i n ea n de x p e r i e n c emo r t a l i t yr a t e sa b o u t t h es a mea st h en e v e r ‑ u s e dp o p u l a t i o n ・ Ch a p t e r 7 Dy n a mi c so fS t o c k sa n dF l o ws 257 ( e . g. , u s e r so fs o u pk i t c he nso rr e s i d e n t so fs t r e e te n c a mpme n t s )a ndt hos ei n c a r c e r ‑ a t e di nc o u n t yj a i l so rSt a t ea n dFe d e r a l p r i s o ns( SAMHSA1 9 9 4 ) . Tha ti s ,f e wf e de r a lwor ke r sa r ewi l l i ngt oknoc ko nt hedoor sofac r a c khous et o a s kt heo c c upa nt swhe t he rt he yus ei l l e ga ldr ugs ・Cons e que nt l y,a c t i vea nde s pe ‑ c i a l l yc o mpul s i veus e r sa r eunde r r e pr e s e nt e di nt hes ur ve ys . Be c a us et hes epo pu‑ 1 a t i onsgr e wr a pi dl yl nt he1 980S ,t hes ur ve yss ys t e ma t i c a l l yunde r e s t i ma t e dt he gr owt hi nc oc a i neus e. Se c o nd,a ndmor ei mpor t a nt l y,1 nC r e a S l ngl e ga lr i s ksc a us e dal a r ge rf r a c t i on ofc ur r e nta nde s pe c i a l l yf or me rus e r st ode nyt he ye ve rus e dc oca i ne・ I npl a i nl a n‑ gua ge, mo r epe o pl el i e da boutt he i rpa s tc oc a i neus e. Thec ha ngi ngdi s t r i but i onof c oc a i neus e r sa ndde c l i nl ngS OC i a la c c e pt a nc eofc oc a i nel e dt os ys t e ma t i cunde r ‑ e s t i ma t i o nofc oc a i nepr e va l e nc ei nt hes ur ve yda t a. Byi nt e g r a t i n ga l lt hea va i l a bl eda t ai nt oac ons i s t e nta nduni f i e df r a me wor k, t hemode lpr ovi d e dmor ea c c ur a t ees t i ma t e sofdr u gus et ha nwe r ea va i l a bl epr e vi ‑ ous l y. Mode le s t i ma t e soft hee ve r ‑ us e dpo pul a t i on( a l o ngwi t ht heot he rca t e go r i e s ofdr ugus e )We r ede r i ve dt obec ons i s t e ntwi t hot he rde mogr a phi c,c r i me ,he a l t h, pr l C e , a ndpur i t yd a t a, c ons t r a i ne dbyt hes t oc ka ndf lOws t r uc t ur eoft hepopul a t i on a nde pi de mi ol og l Ca la ndme di c a lda t aonhe a l t hr i s ks . Unde r s t a l l di ngt hedyna m‑ i c soft hes t oc ksa ndf lOwsofus e r she l psr e c onc i l et hea ppa r e nt l yc ont r a di c t or y da t a. Fi g ur e71 1 5c ompa r e st hemode l ' sbe ha vi orf orr e por t e dl i f e t i meus ea ga l nS t t hes ur ve yda t a , a l ongwi t ht hemode l ' se s t i ma t eoft hea c t ua le ve r ‑ us e dpopul a t i on. Thea c t ua lpopul a t i onofpa s tus e r smus tha vec ont i nue dt ogr owbe c a us et henum‑ be rofpe o pl et r yi ngc oc a i nef ort hef i r s tt i mee xc e e de dt hede a t hr a t eoft hos ewho ha de ve rt r i e di t . Thea va i l a bi l i t y, pur l t y , a ndus eofc oc a i newe r ei nf a c ti nc r e a s l ng t hr ougho utt hel a t e1 98 0sdes pi t et hebi l l i onss pe ntone nf o r c e me nta nds uppl y r e d uc t i on. I nhi nds i ghti ts e e msq ul t eO bvi oust ha tt hes t oc kofpe o pl ewhoha vee ve rus e d c oc a i nec a nnotd e c l i nea sr a pi dl ya st heda t as ugge s t e d,S ot hes ur ve yda t as houl d i mme di a t e l yha vebe e nc ha l l e nge d. Buthi nds i ghti sa l wa ysc r ys t lc a l e a r . Thef a c t r e ma i nst ha tt hed a t awe r enotc ha l l e nge d. I ns t e a d, t hegove mme ntus e dt hes ur ve y da t at ot a kec r e di tf orwi nni ngt hedr ugwa r , t oj us t i f yi nt e ve r nt i oni nt hea f f a i r sof ot he rna t i ons ,a ndt ol obbyf o rt oughe rpe na l t i e s ,gr e a t e rpowe r sf o rl a we nf or c e ‑ me nta ge nc i es ,mor epr l S OnS ,a ndmor er e s our c e st ode f e ndt hebor de r soft heUS a ga l nS tt het hr e a toff or e i gndr ugs . Pe r ha pst hea dmi ni s t r a t i onkne wt heda t aove r s t a t e dt her e d uc t i oni ndmgus e a ndus e di tc yni c a l l yt oma ni pul a t epubl i co pi ni ona ndt hec o ng r e s s ・ Eve ni ft r ue, i ti l nme di a t e l ybe gst heque s t i onofwhyot he r si ngove mme nt ,a l ongwi t ht heme ‑ di a , pol i c ya na l ys t s ,a ndt hepubl i ca tl a r gedi dnotr e c ognl Z et hef la wi nt heda t a. Thea dmi ni s t r a t i on,c ongr es s ,a ndt heme di aa l lf oc us e dont heda t as howi ng r e c e ntus e ‑t heNHSpa s tmont ho rpa s twe e kda t a ,a l ongwi t ht heHSSS‑r a t he r t ha nl i f e t i meus e ・ Re c e ntus epr ovi de sabe t t e rs na ps hotofc ur r e ntdr ugt r e nds ,a nd s howe dt hel a r ge s tde c l i ne,ma ki ngt hec a s emos tf a vor a bl et ot hea dmi ni s t r a t i on. Howe ve r ,t heda t as howi ngde c l i nei nr e c e ntus ec onf ounde dt hea c t ua lde c l i ne i nus ewi t ht hei nc r e a s ei nunde r r e por t l ng. Thet wos our c esofde c l i neca nnotbe di s e nt a ngl e df r om t her e c e nt ‑ us eda t abe c a us et her e c e ntus e rs t oc kc a ndr opa s pe o pl equi t ; l i ke wi s e, pa s tus e r sa geoutoft hehi ghs c hools e ni orpopul a t i on・ I ti s 258 3 0 2 0 1 0 ( uo! tt2一ndod ‑ o uoF t o2 tJI) aUuaH t 2^aJd FJ GURE7 ‑ 15 Si mul at edvs. ac t ual popul at i on ofl i f e t i mecoc ai ne us er s Not et hatwhi l et he suⅣe ydat ash ow adr opl nt heev er ‑ us edpopul at i on af t er1982, t he model es t i mat es f ort heac t ua一 popul at i onof t h osewh oh av e everus edc oc ai ne c on t i nuet or i s e, t houghata dJ r mi ni shi ngr at e. l n cr easl ngl egal r i sk s一 edt oal ar ge i ncr eas ei nt he f r ac t i onoHor mer us er swh odeni ed t hei rc oc ai neu s e. r t I IT o o l sf o rS y s t e ms Th i n k i n g P a 1976 1984 1980 1988 1992 1996 Sour ce. ‑ Ho me r ( 1 993,1 997) . Onl ybye xpl i c i t l ya c c ount i ngf o rt hes t oc ka ndf lows t r uc t ur eofdr ugus e ‑f ort he i ne xor a bl ea c c umul a t i onofus e r si nt ot hee ve r ‑ us e dpopul a t i on‑t ha tt het woc o m‑ pe t i ngS Our C eSOfde c l i nei nc ur r e ntus eda t aca nbes e para t e d.Unf o r t una t e l y,t he a bi l i t yt ounde r s t a ndba s i cs t oc ka ndf lowr e l a t i ons hi psi sf a rt oor a r ei nours oc i ‑ e t yt oda y ,e ve na mo ngma nypr of e s s i ona lpol i c ya na l ys t s . 7L 3. 1 TheCocai neEpi demi ca熊er1990 Themode ls howe dpe r s ua s i ve l yt ha tt hes ur ve yda t as i gni f i c a nt l yunde r e s t i ma t e d c oc a i neus ea ndhi ghl i g ht e dt hef a i l ur eoft hes uppl y‑ s i des t r a t e gy. AsMa c Coun a ndRe ut e r( 1 997, p. 47)puti t , " Thepr o ba bi l i t yofac oc a i neorhe r oi ns e l l e rbe i ng i nc a r c e r a t e dha sr i s e ns ha r pl ys i nc ea bout1 985butt ha tha sl e dne i t he rt oi nc r e a s e d pr l C enorr e duc e da va i l a bi l i t y. MHowe ve r ,ac l os el ooka tt hes i mul a t i oni nFi gur e 7‑ 1 5s howst ha tbyt hel a t e1 98 0st henumbe rofpe opl ewhoha de ve rus e d c oc a i ne ,t houghs t i l lr i s i ng,wa sgr owi nga tadi mi ni s hi ngr a t e・ The r e f or et hei ni ‑ t i a t i onr a t emus tha vebe e nf a l l i ng. Byt hemi d1 990S , hee t pi de mi cbe ga nt oa ba t e: hegr t owt hofc oc a i ne ‑ r e l a t e dme di c a le me r ge nc i esa ndde a t hss l owe d;a r r e s t sf e l l s l i ght l y. TheONDCPes t i ma t e dne ti mpor t si n1 995a tbe t we e n421a nd51 3me t r i c t ons ,wi t h98me t r i ct onss e i z e d,l e a vl ngne tc oc a i nea va i l a bl eont hes t r e e t sof Ame r i c aa ta boutt hr e e‑ qua r t e r st he1 989l e ve l . Themode l ,Or l gl na l l yde ve l ope d i nt hel a t e1 980S ,f or e c a s tt hes edr a ma t i cs hi f t si nc oc a i neus equi t ewe l l( Fi g‑ ur e7‑ 1 6) . Not et ha tt hepoi nt ‑ by‑ poi ntf i toft hemode li nt he1 990si s n' tpe r f e c t , a ndyou s houl dr A I Ote xpe c ti tt obe.Si mul a t e da r r e s t sa r e , t oohi gh,a ndt hemode ldoe snot t r a c kt het e mpor a r ydi pi nc oc a i ner e l a t e dme di c a le me r ge nc i esi n1 990‑ 91 . Ne ve r ‑ t he l es s ,t hemode l ' sa bi l i t yt oc a pt ur et het ur ni ngPOl nti nt hee pi de mi c ,f r om e xpone nt i a lgr owt ht ogr a dua lde c l i ne,i squl t er e ma r ka bl e,c ons i de r i ngt ha tt he s i mul a t i onss howni nFi g ur e7‑ 1 6We r eba s e donda t aa va i l a bl eonl yt hr ough1 989. Theon lye xoge nousi nput sa f f e c t l ngmode lbe ha vi ora f t e r1 990a r et het a r ge t popul a t i on( t hos ea ge1 2a ndove r )a ndt hepr e va l e nc eofma r i j ua naus e( apr oxy f ors oc i a lt ol e r a nc eofdr ugs ) .Cha ngesi nda t a ‑ r e por t i ngs ys t e msa ndde f i ni t i ons we r enoti nc l ude d. Cha pt e r7 259 Dy n a mi c so fS t o c k sa n dF l o ws FI GURE7 ・ 16 6 0 0 J ea^p 一 0 0 4 doad 0 0 2 nouト pues Si mu一 at edvs. ac t ual c ocai ne epi demi c Dash edl i nes, dat a; s ol i dl i n es, model . 1976 1992 1996 1980 1984 1988 1992 1996 1980 1984 1988 1992 1996 OL I J 5 2 pu 2Sn 5 0 0 4 0 0 3 0 0 O 1 1988 0 L do¢ d 1976 ( uo! t t 2 n 1d od 0u Ut ぶ) aOua一。^j a d 1984 5 Jt 2a^P 1 9 8 0 2 0 0 !I 1 0 0 1976 Sour ce:H o me r ( 1 993,1997) . Addi nga dd i t i ona le xoge nousi nput sC Oul di mpr ovet hef i tt ot heda t a.But mode l ss houl dn otbet une dt of i tda t abyi nt r oduc i nge xoge nousva r i a bl e swhos e s ol ef u nc t i oni st oi mpr ovet hec o r r e s pond e nc eofmode lout putt oda t a・ Exoge no us va r i a bl e smus tb ej us t i f i e dbys i gni f i c a ntr ea lwor l de vi de nc ei nde pe nde ntoft he i r pot e nt i a lc ont r i b ut i ont ohi s t or i c a lf i t . Fur he t r , Va r i a bl esi nvol ve di na nyf e e d ba c k l oo psj udge dt obepot e nt i a l l ys i gni f i c a ntr e l a t i vet ot hemode lpur pos emus tbe c a pt ur e da spa r toft hemode l ' se ndoge nouss t r uc t ur ea ndc a nnotbeus e da se xoge ‑ no usI nput st Oi mpr ovehi s t or i c a lf i t . 260 Pa r t I IT わ o l sf o rS y s t e msTh i n k i n g Whi l et hemode ls howst ha tt hes ur ve yda t aove r e s t i ma t edt hede c l i nei nc o‑ ca i neus e,mode l ‑ ge ne r a t e de s t i ma t e soft hea c t ua lnumbe rofa c t i veus e r s ,whi l e r e ma i ni ngS i gni f i c a nt l yhi ghe rt ha nt hee s t i ma t esr e por t e di nt hes ur ve ys , dos how ade c l i ne. Thef i e l dr es e a r c ha ndmode lr e s ul t ss howe dt hedr opl nc oc a i neus ewa s notca us e dpr i ma r i l ybyt heSuppl yDi s r upt i onLoopBli nFi gur e7‑ 1 30rbyt he Cl e a nupt heSt r e e t sl oopB2,a ss uppor t e r soft hei nt e r di c t i onpol i c yc l a i me d. Ra t he r , t hee xpo ne nt i a lg r owt hofc oc a i neus ewa se ve nt ua l l yha l t e dbyt wone ga ‑ t i vef e e dba c ksi nvol vi ngpubl i cpe r c e pt l OnSOfc oc a i ne' she a l t ha ndl e ga lr i s ks . Fi r s t , c oc a i nei snott hebe ni gns ubs t a nc ei twa st houghtt obei nt he1 970S . Aspe o‑ pl ebe ga nt oe xpe r i e nc eo rhea ra boutt heNe ga t i veHe a l t ha ndSoc i a lEfe c t soft he dr ug, t he ybe c a mel e s sl i ke l yt os t a r ta ndmor el i ke l yt os t op( ba l a nc i ngl oo pl i 3i n Fi gur e7‑ 1 3) . Se c ond, g r owi ngl e ga lr i s ksofdr ugus eduet ohi ghe ra r r e s tr a t e sa nd l onge rs e nt e nc e sde c r e a s e dt hewi l l i ngnes sofpe o pl et os t a r ta ndi nc r e a s e dt hequl t r a t e ‑t heFea rofAr r e s tr e d uc e dus a ge( ba l a nc i ngl oopB4) ・ Ast hepopul a t i onof a c t i veus e r sbe ga nt of a l l , t hes oc i a le xpos ur eofnonus e r sa l s of e l l , We a ke ni ngt he r e i nf or c i ngWo r dofMo ut hl oop( Rl ) . Unf or t una t e l y , bot hoft he s ene ga t i vel oo psi nvol vel ongde l a ys . Fi r s t , t he r ei s al a gbe t we e ngr owt hi nc oc a i neus ea ndt hei nc i de nc eofha mf u lhe a l t ha ndl e ga l e fe c t s . Ast hei ni t i a t i onr a t egr e we xpone nt i a ly,s odi dt hes t oc kofa c t i vec a s ua l us e r s . Thes t oc kofc ompul s i veus e r sa l s or os ee xpone nt i a l l y,t houghwi t has ub‑ s t a nt i a ll a g. Thel a gi nt hegr owt hoft hec ompul s i veus e rpo pul a t i oni si mpo r t a nt be c a us ec ompul s i veus e r sa r emo r el i ke l yt oe xpe r i e nc es e ve r ehe a l he t fe c t s( e s ‑ pe c i a l l ya st he yt ur nt oc r a c k)a ndmor el i ke l yt oc ommi tdr ug‑ r e l a t e dc r i me si n‑ c l udi ngpus hi ngt hed r ugt of i na nc et he i rownha bi t s . Thust hee xpone nt i a lgr owt h i nc oc a i ne ‑ r e l a t e dc r i me ,a r r e s t s , me di c a le me r ge nc i e s ,a nddea t hsl a gsbe hi ndt he gr owt hoft hec a s ua lus e rpo pul a t i on, whi c hi nt ur nl a gsbe hi ndt hei ni t i a t i o nr a t e. The r ei saf ur t he rl a gl nt hepe r c e pt i onbyt hepubl i coft het r uehe a l t he f f e c t s ofc oc a i ne. Mos tpe opl edon' tr e a dt heNe wEngl andJ our nalo fMe di c i neort he Annal so fAddi c t i o nt ol e a r na boutt hehe a l t hr i s ksofi l l e ga ldr ugs . I ns t e a d, Publ i c pe r c e pt l OnSOfr i s ka r es t r ongl yc ondi t i one dbype r s ona le xpe r i e nc e ,pe r s ona l a c qua i nt a nc ewi t hs ome oneha r me dbyc oc a i ne,a ndme di ar e por t sofhi gh‑ pr of i l e i ndi vi dua l swhowe r ea r r e s t e df or , i n j ur e dby, ordi e df r omc oc a i neus e,s uc ha st he come di a nRi c ha r dPr yo r ,whowa ss e ve r e l ybur ne dwhi l ef r e e ba s i ng,ort heUni ‑ Ve r s l t yOfMa r yl a ndba s ke t ba l ls t a rLe nBi a s , whodi e dofa c ut ehe a r tf a i l ur ewhi l e doi ngc oc a i net oc e l e br a t ehi ss e l e c t i ona sat opdr a f tpi c kbyt heBos t onCe l t i c sof t heNa t i ona lBa s ke t ba l l As s oc i a t i on. f or el a gsbe hi nd Thes t r e ngt hofa l lt he s ec ha nne l sofpubl i ca wa r e ne s st he r e t hepopul a t i onofa c t i veus e r sdr i vi ngt hegr owt hoft hee pi de mi c・Expone nt i a l gr owt hi nc oc a i neus ed i de ve nt ua l l yr e duc et hes oc i a la c c e pt a bi l i t yoft hed r uga nd t hust hei ni t i a t i onr a t e. Howe ve r , t hes t oc kofa c t i veus e r sl a gswe l lbe hi ndt hei ni ‑ t i a t i onr a t e. Thes t oc kofa c t i veus e r swi l lr i s ea sl onga si ni t i a t i one xc e e dst her a t e a twhi c hpe opl es t opus l ng,a ndt hes t oc kofc ompul s i veus e r si nc r e a s e sa sl onga s t hees ca l a t i onr a t ee xc e e dst her a t ea twhi c hc ompul s i veus e r ss t o p. Thedyna mi c s oft hes t oc ka ndf lOws t r uc t ur ei ne vi t a bl yme a nt ha tt hepopul a t i onofdr ugus e r s , es pe c i a l l yt hec ompul s i veus e r sr e s pons i bl ef ormos toft hec r i mea ndhe a l t he f ‑ f e c t s , c ont i nue st ogr owe ve na f t e rt hei ni t i a t i onr a t epe a ksa ndf a l l s . Thede l a ye n‑ s ur e st ha tt her e i nf or c i ngs oc i a le xpos ur ea ndwo r dofmout hf e e d ba c ksdomi na t e l Ch a p t e r7 Dy n a mi c so fS t o c k sa n dFl o ws 261 t hene ga t i ver i s kpe r c e pt l Onl oopsi nt hee a r l yye a r soft hee pi de mi c,l e a di ngt oa l a t e ra ndhi ghe rpe a kf ori nc i de nc ea ndpr e va l e nc e. St i l l , byt hel a t e1 98 0S , ne a r l ye ve r yc o mmunl t yha de xpe r i e nc e dt hea r r e s t , i n‑ j ur y,Orde a t hofa tl e a s toneofi t spr omi s l ngyoungpe opl e,S l owl ys t r e ngt he ni ng t hene ga t i vef e e d ba c kst ha ts l owt hei ni t i a t i onr a t e. I r oni c a l l y , hec t oc a i nee pi de mi c di dnota ba t ebe c a us ei nt e r di c t i onma det hed r u gl es sa va i l a bl e; ont hec ont r a r y , t he da t as howe dgr o wl nga c c e s s i bi l i t y , pur i t y, a nda f f or da bi l i t yt hr oughoutt he1 98 0S . i ns t e a d,t heve r ya bunda nc eofc oca i ne, byl e a di ngt oal a r gei nc r e as ei npe r s ona l knowl e dgeofi t sha r mf ule fe c t s , l e dpe opl et ot ur na wa yf r omt hedr ug・ Nol onge r c hi c,S t r l PPe dofi t ss oc i a la ur aa ndbe ni gni ma ge,t hos ewhoc r a ve des c a pef r om t hewor l dt ur ne df r om c oca i net oot he rd r ugs . Thus ,t hec oc a i nee pi de mi cwa sul ‑ t i ma t e l ys e l f ‑ 1 i ml t l ng. Thef e e d ba c ks t uc r t ur eout l i ne di nFi gur e7‑ 1 3i squl t ege ne r a la nda ppl i e st o a nyha rmf uldr ug, l e ga lori l l e ga l . Thepos i t i vef e e dba c ksge ne r a t i nggr owt hi nus ‑ a gea c ts wi f t l y, whi l et hene ga t i vef e e dba c kst ha tde t e rus a ge,pa r t i c ul a r l ypubl i c r e c ognl t l OnOfad r ug' sha r mf ule f f e c t s , a r eonl ype r c e i ve ds l owl y. Ther e s ul ti st he c ha r a c t e r i s t i cbo oma ndbus tpa t t e mf o rd r ugus e・ Ea c hne worne wl ypopul a rd r ug ge ne r a t esawa veofna i vee nt hus i a s mi nwhi c hus e r se xt oli t sbe ne f i t s , onl yt odi s c o ve ra st hepopul a t i onofus e r sgr owsa ndmo r epe opl ee s c a l a t et oc ompul s i veus e t ha tt hedr ugl S n' tasbe ni gna spe opl ewe r el e dt obe l i e ve. I nf a c t , t hec oc a i nee pi de mi coft he1 98 0swa snott hef i r s t . As i mi l rbooma a nd bus ti nc oc a i neus eoc c ur r e di nt hel a t e1 8 00S . I tbe ga nwi t hme di c i na lus e,a sc o‑ c a i newa spr a i s e dbyt heme di c a lc ommunl t y , i nc l udi ngFr e udi nhi sf a mous1 88 4 pa pe r" OnCoca , "a sac ur ef oropl uma ddi c ion,a t l c ohol i s m,f a t i gue,de pr e s s i on, ne r vo us nes s ,t i mi di t y,i mpot e nc e,a nds e a s i c kne s s ,a mongot he rc ompl a i nt s . Fol l l owl ngt hec l as s i cpa t t e r n,c oc a i nemo ve di nt omor ege ne r a la ndr e c r e a t i ona lus e, be c o ml nga nI ng r e di e nti nCoc a ‑ Co l aa nds omec l ga r e t t e S . Asus es pr e a d,a va i a bi l i t ya ndpur i t yI nc r ea s e d;i ns t e a dofi n j e c t i ngOrdr i nki ngt hepr e pa r a t i on, po w‑ de rf ors nor t i ngbe c a mepopul a r . Soo nt heha mf r ule f f e c t sbe ga nt obee xpe ie r nc e d, obs e r ve d,a ndr e por t e di nt heme di c a la ndpo pul a rpr es s .Byt hee a r l y1 900S ,c o‑ c a i neus eha ds pr e a d丘・ oms oc i a le l i t e st ol owe rs oc i a lc l a s s e s . Communi t i e sa c r os s t hec ount r ys t r ug gl e dt ode a lwi t hc o mpul s i veus e r s( knowna s" c okef i e nds " ) , a nd " by1 91 4t heAt l a nt apol i c ec hi e fwa sbl a mi ng70pe r c e ntoft hec r i me s[ i nt hec i t y] onc oc a i ne "( Gr i ns poona ndBa ka l a r1 985,p.38) .I nr es pons e,l e ga lr es t r i c t i ons a ndpr ohi bi t i onsgr e wi nc r e a s l ng lys e ve r e;i n1 922c ongr e s sde f i ne dc oc a i nea sa na r c ot i ca ndba nne di mpor t a t i onofc oc a; by1 931e ve r ys t a t eha dr e s t r i c t e di t ss a l e a ndmos tma depos s es s i onac r i me.Coc a i neus ef e l lf r om i t spe a ka ndr e ma i ne d l ow a s1 ) e Ol ) 1 et ur ne dt oot he rdr ugs ,unt i lt hec ur r e nte l ) i de mi cbe ga n.Si mi l a r wa ve sofdr ugus eha vebe e nr e pe a t e dl yo bs e r ve df ort heopi a t es , f orps yc he de l i cs , a ndf orva r i ouss t i mul a nt sa ndba r bi t ur a t es . l i mi t i ng( i f Whi l ee pi de mi c sofa nypa r t i c ul a ri l l e ga ldr uga r eul t i ma t e l ys e l f ‑ t hed r u gi sha r mf ule nough)pe o pl eha vea l wa yss oughtoutmi nd‑ a l t e r i ngs ub‑ s t a nc e s . Eve nasonedr ugf a l l so utoff a vor , ne we pi de mi c sbe gi n, c e nt e r e donne w dr ugsf orwhi c ht he r ei sa sye tnoe xpe r i e nc eofha r mf ule fe c t soronol ddr ugsf or whi c ht heha r d‑ wonk n owl e dgeofha r m ga i ne dbypr l Orge ne r a t i onshasf a de d f r o mc ol l e c t i veme mor y. Themodes tde c l i nei nc oc a i neus ei nt he1 990sl e dt oa n i nc r e a s ei nt heus eofot he rdr ugs ,i nc l udi ngma r i j ua na ,me t ha mphe t a mi ne,a nd ‑ レ 26 2 Pa r t I IT o o l sf o rS y s t e ms Th i n k i n g a r sa f t e rt hel a s twa ve mos tt r oubl i ng,ar e s ur ge nc eofhe r oi nus e,mor et ha n20ye ofhe r oi nc r es t e d,Thi sl a t es the r oi ne pi de mi cwa ss t i mul a t edbyt heus ua ls e l f ‑ r e i nf or c i ngwor dofmo ut ha ndme di af e e d ba c ks ,i nc l udi ngt hegl or i f i c a t i onof " he r oi nc hi c "i npo pul a rc ul t ur ea ndCa l vi nKl e i nunde r we a ra ds ・ 5 7. 4 SuMMARY Thi sc ha pt e rs howe dhows t oc ksa ndf lowsge ne r a t edyna mi cs . Thepr oc e s sofa c‑ c umul a t i oni se qul Va l e ntt oi nt e gr a t i oni nc a l c ul us . Thea mounta dde dt oas t oc ki n a nype r i odi se qua lt ot hea r e as we ptoutbyt hene tr a t eofc ha ngei nt hes t oc kove r t ha tpe r i od. Conve r s e l y ,t hes l opeoft het r a j e c t or yOfas t oc ka ta nyt l mei si t sde ‑ r i va t i ve, t hene tr a t eofc ha nge.Gr a phi c a lme hodsf t ori nt e g r a t i ona nddi f f e r e nt i a ‑ t i onwe r ei nt r oduc e d.Gi ve nt hebe ha vi orove rt i mef o rt her a t e sa fe c t i nga ny s t oc k,youc a nde duc et hebe ha vi oroft hes t oc k;gl Ve nt het r a j e c t o r yOft hes t oc k youc a nde duc ei t sne tr a t eofc ha nge,a l lwi t houtus eofc a l c ul us . Thea bi l i t yt or e‑ 1 a t es t oc ksa ndf lowsi nt ui t i ve l yi se s s e nt i a lf ora l lmode l e r s ,e ve nt hos ewi t he x‑ t e ns i vema t he ma t i c st r a i nl ng,be c a us emos tr e a l i s t i cmode l sha venoa na l yt l C a l s ol ut i ons .Exa mpl e ss howt ha tunde r s t a ndi ngt hedyna mi csofs t oc ksa ndf lows , e ve nwi t houtf e e d ba c k, c a nyi e l di ns i ghti nt oi mpor t a ntpr obl e ms . 5 F u r he t rr e a d i n g : S h r e c k e n g o s t d e v e l o p e damo d e l f o rt h eUSCI At oe s t i ma t eh e r o i ni mp o r t s b yi n t e g r a t i n gp r e v a l e n c e , c r i me , p r i c e , p u r i t y , a n do t h e rd a t a( Ga r d i n e ra n dS h r e c k e n g o s t1 9 8 7 ) . S h r e c k e n g o s t ( 1 9 9 1 )a p p l i e st h ef ra me wo r kt oc o c in a e ・ Le in v , Hi r s c h , a n dRo b e r t s( 1 9 7 5 ) , i nThe Pe r s i s t e ntPo ppy , d e v e l o pas y s t e md y n a mi c smo d e l o fh e r o i nu s ea n da b u s ei nac o mmu n i t yb a s e d o nac a s es t u d yo f t h es o u t hBr o n x . Th e yu s et h emo d e l t oe x p l o r eav a r i e t yo f p o l i c yo p t i o n si n c l u d i n gd e ma n d ‑ s i d ep o l i c i e s , i n c r e a s e de n f o r c e me n t , a n dme t h a d o n ema i n t e n a n c e .S e ea l s oLe v i n , Hi r s c h , a n dRo b e r t s( 1 9 7 8 ) . Ri c h a r d s o n( 1 9 8 3 )d e v e l o p sas i mp l emo d e l t oe x p l a i nwh ya g g r essive p o l i c ee f f o r t t os e i z es t r e e t s u p p l i e so f h e r o i na c t u a l l yI n c r e a s e sd r u g ‑ r e l a t e dc r i me ・ G6 1 u k e, La n d e en , a n dMe a d o ws( 1 9 8 la , 1 9 8 1 b )d e v e l o p e damo d e l o fa d d i c t i v eb e h a v i or , f o c u s i n go n a l c o h o l i s m. Ho l d e ra n dBl o s e( 1 9 8 7 )d e v e l o pamo d e l o fc o mmu n i t yl e v e l p o l i c yre s p o n s e st o a l c o h o l i s m. Ho me re t a l . ( 1 9 8 2 ) p r e s e n t as y s t e md y n a mi c smo d e l o f( t o b a c c o )s mo k i n ga n d a n a l y z eav a ri e t yo fp o l i c i e s . ‑ ● C呈 os i 王 1 g音 量 はf ̲ } 榊声:̲ ‑ i ! き ‑ naI f ̲ 1 3 ̲ 呈 e Sポ S畳 mp 旦 eS息 丁 眠息 覗TeS Amat he mat i c alt h e oT TI Snott Obec o ns i de r e dc o mpl e t eu nt i l youhav ema dei t s ocl e art hat youc ane x pl ai ni tt ot hej i ' r s t manwho my oume e tont hes t r e e t . ‑Da v i dHi l b e r t Iho pet os ho w. ‥ t hatmat he mat i c al n ot at i o nc anbek e ptc l o s et ot hev oc a bu l af T o fbu s i ne s s , ・t h ate ac hv ar i abl ean dc o ns t a nti na ne qu at i onhasi ndi v i du al me anl n gt Ot h epr ac t i c i n gma na ge r , ・ t h att h er e qui r e dmat he mat i c si swi t hi nt he r e ac ho fal mo s tan yonewhoc a ns u c c e s s f u l l yma nageamo de r nc or por at i o n. lJ a yW.F o r r e s t e r( I n d u s t r i a l Dy n a mi c s ,1 961 , p. 9) Th i sc ha pt e rf o r ma l i z e st hec o nne c t i o nbe t we e ns t r uc t u r ea ndbe ha vi o rbyl i n ki ng f e e d ba c kwi t hs t o c ka ndf lOws t r uc t ur e s I Thef o c usi st hes i mpl e s tf e e d ba c ks ys ‑ t e ms , t hos ewi t ho nes t oc k( k nowna sf i r s t ‑ o r de rs ys t e ms ) . Li ne a rf i r s t 1 0 r de rs ys ‑ t e ms( de f i ne di nt hi sc ha pt e r )C a nge ne r a t ee x po ne nt i a lg r o wt ha ndgoa l ‑ s e e ki ng , be ha v i o r . No ni i r l e a r i t yi r .f i r s L ‑ O r de rs ys t e msc a us e ss hi f t si nt hedo mi na ntl oo ps 1 e a d i ngf o re xa mpl et oS‑ S ha pe dg r owt hThec ha pt e ra l s oi nt r od uc e st hec o nc e pt ot ‑ ag r a phs howi ngho wt hene tr a t eo fc ha ngeo fas t oc ki sr e l a t e d o faphasepl t ot hes t oc ki t s e l f ‑a nds howshowdyna mi c sc a nbed e r i ve df r omt hepha s epl o t wi t ho utc a l c ul uso rdi f f e r e nt i le a q ua t i o ns . 8t l F旧ST‑ ORDERSYsTEMS Cha pt e r4di s c us s e dt heba s i cmode sofbe ha vi o rge ne r a t e dbyc o mpl e xs ys t e ms a ndt hef e e d ba c ks t uc r t ur e sr e s pons i bl ef o rt he m. Themos tf unda me nt a l mod e sa r e 263 264 Pa r t I I To o l sf o rS y s t e msTh i n k i n g FI GURE8‑ 1 Gr owt handgoal seeki ng:s t r uc t ur eandbehavi or Goal ( Desl ] r ed St at eofSyst em) + St at eoft he hcr ease ; . : ; ; t a ̲ Sニ ) oft he 毒l S ヽ ′ y st em A c t i o n R・ at L + exponent i a lgr owt ha nd goa ls e e ki ng.Pos i t i vef ee dba c k ca us ese xponent i a l Fi gur e8‑ 1 ) . gr owt h,a ndne ga t i vef ee dba c kc a us esgoa l ‑ s e e ki ngbe ha vi or( Thes i mpl es ts ys t e mt ha tca nge ne r a t et hes ebe ha vi or si st he丘r s t ‑ or de r ,l i nea r f e edba c ks ys t em.Theoy de rofadyna mi cs ys t em orl oopi st henumbe rofs t a t e va r i a bl es ,ors t oc ks ,i tcont a i ns . Af i r s t 1 0r de rs ys t e mc ont a i nsonl yones t oc k. Li n‑ e ars ys t emsa r es ys t e msi nwhi c ht her a t eequa t i onsa r el i nea rc ombi na t i onsoft he s t a t eva r i a bl esa nda nye xoge nousi nput s . Thet e r mH l i nea r "hasapr ec i s emea nl ngi ndyna mi cs :i nal i nea rs ys t e mt he r a t eequa t i ons( t hene ti nf lowst ot hes t oc ks )a r ea l wa ysawe i ght e ds um oft hes t a t e va r i a bl es( a nda nye 呆oge nousva r i a bl es ,de not edUj): dS/ d t= Ne tI nf lo w= a l Sl+a 2 S2+ ・・・+ a n Sn+bl Ul+b2 U2+ ・ ・ +bmUm (811) ・ whe r et hec oe f f i c i e nt sa l a ndb,a r econs t a nt s ・ Anyot he rf or mf ort hene ti nf lowsi s nonl i nea r . 1 8. 2 Posm vEFEEDBAeKAND ExpoNENTE ALGROWTH Thes i mpl es tf ee dba c ks ys t e mi saf i r s t 1 0r de rpos i t i vef e edl Da C ki oop・l naf i r s t ‑ or de rs ys t e m,t he r ei sonl yones t a t eva r i a bl e( s t oc k) ,de not edhe r ebyS・ Thes t a t e oft hes ys t em a c c umul a t esi t sne ti nf lowr a t e; i nt ur n, t hene ti nf lowde pe ndsont he l Fo re x a mp l e , f o r mu l a t i o n sf o rt h en e t i n lO f ws u c ha sa l *Sl*S2 ,a l *Sl / S 2 , OrMAX( 0 ,a l *Sl ) a r ea l l n o n l i n e a r . Th et e r m" n o li n n e a r "i so ft e nus e di no t h e rs e n s e s , f o re x a mp l et od e s c r i b et h e n o n c h r o n o l o g l C a l n a r r a t i v es t r u c t u r eo fn o v e l ss u c ha sCo r t a z a r ' SHo ps c ot c h ・ Th et e r mH n o n l i n e a r H i nt h e s ec o n t e x t sa c t u a l l yme a n s" n o n s e q u e n t i a l "a n dha sn o t h i n gt od owi t ht h et e c h n i c a l me a n l n g o fl i n e a r l t y . Ch a p t e r8 Cl o s i n gt h eLo o p: Dy n a mi c so fS i mp l eS t r u c t ures 26 5 s t a t eoft hes ys t e m( f ornow,as s umenoe xoge nousi nput s ) .I nge ne r a l ,t hene ti n‑ fowi l sapos s i bl ynonl i nea rf unc t i onoft hes t a t eoft hes ys t e m: S‑I NTEGRAL( Ne tI n f l o w, S( 0) ) ( 8 ‑ 2) Ne tI n low‑f( f S) . ( 8‑ 3) I ft hes ys t e mi sl i nea r ,t hene ti nf low mus tbedi r ec t l ypr opor t i ona lt ot hes t a t eof t hes ys t e m: Ne tI nf low‑gS ( 8‑ 4) whe r et hecons t a nt蛋hasuni t sof( 1 / t i me)a ndr e pr es e nt st he丘' a c t i ona lgr owt hr a t e oft hes t oc k. 2 Fi gur e8‑ 2s hows血es t r uc t ur eoft hi ss ys t e m asaca us a ldi a gr a ma nda l s oasa s e tofe qua t i ons . Ase xa mpl es ,cons i de rt hea cc umul a t i onofi nt e r es ti ncomei nt oa ba nka c countort hegr owt hofapopul a t i on. Thepr l nC l pa la ndpr eva i l i ngI nt e r es t r a t ede t e r mi net hei nt e r es tpa yme nt ;popul a t i ona ndt hef r a c t i ona lne tbi r t hr a t e de t e r i net m hene tbi r t hr a t e. 3 Wha twi l lt hebe ha vi oroft hes ys t e m be?Se c t i on8. 2. 1us esbas i cca l c ul ust o s ol vet hedi f f e r e nt i a lequa t i on;t hes ol ut i oni st hee xpone nt i a lf unct i on S( t )‑S( 0) e x p( gt ) ( 8‑ 5) whe r eS( 0)i st heva l ueofSa tt hei ni t i a lt i met‑ 0・ Thes t a t eoft hes ys t e m gr ows e xpone nt i a l l yf r om i t si ni t i a lva l uea tacons t a ntf r a c t i ona lr a t eofgpe rt i meuni t ・ 8. 2. 1 Anal yt i cSoJ ut i on紬! . t he Li nearF室 r sトOr derSyst em Tos ol vet hedi f f e r e nt ia le qua t i onf ort hef i r s t 1 0r de rl i nea rs ys t em, dS/ dt‑gS,f i r s t s e pa r a t eva r i a bl e s ,t oobt a i n 普 ‑gdt ( 8‑ 6) Now,i nt e gr a t ebot hs i des I ;‑Igdt ( 8‑ 7) t oge t l n( S)‑g t+c ( 8 ‑ 8 ) whe r eci sac or i S t a nt . Ta ki r l ge XPOr i e nt i a i sofbot hs i desgi ves ,dS/ dt , a r eaf un c t i o nf ( )o ft h e 2 I nt h eg e n e r a l c a s eo famu l t i s t a t es ys t e m, t h er a t e so fc h a n g e s t a t ev e c t o rSa n da n ye x o g e n o u sv a ia r b l e sU: dS/ dt‑i ( S,U) ・ I nal i n e a rs y s t e m, t h er a t e sare l i n e a rc o mb i n a t i o n so ft h es t a t e sa n de x o g e n o u sv a r i a b l e s : d S / d t‑AS+BUwh e r eAa n dBa r e ma t r i c e so fc o e fi c i e n t s . Fo rg o o dt r e a t me n t so fl i n e a rs ys t e mt h e o r y , s e e , e ・ g・ , Og a t a( 1 99 7)a n d Ka no r p p, Ma r g o l i s , a n dRo s e n b e r g( 1 99 0) . 3 Re p r e s e n t l n gp o p u l a t i o ng r o wt ha saf i r s トo r d e rp r o c e s sa s s u me st he r ei sn od e l a yb e t we e n b i r t ha n dt h ea b i l i t yt or e p r o d u c e , ap o o ra s s u mp t i o nf o rma mma l s , b u t r e a s o n a b l ef o rma n y u n ic e l l l l l a ra n do t h e rs ma l lo r g a n i s ms . 2 6 6 P a r t I IT o o l sf o r S y s t e ms Th i n k i n g FI GURE8 ‑ 2 Fi r s トor der , l i n earp os i t i v ef ee db a cks y s t em: S t r u c t ur ean de x ampl es Gener alSt r uct ur e dS/ dt≡Netl nf l owRa t e≡gS Examp一 es Netl nt er es tl ncome =lnterestRate★Principa一 Ne tBi r t hRat e =Fracti ona一Ne tBi r t hRa t e★Popul a t i on S‑C* e x p( g t ) ( 8 ‑ 9) whe r ec *i se x p( C ) . Theva l ueofSa tt hei ni t i a lt i me , whe ne x p( g t )‑1 , i sbyd e f i ‑ ni t i o nS( 0) , s oc *mus te q ua lS( 0) . Subs t i t ut i o nyi e l dse c i ua t i o n( 8 ‑ 5) 三 8. 2. 2 Gr aph; capSoh j t i onoft he Li nearF喜 r st ‑ Or derPosi i ; veFeedbackSyst em Yo udono tne e dc a l c ul ust os ol vet hee qua t i onf o rt hef i r s t ‑ o r de rl i ne a rs ys t e m. Yo uc a na l s od e d uc ei t sbe ha vi o rg r a phi c a l l y・ Fi gu r e8 ‑ 3s ho wsat hi r dr e pr e s e nt a ‑ t i o no ft hes t r uc t u r eo ft hes ys t e m: aphas epl ot ‑ag r a phs ho wl n gt hene tr a t ea sa f unc t i onoft hes t a t eo ft hes ys t e m. Theg r a phs howst ha tt hene ti nf lowr a t ei sa s t r a i g htl i nes t a r t l nga tt heo r l g l nWi t hpos i t i ves l opeg. 26 7 o s i n gt h eLo o p : Dy n a mi c so fS i mp l eS t r u c t ures Ch a p t e r8 Cl = FI GURE8 ‑ 3 = dS/ dt Netl nt l ow Rat e gS ( a∈! t J s t !un) a l E ! t ]N t Ol ‑ u aN Phas epl otf or t hef i r s t ‑ or der , l i nearposi t i ve f eedbacks ys t em St at eoft heSys t em( uni t s) o t\ \ Uns t abl e Equi h L br i um r o,t hene ti nf lowi sa l s oz e r o. Ze r oi s Not et ha ti ft hes t a t eoft hes ys t e mi sz e a ne qui l i br i umoft hes ys t e m: nos a vl ngS , nOi nt e r e s ti nc ome;nope opl e , nobi r t hs . Howe ve r ,t hee q ui l i br i umi su ns t abl e :a dda nyqua nt l yt t ot hes t oc ka ndt he r ewi l l nowbeas ma l l ,pos i t i vene ti nf low,i nc r e a s l ngt hes t a t eoft hes ys t e m abi t . The gr e a t e rs t a t eoft hes ys t e ml e a dsnowt oas l i ght l ygr ea t e rne ti nf low a ndas t i l l l a r ge ra ddi t i ont ot hes t oc k. Thes l i ht g es tde pa r t ur ef r om t hee qui l i br i uml e a dst o f ur t he rmove me nta wa yf r omt hee qui l i br i um, j us ta Saba l lba l a nc e de xa c t l ya tt he l l ,i fd i s t ur be de ve ns l i g ht l y ,wi l lr ol le ve rf a s t e ra wa y丘. om t heba l a nc e t opofahi nt .Thegr ea t e rt hes t a t eoft hes ys t e m,t hegr e a t e rt heneti nf low:t hi si spr e ‑ pol c i s e l yt heme a nl ngOft hepos i t i vef e e d ba c kl oopc oupl i ngt hes t oc ka ndi t sne ti n‑ low. f I nt hege ne r a lc a s ewhe r et hepha s epl otofas t a t eva r i a bl ec a nbenonl i ne a r , t hes t a t eoft hes ys t e mwi l lg r owwhe ne ve rt hene tr a t ei sa ni nc r e a s i ngf unc t i onof t hes t oc k. Ane q ui l i br i umi suns t a bl ewhe ne ve rt hes l o peoft hene tr a t ea tt hee qui ‑ l i br i umpol nti spos i t i ve. Be ca us et her a t ee qua t i oni nt hee xa mpl ei sl i ne a r ,t hene ti nc r ea s er a t egr ows e xa c t l yi npr opo r t i ont ot hes t a t eo ft hes ys t e m. Eve r yt l met hes t a t eoft hes ys t e m doubl es ,s ot oowi l li t sa bs ol ut er a t eofi nc r e as e.The r e f or e,t het r a j e c t or yOf t hes ys t e mi nt i mes howsa ne ve r ‑ i nc r e a s l nga c c e l e r a t i on. Fi gur e8‑ 4s howst het r a j e c t or yOft hef i r s t ‑ o r de rl i ne a rpos i t i vef e e dba c ks ys t e mont hepha s epl ota nda sa ‑ oft hes ys t e mi s1uni t . Thea r r owsa l ongt hepha s epl ots howt ha tt hef lOwoft he nt .Fr om a nynonne ga t i ves t a r t l s ys t e mi sa wa yf r om t heuns t a bl ee qui l i br ium pol l ngpOl nt ,t hes t a t eoft hes ys t e m gr owsa ta ne ve r ‑ a c c e l e r a t l ngr a t ea Si tmove s a l ongt hel i neNe tI nf low ‑gS・ 4Thea c c e l e r a t i nggr owt hi se a s i l ys e e ni nt het i me 4 Th es y s t e mf ss y mme t icf r o rn e g a t i v ev a l u e so ft h es t a t ev a ia r b l e ・ I fS ( 0) <0, Swi l l b e c o me e v e rmor en e g a t l V ea t e x p o n e n t i a l r a t e s . I nmo s t s y s t e ms , h o we v e r , t h es t a t ev a r i a b l e sare r e s t r i c t e d er ec a nb en on e g a t i v ep o p u l a t i o n s ) . t on o n n e g a t i v ev a l u e s( t h 26 8 Pa r tI I Tわol sf orSys t e msThi nki ng FI GURE8 ‑ 4 Exponen t i al gr owt h: s t r uc t ur e( ph as epl ot )andbehavi or( t i mepl o t ) Thef r ac t i onal gr owt hr at eg‑0. 7%/ t i meuni t .l ni t i al s t at eoft hes ys t em ‑1uni t lPoi n t sonpl otshow ever ydoubl i ng( 1 0t i meper i ods ) St r uct ur e Behavi or tw n)u a Ne lnflo (sl ! u L u! tJ選 u n )J V L Ol l u aN (a iO 6 5 2 a le lS 8 2 1 ( un itJ st i m e) 1 5 lS ^ S aL l t 0 128 256 512 St at eofSyst em ( uni t s) 1024 0 200 400 600 Ti me 800 1000 do ma i n. Thes l opeoft hes t a t eva ia r bl ea te ve r ypoi nti se xa c t l ypr opo r t i ona lt ot he qua nt l t yl nt hes t oc k,a ndt hes t a t eoft hes ys t e m doubl ese ve r y1 00t i mepe r i ods ( S e es e c t i on8. 2. 3) . Not et ha tc ha ngl ngt hef r a c t i ona lgr owt hr a t ec ha nge st hes l opeoft hel i neNe t I nf low‑gSa ndt he r e f o r et her a t eofgr owt h,butnott hee xpone nt i a ls ha peoft he C ur ve. 8. 2. 3 ThePowerofPosi t i veFeedback: DL Rt Jb軸 gTi mes Be f or ec o nt i nul ng, t r yt hef ol l owi ngC ha l l e nge. Paper『0日 di mg Ta kea no r di na r ys he e to fpa pe r . Fol di ti nha l f ・ Fol dt hes he e ti nha l fa ga i n. Thepa ‑ pe ri ss t i l ll es st ha nha l fami l l i me t e rt hi c k. I fyouwe r et of ol di t40mor et i mes , how t hi c kwoul dt hepa pe rbe?I fyouf ol de di tat ot a lof1 00t i me s ,how t hi c k woul di tbe?Gi veyouri nt ui t i vees t i ma t e,wi t ho utus i ngaC a l c ul a t or .Gi veyour 95%uppe ra ndl owe rc onf i de nc eboundsf oryoure s t i ma t e s( t ha ti s ,ar a ngeofe s t i ma t e syoua r e95% s ur ei nc l ude st her i ghta ns we r . Your95% c onf i de nc ebo I J i nd me a nsyoube l i e vet he r ei sonl ya5% c ha nc et hec or r e c ta ns we rf a l l sout s i det he uppe ra ndl owe rboundsyougi ve ) ・ As kyourf ie r ndsa ndf a mi l yt ot r yt hec ha l l e nge a swe l l , not l ngdownt he i ra ns we r sa ndc onf i de nc eba nds . ‑ TheRul eof70 Pos i t i vef e e dba c kl oo psa r et hemos tpowe r f ulpr oc e s s e si nt heuni ve r s e.The i r powe ra r i s e sf r omt hef a c tt ha tt her a t eofi nc r e a s egr owsa st hes t a t eoft hes ys t e m Ch a p t e r8 Cl o s l n gt h eLo o p: Dy n a mi c so fS i mp l eS t r u c t ur es 269 gr ows . W he nt hef r a c t i ona lne ti nc r eas er a t ei sc ons t a nt , pos i t i vef e e dba c kl ea dst o e xpone nt i a lgr owt h. Expone nt i a lgr owt hha st her e ma r ka bl epr ope r t yt ha tt hes t a t e oft hes ys t em d oubl e si naf i xedpe r i odoft i me, noma t t e rhow l a r gei ti s . I nt hee x a mpl ei nFi gur e8‑ 4,t hes t a t eoft hes ys t e m doubl eseve r y1 00t i mepe r i ods ・I t t a kes1 00t i mepe r i odst ogr ow f r om t hei ni t i a lva l ueof1t o2uni t sa ndonl yl oo t i mepe r i odst ogr ow f r om 1 000t o20000rf r om 1bi l l i ont o2bi l l i on・ Anyqua n t i t yt ha tgr owsbypos i t i vef e edba c k,t ha tdoubl esi naf i xe dpe r i odoft i me,ge t s ve r yl a r gea f t e rJ us taf ewdoubl i ngs . You ca nr ea di l yde t e r mi net hedoubl i ngt i mef ora ny e xpone nt i a lgr owt h pr oc es s .Todos os ol veequa t i on( 81 5)f ort hei nt e r va loft i met dt ha ts a t i s f i est he e qua t i onwhent hes t oc khasr ea c he dt wi cei t si ni t i a lva l ue:2S( 0)‑ S( 0) e xp( gt d). Ther es ul ti s ‑ ‑ t d ‑1 n( 2) / g ( 8 ‑ 1 0) whe r et di st hedoubl i ngt i me. 5Th ena t ur a ll ogof2‑ 0. 6931… Roundi ngl n( 2) t o0. 70a nde xpr es s l ngt hef r a c t i ona lgr owt hr a t ei npe r c e ntpe rt i mepe r i odgi ves t heRu l eo f7 0: t d ‑7 0 / ( l oo雷 ) . ( 8 ‑ l l ) Thusa ni nves t me nte a r ni ng7%/ yea rdoubl esi nva l uea f t e r1 0yea r s ・ 6Ass howni n Fi gur e4‑ 2,t hea ve r a gegr owt hr a t eofr ea lGDPi nt heUSove rt hepas t1 00yea r s hasbe e n3. 4%/ yea r ,s ot hedoubl i ngt l mei sr oughl y20yea r s . Thepas t200yea r s ha vewi t nes s ed1 0doubl i ngs ,i nc r eas l ngt hes i z eoft heUSe conomybyr oughl ya f a c t orofonet hous a nd( 21 0‑ 1024). 8 . 2適 M岳 s p e r e e p 色 盲 om s⑳ 菅EXp ⑳m em 骨 i a L EGr ⑳ Wを h W hi l et heRul eof70i ss i mpl ea ndeas yt oa ppl y,t hei mpl i ca t i onsofe xpone nt i al gr owt ha r edi fi c ul tt ogr as pi nt ui t i vel y.Wa ge naa r( 1 978)a ndWa ge na a ra nd Sa ga r i a( 1 975 )s t udi ed pe opl e' sa bi l i t yt o ext r a pol a t ee xpone nt i a lgr owt h pr oces s es .The yf oundpeopl egr os s l yunde r es t i ma t e dt her a t eofgr owt h,t e ndi ng t oe xt r a pol a t el i nea r l yi ns t e adofe xpone nt i a l l y. Tha ti s ,wet endt oa s s umeaqua n‑ t l t yI nc r eas esbyt hes a mea bs ol ut eamountpert i mepe r i od,whi l ee xpone nt i al gr owt hd oubl e st hequa nt i t yl naf i xedpe r i odoft i me・Whe nt hegr owt hr a t ea nd f or e cas thor i zo na r es ma l l ,l i nea re xt r a pol a iOni t sar eas ona bl ea ppr oxi ma t i ont o 5D i v i d i n ge q ua t i o n( 8 ‑ 5 )t h r o u g hb yS( 0 )y i e l d s2‑ e x p( g t d).T h a t i s , t h ed o u b l i n gt i mei si n ‑ d e p e n d e n to ft h ei n i t i ls a i z eo ft h es t o c k・ Ta k i n gt h en a t u r a l l o go fbo t hs i d e sa n dd i v i d i n gt h r o u h g b ygg l V e St d ‑1 n ( 2 ) / g . 6 Th eRu l eo f7 0i sb a s e do nt h ea s s u mp t 1 0 nt h a t t h eg r o wt hp r o c e s si sc o n t nu i o u si nt i me ・ I n t h ei n v e s t me n t e x a mp l e , t h ea s s u mp t l O ni st h a t i n t e r e s t i sc o mp o u n d e dc o n t i n t l O u S l y ・ Co mp o u n d i n g a t d i s c r e t ei n t e r v a l sr e d u c e st h ee f f e c t i v ey i e l da n dl e n g t h e n st h ed o u b l i n gt l me Jnd i s c r e t et i me , e q u a t i o n( 8 1 5 )n ol o n g e rh o l d s ; i n s t e a dt h es t a t ev a r i a b l el Sg i v e nb yS( t )‑S( 0) ( 1 +g / p ) P t wh e r e pi st h ec o mp o u n d i n gp e r i o d( f o re x a mp l e ・ p= 1 2f o rmo n t h l yc ? mp o u n d i n gwh e ngi st h ei n t e r e s t r a t ep e ry e a r ) . Th ed o u b l i n gt i meo ft h ed i s c r e t et i mep r oc e s si sg l V e nb yt d ‑l n ( 2 ) / ( p l n ( 1十g / p ) ) ・ Si n c el n ( l+g / p)記g / pf o rs ma l lg / p , t h eRu l eo f7 0r e ma i n sチg o o da p p r o x i p l a t i o no fd i s c r e t e t i mep o s i t i v ef e e d b a c kp r oc e s s e sa sl o n ga st h ec o mp o u n d i n gI n t e r v a l i sr e l a t l V e l ys h o r t c o mp a r e d t ot h ed o l l b l i n gt l me . Fo re x a mp l e , ap r o c e s sg r o wl n ga tar a t eO f7%/ y e a rc o mp o u n d e do n l ya n ‑ n u a l l yd o u b l e si n0 . 2 4y e a r sc o mp a r e dt o9 . 9 0y e a r swh e nc o mp o u n d i n gi sc o n t i n u o u s( u s i n gt h e e x a c t v a l u eo fl n( 2 )t oc a l c u l a t et d).I nt h el i mi t a spぅ c o ,( 1+g / p)(pt)‑ e x p ( g t ) . 1 2 70 I IT わo l sf o rS y s t e msTh i n k i n g Pa r t e xpone nt i a lgr owt h. Howe ve r ,ast hegr owt hr a t ei nc r eas esort hef わr ecas thor i zon l e ngt he ns ,t hee r r or sbe comehuge, Howt hi c kdi dyout hi nkt hes he e tofpa pe rwoul dbea f t e rf ol di ngi t42t i mes ? Af t e r1 00t i mes ?Mos tpe opl ees t i ma t et hepa pe rwi l lbel es st ha name t e rt hi ck ( 3. 3f ee t )e ve na f t e r1 00f わl ds .I nf a c t ,a f t e r42f ol dst hepa pe rwoul dbe440, 000 ki l ome t e r st hi c k‑ mor et ha nt hedi s t a ncef r om t heea r t ht ot hemoon!Anda f t e r 1 00f ol ds , t hepa pe rwoul dbea ni ncompr e he ns i bl yl mme nS e850t r i l l i ont i mest he di s t a nc ef r om t heea r t ht ot hes un! 7 Theunde r es t i ma t i onofe xponent i a lgr owt hi sape r vas i vea ndr obus tphe nom‑ e non. Wa ge na a ra ndcol l ea guesf oundt ha tt heunde r es t i ma t i onwasr obus tt ot he e pr es e nt a t i onoft heda t ai nt a bul a rvs .gr a phi cf or m.Sur pr l S l ngl y,s howi ngmor da t at e ndst owo r s e nt heunde r es t i ma t i on,a ndt r a i nl ngl nma t he ma t i csdi dnothe l p ( Wa ge naa ra ndTi mme r s1 979) . Thec ount e r i nt ui t i vea ndi ns i di ousc ha r a c t e rofe xpone nt i a lgr owt hca nbes e e n bye xa mi nl ngl tove rdi f f e r e ntt i mehor i z ons . Fi gur e81 5S howsapos i t i vef e edba c k pr oces sgr owl nge XpOne nt i a l l ya tacons t a ntr a t eof0. 7%/ t i mepe r i od,wi t hf our di f f e r e ntt i mehor i z ons .Byt heRul eof70,t hedoubl i ngt i met d‑ l oot i mepe r i ‑ ods ・Ove rat i mehor i zonofone ‑ t e nt ht hedoubl i ngt l me,gr owt hi si mpe r c e pt i bl e. Ove rat i mehor i z onofonedoubl i ngt i me,t hegr owt ha ppea r st obec l os et ol i nea r . Ove r1 0doubl i ngs ,t hea cc el e r a t l ngC ha r a ct e rofe xpone nt i a lgr owt hi sc l ea r l yvi s ‑ i bl e.Ove r1 00doubl i ngs ,i ta ppea r st ha tnot hi ngha ppe nsa ta l lunt i la bout90% of t het i mehaspa s s ed. Ma nype opl e, e xa mi nl ngt hebe ha vi orove rt hel ongt l mehor i ‑ zon,c onc l udet ha tt he r emus tha vebee nadr a ma t i cc ha ngei nt hes t r uc t ur eoft he s ys t e ma r oundt i me9000.I nf a c t ,t hes a mepr oc es sofa c c umul a t i onpowe r edby pos i t i vef ee dba c ki sope r a t l ngt hr oug h outt hee nt i r ehi s t or y,butonl yt hel as tf e w doubl i ngsa r enot i cea bl e. Ofc our s e, nor ea lqua nt l t yCa ngr owf or e ve r . Be ca us ee xpone nt i a lgr owt hdou‑ bl esi naf i xedt i mei nt e r va l ,pos i t i vef e edba c kpr oc es s esa ppr oa c ht he i rl i mi t s l .( 1 972, p. 29)i l l us t r a t ewi t ha nol d r a pi dl ya ndof t e nune xpe c t e dl y. Meadowse ta Fr e nc hr i ddl e: Suppos eyo uo wnapo ndo nwhi c hawa t e rl i l yl Sg r O Wl ng. Thel i l ypl a ntdo ubl e s i ns i z ee a c hda y . I ft hel i l ywe r ea l l owe dt og r o wunc he c ke d, i twoul dc o mpl e t e l y c ov e rt hepo ndi n3 0da ys , c ho k i ngo f ft heot he rf o r mso fl i f ei nt hewa t e r . Fo ra l o ngt l met hel i l ypl a n ts e e mss ma l l ,a nds oyo ude c i deno tt owo r r ya bo utc ut t l ng i tba c kunt i li tc o ve r sha l ft hepo nd. Onwha tda ywi l lt ha tbe ?Ont het we nt y‑ ni n t h da y , o fc o u r s e ・ Yo uha veoneda yt os a veyou rpo nd・ 8 k n e s so ft he p a p e r ・ At y p i c a l s h e e t o fp a p e ri sa b o u tO ・ 1mmt h i c k ・ 7 Ea c hf o l dd o u b l e st h et h i c Af t e rt wof o l d si t i s0 . 4mmt h i c k; a f t e rf i v ef o l d s , j u s t3 . 2mm. Af t e r4 2d o u b l i n g st h et h i c k ne s s ha si n c r e a s e db yaf a c t o ro f2 4 2; 岩4・ 4t r i i l i o n・ Mu l t i p l y i n gb yt h ei n i t i a l t h i c ne k s so fO ・ 1mma n d c o n v e r t l n gt Ok i l o me t e r sg i v e sat h i c ne k s so f4 4 0 , 0 0 0k m. Af t e r1 0 0f o l d st het h i c k n e s sh a si n ‑ c r e a s e db yaf a c t o ro f2 1 0 0‑ 1 1 2 7xl O 3 0 l Mu l ip t l y i n gb yt h ei n i t i a l t h i c k n e s s , c o n v e r t l n gt Ok i l o me ‑ t e r s , a n dd i v i d i n gb yt h eme a ne a r t h ‑ s o l a rd i s t a n c eo f9 3mi l l i o nmi l e s‑1 4 9mi l l i o nk mg l V e Sa t h i c ne k s so f8 5 2×1 01 2t i me st heme a ns o l a rd i s t a n c e ‑mo r et h a n1b i l l i o nl i g h t ‑ y e a r s ・ Ofc o u r s e , y o uwo u l dn e e dav e r yl a r g es h e e to fp a p e rt oc a r r yt h ee x p e r i me n t t h r o u g h. 8 I nf a c t , t h el i l yp a dwo u l db emi c r o s c o p i cf o rmu c ho ft h e3 0d a y s ・ I n i t i a u yt h el i l yc o v e r so n l y 93×1 0 ‑ 8 %o ft h ep o n d' sa r e a ・ I t r e a c h e s1% o ft h ea r e ao lya n f t e rt he2 3 r dd a y . ㌔ ・㌧ \ \ \ \ 000 9 0 0 0 寸 ・ 11 1 p 1 00戸 = uO=! JOH a∈! 1 \ p li = uO= 葛 H 望 巳. i \ i i 一 ‑‑‑‑ p t o L Z uOZ! JOH auJ ! 1 〜 p tL・ o Z uOZ! JOH au ! 1 0 N 0 suoz. J ouaL u! )t uaJ a⊆ P J a^OL l l l V L OLB b t 2! t uauOdx山 0 00L 0 l 甲 9 uun DU 比 . ( spo! J ada∈ !100LI a∈ 1 !6u! l qnOP)SaSCD ニe u!PO! J adeL u.L t J% ト. Ol Oal eJ LltJ VL OLBa∈t 2 SaL 1 7^qua^.I6SL . ∈al S^SaL l lJ Oal t 2 1 Sau ( sl ! un)uJ al S^s e t J l1 0∂l t 2 1 S ( sl ! un)uJ al S^saL J l1 0∂l t 2 1 S ( sl ! un)uJ al SIsaL l 11 0al el S ( Suun)Lual S^S別朋 Oal el S ⊂ 〉 一 つ ≡ 271 272 Pa r t I IT o o l sf o rS y s t em s Th l n k l n g Asva r i ousl i mi t sa r ea ppr oa c he d, nonl i ne a r i t i e sa l wa yswe a ke nt hepos i t i vel oops a nds t r e ngt he nt hene ga t i vef e e d ba c ksunt i lt hee xpone nt i a lgr owt hha l t s .Thes e nonl i ne a re f f e c t sa r ei l l us t r a t e dbya no t he rf a mouss t or ya boute xpone nt i a lgr owt h. Ast ol dbyMe a dowse ta l .( 1 972, p. 29) : Th e r ei sa no l dPe r s i a nl e g e n da bo u tac l e v e rc o u r t i e rwhop r e s e n t e dabe a ut i f u l c h e s s bo a r dt ohi ski nga n dr e q u e s t e dt ha tt h ek i n gg l V eh i mi nr e t u r n1g r a i no f r i c ef o rt h ef i r s ts q ua r eo ft h ebo a r d, 2g r a i nsf o rt h es e c o n ds q u a r e , 4g r a i nsf o rt h e t h i r d, a nds of o r t h. Th ek i ngr e a d i l ya g r e e da n do r d e r e dr i c et ob eb r o ug h tf r o m h i ss t o r e s . Thef o u r t hs q u a r eo ft hec h e s s bo a r dr e q ui r e d8g r a i ns , t h et e n hs t q ua r e t o o k51 2g r a i ns , t hef i f t e e n hr t e q u i r e d1 6 , 3 8 4, a n dt h et we n t y‑ f i r s ts q ua r ega v et h e c o u r t i e rmo r et ha nami l l i o ng r a i nso fr i c e . Byt h ef o r t i e t hs q ua r eami l l i o nmi l l i o n r i c eg r a i nsha dt obeb r o u g h tf r o mt h es t o r e r o o ms . Theki n g' Se n t i r er i c es u p p l y wa se x h a us t e dl o n gbe f o r eh er e a c h e dt hes i x t y ‑ f o u r t hs q ua r e . I nf a c t , t het ot a lqua nt l t yOfr i c eona l l64s q ua r e swoul dha vec ove r e da l lofmod‑ e r nda yI r a nt oade pt hofmor et ha n5f e e t . 82. 5 Pr ocessPoi nt :Over comi ngOver conf i dence . Cons i de ra ga l nyoura ns we r st Ot hepa pe rf ol di ngc ha l l e nge・Notonl ydope opl e unde r es t i ma t et het hi c knes soft hepa pe r , butt hec or r e c ta ns we r sf a l lout s i det he i r 95% c onf i de nc eboundsa l mos ta l lt het i me. Tha ti s , pe o pl ea r egr os s l yove r c onf i de nti nt he i rj udgme nt s . Ove r c onf i de nc ei soneoft hemos tr o bus t j udgme nt a lbi a s e sdoc ume nt e di nt he ps yc hol ogi c a ll i t e r a t ur e. I nac a r e f ulr e vi e w,Sc ot tPl ous( 1 993)wr i t es ,H Nopr ob‑ l e mi nj udgme nta ndde c i s i onma ki ngl Smo r epr e va l e nta ndmo r epot e nt i a l l yc a ト a s t r o phi ct ha nove r c onf i de nc e. " Ove r c onf i de nc eme a nst hec o nf i de nc ebo undspe o pl epr ovi dea r oundt he i re s ‑ t i ma t eo fa nunknownqua nt i t ya r et oona rr ow,C a uS l nga nune xpe c t e dl yhi ghr a t e ofi nc or r e c tpr e di c t i ons . Li c ht e ns t e i na ndFi s c hof f( 1 977)f oundt ha tpe opl ewe r e 65% t o70% c onf i de ntofbe i ngr i ghti na ns we r l ngaVa r i e t yofque s t i onswhe ni n f a c tt he ya ns we r e dc or r e c t l ya ton lya boutt hec ha nc er a t eof50%.Suc hr es ul t s ha vebe e nr e pl i ca t e di nawi der a ngeoft a s ksa ndwi t he xpe r t sa swe l la snovi c e s . Li c ht e ns t e i n, Fi s c hof f , a ndPhi l l i ps( 1 98 2)r e vi e we ds t udi e st ot a l i ngne a r l y1 5, 000 j udgme nt sa ndf oundt ha tpe opl e' S98% c onf i de nc eboundsc ont a i ne dt hec or r e c t r e s pons eo nl y68% oft het i me ‑a ne r r o rr a t e1 6t i me sg r e a t e rt ha ne xpe c t e d. Ext e ns i ves t udyoft her e l e va nti s s uec a na c t ua l l ywor s e nove r c onf i de nc e. Os ‑ ka mp( 1 965)S howe dt ha tt hemor ei nf o r ma t i o npe opl er e c e i ve da bouta ni s s ue , t he mor ec o nf i de ntt he ybe ca me ‑ whi l ea c c ur a c ydi dnoti mpr ove.Fi na nc i a li nc e n‑ t i vesdonotr e duc eove r c onf i de nc e: I ns o mes t udi e ss ub j e c t swe r egi ve nt heo pt 1 0n ofbe t t i ngont he i ra ns we r sa tt heoddst he ye s t i ma t e df orbe i ngc or r e c t . The yc on‑ s i s t e nt l yl os tmone y. si t ua t i onsi nwhi c hpe opl e' sc onf i de nc eboundsa r ea ppr oxi ma t e l yc or r e c ta r e r a r e・ We a t he rf or e c a s t e r sa ndpr of es s i ona lc a r dpl a ye r sa r ea mongt hef e wgr o ups whos ej udgme nt sha vebe e nf oundt obewe l lc a l i br a t e d.The s ea r ena r r owl y bounde dc ont e xt swhe r et her e l e va ntf a c t or sa r ewe l lknown・ Thous a ndsofr e pe ‑ t i t i onspr ovi def e e dba c ke na bl i ngt heme t e or ol ogi s ta ndga mbl e rt ol ea r nf r om e xpe r i e nc e. Thes ec ondi t i onsdonothol df ormos tdyna mi ca l l yc ompl e xs e t t l ng ‑ S, Ch a p t e r8 Cl o s i n gt h eLo o p: Dy n a mi c so fS i mp l eS t r u c t u r e s 273 i nc l udi ngj udg me nt sa boutt hel i ke l ybe ha vi oroff e e d ba c ks ys t e ms :t heca us a l s t r uc t ur e,r e l e va ntva r i a bl es ,a ndpa r a me t e r sa r ehi ghl yunc e r t a i na ndl a r ge l yun‑ known( s e ec ha pt e r1 ) . I nmos ts oc i a la ndbus i ne s ss i t ua t i onst het i mede l a ysa r es o l ongt he r ei sl i t t l eornoc ha nc et ol e a r nf r om e xpe r i e nc e;byt het i mef e e dba c ki s a va i l a bl ei twi l lbet ool a t et ot a kee fe c t i vea c t i on・Ma nyl nVe S t Or Sa ndmone y ma na ge r sdur i ngt hegr e a tbul lma r ke t soft he1 920sa nd1 980S ‑90sne ve re xpe r i ‑ e nc e dama r ke tc r a s ha ndunde r e s t i ma t e dt hel i ke l i hoodofdec l i ni ngs ha r epr i c e s . Andf o ri s s uess uc ha sgl oba lc l i ma t ec ha nget hewor l dmus ta doptpol i c i esr e ‑ ga r di nge mi s s i onsofgr e e nhous ega s e sde c a de sbe f or et hef ul li mpa c tofhuma n a c t i vi t yOngl oba lc l i ma t ewi l lbeknown.Ove r c onf i de nc eme a nsyouwi l lpr oba ‑ bl ybuyt ool i t t l ei ns ur a nc ea nda r el i ke l yt owa keuponeda yt of i ndyouha vei n‑ s uf f i c i e ntc ove r a ge・Be f or et heCha l l e nge re x pl os i o nNASAe s t i ma t e dt her i s kof c a t a s t r o phi cl a u nc hf a i l ur ea t1i n1 00, 000・9 Asa ni l l us t r a t i ont ha te xpe r t sa r ef a rf r o mi mmunet oo ve r c onf i de nc e , c ons i de r t hede ba t eove rgl oba lwa r mi ng。Thee c onomi s tWi l l i a m Nor dha us( 1 994)c on‑ duc t e das ur ve yofdi s t i ngui s he de xpe r t songl o ba lc l i ma t ec ha nget oa s s es st he i r vi e wso nt hel i k e l ye c onomi ce fe c t sofgl oba lwa r ml ng. Nor dha usa s ke dt hepa ne l t oe s t i ma t et hel os sofgr os swor l dpr oduc t( GWP)Ca us e dbyva r i ousa mount sof wa r ml ng. Ther es ul t ss howe dahugegul fbe t we e nt hees t i ma t e soft hes c i e nt i s t s c ompa r e dt ot hee c onomi s t s ・Sc i e nt i s t se s t i ma t e dt hepr oba bi l i t yofaH hi gh‑ c ons e que nc ee ve nt "( ac a t a s t r ophi cc ha ngei nc l i ma t ec ut t i ngGWPby25% or mo r e )a s20t o3 0t i mesmor el i ke l yt ha nt hee c o nomi s t sdi d. Es t i ma t e soft hemos t l i ke l yr e d uc t i oni nGWPwe r es i mi l a r l ybi moda l , Wi t hs c i e nt i s t sge ne r a l l ye s t i ma t ‑ 1 ngl a r gei mpa c t sa nde c onomi s t sge ne r a l l ye s t i ma t l ngS ma l lore ve npos i t i vei m‑ pa c t sofwa r ml ngOnt hegl oba le c onomy.Noo neknowswhi c hgr oupl Sc or r e c t . Wha ti ss t r i k i ng,howe ve r ,i st hes ma l lr a ngeofunc e r t a i nt ye a c he xpe r ta l l owe d. Ea c hpr ovi de d90% c onf i de nc eba ndsa r o undt he i rbe s te s t i ma t es ,ye ti nma ny c a s e st he s er a nge swe r es os ma l lt he ye xc l ude dt hema j or i t yOft heot he re xpe r t s ' vi e ws . Ec onom is t s , whot e nde dt opr e di c ts ma l le fe c t s , t e nde dt oha vet hena r r ow‑ e s tc onf i de nc eba nds . Onee c onomi s twr ot e ," I ti si mpos s i bl et oc ont e mpl a t ewha t s oc i e t ywi l lbel i keac e nt ur yf r om nowa st e c hnol ogyc ha nges "ye te s t i ma t e dt ha t a30 Cr i s ei ngl oba lme a nt e mpe r a t ur eby2090woul dpr oduc eac ha ngei nGWP r a ngi ngf r om ‑2%t o+1 %, Oneoft hes ma l l e s tr a nge sof f e r e dbya nyr es ponde nt . Ove r c oml n gOVe r C Onf i de nc er e qui r e sg r e a t e rhumi l i ya t boutt hel i mi t sofo ur e x pe r t i s e.Se ve r a lt e c hni que sc a nhe l p.Li s ta l lt her e a s onsyouropl ni onc oul dbe wr ong・ Tr yt oi de nt i f yt hei mpl i c i ta s s umpt 1 0nSOfyo urme nt a lmode la ndc ons i de r howt heo ut c omemi ghtc ha ngei fdi fe r e nta s s umpt i onsWe r eus e d. Be ca us ei de n‑ t i f yi ngt hehi dd e nbi a s e si nourownme nt a lmode l si sdi f f i c ul t , i ti se s pe c i a l l yva l u‑ a bl et os o l i c i tt hej udgme nt sa ndopi ni onso fadi ve r s eg r oupofpe opl e,es pe c i a l l y t hos ewi ho t ppos i t evi e ws . Yourc r i t i cswi l lus ua l l ybef a rmor ee f f e c t i vei nhe l pl l ngyouC a l i br a t ea ndi mpr oveyourj udgme ntt ha nyour丘. ユ e nds ‑s e e kouta ndwe ト c omet he i rvi e ws . Yous houl dbees pe c i a l l ys us pe c tofs t a t e me nt st ha ts ome t hi ngl S a bs ol ut e l yc e r t a i n,i ne vi t a bl e,wi t houtdoubt ,o raonei nami l l i onc ha nc e,e s pe ‑ c i a l l yi ft hes i t ua t i oni nvol veshuma nbe ha vi orori fpe o pl e' sj udg me nt sr e qul r e 9 ofc o u r s e , NAS A' se s t i ma t ec o u l dh a v eb e e nc o r r e c t a n dt h eCh a l l e n g e rd i s a s t e r , J u s t e x t r a o r d i n a r i l yb a dl u c k . Wh i l el o g l C a l l yp o s s i b l e , C a r e f u l s t u d i e so f t h ed i s a s t e rb el i et h a t v i e w. 274 P a r tI IT o o l sf o rS y s t em s Th i n k i n g me nt a ls i mul a t i onofdyna mi c a l l yc ompl e xs ys t e ms ・Whe nas s es s l ngt hec onf i ‑ de nc ei nt e r va l spr ovi de dbyf o r ma lmode l sors t a t i s t i c a la na l ys i sofda t a ,r e me m‑ be rt ha tt hec onf i de nc eboundspr ovi de dbys t a t i s t i c a lmode l sme a s ur eonl yt he unc e r t a i nt yduet os a mpl i nge r r or ,a ndnott ha tduet os pe c i f i c a t i one r r o r( e r r or si n t hemode lbounda r ya ndi nt hema i nt a i ne dhypot hes e soft hes t a t i s t i c a lme t hod) . Thes el a t t e rs our c e sofe r r ora r et ypl C a l l ymuc hl a r ge rt ha nunce r t a i nt yduet os a m‑ pl i nge r r or ・ Whe nf or ma lmode l sa r ea va i l a bl e ,c onduc te xt e ns i ves e ns i t i vi t yt e s t s , notonl yoft her e s pons et opa r a me t r i cunc e r t a i nt ybuta l s ot ounc e r t a i nt ya boutt he mode lbounda r y, f e e d ba c ks t r uc t ur e,a ndot he rs t r uc t ur la a s s umpt l OnS . 8. 3 NEGATI VEFEEDBACKAND ExpoNENTI ALDECAY Fi r s t l 0r de rl i ne a rpos i t i vef e e dba c ks ys t e msge ne r a t ee xponent i a lgr owt h.Fi r s t ‑ o r de rne ga t i vef e e dba c ks ys t e msge ne r a t egoa l ‑ s e e ki ngbe ha vi or . Whe nt hes ys t e m i sl i ne a r , t hebe ha vi ori spur ee xpone nt i a lde c a y. Thef e e dba c ks t r uc t ur er e s pons i bl ef ore xpone nt i a lde c a yi ss howni nFi g‑ ur e8‑ 6. s e A xa mpl es , c ons i de rt hede a t hr a t eofapopul a t i onort hede pr e c i a t i onof a na s s e t . I nbot hc a s e s , t hene tout lowi f spr o por t i ona lt ot hes i z eoft hes t oc k. The e q ua t i onf o rt hene tr a t eofc ha ngeoft hes t oc ki s Ne tI n no w‑‑Ne tOu t lo f w‑‑d S ( 8 1 1 2 ) whe r edi st hef r a c t i ona lde c a yr a t e( i t suni t sa r e1 / t i me ) A Ther ec i pr oc a loft hef r a c ‑ t i o na lde ca yr a t ei st hea ve r a gel i f e t i meofuni t si nt hes t oc k( s e ec ha pt e r1 1onde l l a ysf o rapr oof ) . Tode duc et hebe ha vi oroft hel i ner , f i r s t 1 0 r de rne ga t i vef e e dba c ks ys t e mnot e t ha tequa t i on( 8‑ 1 2)i st hes a mea se qua t i on( 8‑ 4)e xc e ptt ha tt hene ga t i veoft he f r a c t i ona lde c a yr a t er e pl a c e st hef r a c t i ona lne ti nc r e a s er a t e. Thes ol ut i oni st he r e ‑ f or egl Ve nbyt hes a mee xpone nt i a lf unc t i on,wi t h‑dr e pl a c i ngg: a S( t )‑S( 0 ) e x p( ‑d t ) ( 8‑ 13) Fi gur e8‑ 7s howst hepha s epl o tf o rt hef i r s t 1 0 r de rl i ne a rne ga t i vel oo ps ys t e m. The ne tr a t eofc ha ngeoft hes t oc ki snowas t r a i g htl i newi t hne ga t i ves l o pe‑d. Asbe ‑ f or e, t hepoi ntS‑0i sa ne q ui l i br i um: whe r et he r ea r enope opl e , t he r ec a nbeno de a t hs ; whe nt heva l ueofa na s s e tha sde c l i ne dt oz e r o, nof u r t he rde pr e c i a t i onc a n bet a ke n Unl i ket hepos i t i vef e e dba c kc a s e,t hee qui l i br i um i ss t a bl e. I nc r e a s l ng t hes t a t eoft hes ys t e mi nc r e a s est hede c a yr a t e,movl ngt hes ys t e m ba c kt owa r d z e r o. As ys t e m wi t has t a bl ee qui l i br i umi sl i kea nor a nger es t l nga tt hebot t om of abowl .I fyoupus ht heor a ngeupt hes i deoft hebowla ndr e l e a s ei t ,i tr ol l sba c k downunt i li tc omest or e s ta ga l na tt hebot t om.De vi a t i onsf r om t hee qu1 1 1 D r l um a r es e l f ‑ c or r e c t i ng. Fi gur e8‑ 8S howst hedyna mi csoft hes ys t e mo nbot ht hepha s epl ota ndi nt he t i medoma i n. The丘. a c t i ona lde c a yr a t ei nt hee xa mpl ei s5%/ t i mepe r i od,a ndt he i ni t i a ls t a t eoft hes ys t e mi s1 00uni t s ・I ni t i a l l y,t hede c a yr a t ei s‑ 5uni t s / t i mepe ‑ r i od・Thede ca yr a t ei sdi r e c t l ypr opor t i ona lt ot hes t a t eoft hes ys t e m,s oa st he s t a t eoft hes ys t e mde c l i ne s , s ot oodoe st hede c a yr a t e. Thef lowo ft hes ys t e m, de ‑ not e dbya r r owsi nt hepha s epl o t , i sa l wa yst owa r dt hes t a bl ee qui l i br i um. Thedot s ont hepha s epl ots howt hel oc a t i onoft hes ys t e me ve r y1 0t i meuni t s . Not ehow 275 Cha p t e r8 Cl os i n gt heLoo p: DyI ‑ a mi c sofSi mp l eSt r uc t ur e s Ft GURE8 ‑ 6 Gener alSt r uct ur e Fi r s トor derl i near negat i vef eedback: s t r uct ur eand exampl es Netl n刑owRat e =‑NetOut 朋ow Rat e=‑dS d Fr act i onal DecayRat e Exampl es Depr eci at i onRat e =BookValue/AssetLi f et i me FI GURE8 ‑ 7 ≡‑ dS t l ow Rat e Netl nt l ow Rat e=‑NetOut 0 ( a u! t J st! un) a t t 2 t ]きOl I uJl a N Phasep一 otf or exponen t i aldecay vi a‖ nearnegat i ve f eedback 276 Pa r t I IT わ o l sf o rS y s t e msTh i n k i n g ‑ 8 Exponent i al dec ay:s t r uc t ur e( ph as epl ot )andbehavi or( t i mepl ot ) FI GURE8 Thef r ac t i onal decayr at ed‑5%/ t i meuni t .I ni t i al s t at eoft hes ys t em ‑1 00uni t s. Behavi or St r uct ur e 5 40 60 80 S t a t eo fS y s t e m( u n i t s ) 100 i tsJti m e) 20 N e t l n f l o w ( r i g h t s c a l e ) 20 n fl w a lt 2 tS N a 0 o (uコ J l10 OL un )N O L [ i u ! IJSl! 0 5 n)uJa l S^S Ne (sl! u ∈ (a S t a t eo Hh eS y s t e m ( l e f t s c a l e ) 40 60 Ti me t hea d j us t me nti sr a pi da tf i r s ta ndf a l l sove rt i me. Thes t a t eo ft hes ys t e mf a l l sa ta di mi ni s hi ngr a t ea si ta ppr oa c he sz e r o・ Thee xpone nt i a lde c a ys t r uc t ur ei sas pe c i a lc a s eoft hef i r s t 1 0 r de rl i ne a rne ga t i vef e e dba c ks ys t e m. Asdi s c us s e di nc ha pt e r4,a l lne ga t i vef e e dba c kl oo psha ve goa l s Jnt hec a s eofe xpone nt i a lde c a y,s uc ha st hede a t hr a t ea ndde pr e c i a t i one x‑ a mpl es ,t hegoa li si mpl i c i ta nde qua lt oz e r oJnge ne r a l ,howe ve r ,t hegoa l sof ne ga t i vel oo psa r enotz e r oa nds houl dbema dee xpl i c i t . Fi gur e8‑ 9s howst hege n‑ e r a ls t uc r t ur ef ort hef i r s t 1 0r de rl i ne a rne ga t i vef e e dba c ks ys t e m wi t ha ne xpl i c i t goa l . Exa mpl esi nc l udet hepr oc e s sbywhi c haf i r ma d j us t si t si nve nt or yo rwor k‑ f or c et ot hede s i r e dl e ve l .Pos s i bl ede l a ysi nc ha ngi ngPr oduc t i ono rhi r i ngne w wor ke r sa r eI gnor e d.I nc l udi ngs uc hde l a yswoul da dda ddi t i ona ls t oc kst ot he l . mode I nt hege ne r a lc a s e, t hec oI Te C t i vea c t i onde t e r mi ni ngt hene ti nf lowt ot hes t a t e oft hes ys t e mi sapos s i bl ynonl i ne a rf unc t i onoft hes t a t eoft hes ys t e m,S, a ndt he des i r e ds t a t eoft hes ys t e m,S*: ‑ Ne tI n lo f w‑i ( S, SX ) . ( 8 ‑ 1 4) Thes i mpl es tf or mul a t i on,howe ve r ,i sf ort hec or r e c t i vea c t i ont obeac ons t a nt f r a c t i onpe rt i mepe r i odoft hedi s c r e pa nc ybe t we e nt hede s i r e da nda c t ua ls t a t eof t hes ys t e m: Ne tl n f l o w ‑Di s c r e p a n c y , / AT‑( S*‑S) , / AT ( 8 ‑ 1 5 ) whe r et hepa r a me t e rATi sknowna st hea d j u s t me ntt i meort i mec ons t antf ort he l oop. Not et heuni t sofe qua t i on( 8‑ 1 5) : t hene ti nf lowha sdi me ns i o nsofuni t s / ime t pe r i od・ Thedi s c r e pa nc ybe t we e nt hedes i r e da nda c t ua ls t a t eoft hes ys t e mha sdi 一 me ns i onsofuni t s I Fo re xa mpl e,i ft hedes i r e di nve nt or yofaf i r mi s1 00uni t sa nd c ur r e nti nve nt or yl SOnl y60uni t s , t hedi s c r e pa nc yi s40uni t s . Thea d j us t me ntt i me r e pr e s e nt showqui c kl yt hef i r mt r i est oc or r e c tt hes ho r t f a l l :i ft hef i r ms e e kst o c or r e c tt hes hor t f a l lqui c kl y, t hea d j us t me ntt i mewo ul dbes ma l l . Fore xa mpl e, t he f i r mma ys e tt hea d j us t me ntt i met oAT‑ 1we e k, me a nl ngt ha tt he ywo ul dc or r e c t 277 Cha pt e r8 Cl os i n gt heLo o p: Dyna mi c so fSi mpl eSt mc t u r e s Fl GURE81 9 Fi r s トor derl i nearnega t i vef eedbacks y s t emwi t he xpl i ci tgoal s Gener alSt r uct ur e S★ Desi r edSt at eof t heSyst em dS/ dt≡Netl n¶owRat e =Di scr epancy / AT =( S ‑S) / AT Adust mentTi me ★ Examp一 es Desi r ed hvent or y l nvent or y W Adust mentTi me ・ = ‑ ‑ I‑ I ‑ :I ̲= : 千 Pr oduct i onRat e 警I nvent or yShor t f aH / AT ( Desi r edl nvent or y‑1 nvent or y) / AT ‑ 」 1 nvent or y Shor t f al l + Desi r ed LaborFor ce Ne tHi r i ng A du s t men tTi me ・e f u Ti m. :a ‑ ‑ Labor一〆 ‑ Shor t f al l + NetHi r i ngRat e =LaborShor t f al l / AT =( Desi r edLabo卜 Labor ) / AT t hei nve nt or ya ta ni ni t i a lr a t eof40uni t s / we e k.Be i ngmor eca ut i ousa nds e t t i ng AT‑ 2We e kswo ul de nt a i la ni ni t i a lne ti nf low of20uni t s / we e k,a nda ne ve n mo r ea ggr es s i vef i r mmi ghts e t AT‑0. 5we e ks , l e a di ngt oa ni ni t i a lne ti nf lowof i nve nt or yof8 0uni t s / we e k. Ofc o ur s e , t hes ec or r e c t i vea c t i onsc a us et hei nve nt o r y s hor t f a l lt odi mi ni s h,r e duc i ngt hene ti nf low ove rt i meunt i lt hedi s c r e pa nc yl S e l i mi na t ed. Thedi s c r e pa nc yc a nbene ga t i ve,a swhe nt he r ei se xc e s si nve nt or y; l n t hi sc a s et hene ti nf lowi sne ga t i vea ndt hes t a t eoft hes ys t e mf a l l s . 278 Pa r tI I n) O l sf o rSys t em s Thi n ki ng Ther e c i pr oc a loft hea d j us t me ntt i meha suni t sofl / t i mea ndi se qui va l e ntt o tef h r a c t i ona la d j us t me ntr a t e, C or r e s pondi ngt ot hef r a c t i ona lde c a yr a t ei nt hee x‑ pone nt i a lde c a yc a s e. Thepha s epl otf o rt hes ys t e m( Fi gur e8‑ 1 0)s howst ha tt he ne ti nf lowr a t et ot hes t a t eoft hes ys t e mi sas t r a i ghtl i newi t hs l o pe( I1 / AT)a nd e qua l s0whe nS‑S* ・ Thebe ha vi oroft hene ga t i vel oo pwi t ha ne xpl i c i tgoa li s a l s oe xpone nt i a lde c a y ,buti ns t e a dofde ca yl ngt OZ e r o,t hes t a t eoft hes ys t e m r e a c he se q ui l i br i umwhe nS‑S* ・ I ft hei ni t i a ls t a t eoft hes ys t e mi sl e s st ha nt hedes i r e ds t a t e ,t hene ti nf lowi s pos i t i vea ndt hes t a t eoft hes ys t e mi nc r e a s e s , a tadi mi ni s hi ngr a t e, unt i lS‑S* ・ I f t hes t a t eoft hes ys t e mi si ni t i a l l ygr e a t e rt ha nt hegoa l ,t hene ti nf lowi sne ga t i ve a ndt hes t a t eo ft hes ys t e mf a l l s ,a tadi mi ni s hi ngr a t e , unt i li te qua l st hegoa l . The lowoft f hes ys t e mi sa l wa yst owa r dt hes t a bl ee qui l i br i umpoi nta tS‑S*( Fi g‑ ur es‑ ll ) . =(S★‑S)/AT Netl nf l ow Rat e=‑NetOut f 一 ow Rat e 0 J s l! un) ( a ∈! t let a ]きOl ‑u aN FI GURE8‑ 10 Phas epl o tf or f i r s トor der一 i near negat i vef eedback s y s t emwi t h expl l Ci tgoal FI GURE8‑ ll Exponen t i al appr oacht oagoal Thegoal i sl oo uni t s. Theupper cur vebegl nSWi t h S( 0)‑200;t he l owercur v ebegl nS wi t hS( 0)‑0. The ad j us t men tt i me i nbot hc as esi s 20t i meuni t s. 60 80 100 Ch a p t e r8 Cl o s i n gt h eLo o p : Dy n a mi c so fS i mp l eS t r u c t u r e s 279 8. 3 . 1 Ti meCon s t an t sa n dHa t トLi v e s J us ta se xpone n t i a lgr owt hdoubl e st hes t a t eoft hes ys t e mi naf i xe dpe r i odoft i me, e xpone nt i a lde c a yc ut st hequa nt l t yr e ma i nl ngbyha l fi naf i xedpe r i odoft i me. Theha l f ‑ l i f eofa ne xpone nt i a lde c a ypr oc es si sc a l c ul a t e di nt hes a mef a s hi ona s t hedoubl i ngt i me. Thes ol ut i ont oe qua t i o n( 8‑ 1 5)i s S S( t )‑Sx‑( r ‑ S( 0 ) ) e x p( ‑t / AT) ( 8 ‑ 1 6 ) I ne qua t i on( 8‑ 1 6)S*‑S( 0)i st hei ni t i a lga pbe t we e nt hede s i r e da nda c t ua ls t a t es oft hes ys t e m.Thet e r me x p( ‑t / AT)de c a ysf r om 1t o0a st i mei nc r e a s e s ;i ti s t hef r a c t i onoft hei ni t i a lga pbe t we e ndes i r e da nda c t ua ls t a t esr e ma i nl nga ta ny 0) ) e xp( ‑t / AT)i st he r e f or et hec ur r e ntga pr e ma i ni ng t i met ・ Thepr od uc t( S S( be t we e nt hede s i r e da nda c t ua ls t a t e s . Whe nt het e r me xp( ‑t / AT)ha sde c a ye dt o z e r ot hes t a t eoft hes ys t e me qua l st hegoa l( Fi gur e8‑ 1 2) . Theha l f ‑ l i f ei sgl Ve nbyt heva l ueoft i me ,t h , Whi c hs a t i s f i e s * ‑ O. 5‑e x p( ‑t h / AT)‑e x p( ‑d t ) ( 8 ‑ 1 7 ) / AT. Sol vi ngf ort hyi e l ds whe r et he虫. a c t i ona lde c a yr a t ed‑ 1 n( 2 )‑1 n ( 2 ) / d2 ;0. 7 0 AT‑7 0 / ( 1 0 0d ) t h=ATl ( 8 ‑ 1 8 ) Theha l f ‑ l i f ei sgl Ve nbyt hes a meRul eof70c ha r a c t e r i z i nge xpone nt i a lg r owt h Equi va l e nt l y, t heha l f l l i f ei sgi ve nby70% oft hea d j us t me ntt i me. 1 0 Ea c ht i mepe r i ode qua lt oAT, t hega pr e ma i ni ngf a l l st oe xp( ‑ AT/ AT)‑37% ofi t si ni t i a lva l ue ,a nd1‑e xp( ‑ AT/ AT)‑63% oft hega pi sco r r e c t e d. Whyi s n' t t hee nt i r ega pc o r r e c t e da f t e ronet i mec ons t a ntha spa s s e d?Fr o me qua t i on( 81 1 5) t hei ni t i lr a a t eo fc ha ngeoft hes t a t eoft hes ys t e mi s( S*‑S( 0) ) / AT, t ha ti s , t hei ni ‑ t i a lga pdi vi de dbyt hea d j us t me ntt i me. I ft hei ni t i a lr a t eofa d j us t me ntr e ma i ne d c ons t a nt , t hee n t i r ega pwo ul dbee l i mi na t e da f t e rATt i meuni t s( no t et ha tt het a n‑ ge ntt ot hes t a t eo ft hes ys t e ma tt i me0j us te l i mi na t e st hega pa f t e ro nea d j us t me nt t i me;s e eFi gur e8‑ 1 2) . Howe ve r ,t hene tr a t eofc ha ngeoft hes t a t eoft hes ys t e m doe snotr e ma i nc ons t a nt ・ Ast hes t a t eoft hes ys t e ma ppr oa c he st hegoa l ,t hega p r e ma i ni ngf a l l s , a nds ot oodoe st hec o r r e c t i vea c t i on. Thene ga t i vef e e dba c kg r a d‑ ua l l yr e duc est hea d j us t me ntr a t ea st hegoa li sa ppr oa c he d. Thet a bl ea tt hebot t omofFi gur e81 1 2s howst hef r a c t i onoft hega pr e ma i ni ng f ordi f f e r e ntmul t i pl e soft hea d j us t me ntt i me. Af t e ronea d j us t me ntt i me,63% of t hei ni t i a lga pha sbe e nc o r r e c t e d・ Af t e rt woa d j us t me ntt i mes , t hes t a t eoft hes ys ‑ t e m ha smove d86% oft hewa yt ot hegoa l . Af t e rt hr e ea d j us t me ntt i mes ,t hea d‑ l y,t hega pI Sne ve rf ul l yc or r e c t e d;t he r ei s j us t me nti s95% c ompl e t e.Te c hni c a l pr e ma i nl nga ta nyf i ni t et i me. Howe ve r ,f or lwa a yss omes ma l lf r a c t i onoft hega o mpl e t ea f t e rt hr e et of oura d j us t me ntt i me s llpr a a c t i c a lpur pos esa d j us t me nti sc ha vepa s s e d・ 1 1 1 0 T a k i n gl o g so f b o t hs i d e sg i v e sl n ( 0 . 5 )‑‑t h / ATo rt h‑ ln ( 0 . 5 )*AT‑l n ( 2 )*AT. l l Af t e rf o u ra d j u s t me n t t i me s ,t he g a pr e ma i n l n gl S j u s t 2 %, aq u a n t l yo t f t e ns ma u e rt h a nt h e a c c u r a c ywi t hwh i c ht h es t a t eo ft h es y s t e mc a nb eme a s u r e d . Co n t r o l e n g l n e e r SS p e a ko fas y s t e m' s s e t t l i ngt i me , d e f i n e da st h et i mer e q u i r e df o ras y s t e m, a f t e ras h o c k , t os e t t l ewi t h i nas ma l1 er p ‑ c e n t a g eo fi t se q u i l i b r i u mv a l u e . 280 Pa r tI I Tわol sf b∫Sys t e msThi nki ng Fr GURE8 ‑ 12 Rel at i onshi pbet weent i meconst antandt hef r act i onoft hegapr emai ni ng Rat eequat i onf orf i r stor derl i nearnegat i vel oopsyst em: t l ow Rat e= ( S★‑S) / AT Netl nf l ow Rat e≡‑NetOut Anal yt i cSol ut i on: S( t ) S ' ‑ ( S'‑S( 0) ) ' exp( ‑I / AT) =i Fract i onof i = : 電 =i Desi r ed St at eof t heSyst em St at eot t heSyst em l ni t i al Gap Desi r ed St at eof St at eot t heSyst em ヽ一 t heSyst em i ≡ . 琵 a l Gap a i ni ng l ni ti Rem 一 一 ヽ ′ . . . . . . . . . . . . . ′ GapRemai ni ng 0 1 8 0 6 0 p ( 0 4 2 0 0 ∈a t Jdt 2 9一 E 2 ! l ! ul ‑ Ou O! ) 3 t 2 J j u! uE ! ? 6 1‑exT‑1/AT, l ヽ p( 「1 ′ AT, exp( 1‑ex 2 ( ‑ l A 2 / T A ) ‑ T ‑‑ ):‑‑ ‑ ‑ 1 二 二: ‑exp l 2AT 1AT Ti me( mul t i pl esofAT) ‑exp( ‑ 0) 1‑exp( ‑ 1) 1‑exp( ‑ 2) 1‑exp( ‑ 3) 1‑exp( ‑ 4) 1‑exp( ‑ 5) i 3 03 7 5 8 9 06 8 9 9 9 00 0 0 0 0 Fr act i onofI ni t i alGap Cor r ect ed 二二 二 二 二 二 7 074520 0 3 1.0 0 0 ・1 0 0 0 0 0 二二二二二二 ))))ー) 0 1 2 3 4 5 一( ︻( l( lー l( l ー XXXXXX eeeeee Pn LP P P P 0TTTTT AAAAA 2345 Fr act i onofl ni t i alGap Remai ni ng Ch a p t e r8 C l o s i n gt h eLo o p : Dy n a mi c so fS i mp l eS t r u c t u r e s 2 81 Goaト S e ek i n gb e h a v i or Cons i de rt hel a bo rf o r c es t r uc t ur ei nFi gu r e81 9. As s umet hene thi r i ngr a t ef ora f i r mi spr o po r t i o na lt ot hega pbe t we e nt hede s i r e da nda c t ua lwo r kf o r c e・ Wi t ho ut us l ngac o mput e rO rC a l c u l a t o r , S ke t c ht hebe ha vi o ro ft hewo r kf o r c ea ndne thi r i ng r a t ef ort hef ol l o wl ngS i t ua t i o ns ・ i.Thed e s i r e dwo r kf o r c ei nc r e a s e sf r o m1 00 0t o20 00a twe e k4, t he ns t e ps downt o1 5 0 0a twe e k1 2( Fi g ur e8 ‑ 1 3 ) . As s umet hewo r kf o r c ea d j us t me nt t i meAT‑4We e ksa ndt hea c t ua lwo r kf br c ei ni t i a l l ye q ua l st hede s i r e d wo r kf o r c e . 2.Re pe a ts t e p1f o rt hec a s ewhe r et hel a bo rf o r c ea d j us t me ntt i meAT‑ 2we e ks . 3.Ske t c ht hewo r kf o r c ea ndne thi r i ngr a t ef o rt hec a s ewhe r et hede s i r e d wo r kf o r c ei n c r e a s e sl i ne a r l ybe g i nni ngi nwe e k4( Fi gu r e8 ‑ 1 4) ・ As s umet he Dl esi r e l dLa l borF 】 or c e l 0 4 6 8 1 0 1 2 1 4 1 6 1 8 20 22 24 2 4 6 8 1 0 1 2 1 4 1 6 1 8 20 22 24 0 a o ad) HlaN q (aa N V l et ]6 u a 2 ! ld !) 0 Ti me( week s) 2 8 2 I IT o o l sf o rS y s t em s Th i n k i n g P a r t l a bo rf or c ea d j us t me ntt i meAT‑4we e ks . Doe st hewor kf or c ee ve nt ua l l y e qua lt hede s i r e dwor kf or c e?Whyorwhynot ? F Desi r edL laborFoie 0 4 6 8 10 1 2 1 4 1 6 18 20 22 24 2 4 6 8 1 0 1 2 1 4 16 18 20 22 24 t e ( qaaき o ) a] t B uH N 2 0 P !) ! ld l a ad 0 Tj me( weeks) 8. 格 M uL 7日 PkE‑ 』00PSysTEMS Thedi s c us s i onupt onowt r e a t e dpos i t i vea ndne ga t i vef e e dba c ki ni s ol a t i on. Wha t i st hebe ha vi o rofaf i r s t ‑ or de rs ys t e m whe nt hene tr a t eofc ha ngei sa f f e c t e dby bot ht ype sofl oo p?Cons i de rt hee xa mpl eofapopul a t i on( Fi gur e8‑ 2) . Di s a ggr e 一 ga t et hene tbi r t hr a t ei nt oabi r t hr a t eBRa ndade a t hr a t eDR.Thene tr a t eof c ha ngef o rt hes ys t e mi st he n Po p u l a t i o n‑I NTEGRAL( Ne tBi r t hRa t e , Po p u l a t i o n( 0 ) ) Ne tBi r t hRa t e‑BR‑DR Cons i de rt hel i ne a rc a s ewhe r et hef r a c t i ona lbi r t hr a t ei sac ons t a nt , de not e db, a nd t hef r a c t i o na lde a t hr a t ei sa l s oc ons t a nt ,de not e dd. Thene tbi r t hr a t ei st he n Ne tBi r t hRa t e‑b p‑d P‑( b‑d ) P ( 8 ‑ 21 ) 283 Ch a p t e r8 Cl o s i n gt h eLo o p: Dy n a mi c so fS i mp l eS t uc r t ur es Fi gur e8‑ 1 5S howst hephas epl otf ort hes ys t e m・ Onl yt hr eebe ha vi or sa r epos ‑ s i bl e.I ft hee nvi r onme ntcont a i nsa bunda ntr es our ces ,bi r t hswi l lexce eddeat hs ( b>d) ,a ndt hepopul a t i ongr owse xpone nt i a l l ywi t houtl i mi t ・ Al t e ma t i ve l y, bi r t hs a nddea t hsmi ghte xa ct l yof f s etea c hot he r( b‑ d) ,a ndpopul a t i oni si nequi l i b‑ r i um. Fi na l l y, t hee nvi r onme ntmi ghtbes oha r s ht ha tdea t hse xc e edbi r t hs( bくd) , St r uct ur e( phasepl ot ) b>d Bi r t hRa t e > Behavi or( t l medomai n) b 1 NetBi r t hRat e l b‑ d O Sal et JL J l ea凸 PueL J t J l!g FI GURE8・ 15 Al i nearf i r s t ‑ or ders ys t em cangener at e onl ygr owt h, equi l i br i um, ordec ay. Popu一 at i on 0 Ti me O Sal et jL J l t 2 a凸 PueL J t! g Ti me Popul at i on Sa Exponent i alDecay O E a ! C I up J j LJl lt =t Bi r t hRa t e P L亡! g NetBi r t hRat e Popul at i on 28 4 Pa r tI I n) O l sf o rSys t em s Th i n k i ng a ndpo p ul a t i o nde c l i ne se x pone nt i a l l yt oz e r o.Be c a us et hes ys t e mi sl i ne a r ,t he f r a c t i o na lne tbi r t hr a t ei sac ons t a nt ,i nde pe nde nto ft hes i z ec ・ ft hepo pul a t i on, 丘X e df わra l l t i meonc et heva l ue so fba ndda r ec hos e n・ Thebe ha vi o roft hes ys t e m i st hes um,o rs upe r pos i t i on,oft hebe ha v i o r sge ne r a t e dbyt hei nd i vi d ua ll oo ps . Be c a us et hes ys t e mi sl i ne a r( ba ndda r ec o ns t a nt s ) ,t hedomi na nc eoft het wo , l o o psc a nne ve rc ha nge・ Thepo p ul a t i o nwi l lg r owwi t ho ut bo und, r e ma i nc o ns t a n t o rde c a yt oe xt i nc t i o n. Thes upe r pos i t i onpr ope r t yl St r u eO fl i ne a rs ys t e msofa nyo r de ra ndc o m‑ pl e xi t y . Asl onga sa l lt her a t ee q ua t i o nsi nas ys t e ma r el i ne a r ,t her e l a t i vei mpo ト t a nc eoft hedi fe r e ntf e e dba c kl o opsc a nne v e rc ha nge ‑t he r ec a nbenos hi f t si n l oo pdo mi na nc e. Su pe r pos i t i o nme a nsl i ne a rs ys t e msc a nbea na l yz e dbyr e d uc t i o n t ot he i rc o mpone nt s . Asar e s ul t ,l i ne a rs ys t e ms ,noma t t e rhowc ompl e x,c a nbe s o l ve da na l yt i c a l l y ,ad i s t i nc ta dva n t a g ei nund e r s t a nd i ngt he i rd yna mi c s . Howe v e r , r e a l i s t i cs ys t e msa r ef a rf r o ml i ne a r . Thebe ha vi o ro ft hel i n e a rpo p‑ ul a t i o ng r owt hs ys t e ms howswhy. Be c a us et hed omi na nc eoft hef e e d ba c kl oo ps c a nne ve rc ha nge , t hepo pul a t i o nc a no n l yg r o wf o r e ve r , r e ma i nc o ns t a nt , o rgoe x‑ t i n c t . Re a l po pul a t i onsi nt r o duc e di n t oane wha bi t a twi t ha bu nda ntr e s o ur c e sg r o w a t f i r s t , he t ns t a bi l i z eo rf luc t ua t e . Ther e l a t i ves t r e ng t ho ft hepos i t i vea ndn e ga t i ve l o o psmus tt he r e f o r es hi f ta sapo pul a t i o ng r o wsr e l a t i v et ot hec a r r yl ngC a Pa C l t yO f , t hee n vi r o nme nt . I nr e a ls ys t e ms , t he r emus tbes hi f t si nf e e d ba c kl oo pdo mi na nc e a ndt h e r e f o r et he r emus tbei mpor t a ntno nl i ne a r i t i e si na l lr e a ls ys t e ms . Unf o r t una t e l y , ma nymod e l e r sha ver e s t r i c t e dt h e i ra t t e nt i o nt omode l st ha tc a n bee x pr e s s e da sl i ne a rs ys t e mss ot ha tt he yc a na ppl yt hepo we r f ult oo l so fl i ne a r s ys t e mst he o r y , whi l ema ki ngt hehe r o i ca s s u mpt l O nt ha tt hel i ne a ra ppr o x i ma t i on i sr e a s o na bl e. I nf a i r ne s s ,t her e l i a nc eo nl i ne a rt he o r ya ndt hea voi da nc eo fno n‑ 1 i n e a rs ys t e mswa sJ us t if i a bl epr i o rt Ot hede ve l o pme ntofc omput e rs i mul a t i o nbe ‑ c a us ea na l yt i c a ls ol ut i onst ono nl i ne a rdy na mi cs ys t e msc a nnoti nge ne r a lbe f o und.Ea r l yt he or i s t sofd yna mi cs ys t e msma det hea s s umpt i o nOfl i ne a r i t ybe ‑ c a us ei twa st heo nl ywa yt oma kepr og r e s s .Eve na f t e rt hea d ve ntofc o mput e r s i mul a t i on, howe ve r ,t ooma nymod e l e r sa ndma t he ma t i c i a nsc o nt i nue dt os t r e s s l i ne a rt he o r ya ndbui l dl i ne a rmode l s . Thet e nd e nc yt ot r e a te ve r ys ys t e ma sal i n‑ e a rna i lbe c a us et heha mme rofl i ne a rt he o r yl SS Opowe r f u lha sha mpe r e dt hed e ‑ ve l op me nto fr e a l i s t i ca ndr o bus tmod e l so fc o mpl e x i t y・ Ofc ou r s e , t het r i umpho fl i ne a rme t hodsha sne ve rbe e nc o mpl e t e. Ev e npr l O r t ot hec o mput e re r as e ve r a li mpor t a ntno n l i ne a rmo de l swe r ede ve l o pe d, mos tno‑ t a bl yVe r hul s t ' sf a mous1 8 44l ogi s t i cpo pul a t i ong r o wt hmode l( S e es e c t i o n9. 1 ) a ndt hee q ua l l yf a mo usLo t ka ‑ Vbl t e r r apr e da t o r l) r e ymo de l( Lot ka1 956) . Andt he qua li t a t i vet he o r yo fdyna mi cs ys t e msd e v e l o pe dbyPo i nc a r ga ndo t he r st oa na l y z e t het h r e e ‑ bodypr o bl e mi nc e l e s t i a lme c ha ni c si sf u nda me nt a i i ynonl i ne a r( s e e Di a c ua ndHol me s1 996f o rano nt e c hni c a lt r e a t me n to ft hehi s t o r ya ndt he o r y) . I n t hepa s tf e w de c a de st he r eha sbe e na ne x pl os i onofi nt e r e s ti n,t he or i e sof ,a nd da t as u ppo r t l ngt hei mpo r t a nc eo fno nl i ne a rbe ha v i o ri na l lbr a nc he sofd yna mi c s ( t her i s eo fs oI C a l l e dc ha oso rc o mpl e xi yt t he o r y) . St i l l , Yos hi s ukeUe da , whod i s I c o v e r e dc ha osi nano nl i ne a ros c i l l a t o ra sag r a d ua t es t ude nti nt hel a t e1 95 0S , wa s una bl et oge thi swo r kpubl i s he df o rove rad e c a d ebe c a us ehi sa d vi s o r s , s t e e pe di n l i n e a rt he o r y ,a s s e r t e dt ha thi sme a s u r e me nt sa nda na l ys t smus tbewr o ngbe c a us e t he y… kne wHt ha ts ys t e msc o ul dno tg e ne r a t et hes t r a ngeno nl i ne a rbe ha v i o r 285 Ch a p t e r8 Cl o s i n gt h eLo o p : Dy n a mi c so fS i mp l eS t r u c t ur es ( c ha os )t ha tt oda ywer e c ogni z ea subi qui t ousi nphys i c a l ,bi ol ogi c a l ,a ndot he r s ys t e ms( s e eUe d a1 992) . Li ne a ra na l ys i sr e ma i nsa ni mpor t a ntt ool . Of t e nas ys t e mi sc l os et ol i nea ri n ac e r t a i nne i g hbor hooda ndca nbeus e f ul l ya na l yz e dbyl i ne ar i z at i on,t ha ti s ,by a ppr oxi ma t i ngt henonl i ne a rr a t ee qua t i onsa tapa r t i c ul a rope r a t i ngpoi nt( s e tof s t a t eva r i a bl eva l ues )wi ht t hebes tl i ne a ra ppr oxi ma t i on. Andagr e a tde a lofi m‑ Por t a nti nt ui t i o na boutdyna mi c sc o mesf r omunde r s t a ndi ngs i mpl e , l i nea rs ys t e ms , s uc ha st hef i r s t 1 0 r de rl i ne a rs ys t e msr es pons i bl ef o re xpo ne nt i a lg r owt ha ndde c a y‑ St i l l , unde r s t a nd i ngt hedyna mi c sofr e a ls ys t e msr e qul r e SnOnl i ne a rmode l s . 8u 5 NoNuNE . AR F旧ST1 0RDER SysTEMS:S‑ SHAPEDGROWTH Nor e a lq ua nt l t yC a ngr owf or e ve r .Eve r ys ys t e mi ni t i a l l ye xhi bi t i nge xpone nt i a l gr owt hwi l le ve n t ua l l ya ppr oa c ht hec a r r yl ngC a Pa C l t yOfi t se nvi r onme nt , whe t he r t ha ti st hef oods uppl yf orapopul a ionofmoos t e,t henumbe rofpe opl es us c e pt l ‑ bl et oi nf e c t i o nb yavi us r , Ort hepot e nt i a lma r ke tf o rane wpr oduc t . Ast hes ys t e m a ppr oa c hesi t sl i mi t st ogr owt h,i tgoest hr oughanonl i ne a rt r a ns i t i on血. om a r e gl meWhe r epos i t i vef e e dba c kdomi na t est oar e gl meWhe r ene ga t i vef e e dba c k domi na t e s . Ther e s lti u sof t e nas moot ht r a ns i t i onf r ome xpone nt i a lg r owt ht oe qu 1 i br i um, t ha ti s , S‑ s ha pe dg r owt h( S e ec ha pt e r4) . I nr e a ls ys t e ms , t hef r a c t i ona lbi r t ha ndde a t hr a t esc a nno tbec ons t a ntbutmus t c ha ngea st hepo pul a t i ona ppr oa c hesi t sc a r r yl ngC a pa C l t y. He nc et hee qua t i onf o r t hene tbi r t hr a t ebe c omes l ‑ P/ C) P Ne tBi r t hRa t e‑BRIDR‑b( P/ C) p‑d( ( 81 22) whe r et hef r a c t i o na lbi r t ha nddea t hr a t esba ndda r enowf unc t i onsoft her a t i oof t hepo pul a t i onPt ot hec a r r yi ngC a pa c i t yC・ Fo rnow,a s s umet hec a r r yl ngC a Pa C l t y i sf i xe d‑ne i t he rc o ns ume dnora ugme nt e dbyt hea c t i vi t yOft hepopul a t i on, Fi g ur e8 ‑ 1 6S howst hec a us a ldi a gr a mf ort hes ys t e m。 ‑ FI GURE8 ‑ 16 Cau s al di agr am f orpopul at i on gr o wt hi naf i xed envi r onment F r a c t i ち@ j F : a 諾 o R n a 誌 B i 】 ー ーCa r o n a 一 r t hR a t e Aヲ \ . Popul at i on/ r yi ngCapaci t y) 草 Car r yJ ng Capaci t y Da . 286 Pa r t I IT o o l sf o rSy s t e msTh i n k i n g Nonl i nearBi r t handDeat hRat es Be f or econt i nul ng,S ke t c hagr a phs howi ngt hel i ke l ys ha peoft hef r a c t i ona l bi r t ha nddea t hr a t esf orapopul a t i onasi ta ppr oa c hesi t sca r r yi ngca pa c i t y( Fi g‑ ur e8‑ 1 7) 。Theca r r yi ngc a pa c i t yi sde f i ne dast hepopul a t i ont ha tc a nj us tbes up‑ por t e dbyt hee nvi r onme nt .Bes ur et ocons i de re xt r emecondi t i ons( t ha ti s ,wha t wi l lt hef r a c t i ona lbi r t ha nddea t hr a t esbef orve r yl oworve r yl a r gepopul a t i ons ? ) . Fr om youres t i ma t es ,dr a wt hef r a c t i ona lne tbi r t hr a t e( t hedi fe r e nc ebe t we e nt he f r a c t i ona lbi r t ha nddea t hr a t es ) . 0 ( ¢∈ 空 し) Put 2L JtL!g Sate∝ LJ lt 2aa u O! 1 0eJId r e P op u l a t i o n / Ca r r y l n gCa p a c i t y ( di me n s i on l e s s ) Whe npopul a t i onde ns i t y( t her a t i oP/ C)i ss ma l l , bot hf r a ct i ona lbi r t hr a t ea nd l i f ee xpe ct a nc ys houl dbea tt he i rbi ol ogi ca lma xi ma.Aspopul a t i ongr ows ,r e‑ s our cespe rca pi t ade cl i ne.Fr a c t i ona lbi r t hr a t ea ndl i f ee xpect a ncymus tf a l l .Do t he yde cl i nei mme di a t e l y?I ns omec as es ,e ve ns ma l lr educ t i onsi nr es our c espe r c a pl t ac oul dca us eadec l i nei nf e r t i l i t ya ndl i f ee xpec t a nc y.Forot he rr es our ces s uc ha sf ood, i ndi vi dua l sca nnotc ons umemor et ha nac e r t a i na mount ,S of r a c t i ona l bi r t ha nddea t hr a t ess houl dr e ma i ncons t a ntasl ongasr es our c espe rc a pl t ae xc e ed t hema xi mum ea c hi ndi vi dua l Ca ncons ume.Reduc i nga va i l a bl ef oodf r om 1 0 t i mesmor et ha nne ededt o5t i mesmor et ha nne ededhasnoi mpa c ts i nc ee a c hi n‑ di vi dua ls t i l lge t sa l lt he yca ncons ume・12I nt hi sc as et hef r a c t i ona lbi r t ha nddea t h r a t esr e ma i ncons t a nt ‑ upt oapol nt ‑a SP/ Ci nc r ea s es ・Onc er es our c espe rca pl t a f a l lbel owac e r t a i nl e ve l ,t hef r a c t i ona lbi r hr t a t ef a l l sa ndt hef r a c t i ona lde a t hr a t e i nc r eas es .Byde f i ni t i on,t heca r r yi ngC a pa c i t yl St hepopul a t i ont ha tca nJ us tbe s uppor t e dbyt her es our cesa va i l a bl e,S ot hef r a c t i ona lbi r t hr a t emus tequa lt he , 1 2 Th ea s s u mp t i o nt h a t e x c e s sf o o dh a sn oi mp a c t o nf e r t i l i t yo rmo r t li a t yh o l d so lyi n ft h e o r g a n i s msi nq u e s t i o ne a t o n l ywh a t t h e yn e e da n dd on o t g o r g et h e ms e l v e swh e nas u r p l u si s a v a i l a b l e ・ Fo rt h eh u ma np o p t l l a t i o n , i nc o n t r a s t , a na b u n d a n t f わo ds u p p l ya n dd i e t r i c hi na n i ma l p r o t e i na n df a t t e n d st ol e a dt oo b e s i t ya n ds i g n i f i c a n t l yh i he g rmo r b i d i t ya n dmo r t li a t y . I ns u c ha c a s e , t h ee fe c to ff o o dp erc a p l t aO nt h ef r a c t i o n a l d e a t hr a t ewo u l da c t u a l l yr i s ewh e nf o o dp e r c a p l t ae x c e e d sac e r t a i nl e v e l . Ch a p t e r8 Cl o s i n gt h eLo o p : Dy n a mi c so fS i mp l eS t r u c t ur e s 28 7 f r a c t i ona lde a t hr a t ewhe nP/ C‑ 1 . I ft hepo pul a t i onwe r et or i s ea bovet hec a r r y‑ i ngC a pa c i t y , t hebi r t hf r a c ionwoul t dc ont i nuet of a l la ndt hedea t hf r a c t i onwoul d c ont i nuet or i s e. Asp/ Cc ont i nuest oi nc r e a s e,t hebi r t hf r a c t i onmus tf a l lt oz e r o r e,a ss howni nFi g a ndt hede a t h丘. a c t i onmus tr i s et oave r yl a r geva l ue. The r e f o ur e8 ‑ 1 8,t hef r a c t i ona lne tbi r t hr a t ewi l lbepos i t i vef orP<C,e qua lz e r owhe n P‑ C,a ndf a l lbe l ow z e r oa ta ni nc r e a s l ngr a t eWhe npopul a t i one xc e e dst he c a r r yl ngC a pa C l t yOft hee nvi r onme nt . Whi l et henume r i c a lva l uesf ort hes er e l a t i ons hi pswoul ddi f f e rf ordi f f e r e ntpopul a t i ons ,t he i rqua l i t a t i ves ha pei snoti n doubt . Ne xtc ons t r u c tt hepha s epl otf ort hes ys t e mus i ngt he s enonl i ne a rf e r t i l i ya t nd l i f ee xpe c t a nc yr e l a t i ons hi ps . Thebi r t ha ndde a t hr a t e sa r enowc ur ve sgl Ve nbyt he pr oduc to ft hepo pul a t i ona ndf r a c t i ona lbi r t ha ndde a t hr a t e s( Fi g ur e8‑ 1 9) . Fi r s t , not et ha tt hepoi ntP=0i sa ne qui l i br i um,a si nt hel i ne a rs ys t e m.Si nc et hef r a c t i ona lbi r t hr a t er e ma i nsne a r l yc ons t a ntwhe npopul a t i oni ss ma l lr e l a t i vet ot he c a r r yi ngc a pa c i t y ,t hebi r t hr a t e( i ni ndi vi dua l s / t i mepe r i od)i sne a r l yl i ne a rf わr Pi C. Aspopul a t i onde ns l t yr i s esa ndt hef r a c t i ona lbi r t hr a t ef a l l s , t hebi r hr t a t e, whi l es t i l lg r owl ng, r i s eswi t has ha l l owe ra nds ha l l owe rs l ope・ Ats omepol nt , t he de c l i nei nt hef r a c t i ona lbi r t hr a t er e duc e st ot a lbi r t hsmor et ha nt hei nc r e a s ei n s he e rnumbe r si nc r e a s est he m,a ndt hebi r t hr a t er e a c he sama xi mum.Si nc et he f r a c t i ona lbi r t hr a t ef a l l st oz e r of orhi ghpopul a t i onde ns i t i e s ,s ot oot het ot a lbi r h t r a t emus ta ppr oa c hz e r o.Li ke wi s e,t hede a t hr a t er i s e sne a r l yl i nea r l yf o rPi C, buta sgr e a t e rpo pul a t i onde ns i t yboos t st hef r a c t i ona ldea t hr a t e,t het ot a lde a t h r a t ei nc r e a s e sa ta ni nc r e a s i ngr a t e. Tur nl ngt Ot h edyna mi c s ,i ma gl net hei ni t i a lpo pul a t i oni ss ma l lr e l a t i vet ot he c a r r yl ngC a pa c i t y . Thene tbi r hr t a t er i s e sne a r l yl i ne a r l yf orPi C・ Thebe ha vi o r oft hes ys t e mi nt hi sr e gi meWi l lbene a r l ypur ee xpone nt i a lgr owt h. Aspopul a t i on de ns i t yI nc r e a s e s ,t hene tbi r t hr a t ec ont i nue st or i s e, buta tas ha l l owe ra nds ha l ‑ l owe rs l o pe. Thepopul a t i onc ont i nuest ogr owa ta ni nc r ea s i ngr a t e ,butt hef r a c ‑ t i ona lgr owt hr a t ei ss t ea di l ydi mi ni s hi ng. Ats omepol nt , t hene tbi r t hr a t er e a c he s ama xi mum. Thi spol ntC OmeSa tal owe rpopul a t i onde ns i t yt ha nt hepe a ki nt he bi r t hr a t es i nc ede a t hsa r ei nc r e a s l nga ta ni nc r e a s l ngr a t e・ Thepe a koft hene tbi r t h r a t ec ur veont hepha s epl o tc or r e s pondst ot hei nf l e c t i onpol nti nt het r a j e c t or yO f ‑ ‑ ‑ 0 IJ l!g ( むuJ ! ) [ L) S att2∝ LJIeaelPu佃L J 一 euO! t OeJ L L FI GURE8・ 18 Nonl i near r el at i on shi p bet ween popul at i ondensi t y andt hef r ac t i onal gr owt hr a t e P o p u l a t i o n / Ca r r y l n gCa p a c i t y ( d i me n s i o n l e s s ) 288 FI GURE8‑ 19 Phas ep一 otf or non‖ near popul at i ons ys t em Ar r owssh owdi ‑ r ec t i onoHl ow Posi t i vef eedb ack domi nat est hes y s ‑ t emi nt her eg1 0n wher et henetbi r t h r at ehasposi t i ve sl ope;negat i v e f eedbacki sdomi ‑ nan twher et henet bi r t hr at ehasneg‑ at i vesl ope. The maxi mumnetbi r t h r at eoc cur satt he poi n t( P/ C).n f , t he i n f l ec t i onpoi n ti n t het r a j ec t or yOf popul at i on・ . P o p u l a t i o n / Ca r r y l n gCa p a c i t y ( d i me n s i o n F e s s ) po pul a t i oni nt het i medoma i n( t hepoi nta twhi c ht hepopul a t i oni sr i s i nga ti t s ma xi mumr a t e ) . Be yondt hei nf l e c t i onpoi nt , t hei nc r ea s ei npopul a t i onde ns i t yr e ‑ duc e st hene tbi r t hr a t emor et ha nt hei nc r e a s ei nt ot a lpopul a t i ons i z ei nc r e a s esi t . Thene tbi r t hr a t e,whi l es t i l lpos i t i ve,dr ops ,f a l l i ngt oz e r oJ us tWhe nt hepo pul a ‑ t i one qua l st hec a r r yl ngC a pa C l t y. I ft hepopul a t i one xc e e de dt hec a r r yl ngC a pa C l t y , r es our c e spe rca pl t aWOul dbes os c a r c et ha tdea t hswoul de xc e e dbi r t hs ,a ndt he po pul a t i onwoul df a l lba c kt owa r dt hec a r r yi ngC a Pa C l t y・ Thee qui l i br i uma tP‑C i st he r e f or es t a bl e. Fi gur e8‑ 20S howst hebe ha vi o roft hes ys t e m ove rt i mef ort woc a s e s : ( 1 )whe nt hei ni t i a lpopul a t i oni smuc hs ma l l e rt ha nt hec a r r yi ngc a pa c i t ya nd ( 2)whe nt hei ni t i a lpo pul a t i oni smuc hl a r ge rt ha nt hec a r r yi ngc a pa c i t y.Whe n P( 0)i C, hene t tbi r t hr a t ei si nc r e a s i ngi nt hepopul a t i on. Asl onga st hes l opeof t hene tbi r t hr a t ec ur vei nt hepha s epl oti spos i t i ve, t hes ys t e mi sdomi na t e dbyt he pos i t i vef e e dba c kl oopa ndpo pul a t i ongr owse xpone nt i a l l y・ Unl i ket hel i ne a rs ys t e m, howe ve r , t hes l opeo ft hene tbi r t hr a t ec ur vei snotc ons t a nt ,S ot hegr owt hi s notapur ee xpone nt i a l .I ns t e a d,t hef r a c t i ona lgr owt hr a t ef a l l sa spopul a t i on gr ows .Popul a t i ongr owt hr e a c he si t sma xi mum whe nt hepopul a t i onr e a c hest he va l uede not e d( P/ C) I m f ,t hei nf le c t i onpoi nti nt het r a j e c t or yoft hepo pul a t i on. At t ha tpol ntt hes l opeoft hene tbi r t hr a t ec ur vei sz e r o;t hepos i t i vea ndne ga t i ve l oopse xa c t l yof f s e tonea not he r . Aspopul a t i onc ont i nue st ogr ow, t hes l o peoft he ne tbi r t hr a t ec ur vei nt hepha s epl otbe c omesne ga t i ve; f orP/ C> ( P/ C)1 n f , t hes ys ‑ t e mi sdomi na t e dbyne ga t i vef e e dba c k.Be ca us et hene tbi r t hr a t eha sane ga t i ve s l opei nt hi sr e gl On, t hee qui l i br i umpoi nta tP‑Ci ss t a bl e, Apopt l l a t i onl e s st ha r ) t hec a r r yl ngC a pa C l t yWi l lgr owa tadi mi ni s hi ngr a t eunt i li tr e a c hest hec a r r yl ng c a pa c i t y;apopul a t i onl a r ge rt ha nt heca r r yl ngC a Pa C l t yWi l lf a l lunt i li tr ea c he st he c a r r yi ngCa pa c i t yf r o ma bove. ‑ 8. 5. 1 For ma‡De伽 i t i omo菅LoopDom岳 mamee Thepha s epl ots howst heor l g i noft het e r mspos i t i vea ndne ga t i vef e e dba c k. Pos i ‑ t i vef e e dba c kdomi na t eswhe ne ve rt her a t eofc ha ngeoft hes t a t eva r i a bl ei s 289 Ch a p t e r8 Cl o s i n gt h eLo o p: Dy n a mi c so fS i mp l eS t r u c t u r e s 0 2 Bot t om:P( 0)>,C, t hepopul at i on r api dl ydecays backt ot hest abl e equi l i br i um at P‑C. N et B irt h R ate n t T op:P( 0)iC ; Popul at i onf o" ows shaped anS‑ t r aj ect or y ,Wi t h 州 ec t i onpoi ntat ( P/ C).n f . C J H u 岬 ^1 ! 3t 2 d t 2 0 6u !^ J Je3u J O! e r n dod Ft GURE8 ‑ 20 Nonl i near popul at i ongr owt h: t i medomai n A) !od e 3 e 6 u !^ヒ 3 C J uO! te Pd od Thet i meaxi si n bot hsi mul at i onsi s t hesame; ve「 l i c al sca一 esdi f f er . i nc r eas l ngl nt hes t a t eva r i a bl e, t ha ti s , asl ongast hes l opeoft hene tr a t eofc ha nge asaf unc t i onoft hes t a t eva r i a bl ei spos i ive. t Ne ga t i vef ee dba c kdomi na t eswhe n‑ e ve rt hene tr a t eofc ha ngei sde c r ea s l ngl nt hes t a t eva r i a bl e,t ha ti s ,asl onga st he s l opeoft henetr a t ei snega t i ve. Thi sobs e r va t i onl ea dst oaf or ma lde f ni i t i onofl oopdomi na nc ef orf i r s t ‑ or de r s ys t e ms( Ri c ha r ds on1 986b,1 995) : 莞 0= ⇒Pos i t i vef e e d ba c kdo mi na nt 0⇒ None tf e e d ba c kf r o ms t a t et or a t e (< :0⇒ Ne g a t i vef e e d ba c kdo mi n a n t ( 8‑ 23) whe r e s‑ 慧 De t e r mi ni ngWhe t heras ys t e mi sdomi na t edbypos i t i veornega t i vef e edba c ki s mor edi fi c ul ti nhi ghe r 1 0r de rs ys t e msbe ca us eal oopwi t ht i mede l a ysca nha vea wea ks hor t ‑ r unbutl a r gel ong‑ une r fe c t .Ka mpma nn( 1 996)pr ovi dess omeme hl t odst odet e r mi net hedomi na ntl oopsi nmul il t oop,hi ghor de rs ys t e ms ;s e ea l s oN. For r es t e r( 1 982)a ndMo j t a hedza de h( 1 997) . 290 Pa r tI I To o l sf o rS y s t e msTh i n k i n g 8, 5. 2 Fi r st 1 0r deFSysモ emst =annotOsci i E at e Asaf i na lobs e r va t i on on t hege ne r a lnonl i nea rf i r s t 1 0r de rs ys t e m,c ons i de r whe t he raf i r s t l 0r de rs ys t e m ca nos c i l l a t e.Se c t i on8. 4de mons t r a t e dt ha tt hel i nea r f i r s t ‑ or de rs ys t e m ca nge ne r a t eonl ye xpone nt i a lgr owt h,deca y,ore qui l i br i um. Nonl i ne a rf i r s t ‑ or de rs ys t e msge ne r a t emor ecompl e xdyna mi cs , butca nne ve ros ‑ c i l l a t e,noma t t e rt hef or m oft henonl i nea r i t y・ Tos e ewhy,c ons i de rt hephas epl ot 1 1 9. Toos ci l l a t e,t hes t a t eva r i a bl emus tgo f ort hef i r s トor de rs ys t e mi nFi gur e8 t hr oughpe r i odsofi nc r ea s ef ol l owe dbype r i odsofde c r e as e. The r e f or e, t hene tr a t e ofc ha ngei nt hepha s epl otmus tcr os sf r om pos i t i vet one ga t i veva l ues ,a tl eas ti n onepl a ce。Howeve r ,a nypol ntWhe r et henetr a t eofc ha ngei sz e r oi sa ne qui l i b‑ r i um oft hes t a t eva r i a bl e.Si nc ef i r s t 1 0r de rs ys t e msha veonl yones t a t eva r i a bl e, e ve r ys uc hpol nti sa nequi l i br i um f ort hes ys t e ma swe l l . Ever ye qui l i br i um pol nt i se i t he rs t a bl e( t hes l o peoft hene tr a t ec ur vei nt hene i ghbor hoodoft hee qui l i b‑ r i um i sne ga t i ve )oruns t a bl e( pos i t i ves l opei nt henei ghbor hoodoft hee qui l i br i um poi nt ) . 1 3I faf i r s t 1 0r de rs ys t e mi sdi s t ur be df r om a nuns t a bl ee qui l i br i um, i twi l ldi ‑ ve r ge丘. om i t ,e i t he rwi t houtbot l nd( notos ci l l a t i ng)Orunt i li ta ppr oa c hesas t a bl e equi l i br i um pol ntWhe r ea l lc ha ngec eas es . The r e f or et oos c i l l a t e, as ys t e m mus tbe a tl eas ts e condor de r ,mea nl ngt he r emus tbeaf ee dba c kl oopwi t ha tl eas tt wo s t oc ksi ni t . 1 4 8。 6 SuMMARY Thi sc ha pt e rexpl or edt hedyna mi csofs i mpl es ys t e ms ,s pec i f i ca l l y,f i r s t 1 0r de r l i nea rs ys t e ms IS yS t e mSWi t honl yones t oc k( s t a t eva r i a bl e )a ndi nwhi c ht her a t es off lOwa r el i nea rf unc t i onsoft hes ys t e ms t a t e. Thes es i mpl es ys t e msa r et hebui l d‑ 1 ngbl oc ksoutofwhi c ha l lmodel sa r ebui l ta ndf r om whi c hmor ecompl e x dyna mi cse me r ge・ Fi r s t ‑ or de rl i nea rpos i t i vef e e dba c ks ys t e mspr oduc epur ee xp nent i a lgr owt h.Expone nt i a lgr owt hhast her e ma r ka bl epr ope r t yt ha tt hes t a t eof t hes ys t em doubl esi naf i xedpe r i odoft i me,noma t t e rhow l a r gei ti s .The doubl i ngt l meC ha r a c t e r i zest hes t r e ngt hoft hepos i t i vel oop.Si mi l a r l y,f i r s t ‑ or de r l i nea rnega t i vef ee dba c ks ys t e msgene r a t eexpone nt i a lde ca yt oagoa l ・ Thedeca y r a t ei sc ha r a c t e r i z e dbyt heha l f l l i f e, t het i mer e qui r e df ort hega pbe t we e nt hes t a t e oft hes ys t e ma ndt hegoa lt obec uti nha l f .Thec ha pt e ra l s oi nt r oduce dt hephas e O ‑ 1 3 I ft h en e t r a t eo fc h a n g ei sz e r oo v e raf i n i t ei n t e r v a l i ns t a t es p a c e , t h e s ep o l n t Sh a v en e u t r a l s t a D l l l t y; ad i s t u r l D a n C eL Wi t h i nt h a t r a n g e )C a u s e sn e i t h e rar e s I L O r a l L i v ei l O i t d i v e r g e r l t C h a n g ei l l t l r . e n e t r a t e , J u s ta Sab a l l p l a c e da ny wh er eo naf la ts u r f a c ew il l r e ma i na t t h a t p o l n t . 1 4T e c h n i c a l l y , f i r s t ‑ o r d e rs y s t e msc a n n o t o s c i l l a t ep r o v i d e dt i mei st r e a t e dc o n t i n u o u s l y ・ Fi r s t l o r d e rs ys t e msi nd i s c r e t et i mec a no s c i l l a t e . Fore x a mp l e , t h el o g l S t i cma p, t h ef i r s t ‑ o r d e rn o n l i n e a r d i s c r e t et i me禦a pX ( t+1)‑k x ( t ) ( 1IX( t ) ) , Wh e r e0≦k≦4a n dO<x ( 0) <1 , n o t o n l yo s c i l ‑ l a t e sf o rc e r t a i nV a l u e so fk , b u t g e n e r a t e sp e r i o dd o u b l i n ga n dc h a o sa swe l l . Ho wev e r , hes t t a t e‑ me n t t h a to s c i l l a t i o nr e q u l r e Saf e e d b a c kl o o pwi t ha t l e a s t t wos t o c k si ss t i l l v a l i d : i nd i s c r e t et i me mo d e l s , t h et i mes t e pb e t we e ni t e r a t i o nsc o n s t i t u t e sa n irr e d u c i b l et l med e l a yl ne v e r yf e e d b a c k l o o p. Ev e r yt l mel a gc o n t a i n sas t o c kwh i c ha c c u mu la t e st hei n lo f wt ot h ed e l a yl e s si t so u t f l o w. Ev e r yd i s c r e t ed y n a mi cs y s t e mc a nb ec o n v e r t e di n t oa ne q u l V a l e n t c o n t i n u o u st i mes y s t e mb y i n t r o d u c i n gal a ge q u a l t ot h et i mes t e pa te veI YS t a t eV a r i a b l e , i n cr e a s l n gt h eo r d e ro ft h es y s t e m ( s ee Lo w1 98 0f o ra ne x a mp l e ) . Ch a p t e r8 Cl o s i n gt h eLo o p: Dy n a mi c so fS i mp l eS t r u c t ur e s 291 pl ot ,aus e f lt u oo lt oa na l yz et hedyna mi csofs ys t e msgr a phi ca l l y, wi t houtt heus e ofca l c ul us . Ana l ys I SOft hepha s epl ot sf o rf i r s t 1 0 r de rs ys t e mss howst ha ti ns ys t e mswi t h mor et ha nonef e e d ba c kl oo p, t hedyna mi c sde pe ndonwhi c hl oopi sdomi na nt . I n l i nea rs ys t e ms , t hedomi na nc eoft hedi f f e r e ntl oo psc a nne ve rc ha nge. Thusl i ne a r f i r s t 1 0r de rs ys t e msc a nonl ye xhi bi tt hr e ebe ha vi o r s : e xpone nt i a lgr owt h( whe nt he pos i t i vel oopsdo mi na t e ) ,e xpone nt i a lde c a y( whe nt hene ga t i vel oo psdomi na t e ) , a nde qui l i br i um( whe nt hel oo pse xa c t l yofs e tonea not he r ) . Nonl i ne a rf i r s t ‑ o r de r s ys t e msca ne xh i bi tSI S ha pe dgr owt hbe c a us et hedomi na ntf e e dba c kl oopss hi f ta s t hes ys t e me vol v es . Ast hepo pul a t i ona ppr oa c hesi t sc a r r yl ngC a pa c i t yt hepos i t i ve l oopsdr i vi nggr o wt hwe a ke na ndt hene ga t i vel oo psr e s t r a i nl ngg r owt hs t r e ngt he n, unt i lt hes ys t e mi sdomi na t e dbyne ga t i vef e e dba c k,a ndt hepopul a t i ont he n s moo t hl ya ppr oa c hesas t a bl ee qui l i br i uma tt hec a r r yl ngC a pa C l t y. §‑ Si l i a盲 準尋i I ‑ ; ぞ串W睦;互声量 de m量 g s 千 言 i ‑ 1 即 ち 主音 享 和 I i 7 5 主 熟呈 § 畳 紙 員n封 もe Gr owも hi ) fNe w喜 〉 r o戚ue 息 S き Ev e Z Tt hi n gt hatr i s e smu s tc o nv e r ge . ‑F l a n n e r yO' Co n n o r Ass e e ni nc ha p t e r8,pos i t i vef e e d ba c kc r e a t e se x po ne nt i a lg r o wt h.Butnor e a l q ua nt i t yC a ng r o wf o r e ve r . Eve r ys ys t e mi ni t i a l l ydo mi na t e dbypos i t i vef e e d ba c ks e ve n t ua l l ya p pr o a c he st hec a r r yl ngC a pa C l t yOfi t se nvi r o nme nt . Ast hel i mi t st o g r owt ha p pr oa c h , t he r ei sano nl i ne a rt r a ns i t i o nf r o mdo mi na nc ebypos i t i vef e e d‑ ba c kt odo mi na n c ebyne ga t i vef e e dba c k.Unde rc e r t a i nc o nd i t i ons ,t her e s ul ti s S‑ s ha pe dg r o wt h , whe r et heg r owl ngpo pul a t i o ns moo t hl ya pp r o a c he se q ui l i br i um. Thi sc ha pt e rs ho wsho wS‑ s ha pe dg r owt hc a nbemode l e d, it w ha ppl i c a t i o nst ot he , d i f f us i o no fi n no va t i o ns ,t hes pr e a do fi nf e c t i o usdi s e a s e sa . ‑ . dc omput e rVi r us e s t heg r owt ho ft hema r ke tf o rne wpr od uc t s ,a n do t he r s ・ Ava r i e t yofi mpo r t a nta nd wi de l yus e dmo d e l so fS‑ S ha pe dgr owt ha r ei nt r o duc e da nda na l yz e d,t heus e oft he s emod e l sf o rf o r e c a s t l ngi sdi s c us s e d,a nde xt e ns i o nst ot hemode l sa r e pr e s e nt e d・Ca s e se xa mi ne di nc l udet hes pr e a do fma dc o wd i s e a s ea ndHI Va nd t heg r owt ho ft hema r ke t sf o rhi g h‑ t e c hpr od uc t ss uc ha sc o mput e r sa ndc o ns ume r s e r v i c e ss uc ha sc a bl et e l e vi s i on. 295 2 96 9. 1 Pa r t I I I Th eDy n a mi c so fGr o wt h MoDEuNG S‑ SHAPEDGROWTH Thenonl i ne a rpopul a t i onmode lde ve l o pe di nc ha pt e r8i squl t ege ne r a l ・ Thepo p‑ ul a t i oni nt hemode lc a nbea nyqua nt i t yt ha tg r owsi naf i xe denvi r onme nt , f o re x‑ a mpl e, t henumbe rofa do pt e r sofa ni nnova t i on, t henumbe rofpe o pl ei nf e c t edby adi s e a s e,t hef r a c t i onofa nygr oupa dhe r i ngt oa ni de aorpur c ha s i ngapr oduc t , a nds oon. I ft hepopul a t i oni sd r i ve nbypos i t i vef e e d ba c kwhe ni ti ss ma l lr e l a t i ve t oi t sl i mi t s ,t he nt her es ul t i ngbe ha vi orwi l lbeSI S ha pe dgr owt h,pr ovi de dt he r e a r enos i gni f i c a ntde l a ysi nt hene ga t i vef e e d ba c kst ha tc ons t r ai nt hepo pul a t i on. I f t he r ea r ede l a ysi nt her e s pons eoft hepo pul a t i ont ot hea ppr oa c hi ngc a r r yl ngC a ‑ pa c l t y , t hebe ha vi orwi l lbeS‑ S ha pe dgr owt hwi t hove r s hoota ndos c i l l a t i o n; i ft he c a r r yl ngCa pa c i t yl Sc ons ume dbyt hegr owl ngPOPul a t i on,t hebe ha vi o rwi l lbe ove r s hoota ndc ol l a ps e( S e ec ha pt e r4) .Conve r s e l y,whe ne ve ryo uo bs e r veas ys ‑ t e mt ha tha se xpe r i e nc e dS‑ s ha pe dg r owt h,youknowt ha ti ni t i a l l yt hebe ha vi or wa sdomi na t e dbypos i t i vef e e d ba c kl oops ,buta st hes ys t e m gr e w,t he r ewa sa nonl i ne a rs hi f tt odomi na nc ebyne ga t i vef e e dba c k. 9. i. 1 Logl ‑ St t l cGr owt h Asi l l us t r a t e di nt henonl i ne a rpopul a t i ongr owt he xa mpl ei nc ha pt e r8,t hene t f r a c t i ona lgr owt hr a t eoft hepopul a t i onPmus tf a l lf r om i t si ni t i a lva l ue,pa s s t h r o ughz e r owhe nt hepopul a t i one qua l st hec a r r yl ngC a pa c i t yC, a ndbe c o mene g‑ a t i vewhe nP>C.Cons e que nt l y ,t hepha s epl otoft hene tbi r t hr a t emus tha vea s ha per oughl yl i kea ni nve r t e dbowl :Ne tbi r t hsa r ez e r owhe nt hepo pul a t i oni s z e r o, r i s ewi t hi nc r e a s l ngpo pul a t i onupt oama xi mu m, f a l lt oz e r oa tt hec a r r yl ng c a pa c l t y ,a ndc ont i nuet odr op,be c omngl nC r e a S l ngl yne ga t i ve,whe npopul a t i on e xc e e dst hec a r r yl ngC a Pa C i t y・ Howe ve r ,t he r ea r ea ni nf i ni t enumbe roff r a c t i ona l ne t bi r t hr a t ec ur ve s , a ndhe nc epha s epl ot s , s a t i s f yi ngt he s ege ne r a lc o ns t r a i nt s ・ An i mpor t a nts pe c i a lc a s eofSI S ha pe dgr owt hi sk n owna sl o gi s t i cgr owt h, o rVe r hul s t g r owt h,a f t e rFr a n9 0i sVe r hul s twhof i r s tpubl i s he dt hemode li n1 8 38( s e e Ri c ha r ds on1 991 ) . Thel ogl S t i cgr owt hmode lpos i t st ha tt hene tf r a c t i ona lpopu la t i ongr owt hr a t e , i sa( downwa r ds l opi ng)l i ne a rf unc t i onoft hepopul a t i on・ Tha ti s Ne tBi r t hRa t e‑g( P ,C) p‑g U IP/ C) P ( 91 1 ) whe r eg( P, C) , t hef r a c t i ona lgr owt hr a t e , i saf unc t i onoft hepo pul a t i ona ndc a r r y‑ i ngc a pa c i t ya ndg*i st hema xi mumf r a c t i ona lgr owt h( t hef r a c t i ona lg r owt hr a t e whe nt hepopul a t i oni sve r ys ma l l ) ・Thel ogi s t i cmode lc onf or mst ot her e qui r e ‑ me nt sf orSI S ha pe dgr owt h:t hef r a c t i ona lne tgr owt hr a t ei spos i t i vef o rP<C, z e r owhe nP‑C,a ndne ga t i vef orP>C・ Thel ogl S t i cmode lha ss omea ddi t i ona l c ha r a c t e r i s t i c s . Re a r r a ngi nge qua t i on( 9‑ 1 )gi ves ( 1‑ P/ C) p‑g帯 p‑gt i ' p2/ C Ne tBi r t hRa t e‑g決 ( 9‑ 2 ) Thef i r s tt e r m g* pi sas t a nda r df i r s t ‑ o r de rl i ne a rpos i t i vef e e dba c kpr oc es s ;t he s e c ondt e r m,一g* p2/ C,i snonl i ne a ri nt hepopul a t i ona ndr e pr e s e nt st hee ve r ‑ S t r onge rne ga t i vef e e dba c kc a us e dbyt hea ppr oa c hoft hepo pul a t i ont oi t sc a r r y‑ l ngC a pa C l t y・ Ch a p t e r 9S I S h a edGr p o wt h : Ep i d e ic m s , I n n o v a t i o nDi f us f i o n , a n dt h eGr o wt ho f Ne wP r o d u c t s2 9 7 Whe ndoest hene tgr owt hr a t er ea c hi t sma xi mum?I nt hel ogl S t i cmode lt he 9‑ 2)i sa ni nve r t e dpa r a bol awhi c hpa s s e st hr ough ne tbi r t hr a t egi v e nbye qua t i on( z e r oa tt hepol n t SP 0a ndP‑ C.Be c a us eapa r a bol ai ss ymme t r i ca r oundi t s pe a k,t hema xi mum ne tbi r t hr a t eoc c ur swhe n ‑ P. n f‑C/ 2 ( 9 ‑ 3 ) whe r ePi n f i st heva l ueofpopul a t i o nwhe r et hene tgr owt hr a t ei sa tama xi muma nd t he r e f o r et hei nf le c t i onpoi nti nt het r a j e c t o r yOft hepopul a t i on・ 1 Thema xi mumne t g r owt hr a t eoc c ur spr e c i s e l yha l f wa yt ot hec a r r yl ngCa Pa C i t y・ Fi gur e9‑ ipl ot st he f r a c t i ona lgr owt hr a t e, pha s epl ot , a ndt i medoma i nbe ha vi orf ort hel ogl S t i cmode l . Thel ogl S t i cmode li si mpor t a ntf ors e ve r a lr ea s ons ・Fi r s t ,ma nyS‑ S ha pe d g r owt hpr oc e s s e sca nbea ppr oxi ma t e dwe l lbyt hel ogl S t i cmode l ,de s pi t et her e ‑ / 2. Se c ond, t hel ogl S t i cmode l s t r i c t i ont ha tt hei nf l e c t i o npol ntoc c ur sa tPr e c i s e l yC c a nbes ol ve da na l yt i ca l l y.Fi na l l y ,t hel ogl S t i cmode l ,t houghi nt r i ns i c a l l ynon‑ 1 i ne a r ,Ca nbet r a ns f or me di nt oaf o r mt ha ti sl i ne a ri nt hepa r a me t e r ss oi tc a nbe e s t i ma t e dbyt hemos tc ommonr e gr es s i ont e c hni que,or di na r yl e a s ts qua r e s( S e e s e c t i on9. 3. 1 ) . 9. 1u 2 AnaF yt i cSol ut i onof的eLogi st k Equat i on Thoughi ti snonl i ne a r ,t hel ogi s t i cmode ls howni ne qua t i on( 9‑ 1 )c a nbes ol ve d a na l yt i c a l l y. Fi r s ts e pa r a t et heva r i a bl e s , t he ni nt e gr a t e: ( 9‑ 4) J薄 ‑恒 Re a r r a ngi ngt hel e f t ‑ ha nds i degi ve s ‑ I l g・詩 I詰 ‑ fg* d t ] d P l nt e gr a t l ngbot hs i desyi e l ds l n ( P)‑1 n( C‑P)‑gx t+c whe r eci sac ons t a nt . Si nc ebyde f i ni t i onP( t )‑P( 0)whe nt‑0, 1 n( P)‑1 n( CIP)‑g串 t+l n( P( 0 ) )一1 n[ C‑P( 0 ) ] . Ta ki nge xpone nt i a l syi e l ds P P( 0 ) e x p( g * t ) ( C‑p) C‑p( o ) ( 9‑ 8) whi c hc a nber e a r r a ngeda s P ( t )‑ [ i S rl ] e x p 仁 g * t ) ( 9 ‑ 9 ) I・ l Th ema x i mu mn e t b i r t hr a t e , a n dt h e r e f o r et h ei n f e c t i o np o l n t i nt h ep o p u l a t i o n , o c c u r swh e n ,C )*P] / ∂ p‑g 一2 g x P / C‑0. ∂ [ g ( P S o l v i n gf o rPy i e l d s P l 。 f ‑C/ 2. 祥 2 9 8 Pa r tI I I TheDyna mi csofGr owt h alt 2tJ Lf tJ U t Og J FI GURE 9 ‑ 1 Thel ogi st i cmodel l aN T op: Thef r ac t i onal gr owt hr at ede cl i nesl i near H yas popul at i ongr ows Mi ddl e: Thephase pl oti sani nver t ed par abol a,s ymmeト r i cabout( P/ C)‑ 0. 5.Bot t om:Popu‑ l at i onf ol l owsan S‑ shapedcuⅣe wi t hi nf l ec t i on P/ C)‑ poi ntat( 0. 5; t henetgr owt h r at ef ol l owsabeH ‑ Shapedcur vewi t h amaxi mum val ue of0. 25Cpert i me per i odl Thet i me axi si ss cal edso , t hatluni t‑ 1 / g' Wi t ht hei nf 一 ect i on poi ntcent er edat t i meh‑0. ‑ 届 uOE t OeJlj . Popul at i on/ Car r yl ngCapaci t y ( di mensi onl ess) (U ale t]L J l J V t O D JI t aN Popul at i on/ Car r yl ngCapaci t y ( di mensi onl ess) Ne t 5 0 (ssal uO ! Sua∈ ! P) ^l!3 ed t23 6u^ !J L eO\ uO! l eln dod Bi r th R a ≧ te JC 一 ( ar ∃ r ying Ca e ) p ac it y 0 ‑4 ‑2 O Ti me 2 4 ore qul Va l e nt l yas ( t ) P 1+ e xp卜 ( 91 1 0) g H( t ‑ h)] whe r eh i st he t i me a twhi c ht he popul a t i on r ea c heshal fi t sc a r r yl ng Ca‑ pa ci t y;s et t i ngP( h)‑ 0 . 5C i ne qua t i on( 9‑ 1 0)a nds ol vi ngf orhyi el dsh ‑ l n[ ( C/ P( 0) )‑ 1 ] / g* . Equa t i ons( 9‑ 9)a nd( 9‑ 1 0)∬et wof or msoft hea na l yt i cs ol u‑ t i ont ot heequa t i onf orl ogi s icgr t owt hgi ve nbye qua t i on( 9‑ i ) . Ch a p t e r9 S ‑ S h a p e dGr o wt h : Ep i d e mi c s , I n n o v a t i o nDi ml S i o n , a n dt h eGr o wt ho f Ne wP r o d u c t s299 9. 1. 3 0t herCommonGr owt hMode一 s Duet oi t ss i mpl i c i t ya nda na l yt i ct r a c t a bi l i t y , t hel ogl S t i cmode li st hemos twi de l y us e dmode lofS‑ s ha pe dgr owt h.Howe ve r ,t he r ea r ema nyot he rmode l sof S‑ s ha pe dgr owt h. The s emode l sr e l a xt her e s t r i c t i vea s s umpt i ont ha tt hef r a c t i ona l gr owt hr a t ede c l i ne sl i ne a r l yi nt hepopul a t i on. The s egr owt hc ur vesa r ei nge ne r a l nots ymme t r i c. TheRi c ha r dsc ur vei sonec ommonl y us e dmode l( Ri c ha r ds 1959) .I n Ri c ha r ds 'mode lt hef r a c t i ona lgr owt hr a t eoft hepopul a ioni t snonl i ne a ri nt he po pul a t i on: ・e tBi nhRa t e‑芸 ‑諾 ㌔ [ 1‑ ( E) mー1 ] ( 91 11 ) Whe nm ‑2, t h eRi c ha r dsmode lr e duc est ot hel ogl S t i c.Ot he rva l uesofmc a us e t hef r a c t i ona lg r owt hr a t et obenon li nea ri nt hepopul a t i on( t r ys ke t c hi ngt hef r a c ‑ t i ona lgr owt hr a t ea saf u nc t i onofpopul a t i onf ordi f f e r e ntva l ue sofm) . Thes ol u t i onoft heRi c ha r dsmode li s ‑ S t ) ) 1 / ( 1 ‑ m ) P( t )‑C( 1Ik e x p( ‑g ( 91 1 2) whe r eki sapa r a me t e rt ha tde pe ndsont hei ni t i a lpo pul a t i onr e l a t i vet ot hec a r r yl l ngC a pa C l t y・ As pe c i a lc a s eoft heRi c ha r dsmode li st heGompe r t zc ur ve,gl Ve nbyt he Ri c ha r dsmode li nt hel i mi twhe nm ‑ 1.Not et ha twhi l ee qua t i on( 9‑ 1 2)i sun‑ , de f i ne dwhe nm ‑ i ( Xa‑ 1 i l l l a →O a 1 ) ‑1 m ( Ⅹ) ( 9‑ 1 3) s ot heGompe r t zc u r vei sgl Ve nby P( t )‑Ce x p( ‑ke x p( ‑g x t ) ) . ( 91 1 4) I nt heGompe r t zmode l ,t hef r a c t i ona lgr owt hr a t ede c l i nesl i ne a r l yi nt hel oga ‑ r i t hm oft hepo p ul a t i o n,a ndt hema xi mum g r owt hr a t eoc c ur sa tP/ C ‑0. 368. Anot he rc o mmonl yus e dgr owt hmode li sba s e dont heWe i bul ldi s t r i but i on: P( t )‑ C( 1‑e x p卜 ( Vb) a ] ) ( 9‑ 1 5) whe r ea, b>0a r ek nowna st hes ha pea nds c a l epa ra me t e r s , r es pe c t i ve l y. Thec a s e a‑2i sknowna st heRa yl e i ghdi s t r i but i on・ TheRi c ha r dsa ndWe i bul lmode l spr ovi det hemode l e rwi t ha na lyt i c a l l y t r a c t a bl egr owt hf u nc t i onst ha tc a nr e pr es e ntava r i e t yofnonl i ne a r血. a c t i ona lne t i nc r e a s er a t e s . Howe ve r , t he r ei snogua r a nt e et ha tt heda t awi l lc onf o m t ot hea s ‑ s umpt 1 0nSOfa n yo ft hea na l yt i cgr owt hmode l s . For t una t e l y, wi t hc omput e rs i mul l a t i on,youa r en otr e s t r i c t e dt ous et hel ogl S t i c,Gompe r t z ,Ri c ha r ds ,We i bul l ,or a nyot he ra na l yt i cmode l . Youc a ns pe c i f ya nynonl i ne a rr e l a t i o ns hi pf o rt hef r a c ‑ t i ona lbi r t ha ndde a t hr a t ess uppo r t e dbyt heda t aa ndt he ns i mul a t et hemode lt o e xpl or ei t sbe ha v i o rove rt i me. 300 P a r t I I I Th eDy n a mi c so fGr o wt h 9. l. 4 Test i ngt heLogi st i cN! odel Toi l l us t r a t et heus eoft hel ogl S t i cmode l ,c ons i de rt hee xa mpl esofS‑ s ha pe d gr owt hi nFi gur e41 9. Fi gur e91 2s howst her e s ul toff i t t i ngt hel ogl S t i cmode lt ot he da t af ort heg r owt hofs unf lowe r s .Thebe s tf i tl ogl S t i cmodelma t c hest hes un‑ lowe f rda t ar e a s ona bl ywe l l , t houghi tunde r e s t i ma t e st heg r owt hi nt hef i r s tmont h a ndove r e s ima t t e si tl a t e r .The s edi f f T e r e nc e ss ugge s tabe t t e rf i tmi ghtbega l ne d t hr o ug hus eo fadi fe r e ntgr owt hmode l ,s uc ha st heRi c ha r dsmode l , i nwhi c ht he f r a c t i ona lg r owt hr a t ei snonl i ne a ri nt hepo pul a t i on・Se c ion9・ t 3・ lpr ovi desa ddi ‑ t i o na le xa mpl e s . 9R 2 DYNAMI CSOFDI SEASE:MoDEuNG EpI DEME CS Epi de mi c sofi nf e c t i ousdi s e a s e sof t e ne xhi bi tSI S ha pe dgr owt h・ Thec umul a t i ve numbe rofc a s e sf ol l owsa nSI S ha pe dc ur vewhi l et her a t ea twhi c hne wca s esOC I c urr i s e se xpone nt i a l l y,pea ks ,t he nf a l l sa st hee pi de mi ce nds ・Fi gur e9‑ 3S hows t hec our s eofa ne pi de mi cofi nf lue nz aa ta nEngl i s hboa r d i ngs c hooli n1 978・ The e pi de mi cbe ga nwi t has i ngl ei nf e c t e ds t ude nt( pa t i e ntz e r o) ・Thef lus pr e a ds t hr oughc ont a c ta ndbyi nha l a t i onofvi r us ‑ l a de na e r os ol sr e l ea s e dwhe ni nf e c t e d i ndi vi dua l sc o ugha nds ne e z e. Thef lus pr e a ds l owl ya tf ir s t , buta smor ea ndmo r e s t ude nt sf e l li l la ndbe c a mei nf e c t i o us ,t henumbe rt he yi nf e c t e dgr e we xpone n‑ t i a l l y, Duet ot hec l os equa r t e r sa ndt hushi ghr a t eofe xpos ur e ,a boutt wo‑ t hi r dsof t hepopul a t i one ve nt ua l l ybe c a mei l l ,a ndt hee pi de mi ce nde dduet ot hede pl e t i on oft hepoolofs us c e pt i bl epe opl e. Fi gur e9‑ 3a l s os howst hec our s eofa ne pi de mi c ofpl a guei nBomba yi n1 905 ‑6. Thebe ha vi o ri sq ul t eS i mi l a r ,de s pi t et hedi fe r e nc esi nt i mefra me,mor t a l i t y,a ndot he ra s pe c t soft hes i t ua t i on.Thepa t hoge n doe snotha vet obeabi ol ogi c a la ge nt ‑e pi de mi c so fc omput e rvi r us e sf ol l ows i m‑ i l a rdyna mi cs . ‑ 9. 2. 1 AS血 pヨ eM◎deを⑳曹E m甘 ee竜 岳 ousDi sease Fi g ur e91 4S howsas i mpl emode lofi nf e c t i ousdi s e a s e. Thet ot lpo a pul a t i onoft he c ommunl t yOrr e gi onr e pr e s e nt e di nt hemode li sdi ide v di nt ot woc a t e gor i es : t hos e s us c e pt i bl et ot hedi s ea s e,S,a ndt hos ewhoa r ei nf e c t i ous ,I( f ort hi sr e a s ont he Ft GURE9‑ 2 Thegr owt hof sun f l ower sand t hebes tf i t l ogi s t i cmodel 0 14 28 42 Da y s 56 70 84 Ch a p t e r9 S ‑ S h a p e dGr o wt h: Ep i d e ic m s , I n n o v a t i o nDi fu s i o n, a n dt h eGr o wt ho fNe wPr o d u c t s301 Imodel ) . Aspeopl ea r ei nf ec t edt heymovef r om t hes us modeli sknownast heS cept i bl eca t egor yt ot hei nf ect i ousca t egor y.TheS Imodeli nvokesanumberof s i mpl i f yi ngas s umpt i ons ;S ec t i on 9. 2. 2devel opsamor er eal i s t i cmodel .Fi r s t , ‑ FI GURE9・ 3 Dynami csofepl‑ demi cdi sease FI GURE9‑ 4 St r uc t ur eofa si mpl emodelof anepi demi c B州1 S,deat hs, andmi gr at i onar e omi t t edsot he t ot alpopul at i oni s aconst ant ,and peop一 er emai n i nf ect i ous i ndef i ni t el y. 1/ 30 2/1 2/ 3 0 5 2 ‑ 1/ 28 0 0 5 Bot t om:Epi demi c ofp一 ague,Bom bay,I ndi a190516r Dat ashowt he deat hr at e ( deat hs / week) . Sour c e:K e r ma c kan d c k( i 9 2 7, Mc Ke n dri p71 4 ) l F or f ur t h er d i s I , c u s s i o no fb o t hc a s e s s e eMu r r a y( 1 9 9 3 ) . ︼ 苛 p . 5 8 7 ・ 1/ 26 0 5 7 Soul ℃e:Br J t I ' shMedl ' C aI l , 4Mar c h1 9 7 8, Jour na 1 / 24 ( aき P一 doa d) st ue a凸 T op:I nf l uenza epi demi catan Engl i shboar di ng school , Januar y 22‑Febr uar y3, 1978.Thedat a showt henumber ofst udent s conf i nedt obedf or i nf l uenzaatany t i me( t hest ockof sympt omat i c i ndi vi dual s) . 0 5 10 15 We ek s 20 25 30 302 P a r t HIT h eDy n a mi c so f Gr o wt h bi r t hs ,de a t hs ,a ndmi g r a t i ona r eI gno r e d.Se c o nd, onc epe o pl ea r ei nf e c t e d, t he y r e ma i ni nf e c t i o usi nde f i ni t e l y , t ha ti s , t hemo de la ppl i e st oc hr o ni ci nf e c t i o ns , no t a c ut ei l l ne s ss uc ha si nf lue nz ao rpl a g ue. TheSImo de lc o nt a i nst wol oo ps , t hepos i t i v eCo nt a gi o nl oo pa ndt hene ga t i v e De pl e t i o nl oo p. I nf e c t i o usdi s e a s e ss pr e a da st hos ewhoa r ei nf e c t i o usc omei nt o c on t a c twi t ha ndpa s st hedi s e a s et ot hos ewhoa r es us c e pt ibl e,i nc r e a s l ngt hei n‑ f e c t i o uspo pul a t i o ns t i l lf ur t he r( hepos t i t i v el oo p)whi l ea tt hes a met i med e pl e t ‑ i ngt hepo olofs us c e pt i bl e s( t hene ga t i v el o o p) . Thei n f T e c t i ouspo pul a t i o nli si nc r e a s e db yt hei nf e c t i onr a t eI Rwhi l et hes us ‑ t : c e pt i bl epo pul a t i o nSi sde c r e a s e dbyi Ⅰ ‑I NTEGRAL( I R,Io) S‑I NTEGRAL( ‑I R, N‑Io) ( 9‑ 1 6) ( 9 1 1 7 ) whe r eNi st het ot a lpopul a t i o 汀i nt hec o mmunl t ya ndI 。i st hei ni t i a lnumbe ro f i nf e c t i o uspe o pl e( as ma l lnumbe ro re ve nas i ngl ei ndi v i dua l ) . Tbf o r mul a t et he i nf e c t i o nr a t e , c o ns i de rt hepr o c e s sbywhi c hs us c e pt i bl epe op l ebe c o mei nf e c t e d. me a ‑ Pe o pl ei nt hec ommuni t yi nt e r a c ta tac e r t a i nr a t e( t heCont a c tRa t e ,C, s ur e di npe o pl ec o nt a c t e dpe rpe r s o npe rt i mepe r i od, or1 / t i mepe r i od) ・ Th ust he s us c e pt i bl epo pul a t i onge ne r a t eSce nc o unt e r spe rt i mepe r i od. So meoft he s ee n c o unt e r sa r ewi t hi nf e c t i ouspe o pl e . I fi nf e c t i o uspe o pl ei nt e r a c ta tt hes a mer a t ea s s us c e pt i bl epe o pl e( t he ya r enotqua r a n t i ne do rc o nf i ne dt obe d) , t he nt hepr o ba ‑ bi l i t yt ha ta nyr a ndo ml ys e l e c t e de nc o un t e ri sa ne nc o unt e rwi t ha ni nf e c t i o usi n‑ d i v i d ua li sI / N. Note ve r ye nc o unt e rwi t ha ni nf e c t i o uspe r s o nr e s ul t si ni nf e c t i o n. Thei nf e c t i vl t y ,i ,oft hed i s e a s ei st hepr o ba bi l i t yt ha tape r s onbe c ome si nf e c t e d a f t e rc ont a c twi t ha ni nf e c t i ouspe r s on.Thei nf e c t i o nr a t ei st he r e f or et het ot a l n umbe ro fe nc ount e r sScmul t i pl i e db yt hep r o ba bi l i t yt ha ta nyo ft hos ee n c o un t e r s i swi t ha ni nf e c t i o usi nd i vi dua lI / Nmu lt i pl i e dbyt hepr o ba bi l i t yt ha ta ne nc o u nt e r wi t ha ni nf e c t i o uspe r s o nr e s ul t si ni n f e c t i o n: ‑ I R‑( c i S) ( Ⅰ / N) ( 9 ‑ 1 8 ) a‑ Thed yna mi c sc a nbede t e r mi ne dbyno t l ngt ha twi t ho utbi r t hs ,de a t hs ,o rml g r t i o n, t het o t a lpo pul a t i oni sf i xe d: S+Ⅰ‑N ( 9 ‑ 1 9 ) Tho ug ht hes ys t e mc o nt a i nst wos t oc ks , i ti sa c t ua l l yaf i r s t ‑ o r de rs ys t e mbe c a us e o neo ft hes t oc ksi sc o mpl e t e l yde t e r mi ne dbyt heo t he r ・Subs t i t ut l ngN IIf o rS i n( 9‑ 1 8 )yi e l ds Ⅰ / N ) I R‑( C ) ( i ) I ( 1‑ ( 9‑ 20) Equa t i on( 9‑ 20)i si de nt i c a lt oe q ua t i o n( 9‑ 1 ) ,t hene tbi r t hr a t ei nt hel o gi s t i c mo de l . Ane pi de mi c ,i nt hi smod e l , g r owse xa c t l yl i keapo pul a t i o ni naf i xe de n‑ vi r o nme nt . Thec a r r yl ngC a pa C l t yi st het o t a lpo pul a t i o n, N. I nt heSImo de l , o nc e a ni nf e c t i o usi ndi vi d ua la r r i ve si nt hec o mmunl t y , e ve r yS us c e pt i bl epe r s one v e n‑ t ua l l ybe c ome si nf e c t e d, Wi t ht hei nf e c t i o nr a t ef o l l owl ngabe l l ‑ s ha pe dc ur v ea nd Ch a p t e r9 S I S h a p e dGr o wt h : Ep i d e ic m s , I n n o v a t i o nDi fu s i o n , a n dt h eGr o wt ho f Ne wP r o d u c t s3 0 3 t het ot a li nf e c t e dpo pul a t i onf ol l owl ngt hec l a s s i cSI S ha pe dpa t t e r noft hel ogl S t i c c ur ve( Fi gur e9‑ 1 ) .Thehi ghe rt hec ont a c tr a t eort hegr e a t e rt hei nf e c t i vi t y,t he f a s t e rt hee pi d e mi cpr og r e s s e s . TheSImo d e lc a pt ur e st hemos tf unda me nt a lf e a t ur eofi nf e c t i ousdi s e a s e s : t he di s e a s es pr e a dst hr o ughc ont a c tbe t we e ni nf e c t e da nds us c e pt i bl ei ndi vi dua l s . I ti s t hei nt e r a c t i onoft he s et wogr oupst ha tc r e a t e st hepos i t i vea ndne ga t i vel oops a ndt henonl i ne a r l t yr eS PO nS i bl e氏) rt hes hi f ti nl oo pdomi na nc ea st hes us c e pt i bl e po pul a t i oni sd e pl e t e d.Thenonl i ne a r l t ya r i s e sbe c a us et het wopopul a t i onsa r e mul t i pl i e dt oge t he ri ne qua t i on( 91 1 8) ; i tt a ke sbot h as us c e pt ibl ea nda ni nf e c t i ous pe r s ont oge ne r a t eane wc a s e・ 9. 2. 2 Mode! i ngAcut ehf ect i on:TheS旧 Mode! Whi l et heSImode lc a pt ur est heba s i cpr oc e s sofi nf e c t i on, i tc ont a i nsma nys i m‑ pl i f yi nga ndr e s t r i c t i vea s s umpt l OnS . Themode ldoesnotr e pr es e ntbi r t hs ,de a t hs , orml g r a t i on. Thepopul a t i oni sa s s ume dt obehomoge ne ous :a l lme mbe r soft he c ommuni t ya r ea s s ume dt oi nt e r a c ta tt hes a mea ve r a ger a t e( t he r ea r enos ubc ul ‑ t ur e so rg r o upst ha tr e ma i ni s ol a t e df r omt heot he r si nt hec ommunl t yOrWhos ebe ‑ ha vi ori sdi f f e r e ntf r om ot he r s ) .Thedi s e a s edoesnota l t e rpe opl e' sl i f e s t yl es : i nf e c t i ve sa r ea s s ume dt oi nt e r a c ta tt hes a mea ve r a ger a t ea ss us c e pt i bl e s . The r ei s nopos s i bi l i t yo fr e c ove r y,quar a nt i ne, ori mmuni z a t i on. Al lt hes ea s s umpt l OnSC a nber e l a xe d. Thes us c e pt i bl epopul a t i onc a nbedi s ‑ a gg r e ga t e di nt os e ve r a ldi s t i nc ts ubpopul a t i ons ,Ore ve nr e pr es e nt e da sdi s t i nc ti n‑ di vi dua l s ,e a c hwi t has pe c i f i cr a t eofc ont a c twi t hot he r s . Ana ddi t i ona ls t oc kc a n bea dde dt or e pr es e ntqua r a nt i ne dorva c c i na t e di ndi vi d ua l s ・Bi r t ha ndde a t hr a t e s c a nbea dde d. Ra ndom e ve nt sc a nbea dde dt os i mul a t et hec ha nc ena t ur eofc on‑ t a c t sbe t we e ns us c e pt i bl esa ndi nf e c t i ves . Themos tr e s t r i c t i vea ndunr e a l i s t i cf e a t ur eoft hel ogl S t i cmode la sa ppl i e dt o e pi de mi c si st hea s s umpt i ont ha tt hedi s e a s ei sc hr oni c,Wi t ha f f e c t e di ndi vi dua l s r e ma i ni ngi nf e c t i ousi nde f i ni t e l y.Cons e que nt l y,onc ee ve nas l ngl ei nf e c t i ousi n di vi d ua la r r i ve si nt hec ommuni t y, e ve r yS us c e pt i bl ee ve nt ua l l ybe c omesi nf e c t e d. Whi l et hea s s umpt i onofc hr oni ci nf e c t i oni sr e a s ona bl ef ors omedi s e a s es( e. g. , he r pe ss i mpl e x) , ma nyi nf e c t i ousdi s e a s espr oduc eape r i odofa c ut ei nf e c t i o us nes s a ndi l l ne s s ,f ol l owe de i t he rbyr e c ove r ya ndt hede ve l o pme ntofi mmuni t yOrby de a t h.Mos te pi de mi cse ndbe f or ea l lt hes us c e pt i bl esbe c omei nf e c t e dbe c a us e pe o pl er e c ove rf a s t e rt ha nne wc a s esa r i s e.Ke r ma c ka ndMcKe ndr i c k( 1 927)de ‑ ve l o pe damod e la ppl i ca bl et os uc ha c ut edi s e a s es .Themode lc ont a i nst hr e e s t oc ks : TheSus c e pt i bl epo pul a t i or l ,S, t heI r . f e c t i o‑ uspopui a t i or . , I , a ndt heRe c ov‑ e r e dpopul a t i on,良( Fi gur e9‑ 5) .Longknowna st heSI Rmode l ,t heKe r ma c k‑ Mc Ke ndr i c kf o r mul a t i oni swi de l yus e di ne pi de mi ol ogy.Thos ec ont r a c t l ngt he di s e a s ebe c o mei nf e c t i ousf orac e r t a i npe r i odoft i mebutt he nr e c ove ra ndde ve l op pe r ma ne nti mmuni t y. Thea s s umpt l Ont ha tpe opl er e c ove rc r ea t esonea ddi t i ona l f e e dba c k‑t hene ga t i veRe cove r yl oop.Thegr e a t e rt henumbe rofi nf e c t i ous ‑ 304 Pa r t I I I Th eDy n a mi c so fGr o wt h FI GURE9‑ 5 St r uc t ur eoft heSI Repi demi cmodel Peopl er emai ni n f ec t i ous( an dsi ck )f oral i mi t edt i me, t h enr ec overanddevel opi mmuni t y ・ i ndi vi dua l s ,t hegr e a t e rt her e c ove r yr a t ea ndt hes ma l l e rt henumbe rofi nf e c t i ous pe opl er e ma i nl ng・ Al lot he ra s s umpt l OnSOft heor l gl na lSImode la r er e t a i ne d・2 Thes us c e pt i bl epo pul a t i o n, a si nt heSImode l , i sr e duc e dbyt hei nf e c t i onr a t e. Thei nf e c t i ouspo pul a t i onnowa c c umul a t e st hei nf e c t i onr a t el es st her e c ove r yr a t e RRa ndt her e c ove r e dpo pul a t i on良a c c umul a t e st her e c ove r yr a t e: S‑I NTEGRAL( ‑I R, N‑ⅠO‑ Ro ) Ⅰ‑I NTEGRAL( I R‑RR,Io) 良 ‑I NTEGRAL( RR, Ro ) Thei ni t i a ls us c e pt i bl epo pul a t i oni st het ot a lpopul a t i onl es st hei ni t i a lnumbe rof i nf e c t i vesa nda nyi ni t i a l l yr e c ove r e da ndi mmunei ndi vi dua l s . Ther e c ove r yr a t ec a nbemode l e ds e ve r a lwa ys ・ I nt heSI Rmode l , t hea ve r a ge dur a t i onofi nf e c t i vi t y , d, i sa s s ume dt obec ons t a nta ndt her e c ove r ypr oc es si sa s s ume dt of ol l owaf i r s t ‑ or de rne ga t i vef e e dba c kpr oc es s : ‑ RR‑Ⅰ / d. ( 9‑ 2 4) Thea ve r a gedur a t i onofi nf e c t i vi t y,d, r e pr es e nt st hea ve r a gel e ngt hoft i mepe opl e a r ei nf e c t i ous . Thea s s umpt i ont ha tt her e c ove r yr a t ei saf i r s t 1 0 r de rpr oc e s sme a ns 2 I nt h eS I Rmo d e l t h er e c o v e r e dp o p u l a t i o ni so f t e nt e me r d" Re mo v a l s "a n dt her e c o v e r yr a t eis t h e nc a i i e dt h er e mo v a i r a t e . Ma n ya p p i l C a t i o n so ft h emo d e l i n t e r p r e t t h er e mo v a l r a t ea st h es u m o ft ho s er e c o v e r i n gf r o mt h ed i s e a s ea n dt h o s ewh od i ef r o mi t ・ Ho we v e r , t h i si n t e r p r e t a t i o ni si n ‑ c o rr e c t , s i n c et h o s ewh od i er e d u c et h et o t a l p o p u l a t i o n , wh i l ei nt h eS I Rmo d e l t h et o t a l p o p u l a t i o n i sc o n s t a n t . Th ea g g r e g a t i o no fd e a t h sa n dr e c o v e r i e si n t oas i n g l ef l o wo f r e mo v a l sa n das l n le g s t o c ko fc u mu l a t i v er e mo v lsi a su s u a l l yJ u s t i f i e db ya r g u l n gt h a t mo r t a l i t yl SO f t e nas ma ll f r a c t i o n o ft h et o t a l p o p u l a t i o n . Ev e nwh e nt hi si st ue r , i t i sb a dmo d e l i n gp r a c t i c et oa g g r e g a t et h el i v l n g wi ht t h ed e a d , s i n c et he i r b e h a v i o ri so f t e nq u i t ed i fe r e n t . I nt h i sc a s e , ho t s ewh or e c o v e rc o n t i n u e t oi n t e r a c t wi t ht h er e ma i n i n gS u s c e p t i b l ea n di nf e c t i o u sp o p u l a t i o n s , wh i l et h o s ewh od i eu s u a l l y t . d on o Ch a p t e r9 S I S h a edGr p o wt h : Ep i d e mi c s , I n n o v a t i o nDi fu s i o n , a n dt h eGr o wt ho fNe wP r o d u c t s305 pe opl edonota l lr e c ove ra f t e re xa c t l yt hes a met i me, butr a t he ragl Ve npo pul a t i o n ofi nf e c t i ousi n di vi dua l swi l lde c l i nee x pone nt i a l l y,wi t hs omepe o pl er e c o ve r l ng r a pi dl ya ndot he r smor es l owl y・ 3Thei nf e c t i onr a t ei sf or mul a t e de xa c t l ya si nt he SImode li ne qua t i on( 9‑ 1 8) . 9 . 2 . 3 Mo de=∋ e h a vi or : Th eTi ppi n gP1 3ht Unl i ket hemod e l sc ons i de r e dt husf a r ,t hes ys t e mi snow s ec ond‑ or de r( t he r ea r e nt , o nl yt woa r ei nde pe nde nt ) . Ho we ve r , t hr e es t oc ks , buts i nc et he ys umt oac ons t a i ti ss t i l lpos s i bl et oa na l yz ei t sdyna mi c squa l i t a t i ve l y.Fi r s t ,unl i ket heSImode l , i ti snowpos s i bl ef ort hedi s e a s et odi eo utwi t houtc a us l nga ne pi de mi c. I ft hei n‑ f e c t i onr a t ei sl es st ha nt her e c ove r yr a t e,t hei nf e c t i ouspopul a t i onwi l lf a l l . Asi t f a l l s ,s ot oowi l lt hei nf e c t i onr a t e. Thei nf e c t i ouspo pul a t i onc a nt he r e f o r ef a l lt o z e r obe f or ee ve r yonec ont r a c t st hedi s e a s e. Unde rwha tc i r c ums t a nc e swi l lt hei nt r oduc t i onofa ni nf e c t i ousi ndi vi d ua lt o ur , t hei nf e c t hepopul a t i onc a us ea ne pi de mi c?I nt ui t i ve l y ,f ora ne pi de mi ct ooc c ionr t a t emus te xc e e dt her e c ove r yr a t e; i fs o,t hei nf e c t i o uspopul a t i onwi l lg r ow, l e a di ngt os t i l lmor ene wc a s es . I f ,whi l ee a c hpe r s onwa si nf e c t i oust he ypa s s e d t hedi s e as eont oe xa c t l yonemor epe r s on,t he nt hes t oc kofi nf e c t i ve swo ul dr e ‑ ma i nc ons t a nts i nc et hei nf e c t i onr a t ewoul dbej us tof f s e tbyt her e c ove r yr a t e. ur , e a c hi nf e c t i vemus t ,ona ve r a ge, pa s st hedi s The r e f or e, f ora ne pi de mi ct ooc c e a s eont omor et ha noneot he rpe r s onpr l Ort Or e C OVe r l ng. Theques t i onofwhe t he ra ne pi de mi cwi l loc c uri sr e a l l yaques t i ona bout whi c hf e e dba c kl oo psa r edo i na m ntwhe nt hedi s e a s ea r ive r si nac ommunl t y. I ft he pos i t i vec ont a g l Onl oopdomi na t e st her e c ove r ya ndde pl e t i onl oops ,t he nt hei n‑ t r oduc t i onofe ve nas l ngl ei nf e c t i vei ndi vi dua lt oac ommunl t yt r l gge r Sa ne Pl ‑ de mi c. Thei nf e c t i onr a t ewi l le xc e e dt her e c ove r yr a t e,C a us l ngt hei nf e c t i onr a t e t ogr ow s t i l lf u r t he r ,unt i lde pl e ionoft t hepoolofs us c e pt i bl esf i na l l yl i mi t st he e pi de mi c. I f , howe ve r , t hepos i t i vel oo pl SWe a ke rt ha nt hene ga t i vel oo ps , a ne p1 ‑ de mi cwi l lnotoc c urs i nc ei nf e c t i o uspe o pl ewi l lr e cove rona ve r a gef a s t e rt ha n ne wc a s e sa r i s e . Thenumbe rofne wc a s e sc r e a t e dbyea c hi nf e c t i vepr i o rt Ot he i r r e c ove r y ,a ndt he r e f o r et hes t r e ngt hoft hedi fe r e ntl oops ,de pe ndsont hea ve r a ge dur a t i onofi nf e c t i ona ndt henumbe rofne wc a s esea c hi nf e c t i vege ne r a t e spe r t i mepe r i od. Thehi ghe rt hec ont a c tr a t eo rt hegr e a t e rt hei nf ec t i vl t yOft hedi s e a s e, t hes t r onge rt hepos i t i vel oop. Li ke wi s e , t hel a r ge rt hef r a c t i onoft het ot a lpo pul a ‑ t i ons us c e pt ibl et oi nf e c t i on, t hewe a ke rt hede pl e t i onl oop. Fi na l l y, t hel onge rt he ‑ ‑ 3 wh i l et h ea s s u mp t i o nt h a t r e mo v a l sa r ef i r s t 1 0 r d e ri sr e a s o n a b l ei nt h es i mp l eS I Rmo d e l , t h ec o u r s eo fma n yd i s e a s e si smo r ec o mp l e xa n dt h ed e l a yb e t we e ni n f e c t i o na n dr e mo v a l i so f t e n ce , t h er e mo v a l r a t ewo u l db es ma ll i n i t i a l l y , t h e n n o t e x p o n e n t i l( a i fag r o u pwe r ea l l i n f e c t e da t o n or et a p e r i n go f f ) ・ Ch a p t e r1 1d i s c u s s e sh o wd i f f e r e n t t y eso p fd e l a y sc a nb emo d ‑ b u i l dt oap e a kb e f e l e di nd e p t ha n ds h o wsh o wmo d e l e r sc a ns e l e c t r o b u s t f o r mu l a t i o n sf o rd e l a y st oma t c ht h ed a t a i f f er e n t d i s t r i b u t i o n s . f o rd 3 0 6 Pa r t I H Th eDy n a mi c so fGr o wt h a ve r a gedur a t i onofi nf e c t i on,t hewea ke rt henega t i ver ec ove r yl oopa ndt hemor e l i ke l ya ne pi de mi cwi l lbe・4 Fora nygl Ve npopul a t i onofs us c e pt i bl es , t he r ei ss omec r i t i ca lcombi na t i onof cont a c tf r e que nc y,i nf e c t i vl t y,a nddi s eas edur a t i onJ us tgr ea tenoughf ort hepos i ‑ l PPl ng t i vel oopt odomi na t et henega t i vel oops .Tha tt hr es hol di sknowna st het poi nt ・Be l owt het i ppi ngPOl nt , t hes ys t e mi ss t a bl e: i ft hedi s e as ei si nt r oduc e di nt o t hecommuni t y, t he r ema ybeaf e wnewcas es , butona ve r a ge,peopl ewi l lr e c ove r f as t e rt ha nne w ca s e sa r ege ne r a t e d. Ne ga t i vef ee dba c kdomi na t esa ndt hepopul a t i oni sr es i s t a ntt oa ne pi de mi c。 Pa s tt het i ppl ngpOl nt , t hepos i t i vel oopdomi na t es . Thes ys t e mi suns t a bl ea ndonceadi s eas ea r r i ves ,i tca ns pr ea dl i kewi l df i r e ‑ t ha ti s ,bypos i t i vef e edba c k‑ l i mi t edonl ybyt hede pl e t i onoft hes us ce pt i bl e popul a t i on. Fi gur e9‑ 6s howsas i mul a t i onoft hemode lwhe r et hes ys t e mi swe l lpa s tt he t l ppl ngpoi nt . Thepopul a t i onoft hecommunl t yl S1 0, 000a ndi ni t i a l l ye ve r yonei s s us c e pt ibl et ot hedi s eas e. Att i mez e r o,as i ngl ei nf ec t i vei ndi vi dua la r r i vesi nt he communi t y.Thea ve r a gedur a t i onofi nf ec t i oni s2da ys ,a ndi nf e ct i vl t yi s25%. Thea ver a gecont a c tf r e que nc yl SS i xpeopl epe rpe r s onpe rda y.Ea c hi nf e c t i ve t he r e f or ege ne r a t e s1. 5ne wca s espe rda ya nda na ve r a geoft hr e enewca s esbe f or e t he yr e cove r .Thepos i t i vel oopt he r e f or edomi na t esa ndt hee pi de mi cqui c kl y s pr eads .Thei nf e c t i onr a t epea ksa tmor et ha n2000peopl epe rda ya r oundda y ni ne,a nda ti t spea kmor et ha none‑ qua r t e roft hepopul a t i oni si nf e c t i ous . Thes us ‑ c e pt i bl epopul a t i onf a l l sr a pi dl y,a ndi ti st hi sde pl e t i onofpot e nt i a lne wcas est ha t ha l t st hee pi de mi c.Byt het e nt hda y,t henumbe rofs us ce pt i bl esr e mai nl ngl SS O l ow t ha tt henumbe rofnew cas esdecl i nes .Thei nf e c t i ouspopul a t i onpea ksa nd f ll a saspe opl enowr e cove rf as t e rt ha nne wcas esa r i s e・ Thes us c e pt i bl epopul a t i on cont i nuest of a l l ,t hougha tas l owe ra nds l owe rr a t e,unt i lt hee pi de mi ce nds . I nl es st ha n3wee ks ,as i ngl ei nf e ct i ousi ndi vi dua ll edt oama s s i vee pi de mi ci n‑ vol vi ngnea r l yt hee nt i r ec ommuni t y. Not et ha taf e wl uc kyi ndi vi dua l sne ve rcon‑ t r a c tt hedi s eas e. Unl i ket hec hr oni ci nf e c t i onmode li nwhi c heve r yonee ve nt ua l l y cont r ac t st hedi s eas e,i nt heSI Rmode lt hee pi de mi ce ndsbe f or et hes us c e pt i bl e popul a t i onf a l l st oz e r o.Thes t r onge rt hepos i t i vel oop,howeve r ,t hef ewe rs us I ce pt i bl esr e ma i na tt hee ndoft hee pi de mi c.Al s onot et ha tunl i ket hel ogl S t i c model ,t hebe ha vi ori snots ymme t r i c・ .t hei nf e ct i ouspopul a t i onr i s esf as t e rt ha n i tf a l l s . ‑ 4 Th eS Ia n dS I Rmo d e l swer eo r l g l n a l l yf o r mu l a t e da sd e t e r mi n i s t i cs y s t e msr e p r es e n t l n gt h e a v e r a g ec o n t a c t r a t ea n da b s t r a c t l n gf r o mt h ei n d i v i d u a l e n c o u n t e r sa mo n gme mb e r so ft h ep o p u l a ‑ t i o n, Ke e pl nmi n dt h a t t h ed et e mi r n i s t i cf o r mu l a t i o ni samo d e l i n ga s s u mp t l On , a P P r O P r l a t ei n s o mes i t l J ‑ a t i o n sa ! l dn o t a p p r o p rl a t ei no t h e r s( pa r t i c l l a r l y ,Wbe ! Hh ep o p u l a t i o n sa r es ma l lo rt h e v a ia r n c ei nt hed i s t r i b u t i o no fc o n t a c t r a t e s , i n f e c t i v i t y , a n dr e p ?v e r yt i mei sl a r g e ) . Th emo d e l sa r e e a s i l yg e n e r a l i z e dt oi n c o r p o r a t eS t O C h a s t i ce n c o u n t e r s , i n f e c t l V l t y , a n dr e c o v e ry, e i t h e rb ya d d i n g r a n d o mv a r i a t i o nt ot h er a t ee q u a t i o n so ft h eS I Rmo d e lo rb yr e p r e s e n t l n gt h eme mb e r so ft h ep o p ‑ u l a t i o na sd i s c r e t ei n d i v i d u a l sa n ds p e c i f y i n gd e c i s i o nr le u sf o rt h e i ri n t e r a c t i o n( a na g e n トb a s e d mo d e l ) . I n c o r p o r a t i n gt h e s er a n d o mefe c t sme a n st h e r ewi l l b ead i s t r i b u t i o no fp o s s i b l eo u t c o me s f o ra n ys e t o fp a r a me t e r s . Th es h a r pb o u n d a r yb e t we e na ne p i d e mi ca n ds t a b i l i t yd e f i n e db yt het i p ‑ p l n gp O l n t i nt h ed e t e r mi n i s t i cmo d e l sb e c o me sap r o b a b i l i t yd i s t r i b u t i o nc b a r a c t e r i z l n gt h ec h a n c e a ne p i d e mi cw il l o c c u rf o ra n yg i v e na v e r a g er a t e sO fi n t e r a c t i o n , i n f e c t i v l t y , a n dr e c o v e r y . Li k e‑ wi s e , t h eS Ia n dS I Rmo d e l sa s s u meah o mo g e n e o u sa n dwe l l ‑ mi x e dp o p u l a t i o n , wh i l ei nr e a l i t yl t i so 鮎ni mp o r t a n t t or e p r e s e n t s u b p o p u l a t i o I ‑ Sa n dt h es p a t i a l d i ml S i o no fa ne p i d e mi c . Fo rs p a t i a l mo d e l so ft h es p r e a do fd i s e a s ea n do t h e rr e f i n e me n t s ,s ee Mu r r a y( 1 993) . Cha pt e r9 S‑ Sha p e dGr o wt h: Epi de mi c s , Ⅰ nno va t l o nDi 軌s i on, a ndt heGr o wt ho fNe wPr oduc t s3 0 7 Toi l l us t r a t et het i ppl ngpo i nt ,Fi g ur e9‑ 7s howst hes us ce pt i bl epo pul a t i oni n s e ve r a ls i mul a t i onsoft hemode lwi t hdi f f e r e ntc ont a c tr a t e s ・ Theot he rpa r a me t e r s a r ei de nt i c a lt ot hos ei nFi gur e9‑ 6. Att het i ppi ngpoi nt( t woc ont a c t spe rpe r s on pe rda y) , t henu mbe rofne wc a s e se a c hi nf e c t i vege ne r a t e swhi l ei nf e c t i o usi sj us t e qua lt oone( 2c ont a c t spe rpe r s onpe rda y*01 25pr oba bi l i t yofi nf e c t i on* 2da ys ofi nf e c t i vi y) t . Cont a c t sa tar a t el e s st ha nt wope rpe r s onpe rda ydonotc a us ea n 0 0 5 2 0 0 0 2 sa leE 0 0 5 n I 0 0 0 L l 0 0 5 d Put= uO! 8 3alu E ^O Uatl ^t 2P P E o a d ) ( ^ Ja 0 8 12 Days 16 20 24 4 8 12 Days 16 20 24 0 4 50 60 0 O 5 7 4 oy 3D a 0 l ( al doad)uo! ePdodaq J ao sns 0 A U 0 5 FI GURE9 ‑ 6 Si mul at i onofan epi demi ci nt h e SI Rmode一 Thet o t al popul a t i oni s 10, 000. The con t ac tr at ei s 6perper s on perda y ,i nf ec t i vi t y i s0. 25, and aver agedur at i on ofi n f ec t i vi t yf S 2day s. The i ni t i al i n f ec t i v e popul at i oni si, andal T ot her s ar ei ni t i al l y sus c ept i bl e, 0 0 5 2 !ld o 0 FI GURE9 ‑ 7 m ⁝ 5 7 . 00 0 5 00 5 2 !td 0 ( aF do ad)uo!tepdo daq 一 ao sns Epi demi c dynami c s f ordi f f er en t con t ac tr at es Thec on t ac tr a t e i snot edoneac h cuⅣe; al l ot her par amet er sar e asi nFi gur e91 6. 0 2 S 10 30 8 P a r tI I I Th eDy n a ml C SO f Gr o wt h e pi d e mi c . Whe nt hec o nt a c tr a t er i s e sa bo vet hec r i t i c a lt h r e s hol doft wo, t hes ys t e m be c o meuns t a bl e ,a nda ne pi de mi coc c u r s .Thehi g he rt hec ont a c tr a t e ,t he s t r o nge rt hepos i t i v ec on t a g l Onl oo pr e l a t i vet ot hene g a t i ver e c ove r yl oop, a ndt he f a s t e rt hee pi d e mi cpr og r e s s e s . Fur he t r , t hes t r o ng e rt hepos i t i vel oo p, t heg r e a t e r t hepopul a t i onul t i ma t e l yc ont r a c t l ngt hedi s e a s e . Anyc ha nget ha ti nc r e a s e st he s t r e ngt ho ft hepos i t i vel oo pswi l lyi e l ds i mi l a rr e s ul t s ・ Ani nc r e a s ei ni nf e c t i v l t y s t r e ng t he nst h epos i t i vel o o pa ndi si de nt i c a l i ni mpa c t t oa ni n c r e a s ei nc o nt a c tf r e ‑ q ue nc y. Ani nc r e a s ei nt hed ur a t i o no ft hei nf e c io t uspe r i odwe a ke nst her e c ove r y l n t ・ l o o pa nda l s opus he st hes ys t e mf a r he t rpa s tt het l P Pl ngPO ‑ Exphr i ngt heS旧 ModeI Si mul a t et heSI Rmode lund e rva r i o usc ombi na t i onsofpa r a me t e r s .Wha tde ‑ t e r mi ne swhe t he ra ne pi de mi cwi l lo c c ur ?Wha tde t e r mi ne st hef r a c t i onoft he po p ul a t i o nr e ma i ni nguni nf e c t e di ne q ui l i br i u m?Why? Thee xa c tt l ppl ngpO l n ti nt heSI Rmode lc a ne a s i l ybec a l c ul a t e d. Fo ra ne pi de mi c ur , t hei nf e c t i o nr a t emus te xc e e dt her e c o ve r yr a t e: t oo c c I R>RR=⇒c i S( Ⅰ / N)>Ⅰ / d ( 9‑ 25) o re q ul Va l e n t l y , c i d( 芸)>1 ( 9‑ 26) I ne qua t i o n( 9 ‑ 26) , t hepr o duc to ft hec o nt a c tr a t ea ndi n f e c t i vi t yi st henumbe rof i nf e c t i o usc on t a c t spe rt imepe r i ode a c hi nf e c t i o uspe r s o nge ne r a t e s . Mul t i pl yi ng byt hea ve r a gedu r a t i ono fi nf e c t i on,d,y i e l dst hedi me ns i o n l e s sr a t i oc i d, k nown ont ac tnu mbe y : Ho we ve r , nota l lt he s ec o nt a c t swi l l bewi t hs us c e pt i bl e s , s o a st hec nota l lwi l lr e s ul ti nane wc a s e. Thenumbe rofi nf e c t i o usc ont a c t st ha ta c t ua l l y r e s ul ti nt hei nf e c t i o no fas us c e pt i bl epe r s o nde pe ndso nt hepr o ba bi l i t yt ha tt he i nf T e c t i ve se nc ou nt e rs us c e pt i bl e s . As s umi ngt hepo pul a t i o ni shomoge ne ous ,t he pr o ba bi l i t yo fe nc o unt e r l ngaS us c e pt i bl ei sg l Ve nbyt hepr e va l e nc eo fs us c e pt i bl e s i nt hepo pul a t i o n,S/ N. Thee x pr e s s i o nc i d( S/ N)i sa l s ok no wna st her e pr oduc t i on r at ef o rt hee pi de mi c 。 Eq ua t i o n( 9‑ 26)t he r e f o r ed e f i ne st het i p pi ngpo i n to rt h r e s h ol da t whi c ha ne pi de mi coc c ur si napo pul a t i o na ndi sk no wna st het hr e s hol dt he ‑ or e mi ne pi d e mi ol og y . Not et ha tt hec o nt a c tnumbe rc a nbel a r gei fi nf e c ivl t t yi shi gho ri ft hed ua t i o 王 10 fi nf e c t io ni sl o ng. Thed ur a t i o 王 . l ̲Oft hei nf F Xt Ii o I J Sp er i odf o rd i s e a s e ss uc ha s mea s l e sa ndc hi c ke npoxi sve r ys ho r t ,ama t t e rofda ys , butt he s edi s e a s e sha ve hi ghc ont a c tn umbe r sbe c a us et he ya r ee a s i l ys pr e a dt hr o ug hc a s ua lc ont a c t 。h c o nt r a s t ,t hec ont a c tr a t ea ndi nf e c t i vi t yofHI Va r emuc hl o we r( HI Vc a nno tbe s pr e a d血r o ug hc a s ua lc o nt a c tbuto nl yt hr oug hs e xua lc o nt a c to re xc ha ngeof bl oo dorbl o odpr od uc t s ) . Ne ve r t he l e s s , t hec ont a c tn umbe rf o rHI Vi sh i g ha mo ng t hos ewhoe nga gei nr i s kybe ha vi o r sbe c a us et hed ur a t i o nofi nf e c t i o ni ss ol o ng. Thei n c u ba t i onpe r i o dpr l O rt Ot hede ve l o pme n tofc l i n i c a ls ympt omso fAI DSa v‑ e r a ge sa bo ut1 0ye a r s( S e es e c t i o n9. 2. 7) . r ‑ Ch a p t e r9 S ‑ S h a p e dGr o wt h : Ep i d e mi c s , Ⅰ n n o v a t i o nDi 軌s i o n , a n dt h eGr o wt ho f Ne wP r o d u c t s309 Fi gur e9‑ 8s howshowt het i ppl ngpOl ntde pe ndsont hepa r a me t e r s . Thec ur ve i st hebo unda r ybe t we e ns t a bl ea nduns t a bl er e gl me S . Tot hel e f toft hec ur ve,t he s ys t e mi ss t a bl ea ndt he r ei snoe pi de mi cbe c a us et hei nf e c t i vi t y ,c ont a c tr a t e,du‑ r a t i onofi nf e c t i o n, a ndf r a c t i o nofs us c e pt i bl e si nt hepopul a t i ona r et ool ow. Tot he r i ghtoft hec ur ve , t hes ys t e mi suns t a bl e ,a ndt he r ei sa ne pi de mi c. 9. 2. 4 ⊆ mmun章 Zat i onandt heEr adi cat i onofSmaHpox Thee xi s t e nc eoft het i ppi ngpoi nt( e qua t i on( 9‑ 26) )me a nsi ti st he o r e t i c a l l ypos s i bl et oc ompl e t e l ye r a di c a t eadi s e as e.Er a di c a t i ondoesnotr e qui r eaPe r f e c t va c c i nea ndun i ve r s a li mmuni z a t i onbutonl yt hewe a ke rc ondi t i ont ha tt her e pr o‑ duc t i onr a t eoft hedi s e a s ef a l la ndr e ma i nbe l owones ot ha tne wc a s esa r i s ea ta l owe rr a t et ha no l dc a s e sa r er es ol ve d. Thes t oc kofi nf e c t i ouspe o pl ewi l lt he nde ‑ c l i ne, f ur t he rr e duc i ngt hei nf e c t i onr a t e, unt ilt hepo pul a t i onbe c ome sdi s e a s e ‑ f r e e. Forma nydi s e a s e s , i ti sdi f f i c ul tori mpos s i bl et oa c hi e veo rma i nt a i nt hi sc ondi ‑ t i onduet ohi g hi nf e c t i vl t y ,t hee xi s t e nc eofr e s e r voi r soft hedi s e a s eout s i det he huma npo pul a t i o n( asi nma l a r i aorLymedi s e a s e,bot hofwhi c hha vea ni ma l hos t s ) ,o rt her a pi di nl fuxofs us c e pt i bl epe o pl et hr oughbi r hs t ,mi gr a t i on,ort he de c a yofi mmu nl t y. Sma l l pox, howe ve r ,i sdi fe r e nt .Sma l l poxwa sonc eoneoft hemos tdea dl y di s e a s esa nde nde mi ct hr oughoutt hewor l d. Thei nf e c t i vl t yOfs ma l l poxi shi gh, butt hedur a t i o nofi nf e c t i oni ss hor t .Sur vi vor sa c qui r e dl ong‑ l i ve di mmunl t y. Mos ti mpo r t a n t ,t hes ma l l poxvi r usca nnots ur vi veout s i deahuma nhos t ‑t he r e a r enoa ni ma lo rot he rr e s e r voi r st oha r bort hevi us r . The s eco ndi t i onsme a ntt ha t t hede ve l o pme ntofa ne fe c t i veva c c i ne,de pl oye ds ufi c i e nt l ybr oa dl y ,c oul dr e‑ d uc et hei nf e c t i onr a t ebe l owt her e c ove r yr a t ea nde l i mi na t et hevi r us ,e ve ni fnot e ve r ype r s onc ou l dbei mmuni z e d. Thehi s t or yo fs ma l l poxe r a di c a t i oni swe l lk nown: Edwa r dJ e nne rde ve l ope d hef t i r s te fe c t i veva c c i nei n1 796. Des pi t et hes uc c e s sofJ e nne r ' sva c c i ne , i tt ook ma nyye a r sf o rva c c i na t i ont obea c c e pt e d;s ma l l poxwa ss t i l lama j o rC a us eOf de a t ha tt hes t a r toft he20t hc e nt ur y. Byt he1 950S ,duet oi mpr ove me nt si npubl i c he a l t hpr ogr a msa ndi nt hee fe c t i ve nes sa nds he l f ‑ l i f eoft heva c c i ne,s ma l l pox ‑ FI GURE9 ‑ 8 OI Sua∈ !P) (ssolu (p! ) 3 Lむq L u .nNI DetuO O Dependen ceof t het i ppl n gPOi n t ont hec on t ac t numberand sus c ept i bl e popul at i on c = i d( S/ N) 1 E p i d e mi c ( u n s t a b 一 e ;p o s i t i v el o o pd o mi n a n t ) N oE p i d e mi c s t a b l e ;n e Su s c e p t i b 一 eF r a c t i o n , o fP o p u l a t i o n(S/N) ( d i me n s l 0 n l e s s ) 310 Pa r t I I I Th eDy n a mi c so fGr o wt h ha dbe e ne r a di ca t e di nmos toft hei nd us t r i a l i z e dwor l d.I nt hemi d‑ 1 960S ,t he Wo r l dHe a l t hOr ga ni z a t i on( WHO)C oo r di na t e davi go r ouswor l dwi dec a mpa i gnt o t r a c kt hedi s e a s e,i mmuni z et hes us c e pt i bl e ,a ndqua r a nt i net hes i c k.Thel a s t knownna t ur a l l yoc c ur r i ngCa s eWa sr e por t e di n1 9 77i nSoma l i a.I n1 978,s ome s ma l l poxv i uses r c a pe df r om ar es e a r c hl a bi nEngl a nda ndc a us e dt woc a s e s ,one f a t a l ・ Si nc et he nnof ur t he rc a s esha vebe e nr e po r t e d, a nd, i noneoft hegr e a t e s tt r i ‑ umphsi nt hehi s t or yofme di c i ne,t hena t i onsoft hewo r l ddec l a r e di n1 98 0t ha t s ma l l poxha dbe e ne r a di c a t e df r omt hee a r t h Al mos t .Dur i ngt heCol dWa r ,bot ht heUSa ndSovi e tUni onma i nt a i ne d s t oc ksofs ma l l poxvi r usa spa r toft he i rbi ol ogi c a lwa r f a r epr ogr a ms . Thoughbot h na t i onss l gne dt he1 972Bi ol ogi c a lWe a ponsConve nt i onba nni ngbi owe a ponsa nd bi owa r f a r er e s e a r c h,t he yc ont i nue dt oma i nt a i nt he i rs t oc ksofs ma l l pox,a ndt he Sovi e tUni onc ont i nue dbi owa r f a r er e s e a r c hi nvi ol a t i onoft heConve nt i on. Whi l e t he s es ma l l po xs t oc ksa r ema i nt a i ne di nt hehi ghe s ts e c ur i t ybi oc ont a i nme ntl a bs , t he r ei sna t ur a lc o nc e mt ha tt hevi r usmi g hte s c a pe , a c c i de nt a l l y, t hr ought e r r or i s m, ori nwa r . AWHOpa ne l ,a f t e rl onga nds ome t i me sa c r i moni ousde ba t e,r e c om‑ me nde di n1 994t ha ta l lUSa ndRus s i a ns t oc ksoft hevi r usbedes t r oye dbyJ une 1 999. Howe ve r , ma nya na l ys t sbe l i e vet e r r o r i s t so rna t i onss uc ha sl r a qa ndNor t h Ko r e ama yha vea c qui r e ds ma l l poxf r omt hef o me r rSovi e tUni on. Be c a us epe opl e nol onge rr e c e i ves ma l l poxva c c i na t i ons ,a ndbe c a us et hei mmuni t yC Onf e r r e dby c hi l dhoodva c c i na t i onde c a ys , muc hoft hewo r l d' spo pul a t i ont oda yi ss us c e pt i bl e. Ther e l e a s eofs ma l l poxf r omt he s es t oc ksc oul dt r i gge rama s s i vepa nde mi c. I nr e ‑ s pons e ,Pr e s i de ntCl i nt onor de r e dUSs ma ll poxs t oc ksbepr es e r ve df orr e s e a r c h, a ndWHOs us pe nde di t sa t t e mptt oha vede c l a r e ds t oc ksofs ma l l poxde s t r oye d. TheEf f i c領CyOfhl L muni Za如 FT .甲相 gT amS Equa t i on( 9‑ 26)a ndFi gur e9‑ 8s howhowt hevul ne r a bi l i t yofapopul a t i ont oe pi ‑ de mi cde pe ndsont hepa r a me t e r soft heSI Rmode l . Ma nyi nf e c t i ousdi s ea s e sa r e hi g hl yc ont a gl OuSa ndi ti snotf e a s i bl et or e duc et hec ont a c tnumbe r .I I nmuni z a ‑ t i o n,whe r eva c c i ne sa r ea va i l a bl e,c a nbehi ghl ye fe c t i venotonl yi npr ot e c t i ng t hei mmuni z e di ndi vi dua l sbuta l s oi nmovi nga ne nt i r epo pul a t i onbe l owt het i p‑ pi ngpoi nt . Fore xa mpl e,pol i oha sa l lbutva ni s he di nna t i onswi t hs t r ongpubl i c he a l t hpr og r a msa ndWHOhope st oe r a di c a t ei two r l dwi dewi t hi naf e wye rs a . 1 . Ef f e c t i ve ne s sofi mmuni z at i om。 Thec ont a c tnumbe rf orpol i oi se s ima t t e dt ober oug hl y5t o7( Fi ne1 993) . Wha tf ra c t i onoft hepopul a t i onmus tb eva c c i na t e dt oe ns ur et ha tno e pi de mi cwi l loc c ur ?As s umet heva c c i nei sl OO%e fe c t i ve. Nowc ons i de r me a s l e sa ndpe r t us s i s( whoopi ngc o ugh) , di s e a s e swhos ec ont a c tnumbe r s ree a s t i ma t e dt obe1 2t o1 8( Fi ne1 993) . Wha tf r a c t i onoft hepopul a t i on mus tbeva c c i na t e dt oe ns ur enoe pi de mi cwi l loc c ur ?Wha tf r a c t i onmus tbe va c c i na t e di ft heva c c i nei sonl y90%e f f e c t i ve?Whydome a s l esa nd pe r t us s i spe r s i s twhi l epol i oha sbe e ne fe c t i ve l ye l i mi na t e d? Ne xt ,s i mul a t et heSI Rmode lwi t ht hepa r a me t e r si nFi gur e9‑ 6( C‑6, i‑0・ 25, d‑2, N ‑ 0, 000) ,buta s s umet ha t5 0%oft hepopul a t i onha s 1 dG i Sh Ch S I id 9 311 on rowth ape apter nnovati cs emi eG andth IS onDi軌 s uct rod ewP ofN p :E ‑ , f ? i id d th t ati epopu o c em anep oprevent onmustb mmun e ze d( i b l d lf h ti th ze mmun een ati popu recovere a ot et o ont Setth n e) id l Wh ?Wh i f th ff th ati on em racti popu sth atf c eep ecourseo ect ee .l l id df (ii)Q di i th uaranti comp et sarenot ne act romcont ua n v yremove e w Wh ti f th atf rac ono n ecti ous ・l d l b h ti an exp a nth ng e av or eresu l 9 6( Fi th mu ati es gure n on ‑ i 6 000) 10 N 2 d 25 0 C ‑ ・ , .A f Q C i ssumeth equaranti sper ect Soth atth e uaranti ne ont actR at ,i l Q ti R d lf fth F szero ousva ueso e ne racti on unth emo orvar uaran .i id i ?N d t popu ati onmustb anep oprevent em c owassume ne eqtlaranti h di i l f id lf th atth econt ne n s a enorma eo rat act quaranti vb ua d Wh t esequest cont act rat e atf racti an oprevent now onmust ere .d id i l b dh f t oquaranti ep em can peop e emove neonceth ow must ast eyf li f l C ffi th ati 1rI gParti a ono epoptl on ompareth ee cacyo mmlln zati ・ ̲i l id Wh mmun ingOrS nprevent owlngep em cs zati oquaranti ont ne at .li diff ? t erent s uati ons b i l ?E d ecome n ers erparamet nc ecti ous xp oreth ooth eresponset u 1 ,i fl i f id ldi h th cycons ceo esepo c es po erati onswou n uenceyourc oi f d i h lf (iii)A Q th Ti ssumeth e ers eparamet s a uaranti or use an ay ne me , di i ll l ati sureyour ormu on orth equaranti e s mens ona ycon nerat ‑i A f l id di th ent s st ssumequaranti romth srecover seasew ua v ne n e ・d dth d i C susceptibl e enot a nrat acert esat actR ne ont at uaranti. ,A fl fi l d ( ) th equaranti oth owt n ati popu on eo erat e nerat nef fl i l th d o romth Ows ecti n e ati ouspopu equaranti ont popu ne on .l k i f ll F A tt eth at ormu a esacert n ssume eas o ows equaranti nerat.f l ぬ F peop ean oaquaranti assumeon ya ur er nearea moveth emt, .f F anti ne r id d i f b bl illi B entifi e s as n ecti o equaranti et ngora ousan w ne .f fi f th esameaverage ono n ecti vlt yaSth quaranti osenot ne urati・ f i id l 18 ll (d ri th o erest cen n sma epopu ati pox em co on u nganep ‑i k l f B till db d tt th t es c werequaranti e on ury ost s perm ne ut orexamp ,dif d h f i M S ) t o yth en c oatt on orth e n ecti onrat urc un ay eequati.d i l ibili t th eth nc act ne yth u o quaranti at eposs peop ecome ncont wQ ri d id i Q ti t th o neTi ecti ous e uaranti enot me pe entif n y ,d ul Q d i fT th racti ono ati e enot on n ecti ouspop ua , f al i id di ssumeth e s sth ne esameasth at n ecti quaranti yO vlt u vi ddi f d k H ti oroth n ecti er oesth ow ono ast ea oc o quaranti ne ves .l? d SIR f db k i di id l lt th mo e ureo ruct ac st n v ua sa erth ee f (i)A l d hibi t ssumepeop so oms sympt ya on ne eyex earequaranti erth, ff i f id li E neth xam ecti ee quaranti em anep oprevent cyt neasapo venesso c .f d l i dif k T lt SIR quaranti o east nc yth mo oso ne oc u e ,l id di i s ua v n . f Eff 2 ecti quaranti venesso ne . 1 di b F i eavlng orsome seases pe‑anent utd ecaysoverti me lnmunlt ylSnot ,l f i dif d M t ormer yimmunePeop ore et n ecti o yth emo e esusceptibl on .i l fi d A t mmun e em et ne osso ssume y ecaysat ncorporat.b arat d fi it R lf diff erent yaconst ant average ono mmun y emo e or urati unth・ 3 fi it L osso mlnun y . 312 Pa r tHI TheDyna mi csofGr owt h va l ue soft hea ve r a g ed ur a t i o no fi mmunl t y , Wha ti st hei mpa c to nt he d yna mi c s ?Unde rwha tc o nd i t i o nswi l lt hed i s e a s ebe c o mee nd e mi ci nt he po pul a t i on?Wha ti st h ee q ui l i br i umr e a c he d, a ndwhy?Wha ti mpa c tdo e s l os so fi mmuni t yha veo nt hee fe c t i ve n e s so fi mmun i z a t i on?Ont hea bi l i t y t oe r a di c a t eadi s e a s e ?Why? 9 . 2t 5 Her d貞 mmunは y l nt her e a lwo r l d,apo pul a t i o ni sr e pe a t e d l yc ha l l e nge dbye xpos ur et od i 恥r e n t d i s e a s e s . I nf e c t i o usi ndi v i d ua l s , un wi t t i ng l yc a r r yl ngt hed i s e a s e , ma ya r r i v ef r o m o t he rc o mmuni t i e s . Thes pr e a do ft hebl a c kde a t hi n1 4t hc e nt ur yEu r o pewa sa c c e l e r a t e dbye xt e ns i vet r a d ene t wo r kswi t ho t he rr e gl O nS , t hehi g hr a t eo ft r a ve lo f pi l g ims r , a ndbyt hef li gh to ft het e r r i f i e da ndu nk no wi ngl yi nf e c t e dt ot ownsa sye t une x pos e d.Sus c e pt i bl ei ndi vi dua l sc a na l s oc o mei nt oc o nt a c twi t hot he rr e s e r ‑ vo i r so ft hedi s e a s e,s uc ha sc o nt a mi na t e dd r i nk i ngwa t e r( a si nc ho l e r a ) ,o ra ni ‑ ma ls( buboni cpl a guei snoto nl yt r a ns mi t t e df r ompe r s ont ope r s onbutbyf le a s whopa s st hepl a g ueba c i l l usf r o mi nf e c t e dr a t st ope o pl e ) A So mepa t hog e nsmu t a t e a ndc r os st hes o‑ c a l l e ds pe c i e sba 汀i e r , J umpi ngf r oma ni ma lr es e r vo i r st ohu ma n po pul a t i o ns( a soc c ur si ni nf lue nz aa ndl i ke l yoc c u r r e dwi t hHI V, o ut br e a kso ft he Ebol avi r us ,a nda ppa r e nt l ywi t hBo vi neSpo ngi f o r m Enc e pha l o pa hy( t BSE) ‑ ma dc ow di s e a s e ) .I ft hec o nt a c tr a t e ,i nf e c t i vi t y ,a nddur a t i ono fi nf e c t i o na r e s ma l le noug h, t hes ys t e mi sbe l o wt het i ppl ngpoi nta nds t a bl e・ Suc has i t ua t i o ni s k nowna she r di m uni t y( Fi ne1 9 93 )be c a us et hea r r i va lofa ni nf e c t e di nd i v i d ua l do e snot pr o d uc ea ne pi de i c( m t ho ug haf e wu nl uc k yi ndi vi d ua l sma yc o mei nc o n‑ t a c twi ha t nyi nf e c t i o usa r iva r l sa ndc o n t r a c tt hed i s e a s e , t heg r ou pa sac o mmuni t y i spr o t e c t e d) . Howe ve r ,c ha nge si nt hec o nt a c tr a t e ,i nf e c t i vi t y ,o rdur a t i o no fi l l ‑ l nt . ne s sc a npus has ys t e mpa s tt het i ppl ngpO Fi gur e9‑ 9S howshow c ha nge si nt her e pr o duc t i o nr a t ec a ndr a ma t i c a l l y c ha ng et her e s pons eofapo pul a t i o nt oe xpos u r e. I nt hes i mul a t i o n, t hepo pu l a t i o n i sc ha l l e nge de ve r y5 0da ysbyt hea r r i va lo fas l ng l ei nf e c t e di nd i vi dua l . Thepo p‑ ul a t i o n,i nf e c t i vl t y ,a nddur a t i ono fi nf e c t i o na r ei de nt i c a lt ot hos ei nFi g u r e91 6 ( 1 0, 0 00, 0. 25,a nd2da ys , r e s pe c t i ve l y) . Ho we ve r , t hec ont a c tr a t ei sa s s u me dt o i nc r e a s el i ne a r l yo ve rt i me , be g i n nl nga tZ e r o. Thec o nt a c tr a t emi g hti nc r e a s ea s po pul a t i onde ns l t yg r owsO ra SC ha nge si ns oc i a ls t r uc t ur e sorc ul t ur a lpr a c t i c e s b r i ngpe o pl ei nt omo r ef r e que ntc o nt a c t . Ther a pi dur ba ni z a t i onoft hei nd us t r i a l r e vol u t i o n, f o re xa mpl e, i nc r e a s e dt hec o n t a c tr a t ea ndi nc i de nc eofe pi de mi c sf or ma nydi s e a s e s . Dur i ngt hef i r s t5 00da ys , t her e p r o d uc t i o nr a t e( t hem um‑ b e ro fne wc a s e sge n‑ e r a t e dbye a c hi nf e c t i vepr io rt or e c o v e r y )i sl e s st ha no ne , t hene ga t i vel oo psd o m‑ r ei snoe pi de mi c:Eve r y50 i na t e ,a ndt hes ys t e mi sbe l owt het l PPl ngPOl nt . The da ysa ni nf e c t i ousi ndi vi d ua la r r i ve s ,b uta nype o pl ei nf e c t e dbyt hi spe r s o nr e ‑ nf e c t i ve s . Thepo pul a t i o n c o ve rbe f o r et he yc a nr e pl a c et he ms e l v e si nt hepo olofi e n j oyshe r di mmuni t y. Atda y5 00t het i p pl ngPO l nti sc r os s e d. Nowt hec o n t a g l O n l oo pdo mi na t e s , a ndt hene xti n f e c t i o uspe r s ont oa r r i vet r i gge r sa ne pi de mi c . The se noughf ort hed e pl e t i o na nd e pi de mi ce ndsa f t e rt hes us c e pt i bl epo pul a t i onf a l l r e c ov e r yl oo pst oov e r po we rt hec o n t a g l O nl oo p. Bya boutda y600t hed e c l i nei n ‑ Ch a p t e r9 S ‑ S h a p e dGr o wt h: Ep i d e mi c s , I n n o v a t i o nDi fu s i o n , a n dt h eGr o wt ho fNe wP r o d u c t s313 Fl GURE9・ 9 Successi veepl ‑ demi cwavescr e‑ at edbyi ncr easl ng cont ac tr at e Ever y50days t hepopul at i on i scha" engedby t hear r i valofasi n gl ei nf ec t r l ousI l ndl ‑ I vj duaLAtf i r s t , t he popul at i onhas her di mmuni t y . Thecont actr at e l ' ncr easesh l near l y o,i ncr eas ‑ f r omzer l ng的er e一 at i ver e‑ pr oduc t i onr at e andevent ual l y causmgawaveof epi demi cs ‑ ・ t ( a一 doad) uo.r t2n 1d odaq lI l daosns . 1500 2000 t hes us c e pt i bl epopul a t i onr e duc est her e pr oduc t i onr a t ebel ow onea ndt henega ‑ t i vel oopsoncea ga i ndomi na t et hepos i t i vecont a gi onl oop. Thoughi nf e c t e di ndi vi dua l scont i nuet oa r r i vea t50‑ da yi nt e va r l s ,t hes ys t e m hasbecomes t a bl ea ga l n. Howe ve r ,t hec ont a c tr a t ekee psr l S l ng,l nC r eaS l ngt hes t r e ngt hoft hec ont a gi on l oop・Byda y8 00,t hec ont a gl Onl oopI SOncea ga i ndomi na nt .Thea r r i va loft he ne xti nf ec t i ouspe r s ont r l gge r Sa not he re pi de mi c.Si ncet he r ea r eeve nf e we rs us I c e pt i bl est hi st i mea r ound,i ti sabi tmi l de r ・ Byda y11 00t hede pl et i onoft hes us ‑ c e pt i bl epoolha sonc ea ga l nOVe r Whe l me dt hecont a gl Onl oopa ndt her e pr oduc t i on ‑ 31 4 Pa r tI I I The Dy n a mi c so f Gr owt h r a t ef a l l sbe l owo ne. Thec o mmuni t yl SOnc ea ga l nr e s i s t a ntt oe p i d e mi c , unt i lt he c o nt a c tr a t er i s e se no ug ht opus ht her e pr od uc t i o nr a t ea boveonea ga i n, t r l gge r l ng t het hi r dwa v eofi n f e c t i o n. I nt hi ss i mpl ee xa mpl et hepe r i odi ce pi d e mi c sa r i s ef r o mt hea s s ume ds t e a d y r i s ei nt hec on t a c tr a t e.Suc c e s s i vewa ve so fe pi de mi c sa r ei nf a c to bs e r v e df o r ma nyi nf e c t i ousd i s e a s e s , pe r ha psmos tno t a bl yme a s l e s . Pr i ort ot hei nt r od uc t i o n ofma s si mmuni z a t i o ni nt he1 96 0S , i nd us t r i a l i z e dna t i o nss uc ha st heUSa ndUK e xpe r i e nc e dl a r gea mpl i t ud eme a s l e se pi de mi c sa bo ute ve r y2ye a r s . Duet oi m‑ mun i z a t i o npr o g r a ms , t hea mpl i t udeo ft hec yc l e si smuc hr e duc e dt oda y , but血e t e nd e nc yt owa r dc yc l i cwa ve so fme a s l e spe r s i s t s .I nc o nt r a s tt ot hee xa mpl e a bo ve ,t hec ont a c tr a t ef o rme a s l e sr e ma i nsr e a s ona bl yc o ns t a nt . Thec yc l i cc ha r ‑ a c t e ro ft hee pi d e mi c sa r i s e sf r o mt hei nt e r a c t i o no fhe r di mmun l t yWi t hpo pul a t i on g r owt h・ Ea c he pi d e mi ci nc r e a s e st hei mmunef r a c t i o no ft hepo pul a t i o ne no ug ht o c o nf e rhe r di mmu nl t y , Pr e V e nt l nga no t he re pi de mi ct hef ol l o wl ngy e a r . I i o we ve r , du r i ngt hi st i met hepo pul a t i o nofs us c e pt i bl e si nc r e a s e sa sc hi l d r e na r ebo r n. l y , t hes us c e pt i bl ef r a c t i o no ft hepo pul a t i o nr i s e se n oug ht opus ht hes ys ‑ Eve nt ua l t e mpa s tt het i p pl ngpO l n ta ga l n, a ndt hene xte pi de mi cbe g i ns . TheSI Rmod e lc a n e a s i l ybee xt e nde dt oi nc l ud et hea ges t r uc t ur eoft hepo pul a t i on, i nc l ud i ngbi r t hs a ndde a t hs( S e ec ha pt e r1 2) ・ Wi t hr e a l i s t i cpa r a me t e r st he s emo de l sg e ne r a t epe r ‑ s i s t e ntos c i l l a t i o nsi nd i s e a s ei nc i d e nc ea st hes ys t e mr e pe a t e dl yc yc l e sa bovea nd be l owt het l p pl ngpO l nt . Ther e pr od uc t i o nr a t ef o ra ni nf e c t i o usdi s e a s ei sno ts o l e l yama t t e ro ft hevi r ‑ ul e nc ea ndo t he rbi o l og l C a la t t r i but e so ft hepa t hog e n・ I ti ss t r ong l yi nf lue nc e dby s oc i a ls t r uc t ur e sa ndt heph ys i c a li nf r a s t r uc t ur eofac ommun i t y. Thec o nt a c tr a t e o bvi o us l yr e pr e s e n t st hena t ur eo fs oc i a ls t r uc t ur e si nt hec o l nmu ni t y: Thec o nt a c t r a t ei nr u r a lc o mmun i t i e swi t hl owpo pul a t i o nde ns i t i e si sl owe rt ha nt ha tofhi g hl y ur ba ni z e dpo pul a t i o ns . Thei nf e c t i vl t yO fadi s e a s ei so nl ypa r t l yd e t e mi r ne dbybi l o l og i c a lf a c t o r s . Ca s ua l c o nt a c ta ndi n ha l a t i o nc a ns pr e a di nf lue nz a , wh i l eHI Vc a n onl ybec o nt r a c t e dt hr o ughe xc ha ngeofbl oodo rot he rbodyf lui ds( abi ol ogi c a l f a c t o r ) .Buti nf e c t i vi t yi sa l s os t r ongl ya fe c t e dbys oc i a lpr a c ic t e sa ndpu bl i c he a l t hpol i c i e s ,s uc ha st hea va i l a bi l i t yo fc l e a nwa t e r ,t hepr e va l e nc eofha nd hef r e que nc yo fc o ndo mus e. wa s hi ng, o rt 9E . 2 ・ 6 棚4 . 7 J t . ・ ・ 汗噂 P a S H: 、 , i : ‑ I : ‑ { ' T 矩沖 巧キ ヨFr , h音 : Ma dCo wDi s e a s e Thee pi d e mi co fBSEo rma dc owd i s e a s ei nGr e a tBr i t a i ndu r i ngt he1 99 0si l l us t r a t e sho wc ha n ge si nt e c hni c a la nds o c i a ls t r u c t u r e sc a npus hapo pul a t i o npa s t血e t l ppl ngpoi nt . Pr i o rt o血ee p i de mi c , t hei nc i de nc eofBSEa ndr e l a t e dd e g e ne r a t i ve ne ur ol ogi c a ldi s e a s e ss uc ha ss c r a pi e( i ns he e p)a ndCr ue t z f e l d t ‑ J a c o bDi s e a s e ( CJ D, i nhuma ns )wa se x t r e me l yl ow. Butbe t we e n1 98 5a nd1 9 97, a p pr o x i ma t e l y 1 70, 00 0c a s e so fBSEwe r ec o nf i r me di nt heUK, a nda l mos to nemi l l i o nc a t t l eo ut ofat ot a ll i ve s t oc kpo pul a t i o nofa boutl lmi l l i onwe r ee s t i ma t e dt obei nf e c t e d ( Pr us i ne r1 99 7) . BSE,s c r a pi e , a ndCJ Dpr og r e s s i ve l ya nd, a tpr e s e n t , i r r e ve r s i bl y de s t r oybr a i nt i s s ue;s y mpt o msi nc l udeunc ont r o l l a bl et r e mo r , di s o r i e nt a t i o n, l os s ofmot o ra ndc o g ni t i v ef u nc t i o n, a ndul t i ma t e l yde a t h. ‑ c s , I n n o v a t i o nDi fu s i o n , a n dt h eGr o wt ho f Ne wP r o d u c t s31 5 Ch a p t e r9 S ‑ S h a p e dGr o wt h : E p i d e mi Thec a us eo fBSEi ss t i l lde ba t e d. Mos ts c i e nt i s t sbe l i e veBSEi sc a us e dbypr ons ,a bnor ma lp r ot e i nst ha ta r ehypot hes i z e dt or e pl i c a t ee ve nt hought he ydonot c ont a i na nyDNAo rRNA.Bi ol ogi s tSt a nl e yPr us i ne rr e c e i ve dt he1 997Nobe l Pr i z ef orhi spi o ne e r i ng( a nds t i l lc ont r ove r s i a l )wor ko npr i o ns( s e ePr us i ne r1 997 f o rf u r t he rde t a i l sonpr i onsa ndBSE) .Ot he r sbe l i e veBSE,s c r a pi e ,a ndCJ Da r e c a us e dbya na sye tunde t e c t e da ndpos s i bl ynove lt ypeofvi r us . Si nc eBSEi snott houghtt obedi r e c t l yc ommuni c a bl ef r om a ni ma lt oa ni ma l , t hepos i t i vec on t a gi o nf e e d ba c kdi dnote xi s tunde rt r a di t i ona la ni ma lhus ba ndr y pr a c t i c es .How t he ndi dt hee pi de mi ca r i s e?Tor e duc ec os t sove rt hepa s tf e w de c a des ,C a t t l epr od uc e r sbe ga nt os uppl e me ntt hedi e t soft he i rhe r dswi t hme a t a ndboneme a l( MBM)pr e pa r e df r om t heofa lofs l a ught e r e dl i ves t oc k, i nc l udi ng s he e p,c a t t l e, pュ gs , a ndc hi c ke ns . Tbr e duc ec os t sf u r t he r ,ane wpr oc e s sf わrpr e pa ‑ r a t i onofMBM wa si nt r oduc e di nt hel a t e1 970S . Thene wpr oc e s si nvol ve dl owe r t . t e mpe r a t ur e sf o rr e nde r i ngof f a li nt of e e dpe l l e t sa ndl e f tmo r ef a ti nt hepr oduc I ti st houghtt ha tt hi sc ha ngea l l owe dBSE t oe nt e rt heUK c a t t l epopul a t i on t hr oughMBM ma def r o ms he e pi nf e c t e dwi t hs c r a pi e. I ni t ss ea r c hf o rl owe rc os t s t hel i ves t oc ki nd us t r yc onve r t e di t she r ds丘. om he r bi vor est ounwi t t l ngC a nni ba l s a ndc r e a t e dapa t hwa yf ori nf e c t e dc a t t l et o" c ont a c t "s us c e pt i bl e s , t husc l os i ngt he c ont a gi onl oop. Thepr a c t i c eoff e e di ngMBM t oc a t t l edr a ma t i c a l l yboos t e dt her e ‑ pr oduc t i onr a t ef orBSEi nt hec a t t l epopul a t i ona ndpus he di twe l la bovet het i p‑ pl ngpoi nt . Fur t h e r , whe r e a smos tdi s e a s esa r ec ommuni c a t e donl ybyc l os ec ont a c t be t we e ni nf e c t e da nds us c e pt i bl ei ndi vi dua l ss ot ha te pi de mi c st e ndt obege o‑ gr a phi c a l l yl oc a l i z e d,MBM wa sdi s t r i but e da l love rt heUK,a l l o wl ngaS l ngl ei n‑ f e c t e da ni ma lt opa s sBSEt oot he r shundr e dsofmi l e sa wa y. Thee pi de mi c( Fi g ur e9‑ 1 0)s pr e a dr a pi dl y,muc hf a s t e rt ha nme di c a lknowl ‑ e dgeofi tort her e a c t i onsofpubl i che a l t ha ut hor i t i es .Byt hemi d1 980SBr i t i s h publ i chea l t hof f i c i a l skne wt he r ewa sane w di s e a s ea f f l i c t i ngt hec a t t l ei ndus t r y. BSEwa sf i r s ti d e nt i f i e da st hec ul pr l tOnl yl n1 986. The r ewa saf ur t he rde l a yof s e ve r a lye a r sbe f or et heUKba nnedt heus eofMBM a saf e e ds uppl e me nt . Duet o ト o ■ ≡ e Fi r s t Hi s t op a t hoE ogI C a l Con f i r ma t i on 0 0 0 4 0 0 0 3 0 n V ∩ ) ウ ] 666L 966L 卜 66L 966L S66L 寸66L C66L L66L O66L 6 96L 9 96L ト 96L 9 96L の 96L N 6 6 L 0 0 0 ー L J l u OM Jads asEU ! m d O ∫一 Mont h/ YearofCl i ni calOnse t Sour c e:U KMl n i s t r yo f Ag r i c u l t u r e , F i s h e r l e S , a n dF o o d , <www. ma f f . g o v . u k / a n l ma l h / b s e / b s e ‑ S t a t i s t i c s / I e v e ト 4 ‑ e p i d e mh t mL >,3Au g u s t 1 9 9 9 . 316 P a r t I I IT h eDy n a mi c so fGr o wt h t hel o ngI nc u ba t i o nde l a y,howe ve r ,c o nf i r me dc a s e sc o nt i nue dt or i s et hr o ugh 1 99 2,d e c l i n i ngo lya n sa ni ma l si ni nf e c t e dhe r dswe r ede s t r o ye d. Byt he n,ho w‑ e v e r , Br i t i s hbe e fwa sba nne dbyt heEu r o pe a nUni o na nds h unne dt hr ougho utt he wo r l d. Wo r s e ,ma nys c i e nt i s t sf e a rt ha tBSEha sbe e npa s s e df r om c o nt a mi na t e d be e fo rmi l kt ot hehuma npo pul a t i o n. By1 9 98,23c onf i r me da ndu pt oadoz e n pos s i bl ec a s e so fane wva ia r nto fCJ D( nvCJ D)ha dbe e ni d e nt i f i e d, a l li nt heUK o rFr a nc e . Thene wva r i a nt , unl i ket r a d i t i ona l CJ D, pr i ma r i l ys t r i ke syo ungpe o pl e . Be c a us eCJ D ha save r yl o ngi nc uba t i ont i me( ye a r st od e c a de s ) ,i ti sno tye t nownwh k e t h e rt he s envCJ Dc a s e sr e pr e s e nta ni s o l a t e dg r o upo rt hef i r s tc a s e so f ahu ma ne pi de mi cc a us e dbyc o ns umpt l O nO fBSEc o nt a mi na t e dbe e f . Ma nys c i ‑ e nt i s t sf e a rt ha tBSEha sc r os s e do ve rf r omt hel i v e s t oc kt ot heh uma npo pul a t i o n a ndma ynowbe g i nt os pr e a dt hr oug he xc ha ngeo fbl oo dpr oduc t s .I nJ ul y1 998 t heUKgo ve r nme nta ut hor i z e di t sNa t i o na l He a l t hSe r vi c et oi mpo r tbl oodpl a s ma f r o mna t i o nsa ppa r e nt l yf r e eo fBSEa f t e ri twa sd i s c o ve r e dt ha tt woo ft hevi c t i ms o fnvCJ Dwe r ebl ooddo nor s ,Po t e nt i a l l yt h r e a t e ni ngt hei nt e g r l t yOfUKbl ood s u ppl i e sa ndva c c i ne spr e pa r e df r o mbl oodp r o d uc t s . Ext emd摘g昔 的eS8 円掴⑳de日 TheSI Rmo d e l , us e f u la si ti s ,i nvoke san umbe rofr e s t r i c t i vea s s umpt l OnS . Li ke heSImo t de lofc hr oni ci nf e c t i on,t heSI Rmode ldoe sno ti nc o r po r a t ebi r t hs , d e a t hs , o rml g r a t i o n; a s s ume st hepo pul a t i o ni sho mog e ne o us ; do e sno tdi s t i ng ui s h be t we e npe r s o nsr e mo ve df r o mt hei nf e c t i o uspo pul a t i o nbyr e c ov e r ya ndt hede ‑ ve l o pme n to fi mmunl t yOrbyde a t h; a nda s s u me si mmunl t yl Spe r ma ne nt . Mos ti mpo r t a nt l y ,t hemode la s s ume st he r ei snoi nc u ba t i o npe r i o d. I ndi v i d u‑ a l si n f T e c t e dwi t had i s e a s ei nt heSI Rmode li mme d i a t e l ybe c omei nf e c t i o us . I nr e a l i t y ,mos td i s e a s e sha veal a t e nc y ,o ri nc uba t i onpe r i od,a ndpe o pl ebe c o me i n f e c t i o usbe f o r ee xhi bi t i nga nys ympt omso fi l l ne s s ・ Pe o pl ee x pos e dt oc hi c ke n , po xbe c omehi g hl yi nf e c t i ouss e ve r a lda ysp r i ort Ot hee me r g e nc eo fs ympt oms s o me1 4t o21da ysa f t e ri ni t i a le x pos ur e, Ma nype o pl ei nf e c t e dwi h He t pa t i t i sA s t a r tt oe xhi bi ts ympt omsa boutamo nt ha f t e ri nf e c t i onbutbe c o mehi g hl yi nf e c ‑ t i o usa bo ut2we e kse a r l i e r . Thea ve r a gei nc uba t i o npe r i odf orHI V( t het i mebe ‑ t we e ni nf e c t i o nwi t hHI Va ndt hede ve l o pme n to fAI DS)f o ra d ul t sno tr e c e i vi ng t r e a t me nti sa bo ut1 0ye a r s ・ Thel a t e nc ype r i o dbe t we e ni n f e c t i o na ndt hea ppe a r ‑ a nc eo fs y mpt omsf o rHe pa t i t i sCi se ve nl o nge r ‑a ve r a g l ngpe r ha ps1 5ye a r s . So mef o u rmi l l i onpe opl ea r et ho ug htt obei n f e c t e dwi t hHe pa t i t i sCi nt heUS, a ndwhi l ea bo ut1 5%s po nt a ne o us l yr e c ov e r , i nma n yo t he rc a s e st hed i s e a s ee ve n‑ t ua l l ypr od uc e si r r e ve r s i bl ea ndof t e nf a t a ll i v e rda ma g e・ He † ⊥ ) a t i t i sCi ss pr e a dby t ・ e xc ha ng eo fbl oo dpr oduc t sbuto nl yr a r e l yt h r o ug hs e xua lc o nt a c Mod i f yt heSI Rmode lbydi s a gg r e ga t l ngt hes t o c kofi nf e c t i ousi ndi vi d ua l s i n t ot woc a t e g o r i e s : As ympt o ma t i cI n f e c t i v e sa ndSympt o ma t i cI nf e c t i ve s . Thei n‑ f e c t i o nr a t emove spe o pl ef r om t hes us c e pt i bl ec a t e go r yi n t ot hea s ympt oma t i c i nf e c t i v epo pul a t i on,t ha ti s ,pe opl ewhoa r ei nf e c t e dwi t ht hedi s e a s ebutdo no ty e te xhi bi ta n ys ympt o ms . Af t e rt hei nc uba t i o npe r i od, pe o pl ebe g i nt oe x hi bi t s y mpt o ms( t y pi c a l l ywhi l er e ma i ni ngi nf e c t i o us )a ndmov ei nt ot hes ympt oma t i c ‑ S Sh dG d G I Ch th 9 317 rowth on usi r s nnovati apt ape onDiff an e emi pid :E ro ewP ofN ucts ‑ e c 7 , l b i S di ith th ecancont sease ycomlnglnt e usceptibl epeop ractth W aCt OCOnt er lf i d il h ldi b R th e ora seasew s m art unth emo eti ca an ncu ati onper o ypoth d l dd ib H f i R b t emo e an eth s eresu ow oesth nc us ono ncu unth escr a ‑ . y d b th or erprocessw aconst ncu ati onper o average ant . f i Th di t omati sympt corasympt c n ecti ves ean rat act econt y v or .d h i f ti A hi l b ki fi c n ec egory vecat ssumeth atth w eat erat peop e ecomes sa rst ‑ .i i di id l O f llill(b diff t omati can sympt so en ncepeop e a asympt c n v ua er ‑ .ld i f hibi tanysympt conti oms an are n e ect ex onot oth act ocont nuet ersatth r ,l l f t ayspriort e orexamp peop earemosti n ecti ous rom erth O aysa eap I ,f th diff di f d ti th eso ure capt e er esan rat act ngcont n ecti v omati esympt can asymp ‑f d fill i 4d A S eaverage ono ness s ays sumeanaverageo ssumeth urati et .f )th d f i id t thth act c omati comesympt enre uceth eyo e rcont ew rat s eout ewor ‑ ,f idi i l b ll k th t oavo ert n ingOth ect mp ecauseth o owth oos eyaret c y ersors e rl i ll A di id d sympt s ncont nowth norma ne routi omati c n v ua rast usua y onotk ey 。 ,d Si il f di i th e rat m ar y a Oth seasepriort eemergenceo symp norma n ecti yO vlt ‑ ・ ,f b f l h k?Wh lo啄 th esrema n yth o epopu ati as ecomes c susceptibl eti me on sf l f li b econt s mu eaper at quaranti ect nepo cy lngth ysett e rat act orth omati esympt ci ,5d h i M dif l th ec aract e ormu orth n ecti onrat pearanceo er sti yth cras o ati on et .i i l t c n ecti omati vepopu ati ons . hi k b i dfわ 21d 14 B t c enpox ecauseth ncu ati onper rc o ays s e as ‑ , .f18d hibi b di lf i th ti oseex quaranti ngsympt n e nse ne