SUBSTITUTION I N RECREATION CHOICE BEHAVIOR
George L. P e t e r s o n
D a n i e l J. S t y n e s
Donald H. R o s e n t h a l
John F. Dwyer
ABSTRACT: T h i s review d i s c u s s e s c o n c e p t s and
t h e o r i e s of s u b s t i t u t i o n i n r e c r e a t i o n c h o i c e . It
b r i n g s t o g e t h e r t h e l i t e r a t u r e of r e c r e a t i o n
r e s e a r c h , psychology, geography, economics, and
t r a n s p o r t a t i o n . P a r a l l e l and complementary
developments need i n t e g r a t i o n i n t o an improved
t h e o r y of s u b s t i t u t i o n . R e c r e a t i o n d e c i s i o n
behavior i s characterized a s a nested o r
s e q u e n t i a l c h o i c e p r o c e s s . Examples a r e i n c l u d e d
from urban and d i s p e r s e d r e c r e a t i o n r e s e a r c h .
INTRODUCTION
R e c r e a t i o n r e s o u r c e management i s dependent
on u n d e r s t a n d i n g r e c r e a t i o n c h o i c e b e h a v i o r . Many
management a c t i o n s d i r e c t l y a f f e c t t h e a t t r i b u t e s
of r e c r e a t i o n s i t e s , e . g . , changes i n s e r v i c e s and
f a c i l i t i e s , m o d i f i c a t i o n of s i t e q u a l i t y o r
c a p a c i t y , changes i n u s e r f e e s , and c o n g e s t i o n
management. Such changes may s t r o n g l y modify t h e
q u a n t i t y and t y p e s of r e c r e a t i o n p a r t i c i p a t i o n i n
general a s well a s a t specific s i t e s . I f
management a c t i o n s a r e t o be e f f i c i e n t and
e f f e c t i v e , t h e r e s u l t i n g e f f e c t s on r e c r e a t i o n
c h o i c e need t o b e p r e d i c t a b l e .
How r e c r e a t i o n i s t s respond t o management
a c t i o n s depends l a r g e l y on two f a c t o r s :
(1) t h e
u n d e r l y i n g p r e f e r e n c e s of consumers a s c o n s t r a i n e d
by t h e i r r e s o u r c e s , and ( 2 ) t h e a v a i l a b l e
a l t e r n a t i v e s . I f a new campground i s e s t a b l i s h e d
i n an a r e a where t h e r e a r e s e v e r a l s i m i l a r
campgrounds, t h e changes i n b e h a v i o r w i l l b e
d r i v e n l a r g e l y by r e d u c t i o n s i n t r a v e l c o s t . The
new campground can be expected t o i n t e r c e p t t h o s e
campers f o r whom i t h a s a lower t r a v e l . c o s t ,
t h e r e b y r e d u c i n g v i s i t s a t more d i s t a n t s i t e s .
Paper p r e s e n t e d a t t h e R e c r e a t i o n Choice Behavior
Symposium, Missoula, MT, March 2 2 - 2 3 , 1984.
George L. P e t e r s o n i s P r o j e c t Leader, Rocky
Mountain F o r e s t and Range Experiment S t a t i o n ,
USDA F o r e s t S e r v i c e , F o r t C o l l i n s , CO; D a n i e l J .
S t y n e s i s A s s o c i a t e P r o f e s s o r , Dept. of Park
and R e c r e a t i o n Resources, Michigan S t a t e
U n i v e r s i t y , E a s t Lansing, M I .
Donald H.
R o s e n t h a l i s an Economist, Rocky Mountain F o r e s t
and Range Experiment S t a t i o n , USDA F o r e s t S e r v i c e ,
F o r t C o l l i n s , CO. John F. Dwyer i s P r o j e c t
Leader, North C e n t r a l F o r e s t Experiment S t a t i o n ,
USDA F o r e s t S e r v i c e , Chicago, I L .
And, because of t h e lower c o s t , i t may g e n e r a t e
i n c r e a s e d camping a c t i v i t y . T h i s i n c r e a s e i n
camping may draw p e o p l e away from o t h e r
a c t i v i t i e s , such a s g a r d e n i n g o r t e l e v i s i o n
watching.
I f t h e new campground a l s o d i f f e r s from
a l l t h e o t h e r s by p r o v i d i n g h o t showers, s t i l l
more b e h a v i o r a l change can be expected. The
l o c a t i o n f a c t o r i s a p r i c e change w h i l e t h e h o t
showers a r e a s i t e q u a l i t y change. There may
be p e o p l e who now d r i v e f a r t h e r t h a n b e f o r e i n
o r d e r t o have a camping e x p e r i e n c e t h a t
i n c l u d e s a h o t shower. And, t h e a v a i l a b i l i t y
of showers may a t t r a c t new campers. Unless we
u n d e r s t a n d how i n d i v i d u a l s e v a l u a t e and choose
among r e c r e a t i o n o p p o r t u n i t i e s , s e r i o u s e r r o r s
may be made i n p r e d i c t i n g how t h e y w i l l respond
t o management a c t i o n s .
The t h e o r e t i c a l framework f o r making such
p r e d i c t i o n s h a s n o t been a d e q u a t e l y developed
and a p p l i e d . One of t h e most d i f f i c u l t and
l e a s t understood p a r t s of t h i s problem i s t h e
q u e s t i o n of how p e o p l e t r a d e o f f a c t i v i t i e s ,
s i t e s , and s i t e a t t r i b u t e s when change i s
encountered. T h i s p a p e r d i s c u s s e s t h i s concept
of " s u b s t i t u t i o n " rin r e c r e a t i o n c h o i c e b e h a v i o r
and exposes some common problems. T h e o r i e s of
c h o i c e b e h a v i o r from s e v e r a l d i s c i p l i n e s a r e
reviewed and t h e i r i m p l i c a t i o n s d i s c u s s e d .
Some r e c e n t r e s e a r c h r e s u l t s from urban and
d i s p e r s e d r e c r e a t i o n p r o v i d e examples.
The concern h e r e i s w i t h s u b s t i t u t i o n a s
i t p e r t a i n s t o modeling c h o i c e b e h a v i o r .
People make c h o i c e s i n d e c i s i o n s i t u a t i o n s , and
t h e purpose of a c h o i c e model i s t o a l l o w such
c h o i c e s t o be p r e d i c t e d and a n a l y z e d . A c h o i c e
model might be f o r m u l a t e d a t any of s e v e r a l
l e v e l s of t h e c h o i c e p r o c e s s . People make
c h o i c e s among r e c r e a t i o n s i t e s , among
a t t r i b u t e s of t h o s e s i t e s , among a c t i v i t i e s
t h a t might t a k e p l a c e a t t h e s i t e s , and among
t h e consequences o r outcomes of performing
alternative activities a t alternative sites.
These consequences i n c l u d e t h e s a t i s f a c t i o n of
motives o r e x p e c t a t i o n s t h a t may o r may n o t be
i n t h e r e c i p i e n t ' s domain of awareness.
While t h e r e a r e many i m p o r t a n t r e a s o n s f o r
e x p l a i n i n g r e c r e a t i o n c h o i c e s a t a l l of t h e s e
l e v e l s , o u r purpose i s t o e x p l o r e s u b s t i t u t i o n
among s i t e s and s i t e a t t r i b u t e s i n models based
on o b s e r v a t i o n s of o v e r t c h o i c e b e h a v i o r . What
goes on i n s i d e t h e mind and body of t h e
consumer i s l e f t f o r o t h e r s t o e x p l o r e .
Webster d e f i n e s " s u b s t i t u t i o n " a s , " t o p u t i n
t h e p l a c e of."
Within t h i s concept, s u b s t i t u t i o n
c a n b e d e f i n e d a t d i f f e r e n t l e v e l s . At t h e
s i m p l e s t l e v e l , two o b j e c t s t h a t a r e p h y s i c a l l y
i d e n t i c a l i n every respect a r e l i k e l y t o be
s u b s t i t u t a b l e f o r each o t h e r . Thus, p h y s i c a l
s i m i l a r i t y i s one way t o a t t a c k t h e q u e s t i o n . At
a more g e n e r a l l e v e l , s u b s t i t u t i o n may d e r i v e from
f u n c t i o n a l s i m i l a r i t y . Two p h y s i c a l l y d i s s i m i l a r
o b j e c t s may b e c a p a b l e o f p e r f o r m i n g t h e same
f u n c t i o n . One o b j e c t c a n b e p u t i n t h e p l a c e of
a n o t h e r and p e r f o r m s i m i l a r f u n c t i o n s , e . g . , pen
f o r pencil.
Whether o r n o t two o b j e c t s a r e s u b s t i t u t e s
c a n b e l e a r n e d by o b s e r v i n g b e h a v i o r a l r e s p o n s e t o
changing o p p o r t u n i t i e s . A s i m p l i s t i c approach
would h o l d t h a t , o t h e r t h i n g s b e i n g e q u a l , i f t h e
consumption of A g o e s up when t h e p r i c e of B g o e s
u p , t h e two a r e s u b s t i t u t e s ; i f t h e r e v e r s e i s
t r u e , t h e y a r e complements.
I f nothing happens t o
A when t h e p r i c e o f B c h a n g e s , t h e y a r e
independent.
The t r o u b l e w i t h t h i s a p p r o a c h i s t h a t i t
r e v e a l s o n l y what i s known a l r e a d y .
It i s n o t
p o s s i b l e t o p r e d i c t c h o i c e s u n d e r new circumstances, ( i . e . , t o predict behavioral response t o
innovation). Neither i s it possible t o recognize
when a p p a r e n t s u b s t i t u t a b i l i t y i s s i m p l y t h e
p r o d u c t of s p u r i o u s c o r r e l a t i o n . What i s n e e d e d
i s a theory of choice behavior t h a t e x p l a i n s
c h o i c e s i n t e r m s of t h o s e v a r i a b l e s t o which t h e y
a r e s e n s i t i v e . L a n c a s t e r (1966) and B e c k e r (1965)
r e s p o n d e d w i t h a new consumer t h e o r y b a s e d o n t h e
c o n c e p t t h a t t h e o b j e c t s of c h o i c e a r e n o t t h e
goods t h e m s e l v e s , b u t t h e a t t r i b u t e s p o s s e s s e d by
t h o s e goods. Consumers u s e t h e a t t r i b u t e s a s
i n p u t f a c t o r s f o r a consumption t e c h n o l o g y t h a t
p r o d u c e s u t i l i t y . F o r example, t h e y combine t i m e ,
t r a v e l , e q u i p m e n t , f a c i l i t i e s , and t h e f e a t u r e s of
n a t u r a l environments t o produce outdoor
e x p e r i e n c e s s u c h a s camping.
The a t t r i b u t e s may b e t h o u g h t o f a s parame t e r s d e s c r i b i n g t h e p h y s i c a l s t a t e of a t h i n g .
T h u s , a n a u t o m o b i l e c a n b e d e s c r i b e d i n t e r m s of
c o l o r , make, model, r a t e of f u e l c o n s u m p t i o n ,
braking distance, luxury options, e t c .
In this
sense, s u b s t i t u t i o n again reduces t o physical
s i m i l a r i t y , except t h a t i n a given decision
c o n t e x t o n l y s e l e c t e d p h y s i c a l a t t r i b u t e s may b e
relevant.
Substitution is thus physical
s i m i l a r i t y vis-a-vis only those v a r i a b l e s relevant
t o t h e d e c i - s i o n c o n t e x t . On t h e o t h e r h a n d , a s
e x p r e s s e d by Morishima ( 1 9 5 9 ) , demand i s c r e a t e d
by human o b j e c t i v e s . Goods a r e demanded b e c a u s e
o f t h e i r a b i l i t y t o s e r v e human p u r p o s e s . C e r t a i n
a t t r i b u t e s o r c o n t e x t v a r i a b l e s may m o d i f y t h e
e f f e c t i v e n e s s of a t h i n g i n a g i v e n r o l e .
~ u b & i t u t i o n c a n o c c u r among p u r p o s e s , among
a t t r i b u t e s , o r among g o o d s , and t h i s c o m p l i c a t e s
matters.
I t becomes s t i l l more c o m p l i c a t e d when we
allow decision r u l e s t o vary.
Some g o o d s ,
a t t r i b u t e s , o r p u r p o s e s may b e c o m p e n s a t o r y ,
o t h e r s noncompensatory.
Some noncompensatory
d e c i s i o n s may i n v o l v e l e x i c o g r a p h i c d e c i s i o n
rules.
F o r example, f o r a e r o b i c c o n d i t i o n i n g ,
j o g g i n g and b i c y c l i n g a r e g e n e r a l l y r e g a r d e d a s
compensatory a c t i v i t i e s . More b i c y c l i n g c a n
compensate f o r l e s s j o g g i n g i n t h e m a i n t e n a n c e of
a e r o b i c c a p a c i t y when a m i n o r i n j u r y i n t e r r u p t s a
r u n n e r ' s t r a i n i n g s c h e d u l e . However, more
c a r b o h y d r a t e i n t h e d i e t c a n n o t compensate f o r
iron deficiency.
The two n u t r i e n t s h a v e i n d e p e n d e n t f u n c t i o n s and a r e noncompensatory.
A
lexicographic decision r u l e requires c r i t e r i a t o
be s a t i s f i e d i n s e q u e n t i a l o r h i e r a r c h i c a l o r d e r .
I n shopping f o r formal wear, a conventional male
g o e s f i r s t t o t h e m e n ' s d e p a r t m e n t and t h e n
compares a l t e r n a t i v e s . He d o e s n o t compare
e v e n i n g gowns and t u x e d o e s . T h e r e may a l s o b e
threshold d e c i s i o n r u l e s such t h a t i n a given
r a n g e t h e r e l a t i o n s h i p among a t t r i b u t e s i s
lexicographic, while i n another range t h e att r i b u t e s a r e c o m p e n s a t o r y ( P e t e r s o n and W o r r a l l
1970, d e B e t t e n c o u r t and P e t e r s o n 1981, Krumpe and
McLaughlin 1 9 8 2 ) .
Whatever t h e d e c i s i o n r u l e s , i t i s c l e a r t h a t
t h e y must b e known and u n d e r s t o o d i f p r e d i c t i o n of
s u b s t i t u t i o n i n r e c r e a t i o n choice behavior is t o
b e e f f e c t i v e . A g i v e n model s t r u c t u r e may b e
e n t i r e l y inappropriate i n a given decision
context.
What i s n e e d e d i s a t h e o r y o f r e c r e a t i o n
c h o i c e b e h a v i o r and i n t e r p r e t a t i o n of r e a l c h o i c e
s i t u a t i o n s i n terms of t h a t theory. Therefore,
t h e next s e c t i o n reviews t h e approaches of s e v e r a l
different disciplines.
REVIEW OF SUBSTITUTION RESEARCH
While t h e r e i s a g r e a t d e a l of r e s e a r c h
r e l a t e d t o s u b s t i t u t i o n , o n l y a s m a l l p o r t i o n of
t h i s research confronts the substitution issue
d i r e c t l y . F i r s t , t h e t r e a t m e n t of s u b s t i t u t i o n i n
empirical s t u d i e s w i t h i n r e c r e a t i o n w i l l be
r e v i e w e d , and t h e n , b r i e f l y , more b a s i c r e s e a r c h
from g e o g r a p h y , p s y c h o l o g y , t r a n s p o r t a t i o n , and
economics.
The l a t t e r p r o v i d e some of t h e p i e c e s
f o r a much needed c o n c e p t u a l and t h e o r e t i c a l b a s i s
f o r s u b s t i t u t i o n r e s e a r c h w i t h i n r e c r e a t i o n and
l e i s u r e . We w i l l n o t a t t h i s s t a g e a t t e m p t t o
assemble t h e p i e c e s , b u t hope t o begin t o i d e n t i f y
t h e components of a more c o m p r e h e n s i v e model i n
which s u b s t i t u t i o n may b e a d d r e s s e d .
R e c r e a t i o n R e s e a r c h on S u b s t i t u t i o n
T h e r e a r e two m a j o r b o d i e s of s u b s t i t u t i o n
research within recreation:
(1) r e c r e a t i o n /
l e i s u r e a c t i v i t y s u b s t i t u t i o n , and ( 2 ) r e c r e a t i o n
s i t e s u b s t i t u t i o n . The f o r m e r h a s l a r g e l y b e e n
t h e domain of s o c i o l o g i s t s and p s y c h o l o g i s t s w h i l e
t h e l a t t e r h a s b e e n a d d r e s s e d by g e o g r a p h e r s and
e c o n o m i s t s . A few s t u d i e s examine s u b s t i t u t i o n
between r e s o u r c e s e t t i n g s (O'Leary and D o t t a v i o
1 9 8 1 ) , g e o g r a p h i c a r e a s ( D i t t o n and o t h e r s 1975,
Vaske and D o n n e l l y 1 9 8 2 ) , and p r o v i d e r s ( C o r d e l l
1976).
Hendee and Burdge (1974) r a i s e d t h e import a n c e of t h e s u b s t i t u t i o n concept f o r r e c r e a t i o n
p l a n n i n g and management i n t h e c o n t e x t of
r e c r e a t i o n a c t i v i t y s u b s t i t u t i o n . Growing o u t of
t h e l e i s u r e typology r e s e a r c h was an a t t e m p t by a
number of i n v e s t i g a t o r s t o shed l i g h t on subs t i t u t i o n r e l a t i o n s h i p s by f a c t o r a n a l y z i n g
recreation p a r t i c i p a t i o n data. Recreation
a c t i v i t i e s were grouped i n t o a c t i v i t y t y p e s w i t h
t h e i d e a t h a t a c t i v i t i e s w i t h i n t h e same group a r e
i n some s e n s e " s ~ b s t i t u t a b l e . ~ 'P l a n n e r s could
t h e n meet t h e r e c r e a t i o n needs of c l i e n t e l e groups
by p r o v i d i n g a t l e a s t s e v e r a l a c t i v i t i e s from each
group, r a t h e r t h a n a t t e m p t i n g t o p r o v i d e a l l
a c t i v i t i e s . Beaman (1975) p o i n t e d o u t t h e
i n a p p r o p r i a t e n e s s of f a c t o r a n a l y s i s f o r d e r i v i n g
a c t i v i t y packages, recommending c l u s t e r a n a l v s i s
a s t h e more s u i t a b l e t o o l . Because t h e a c t i v i t y
packages d e r i v e d through f a c t o r a n a l y t i c methods
a r e based upon c o r r e l a t i o n s between p a r t i c i p a t i o n
i n different a c t i v i t i e s , a c t i v i t i e s f a l l i n g i n the
same c l u s t e r a r e j u s t a s l i k e l y t o be complements
a s s u b s t i t u t e s . C h r i s t i a n s e n and Y o e s t i n g (1977)
t e s t e d whether r e c r e a t i o n i s t s would d e r i v e s i m i l a r
' l s a t i s f a c t i o n s " from a c t i v i t i e s w i t h i n t h e same
t y p e c a t e g o r y , concluding t h a t t h e approach of
d e r i v i n g a c t i v i t y packages e m p i r i c a l l y i s t o o
s i m p l i s t i c t o y i e l d much i n s i g h t i n t o s u b s t i t u t i o n
behavior.
A more p r o d u c t i v e approach t o a c t i v i t y
s u b s t i t u t i o n i s t h e development of r e c r e a t i o n
a c t i v i t y packages based upon s i m i l a r i t y judgments
of r e a l o r p e r c e i v e d c h a r a c t e r i s t i c s of r e c r e a t i o n
a c t i v i t i e s . R i t c h i e (1975) and Becker (1976) have
used m u l t i d i m e n s i o n a l s c a l i n g t e c h n i q u e s (MDS) f o r
t h i s purpose. Holbrook (1980) recommends t h e
method of m u l t i d i m e n s i o n a l l y s c a l e d c o r r e l a t i o n s
(MSC) a s p r e f e r a b l e t o b o t h f a c t o r a n a l y s i s and
MDS i n r e p r e s e n t i n g a s s o c i a t i o n among r e c r e a t i o n
a c t i v i t i e s . MSC performs an MDS p r o c e d u r e on t h e
c o r r e l a t i o n m a t r i x of v a r i a b l e s r a t h e r t h a n t h e
v a r i a b l e s themselves. A l i m i t a t i o n of MDS, MSC,
and r e l a t e d a t t i t u d e s c a l i n g methods f o r
s u b s t i t u t i o n r e s e a r c h i s t h e problem of l i n k i n g
a t t i t u d e s w i t h b e h a v i o r . Becker (1976) n o t e s t h a t
s i t u a t i o n a l v a r i a b l e s must be s t u d i e d i n
conjunction with a t t i t u d i n a l d a t a i n order t o
p r e d i c t a c t u a l behavior.
The problem of how t o i n c o r p o r a t e t h e e f f e c t s
of s u b s t i t u t e s i t e s i s common t o b o t h economic
demand models and geographic models of s p a t i a l
c h o i c e . I n v e s t i g a t o r s from b o t h d i s c i p l i n e s t e n d
t o f a v o r r e v e a l e d p r e f e r e n c e approaches i n which a
v a r i e t y of s i t u a t i o n a l f a c t o r s must be c o n t r o l l e d .
M o t i v a t i o n a l and a t t i t u d i n a l v a r i a b l e s t h a t a r e
d i f f i c u l t t o o b s e r v e a r e downplayed, and
o b s e r v a b l e c h a r a c t e r i s t i c s of r e c r e a t i o n i s t s ,
r e c r e a t i o n s i t e s , and s e l e c t e d e n v i r o n m e n t a l
variables a r e studied.
Measures of r e c r e a t i o n s i t e s u b s t i t u t i o n have
been i n c o r p o r a t e d i n t o a g g r e g a t e r e c r e a t i o n demand
and t r i p d i s t r i b u t i o n models. The t r a v e l c o s t
model (Dwyer and o t h e r s 1977, R o s e n t h a l and o t h e r s
1984) and t h e g r a v i t y model (Ewing 1980) have been
t h e primary v e h i c l e s f o r examining s u b s t i t u t i o n i n
r e c r e a t i o n economics and geography, r e s p e c t i v e l y .
To p r e d i c t t h e number of t r i p s o r v i s i t s t o a s e t
of d e s t i n a t i o n s , t h o s e g r a v i t y models t h a t i n c l u d e
a s u b s t i t u t e component t y p i c a l l y c a p t u r e i t by
means of a s i n g l e v a r i a b l e measuring t h e q u a n t i t y
a n d / o r q u a l i t y of a l t e r n a t i v e r e c r e a t i o n
o p p o r t u n i t i e s a v a i l a b l e from each o r i g i n . The
s e l e c t i o n of s i t e s t o be i n c l u d e d a s p o t e n t i a l
s u b s t i t u t e s and t h e measurement of t h e i r
c h a r a c t e r i s t i c s i s most o f t e n done by t h e
i n v e s t i g a t o r , r a t h e r t h a n t h e consumers whose
c h o i c e s a r e t o be p r e d i c t e d . Many of t h e s e
s t u d i e s l i m i t t h e r a n g e of s u b s t i t u t e s t o s i t e s
managed by t h e same a u t h o r i t y o r s i t e s t h a t a r e
s i m i l a r a c c o r d i n g t o some c r i t e r i a d e f i n e d by t h e
i n v e s t i g a t o r . Thus, t e l e v i s i o n viewing i s n e v e r
considered a s u b s t i t u t e t o v i s i t i n g a given s t a t e
p a r k , and i n many c a s e s n e i t h e r i s v i s i t i n g a
county o r urban p a r k . When s t u d y i n g s t a t e p a r k s ,
only o t h e r s t a t e parks a r e l i k e l y t o be
c o n s i d e r e d . Park v i s i t a t i o n models t h a t i n c l u d e a
s u b s t i t u t i o n component a r e t h o s e of Grubb and
Goodwin (1968), Cheung (1972), C e s a r i o (1973), and
Smith (1980).
The s u b s t i t u t i o n i s s u e h a s a l s o been promi n e n t i n t h e development of t r a v e l c o s t models,
which a r e w i d e l y used t o e s t i m a t e t h e demand f o r
and v a l u e of r e c r e a t i o n s i t e s . Such models can
y i e l d very misleading r e s u l t s i f s u b s t i t u t e s i t e s
a r e not properly specified. This i s well i l l u s t r a t e d by Knetsch (1977). Good examples of
a l t e r n a t i v e ways of i n c o r p o r a t i n g s u b s t i t u t e s i n t o
r e c r e a t i o n demand models a r e t h e s t u d i e s of Burt
and Brewer (1971) and C e s a r i o and Knetsch (1976).
Both s t u d i e s e s t i m a t e t h e demand f o r i n d i v i d u a l
p a r k s w i t h i n a system of e q u a t i o n s , t a k i n g i n t o
account t h e p r e s e n c e and a t t r i b u t e s of a l t e r n a t i v e
s i t e s i n e s t i m a t i n g t h e demand f o r any p a r t i c u l a r
site.
Because b o t h t h e g r a v i t y and t r a v e l c o s t
models have t r a d i t i o n a l l y been a p p l i e d t o
a g g r e g a t e d a t a , t h e y can o n l y r e v e a l a g g r e g a t e
p a t t e r n s of s u b s t i t u t i o n . I n o r d e r t o shed more
l i g h t on i n d i v i d u a l d i f f e r e n c e s i n r e c r e a t i o n
c h o i c e s , r e c e n t work i n geography, economics, and
t r a n s p o r t a t i o n h a s e x p l o r e d d i s a g g r e g a t e modeling
of c h o i c e s . These models can be a p p l i e d t o b o t h
a c t i v i t y and s i t e c h o i c e problems, p r o v i d e a
s t r o n g e r t h e o r e t i c a l b a s e f o r a g g r e g a t e models,
and can more f u l l y i n c o r p o r a t e a v a r i e t y of
assumptions about s u b s t i t u t i o n . S i n c e t h e s e new
d i r e c t i o n s i n c h o i c e r e s e a r c h a r e n o t w e l l known
w i t h i n r e c r e a t i o n , we f i r s t p r o v i d e a b r i e f
background on t h e development of c h o i c e models i n
psychology and t h e n d i s c u s s some r e c e n t development i n geography, economics, and t r a n s p o r t a t i o n .
I n summary, w h i l e s o c i o l o g i s t s and psycholo g i s t s have c o n c e n t r a t e d on m o t i v a t i o n a l and
a t t i t u d i n a l d e t e r m i n a n t s of c h o i c e , geographers
and economists have focused more upon s i t u a t i o n a l
f a c t o r s . However, t h e i r s t u d i e s have examined
s u b s t i t u t i o n i n t h e c o n t e x t of s i t e c h o i c e , n o t
a c t i v i t y c h o i c e , and no one h a s r e a l l y a t t e m p t e d
t o l i n k t h e s e two somewhat independent b o d i e s of
research.
Psychology
P s y c h o l o g i c a l c h o i c e r e s e a r c h f o c u s e s upon
i n d i v i d u a l c h o i c e and r e l i e s h e a v i l y upon experi m e n t a l methods. A s t r e n g t h of t h e p s y c h o l o g i c a l
r e s e a r c h i s t h e r e d u c t i o n of c h o i c e t o fundamental
c o n c e p t s and r e l a t i o n s h i p s , r e s u l t i n g i n t i g h t
c o n t r o l s i n research designs. A corresponding
weakness i s t h a t t o a c h i e v e r i g i d e x p e r i m e n t a l
c o n t r o l s t h e c o n d i t i o n s and s e t t i n g s a r e o f t e n
o v e r s i m p l i f i e d and sometimes a r t i f i c i a l . T h i s
makes i t d i f f i c u l t t o g e n e r a l i z e t h e r e s u l t s t o
h i g h l y complex real-world s e t t i n g s .
The r e l e v a n t p s y c h o l o g i c a l r e s e a r c h may be
d i v i d e d i n t o two c l a s s e s :
(1) m a t h e m a t i c a l models
of c h o i c e t h a t e s t a b l i s h s e t - t h e o r e t i c f o u n d a t i o n s
f o r a p p l i e d work, and (2) more a p p l i e d r e s e a r c h ,
which e x p l o r e s c h o i c e i n terms of i n d i v i d u a l
p e r c e p t i o n s , p r e f e r e n c e s , and i n f o r m a t i o n
p r o c e s s i n g . The l a t t e r c a t e g o r y o v e r l a p s
considerably with t h e microlevel geographic
r e s e a r c h , b u t t e n d s t o have a s t r o n g e r
methodological o r i e n t a t i o n .
Along w i t h psychophysics and l e a r n i n g , c h o i c e
i s one of t h e t h r e e primary s u b j e c t a r e a s w i t h i n
mathematical psychology. The models of Luce
(1959) and Tversky (1972a, 1972b) have guided much
of t h e t h e o r e t i c a l c h o i c e r e s e a r c h o v e r t h e p a s t
two decades and p r o v i d e t h e f o u n d a t i o n s f o r t h e
m a j o r i t y of a p p l i e d s t u d i e s of c h o i c e . Both a r e
h i g h l y a b s t r a c t t h e o r i e s couched i n p u r e l y
s e t - t h e o r e t i c terms.
Luce's model f o r m a l i z e s Arrow's (1951)
''independence of i r r e l e v a n t a l t e r n a t i v e s " (IIA)
assumption i n t o a c h o i c e axiom. Because i t
r e l a t e s t o r e c r e a t i o n c h o i c e modeling, t h i s axiom
i s d i s c u s s e d and i l l u s t r a t e d i n a subsequent
s e c t i o n . T h i s powerful and s i m p l i f y i n g assumption
makes t h e Luce model e a s y t o a p p l y , a l t h o u g h i t i s
known t o f a i l i n many simple k i n d s of c h o i c e s
(DeBreu 1960) because of i n t e r r e l a t i o n s h i p s among
choice a l t e r n a t i v e s t h a t a r e not captured i n t h e
h i g h l y a b s t r a c t model. N e v e r t h e l e s s , t h e Luce
model p r o v i d e s a r e a s o n a b l e approximation f o r many
k i n d s of c h o i c e s (Luce 1977) and, p e r h a p s more
importantly, provides a s t a r t i n g point f o r choice
r e s e a r c h i n c l u d i n g s u b s t i t u t i o n phenomena. The
Luce model h a s been shown t o b e e s s e n t i a l l y
e q u i v a l e n t t o T h u r s t o n e ' s (1927) Law of
Comparative Judgement (Case V) i f T h u r s t o n e ' s
assumption of independent, normally d i s t r i b u t e d
random v a r i a b l e s i s r e p l a c e d by double
e x p o n e n t i a l , random d i s t u r b a n c e s ( Y e l l o t t 1977,
McFadden 1973). The d i f f e r e n c e d i s t r i b u t i o n of
two independent double e x p o n e n t i a l random
v a r i a b l e s i s t h e l o g i s t i c d i s t r i b u t i o n , which i s
t h e b a s i s f o r t h e m u l t i n o m i a l l o g i t model (MNL)
(Stynes and P e t e r s o n 1984). Thus, t h e r e i s a
d i r e c t l i n k between t h e w i d e l y a p p l i e d MNL model
and b a s i c t h e o r i e s of c h o i c e s t u d i e d by Luce,
T h u r s t o n e , and o t h e r s . The s i m p l e counterexamples
t o t h e Luce model (DeBreu 1960, Luce 1977, Tversky
1972a) a r e a l s o c a s e s where t h e MNL model w i l l
f a i l . These c a s e s have provided t h e s t i m u l u s and
d i r e c t i o n f o r r e v i s e d c h o i c e t h e o r i e s t h a t more
f u l l y c a p t u r e i n t e r r e l a t i o n s h i p s among t h e c h o i c e
o b j e c t s . Most n o t a b l e of t h e s e w i t h i n psychology
i s t h e Tversky (1972a, 1972b) e l i m i n a t i o n by
a s p e c t s (EBA) model.
Although t h e EBA model, l i k e L u c e ' s , can be
formulated i n p u r e l y a b s t r a c t s e t - t h e o r e t i c t e r m s ,
t h e n a t u r a l i n t e r p r e t a t i o n of t h e model i n v o l v e s
t h e i d e n t i f i c a t i o n of t h e c h o i c e a l t e r n a t i v e s i n
terms of a s e t of a t t r i b u t e s o r c h a r a c t e r i s t i c s .
Luce's model i s a s p e c i a l c a s e i n which t h e
a l t e r n a t i v e s do n o t have any c h a r a c t e r i s t i c s i n
common. The EBA model i s l e x i c o g r a p h i c . A c h o i c e
i s made from a s e t of a l t e r n a t i v e s by s u c c e s s i v e l y
e l i m i n a t i n g t h o s e t h a t do n o t p o s s e s s d e s i r e d
a t t r i b u t e s . There i s a n assumption t h a t
i n d i v i d u a l s have a r a n k i n g of d e s i r e d a t t r i b u t e s
and e l i m i n a t e a l t e r n a t i v e s b e g i n n i n g w i t h t h e most
d e s i r e d a t t r i b u t e , t h e n t h e second most d e s i r e d
a t t r i b u t e , e t c . , u n t i l only a s i n g l e a l t e r n a t i v e
( t h e c h o i c e ) remains. The model i s noncompens a t o r y because a l a c k of one d e s i r e d a t t r i b u t e
cannot b e compensated by a n o t h e r . Any a l t e r n a t i v e
l a c k i n g t h e most d e s i r e d a t t r i b u t e i s e l i m i n a t e d
i n t h e f i r s t s t e p r e g a r d l e s s of what o t h e r
d e s i r a b l e a t t r i b u t e s i t may p o s s e s s . The EBA
model r e s u l t s i n n e s t e d o r s e q u e n t i a l d e c i s i o n
s t r u c t u r e s t h a t can become c o m b i n a t o r i a l l y complex
when t h e a l t e r n a t i v e s p o s s e s s many d i f f e r e n t
a t t r i b u t e s (Krumpe and Mclaughlin 1982). Indow
(1975) q u e s t i o n s whether any mathematical model
can f u l l y c a p t u r e t h e complexity of i n d i v i d u a l
c h o i c e p r o c e s s e s , s u g g e s t i n g computer s i m u l a t i o n
a s an a l t e r n a t i v e approach. G r e t h e r and P l o t t
(1979) have found t h a t i n d i v i d u a l b e h a v i o r i s
o f t e n a t odds w i t h what i s i m p l i e d by t h e f o r m a l ,
and f a i r l y m a t h e m a t i c a l , t h e o r y of consumer demand
i n economics.
The s t r e n g t h of t h e formal mathematical
t r e a t m e n t of c h o i c e l i e s i n t h e p r e c i s i o n w i t h
which c o n c e p t s can b e d e f i n e d and t h e manner i n
which p r o p e r t i e s may be deduced and t e s t e d (See
Luce and Suppes 1965, Tversky and Russo 1969). I n
t h e absence of such approaches, t h e e s s e n t i a l
d i f f e r e n c e s and s i m i l a r i t i e s between a l t e r n a t i v e
c h o i c e models, l i k e t h e T h u r s t o n e and Luce models,
would remain o b s c u r e . By employing a common
mathematical language, t h e t h e o r i e s of c h o i c e
b e h a v i o r from psychology and economics c a n be
shown t o s h a r e common f o u n d a t i o n s . T h i s h e l p s a
g r e a t d e a l t o c l a r i f y t h e p r o p e r t i e s and l i m i t s of
t h e s e models, i n c l u d i n g t h e i m p l i e d assumptions
about s u b s t i t u t i o n .
Applied s t u d i e s of p r e f e r e n c e , u t i l i t y , and
c h o i c e w i t h i n psychology l o o k more c l o s e l y a t t h e
c h o i c e s e t , c h o i c e s e t t i n g , and a t t r i b u t e s of t h e
choice a l t e r n a t i v e s i n order t o explore individual
d i f f e r e n c e s and common p a t t e r n s of c h o i c e
b e h a v i o r . Many of t h e s e s t u d i e s a t t e m p t t o
i d e n t i f y a u t i l i t y f u n c t i o n , and model c h o i c e s a s
a u t i l i t y maximizing p r o c e s s . The methods a r e
v a r i o u s l y known a s i n f o r m a t i o n i n t e g r a t i o n ,
f u n c t i o n a l measurement, c o n j o i n t a n a l y s i s , and
p o l i c y c a p t u r i n g . These k i n d s of methods a r e
w i d e l y a p p l i e d i n geography, m a r k e t i n g , economics,
t r a n s p o r t a t i o n , and r e l a t e d f i e l d s . The
p s y c h o l o g i c a l c o n t r i b u t i o n s t o t h i s a r e a have
i d e n t i f i e d a number of m e t h o d o l o g i c a l i s s u e s t h a t
must be c o n s i d e r e d i n t h e d e s i g n of c h o i c e
experiments. For example, T v e r s k y ' s (1977) review
of t h e concept of s i m i l a r i t y p r e s e n t s b o t h
t h e o r e t i c a l and e m p i r i c a l e v i d e n c e a g a i n s t
r e p r e s e n t i n g s i m i l a r i t i e s between o b j e c t s o r
choice a l t e r n a t i v e s geometrically. This i s
p r e c i s e l y what t h e MDS and r e l a t e d methods do.
Tversky s u g g e s t s t h a t s i m i l a r i t y judgments a r e
t h e r e s u l t of a f e a t u r e matching p r o c e s s and may
n o t s a t i s f y t h e m e t r i c assumptions of symmetry and
t r a n s i t i v i t y . Curry and o t h e r s (1983), i n an
a p p l i c a t i o n t o r e c r e a t i o n , conclude t h a t a number
of c o n t e x t u a l and measurement i s s u e s can
s i g n i f i c a n t l y i n f l u e n c e t h e r e s u l t s of c h o i c e
e x p e r i m e n t s , making i t d i f f i c u l t t o g e n e r a l i z e
from one c h o i c e s e t t i n g t o a n o t h e r . These
problems may e x p l a i n many of t h e a p p a r e n t l y
c o n f l i c t i n g r e s u l t s of c h o i c e e x p e r i m e n t s a s w e l l
a s t h e d i f f i c u l t y of g e n e r a l i z i n g from h i g h l y
a r t i f i c i a l s e t t i n g s t o real-world c h o i c e s .
amount of a g i v e n good consumed by a p e r s o n i s a
f u n c t i o n of t a s t e s and p r e f e r e n c e s , p r i c e s of t h a t
good and of o t h e r goods, and income. The
consumer's p r e f e r e n c e s among c h o i c e o p t i o n s a r e
assumed t o be d e s c r i b a b l e by an o r d i n a l u t i l i t y
function t h a t has certain r e s t r i c t i v e properties.
Income and p r i c e s a r e g e n e r a l l y assumed t o be
f i x e d . Faced w i t h a c h o i c e among s e v e r a l
competing a l t e r n a t i v e s , t h e consumer i s assumed t o
p i c k t h a t o p t i o n which maximizes u t i l i t y , s u b j e c t
t o a budget c o n s t r a i n t . The r e s u l t of t h i s
u t i l i t y maximization i s t h e i n d i v i d u a l demand
function. This function describes f o r t h a t person
t h e r e l a t i o n s h i p between t h e q u a n t i t i e s of goods
consumed and t h e i r p r i c e s . The a g g r e g a t e o r
market demand f u n c t i o n i s t h e sum of i n d i v i d u a l
demand f u n c t i o n s . To a t t a i n more e f f e c t i v e
t r e a t m e n t of s u b s t i t u t i o n and complementarity,
consumer t h e o r y h a s been extended by Morishima
(1959) and L a n c a s t e r (1966).
Geography
Geographic c h o i c e r e s e a r c h f o c u s e s upon
s p a t i a l c h o i c e and i s t h e r e f o r e r e l e v a n t t o t h e
r e c r e a t i o n s i t e c h o i c e problem. Geographic
measures of s u b s t i t u t e and i n t e r v e n i n g opport u n i t i e s provided t h e b a s i s f o r numerous
r e c r e a t i o n a p p l i c a t i o n s of t h e g r a v i t y and r e l a t e d
t r i p d i s t r i b u t i o n models. A t t h e m a c r o l e v e l ,
geographers have become i n c r e a s i n g l y concerned
w i t h t h e e f f e c t s of s p a t i a l s t r u c t u r e on t h e
parameter e s t i m a t e s of g r a v i t y models
(Fotheringham 1981). S p a t i a l s t r u c t u r e of
a l t e r n a t i v e s i t e s cannot be a d e q u a t e l y r e p r e s e n t e d
by a s i n g l e v a r i a b l e , and models i n c o r p o r a t i n g
s p a t i a l s t r u c t u r e more f u l l y a r e b e i n g s o u g h t . A t
t h e m i c r o l e v e l , t h e r e have been numerous e f f o r t s
w i t h i n geography t o b e t t e r e x p l a i n s p a t i a l c h o i c e
by examining d a t a f o r i n d i v i d u a l s . These
i n v e s t i g a t i o n s have added c o g n i t i v e dimensions t o
g r a v i t y models (Cadwallader 1981) and e x p l o r e d
i n d i v i d u a l v a r i a t i o n s i n p e r c e p t i o n s of d i s t a n c e
and a l t e r n a t i v e s . Much of t h i s work o v e r l a p s w i t h
work i n marketing and psychology on f u n c t i o n a l
measurement, i n f o r m a t i o n i n t e g r a t i o n , and t h e l i k e
( s e e Golledge and Rushton 1976 and B u r n e t t 1981,
f o r examples).
Economics
The t h e o r y of consumer demand p r o v i d e s a
d i s c i p l i n e d framework f o r t h e t r e a t m e n t of
s u b s t i t u t i o n . The p r i c e e l a s t i c i t y of demand
g i v e s t h e p e r c e n t change i n demand f o r a good ( o r
a t t r i b u t e ) r e s u l t i n g from (1) a 1%change i n . t h e
p r i c e of t h a t good ( a t t r i b u t e ) , o r ( 2 ) a 1% change
i n t h e p r i c e of some o t h e r good ( a t t r i b u t e ) . The
p r i c e e l a s t i c i t y of demand i s dependent on p r i c e s
and m a r g i n a l r a t e s of s u b s t i t u t i o n . The m a r g i n a l
r a t e of s u b s t i t u t i o n (MRS) i s d e f i n e d by t h e
u t i l i t y f u n c t i o n . It i s t h e amount of good Y t h e
consumer i s w i l l i n g t o g i v e up t o a t t a i n one more
u n i t of good X , Two goods a r e p e r f e c t s u b s t i t u t e s
i f t h e MRS i s c o n s t a n t , no m a t t e r how much X o r Y
i s owned. The p r i c e of a good i s determined by
t h e q u a n t i t y a v a i l a b l e and t h e q u a n t i t y demanded.
When t r y i n g t o p r e d i c t demand o r e s t i m a t e
value f o r a recreation a c t i v i t y o r s i t e , it is
i m p o r t a n t t o a s s e s s t h e a v a i l a b i l i t y of subs t i t u t e s . The demand f u n c t i o n i s t h e b a s i s f o r
p r e d i c t i n g p a r t i c i p a t i o n and e s t i m a t i n g b e n e f i t s
under a l t e r n a t i v e management o p t i o n s . F a i l u r e t o
i n c o r p o r a t e t h e e f f e c t of s u b s t i t u t e s i n t h e
demand f u n c t i o n can produce i n c o r r e c t r e s u l t s .
For example, assume t h e managers of a c e r t a i n
r e c r e a t i o n s i t e want t o r a i s e e n t r a n c e f e e s , b u t
a r e unaware t h a t a p e r f e c t s u b s t i t u t e w i t h e x c e s s
c a p a c i t y i s a v a i l a b l e a s h o r t d i s t a n c e away.
R a i s i n g t h e f e e w i l l simply d i v e r t t o t h e a l t e r n a t i v e s i t e t h o s e u s e r s whose added t r a v e l c o s t i s
l e s s than the p r i c e increase.
Economics i s t h e s t u d y of t h e employment and
consumption of s c a r c e r e s o u r c e s t h a t may have
a l t e r n a t i v e u s e s (Samuelson 1976). Two q u e s t i o n s
a d d r e s s e d a r e (1) how f a c t o r s of p r o d u c t i o n ( e . g . ,
l a n d , l a b o r , c a p i t a l ) should be a l l o c a t e d t o
f i r m s , and ( 2 ) how t h e goods produced by f i r m s
should be d i s t r i b u t e d t o consumers.
Substitution
i n r e c r e a t i o n c h o i c e i s a m a t t e r of consumer
b e h a v i o r , s o t h e r e l e v a n t c o n t r i b u t i o n of
economics i s t h e t h e o r y of consumer demand, which
a l s o h a s a s i m i l a r development i n t h e t h e o r y of
t h e f i r m . The economic p o i n t of view assumes t h a t
p r i c e s a r e t h e key mechanism r e g u l a t i n g t h e
consumer's and f i r m ' s a l l o c a t i o n of s c a r c e
resources.
A d e c i s i o n n o t t o c l o s e t h e s i t e may be
s i m i l a r l y misguided. E s t i m a t e s of t h e n e t
b e n e f i t s t o t h e p u b l i c of a government-operated
s i t e w i l l be t o o h i g h i f an uncongested nearby
s u b s t i t u t e i s i g n o r e d . Assume t h a t c l o s i n g t h e
s i t e w i l l r e q u i r e a l l u s e r s t o t r a v e l one m i l e
f a r t h e r up t h e canyon. The l o s s of b e n e f i t caused
by t h e c l o s u r e i s o n l y t h e c o s t of t h e added one
m i l e of t r a v e l . Of c o u r s e , i f t h e second s i t e h a s
i n s u f f i c i e n t c a p a c i t y , t h e r e w i l l be a l o s s of
q u a l i t y a n d / o r an i n c r e a s e i n p r i c e t h a t w i l l
a f f e c t t h e outcome of t h e c l o s u r e .
The t h e o r y i s w e l l known and i s o n l y summarized here. A f u l l exposition i s available i n ,
f o r example, Henderson and Quandt (1980). The
Thus, t h e demand f o r a r e c r e a t i o n s i t e o r
a c t i v i t y i s a f u n c t i o n of i t s p r i c e p l u s t h e
p r i c e s of a l l o t h e r goods and s e r v i c e s i n t h e
economy. I f demand and s u b s t i t u t i o n a r e t o be
t r a c t a b l e i n t h i s overwhelmingly complex frameComplex
work, some s i m p l i f i c a t i o n i s r e q u i r e d .
demand f u n c t i o n s can b e a c c u r a t e l y r e p r e s e n t e d
through t h e u s e of " f l e x i b l e f u n c t i o n a l forms"
(Simmons and Weiserbs 1979). The demand f u n c t i o n s
themselves can be s i m p l i f i e d through assumptions
about s e p a r a b i l i t y i n t h e u t i l i t y f u n c t i o n ( B a r t e n
1977, Powell 1974). I f t h e u t i l i t y f u n c t i o n i s
weakly s e p a r a b l e , a l l goods can be p a r t i t i o n e d
i n t o a s e t of m u t u a l l y e x c l u s i v e subgroups such
t h a t t h e MRS between two goods w i t h i n a group i s
independent of t h e q u a n t i t y consumed (and p r i c e )
of any good i n a n o t h e r subgroup, h o l d i n g u t i l i t y
c o n s t a n t . T h i s a l l o w s consumer d e c i s i o n s t o be
s t r u c t u r e d i n terms of a n e s t e d u t i l i t y t r e e
(Deaton and Muellbauer 1980), which i n t u r n
e n a b l e s t h e e s t i m a t i o n of c o n d i t i o n a l demand
functions.
What t h i s means i s t h a t consumer d e c i s i o n s
can be viewed a s s e q u e n t i a l (Katzner 1970). A t
one l e v e l , t h e consumer d e c i d e s how much income t o
a l l o c a t e t o each of s e v e r a l groups of goods.
Given t h e a l l o c a t i o n of income, s a y , t o a group of
r e c r e a t i o n s i t e s , c h o i c e s among t h o s e s i t e s a r e
independent of c h o i c e s among goods i n o t h e r
groups. I f t h e p a r t i a l u t i l i t y f u n c t i o n
d e s c r i b i n g how p r e f e r e n c e s a r e o r d e r e d w i t h i n t h e
group i s homothetic ( S i l b e r b e r g 1978, p. 254),
t h e n p r o p o r t i o n a l a l l o c a t i o n s of income among
goods w i t h i n t h e group a r e a l s o independent of t h e
amount of income a l l o c a t e d t o t h e group. T h i s
framework l e a d s t o a n e s t e d c o n d i t i o n a l c h o i c e
s t r u c t u r e t h a t i n c l u d e s a s s p e c i a l c a s e s t h e EBA
model and t h e s e q u e n t i a l model of Krumpe and
McLaughlin (1982).
Such assumptions and c o n d i t i o n s g r e a t l y
s i m p l i f y t h e a n a l y s i s of r e c r e a t i o n c h o i c e
b e h a v i o r . U n f o r t u n a t e l y , t h e s e assumptions a r e
t o o o f t e n hidden and unrecognized.
These h i d d e n
assumptions d e s c r i b e t h e world t o which t h e model
a p p l i e s . The i m p o r t a n t q u e s t i o n i s how f a r t h a t
world i s from t h e r e a l one. T h i s l i n e of economic
r e a s o n i n g r e v e a l s t h e k i n d s of q u e s t i o n s t h a t
s h o u l d be asked when v a r i o u s t y p e s of models a r e
used.
It a l s o p r o v i d e s a framework f o r d e f i n i n g
and answering q u e s t i o n s about s u b s t i t u t i o n . When
we d e c i d e t o c o n s i d e r o n l y a f i n i t e s e t of
s u b s t i t u t e s i n a model, s a y a group of s t a t e
p a r k s , we have made a s t r o n g i m p l i c i t assumption
a b o u t t h e u n d e r l y i n g c h o i c e p r o c e s s . Would i t n o t
be b e t t e r , through r e s e a r c h , t o d i s c o v e r t h e
s t r u c t u r e of t h e c h o i c e p r o c e s s , and t h e n t o a s k
what k i n d s of models and s e t s of s u b s t i t u t e s a r e
i m p l i e d t h e r e b y ? T h i s d i s c o v e r y of t h e u n d e r l y i n g
c h o i c e p r o c e s s e s i s t h e o b j e c t i v e of r e l e v a n t
r e s e a r c h i n psychology, geography, and r e c r e a t i o n .
I n t e g r a t i o n of t h i s work w i t h i n t h e o r g a n i z e d
framework of economics would be a major
c o n t r i b u t i o n . P r o g r e s s i s hampered by a l a c k of
t h e d a t a needed t o v e r i f y and i n t e r r e l a t e t h e
theoretical propositions.
Transportation
Transportation researchers appear t o be a t
t h e f o r e f r o n t of a p p l i e d c h o i c e m o d e l l i n g . Most
of t h e work h a s c e n t e r e d around mode c h o i c e and
t h e m u l t i n o m i a l l o g i t model o r v a r i a t i o n s t h e r e o f .
T r a n s p o r t a t i o n r e s e a r c h e r s seem t o have been
s u c c e s s f u l i n i n t e g r a t i n g economic, g e o g r a p h i c ,
and p s y c h o l o g i c a l v a r i a b l e s i n t o formal c h o i c e
models t h a t c a n be e m p i r i c a l l y e s t i m a t e d and
t e s t e d . Domencich and McFadden (1975) and S t o p h e r
and Meyburg (1975) d e r i v e t h e MNL model i n t h e
t r a n s p o r t a t i o n c o n t e x t based upon u t i l i t y
maximization. Much of t h e r e c e n t work i n
t r a n s p o r t a t i o n a d d r e s s e s some of t h e u n d e s i r a b l e
p r o p e r t i e s of t h i s model, i n c l u d i n g assumptions
about s u b s t i t u t i o n . T h i s h a s l e d t o a v a r i e t y of
models w i t h d i f f e r e n t assumptions about s u b s t i t u t i o n , i n c l u d i n g n e s t e d l o g i t models, p r o b i t
models, and g e n e r a l i z e d extreme v a l u e models (Chu
1981, Amemiya 1981).
A r e c e n t book by Anas (1982) p r o v i d e s a
framework f o r t h e e s t i m a t i o n of c o n d i t i o n a l demand
f u n c t i o n s , based on a n e s t e d o r s e q u e n t i a l
d e c i s i o n p r o c e s s , a s deri.ved from assumptions of
s e p a r a b i l i t y i n t h e u t i l i t y function. H i s
approach p r o v i d e s t h e a n a l y t i c a l framework f o r
t r e a t m e n t of s u b s t i t u t i o n i n c o n d i t i o n a l and
n e s t e d c h o i c e models. These models have t h e
advantage of b e g i n n i n g w i t h assumptions about
i n d i v i d u a l s and t h e n g e n e r a t i n g a g g r e g a t e r e s u l t s
by combining t h e i n d i v i d u a l c h o i c e models under
v a r i o u s d i s t r i b u t i o n a l and s e p a r a b i l i t y assumpt i o n s . I n t h i s way t h e y c a n c a p t u r e t h e common
f e a t u r e s of i n d i v i d u a l decisionmaking p r o c e s s e s
without attempting t o "predict" individual
b e h a v i o r . Recent r e s e a r c h h a s e x p l o r e d i n t e r p e r s o n a l v a r i a t i o n s i n t h e c h o i c e s e t (Richardson
1982), and t h e e f f e c t s of a number of p o s s i b l e
m i s s p e c i f i c a t i o n problems on t r a v e l demand
f o r e c a s t i n g (Williams and O r t u z a r 1982). The MNL
model h a s been a p p l i e d t o r e c r e a t i o n by Stopher
and Ergun (1979, 1982), P e t e r s o n and o t h e r s
(1982), and P e t e r s o n and o t h e r s (1983). S t y n e s
and P e t e r s o n (1984) p r o v i d e a g e n e r a l review of
l o g i t models, drawing c o n c l u s i o n s f o r a p p l i c a t i o n s
t o r e c r e a t i o n c h o i c e s . They, a s does Vickerman
(1978), s p e c i f i c a l l y d i s c u s s t h e independence of
i r r e l e v a n t a l t e r n a t i v e s (IIA) p r o p e r t y of t h e MNL
model i n t h e r e c r e a t i o n c o n t e x t .
CHOICE MODELING AND NESTED CHOICE STRUCTURE
The demand models t y p i c a l l y used i n
r e c r e a t i o n a r e g e n e r a l s h a r e models. They e x h i b i t
t h e I I A p r o p e r t y and imply s t r i c t assumptions
about s e p a r a b i l i t y i n t h e u t i l i t y f u n c t i o n . T h i s
means, i n g e n e r a l , t h a t adding o r d e l e t i n g an
o p t i o n w i l l n o t change t h e p r o p o r t i o n a l s h a r e s of
demand t o t h e o t h e r a l t e r n a t i v e s . For example,
l e t two e x i s t i n g p a r k s , A and B y each r e c e i v e 50
p e r c e n t of park u s e . The I I A p r o p e r t y i m p l i e s t h a t
adding a t h i r d p a r k , C , might reduce t o t a l p a r t i c i p a t i o n a t A and B y b u t t h e p r o p o r t i o n a l a l l o c a t i o n between A and B w i l l n o t change. Both w i l l
c o n t i n u e t o r e c e i v e h a l f of t h e p a r t i c i p a t i o n
a l l o c a t e d t o A and B. C l e a r l y , t h i s i s r e a s o n a b l e
i n some s i t u a t i o n s and n o t i n o t h e r s . The key t o
p r o p e r c h o i c e modeling i s an u n d e r s t a n d i n g of
c h o i c e s t r u c t u r e , i n c l u d i n g t h e s e p a r a b i l i t y and
form of t h e u t i l i t y f u n c t i o n and t h e i m p l i c a t i o n s
for substitution.
The t y p i c a l example used t o i l l u s t r a t e t h e
n
I I A problem comes from mode c h o i c e a n a l y s i s i n
t r a n s p o r t a t i o n p l a n n i n g . The o b j e c t i s t o p r e d i c t
how t r a v e l e r s between two l o c a t i o n s a l l o c a t e
themselves among a u t o m o b i l e , b u s , and r a p i d
t r a n s i t a s a f u n c t i o n of t h e c h a r a c t e r i s t i c s of
t h e t h r e e modes. Assume an a p p r o p r i a t e g e n e r a l
s h a r e model (such a s a l o g i t model) h a s been
developed, based on observed c h o i c e b e h a v i o r .
Assume a l s o t h a t a l l t h e b u s e s a r e r e d . NOW, t h e
planning a u t h o r i t y decides t o p a i n t h a l f t h e buses
b l u e and wants t o p r e d i c t t h e new d i s t r i b u t i o n of
r i d e r s . The a n a l y s t assumes t h a t r e d b u s e s
compete w i t h b l u e buses i n t h e same way t h a t buses
compete w i t h a u t o s and r a p i d t r a n s i t . I f , b e f o r e
t h e p a i n t i n g , t h e t h r e e modes each r e c e i v e d
o n e - t h i r d of t h e u s e , t h e model w i l l a l l o c a t e
one-fourth of t h e u s e t o each mode a f t e r t h e
painting. If the riders a r e indifferent t o color,
o r l e s s concerned about c o l o r t h a n about o t h e r
things, they w i l l continue t o a l l o c a t e one-third
t o b u s e s . The new s i t u a t i o n w i l l be 113 t o a u t o s ,
113 t o r a p i d t r a n s i t , 116 t o r e d b u s e s and 116 t o
b l u e b u s e s , w h i l e t h e model p r e d i c t s 114 t o each.
The m i s t a k e a r i s e s b e c a u s e t h e a n a l y s t f a i l s
t o u n d e r s t a n d t h e r o l e of c o l o r i n mode s u b s t i t u t i o n . Red b u s e s and b l u e b u s e s were s e e n by t h e
r i d e r s a s p e r f e c t s u b s t i t u t e s b u t were assumed by
t h e a n a l y s t t o be i m p e r f e c t s u b s t i t u t e s a t t h e
same l e v e l a s b u s e s v e r s u s a u t o s . T e c h n i c a l l y
s p e a k i n g , t h i s problem i s caused by l a c k of
independence among t h e random e l e m e n t s of u t i l i t y .
When some a l t e r n a t i v e s a r e more s i m i l a r t h a n
o t h e r s , t h e random elements w i l l be c o r r e l a t e d and
t h e I I A assumption w i l l be v i o l a t e d . The t r o u b l e
i s , i t i s p r a c t i c a l l y impossible i n r e c r e a t i o n
a p p l i c a t i o n s t o c o r r e c t l y i d e n t i f y s e t s of
balanced s u b s t i t u t e s w i t h o u t much more t h e o r y and
i n f o r m a t i o n t h a n now a v a i l a b l e .
Other c o n d i t i o n s a l s o c a u s e problems.
D i f f e r e n t s i t e s may a t t r a c t d i f f e r e n t mixes of
a c t i v i t y and d i f f e r e n t mixes of p r e f e r e n c e f o r
s i t e a t t r i b u t e s . Mixing t h e s e p r o c e s s e s v i o l a t e s
t h e I I A assumption, because t h e p a r a m e t e r s and
p e r h a p s even t h e s p e c i f i c a t i o n i n a model w i l l
change f o r d i f f e r e n t s u b s e t s of a g i v e n s e t of
a l t e r n a t i v e s i t e s . The s o l u t i o n i s t o i s o l a t e t h e
s e p a r a t e components of t h e mixed p r o c e s s .
I n t h e mode c h o i c e example t h e a n a l y s t saw
t h e s i t u a t i o n a s f i g u r e 1, i n which r i d e r s f a c e
f o u r s u b s t i t u t a b l e a l t e r n a t i v e s . However, t h e
r i d e r s saw it a s f i g u r e 2, i n which t h e y f a c e , a t
one l e v e l of c h o i c e , t h r e e competing a l t e r n a t i v e s .
Given t h a t bus i s chosen, a new l e v e l of c h o i c e i s
c o n f r o n t e d : r e d o r b l u e . The p r e f e r e n c e s t o which
t h e red versus blue choice r e l a t e s a r e d i f f e r e n t
t h a n t h e p r e f e r e n c e s t h a t govern, i n t h i s c a s e ,
c h o i c e of t r a v e l mode. The two s e t s of
p r e f e r e n c e s may o r may n o t d i f f e r i n r e l a t i v e
importance. I n t h e example, c o l o r was assumed t o
be unimportant t o mode c h o i c e . I n any c a s e , a
d i f f e r e n t u t i l i t y p r o c e s s a p p l i e s t o t h e c h o i c e of
mode t h a n a p p l i e s t o t h e c h o i c e of c o l o r . The
d e c i s i o n s need t o b e s e p a r a t e d , because w h i l e bus
s u b s t i t u t e s f o r a u t o and t r a n s i t , b l u e does n o t .
Choice
Transit
Blue Bus
Red Bus
F i g u r e 1.--The Red Bus
simultaneous choice.
-
Blue Bus problem a s a
F i g u r e 2.--The Red Bus - Blue Bus problem
a s a nested choice.
I n t h e extreme c a s e , p r e f e r e n c e s might b e
hierarchical.
Choices, c h o i c e s e t s , and s u b s t i t u t i o n would have t o b e n e s t e d i n terms of t h e
h i e r a r c h y of o b j e c t i v e s . For example, people have
o b j e c t i v e s t h a t r e l a t e t o c o m f o r t , convenience,
and e s t h e t i c s , i n c h o i c e of t r a n s p o r t a t i o n mode.
They a l s o have o b j e c t i v e s t h a t r e l a t e t o c o s t ,
s a f e t y , and a c c e s s t o d e s i r e d d e s t i n a t i o n . A mode
t h a t does n o t s e r v e t h e d e s t i n a t i o n i s n o t
a c c e p t a b l e , no m a t t e r how cheap o r p r e t t y i t may
be. Given two modes t h a t s e r v e t h e d e s t i n a t i o n ,
c h o i c e w i l l probably be i n f l u e n c e d by s i g n i f i c a n t
d i f f e r e n c e s i n s a f e t y . An abnormally h i g h r i s k of
b e i n g k i l l e d o r i n j u r e d c a n n o t b e compensated by
d i f f e r e n c e s i n c o s t , c o m f o r t , convenience,
e s t h e t i c s , e t c . T h i s approach l e a d s t o a n e s t e d
c o n d i t i o n a l model of r e c r e a t i o n c h o i c e b e h a v i o r
t h a t might t a k e t h e s e q u e n t i a l form proposed by
Krumpe and McLaughlin ( 1982)
.
F i g u r e 3 i l l u s t r a t e s a h y p o t h e t i c a l (and
h i g h l y s i m p l i f i e d ) r e c r e a t i o n c h o i c e p r o c e s s . The
o b j e c t i v e of t h e a n a l y s t i s t o p r e d i c t
participation i n fishing a t five different sites.
Two of t h e s i t e s ( 3 and 4) a r e r e s t r i c t e d t o f l y
f i s h i n g o n l y , w h i l e t h e o t h e r t h r e e (1, 2 and 5)
a r e u n r e s t r i c t e d . Use of a n I I A g e n e r a l s h a r e
model, which t r e a t s a l l f i v e s i t e s a s s u b s t i t u t e s ,
s u f f e r s from t h e "red bus-blue bus" d i s e a s e .
0-0
Choice
Death
&
Life
Leisure
I
*
Chotce
Other.
Chotce
c
Ftshing
Choice
L
WarrnWater
Choice
I
Site 1
Site 1
Site 2
Site 2
Site 5
Site 5
A
Choice
(choice)
F i g u r e 3.--A
n e s t e d f i s h i n g s i t e c h o i c e example.
D i f f e r e n t f i s h i n g methods ( e . g . f l y f i s h i n g )
i n v o l v e d i f f e r e n t s i t e c h o i c e r u l e s , because t h e
r e q u i r e m e n t s of t h e methods and t h e o b j e c t i v e s of
t h e f i s h e r m e n d i f f e r . E f f e c t i v e modeling r e q u i r e s
exposure of t h e n e s t e d c o n d i t i o n a l s t r u c t u r e i n
t h e choice process.
It i s t h e n n e c e s s a r y t o
s t r a t i f y models and p o p u l a t i o n subgroups i n terms
of t h a t s t r u c t u r e . On f a c e v a l u e i t i s t h e same
o l d problem of " i n t e r a c t i o n " commonly e n c o u n t e r e d
i n s o c i a l and b e h a v i o r a l r e s e a r c h ( S o n q u i s t 1970).
I n terms of economic t h e o r y , i t a r i s e s i n
r e c r e a t i o n c h o i c e b e h a v i o r because of 1)
c o n d i t i o n s of s e p a r a b i l i t y i n t h e i n d i v i d u a l
u t i l i t y f u n c t i o n , 2) d i f f e r e n c e s among i n d i v i d u a l
u t i l i t y f u n c t i o n s , and 3) s i m i l a r i t i e s and
d i f f e r e n c e s among t h e c h o i c e o p t i o n s .
Using a g e n e r a l s h a r e model t o p r e d i c t demand
f o r a proposed new f l y - o n l y s i t e ( s i t e 6) would
v i o l a t e t h e IIA assumption because of mixed
p r o c e s s e s and mixed l e v e l s . S i t e 6 competes w i t h
s i t e s 1 , 2 , and 5 o n l y f o r people who have decided
on f l y f i s h i n g . S i t e s 3 , 4 and 6 compete, given
t h a t t h e c h o i c e i s t o go t o a f l y - o n l y s i t e . F l y
f i s h i n g competes w i t h b a i t and s p i n f i s h i n g a t a
d i f f e r e n t l e v e l . The problem i s c o r r e c t e d i n p a r t
by s t r a t i f y i n g by f l y f i s h e r m e n , b u t f l y f i s h e r m e n
who s e l e c t a f l y - o n l y s i t e may f o l l o w a d i f f e r e n t
u t i l i t y p r o c e s s , g i v e n t h i s c h o i c e , t h a n t h o s e who
go t o a g e n e r a l s i t e . The problem i s u l t i m a t e l y
solved o n l y by modeling each d e c i s i o n l e v e l
c o n d i t i o n a l on t h e outcome of t h e h i g h e r l e v e l .
It i s noteworthy t h a t an e a r l y concern w i t h t h i s
t y p e of problem i s i m p l i c i t i n t h e Burt and Brewer
Model (1971). They c l a s s i f i e d t h e i r s i t e s i n t o
subgroups of p e r f e c t s u b s t i t u t e s w i t h i m p e r f e c t
s u b s t i t u t i o n among subgroups.
D i r e c t Evidence From S i t e Choice Modeling i n
Urban F o r e s t R e c r e a t i o n
I n a r e c e n t s t u d y , P e t e r s o n and o t h e r s (1983)
found t h e I I A p r o p e r t y t o b e v i o l a t e d i n a n
a p p l i c a t i o n of a n MNL model t o urban f o r e s t
r e c r e a t i o n s i t e c h o i c e . The c h o i c e s e t c o n t a i n e d
21 s i t e s i n t h e Chicago m e t r o p o l i t a n a r e a ,
i n c l u d i n g two i n d o o r c o n s e r v a t o r i e s , a l a r g e
arboretum, a l a r g e b o t a n i c a l g a r d e n , and 17 f o r e s t
p r e s e r v e a r e a s . V a r i a b l e s used i n t h e model were
t r a v e l d i s t a n c e ( p r i c e ) and f o u r p e r c e i v e d s i t e
a t t r i b u t e s : stimulating-educational, quiet, safe,
and f o r e s t e d . When t h e model was e s t i m a t e d f o r
d i f f e r e n t s u b s e t s of t h e 21 s i t e s , t h e d i s t a n c e
c o e f f i c i e n t was found t o be q u i t e s t a b l e .
Coefficients f o r t h e perceived s i t e a t t r i b u t e s
f l u c t u a t e d c o n s i d e r a b l y , however, w i t h t h o s e f o r
" q u i e t " and " f o r e s t e d " a c t u a l l y v a r y i n g i n s i g n .
T h i s i s prima f a c i a e v i d e n c e of v i o l a t i o n of t h e
IIA p r o p e r t y , and p l a u s i b l e c a u s e s were d i s c u s s e d .
Apparently, t h e s p e c i f i e d choice s e t contained
s i t e s t h a t represented d i f f e r e n t l e v e l s i n a
nested choice process.
Consequently, d i f f e r e n t
s i t e s tended t o a t t r a c t p e o p l e w i t h d i f f e r e n t
purposes. While t h e model presumed t h e s e s i t e s t o
obey s p e c i f i c s u b s t i t u t i o n r u l e s , t h e y c l e a r l y d i d
not.
Subsequently L i n (1983) used t h e same d a t a t o
e s t i m a t e a n e s t e d c h o i c e model. Based on t h e
p e r c e i v e d a t t r i b u t e s c o r e s , L i n used c l u s t e r
a n a l y s i s t o p a r t i t i o n t h e 21 s i t e s i n t o t h r e e
groups. Within a group t h e s i t e s were p e r c e i v e d
a s more s i m i l a r t h a n among t h e groups. It i s n o t
s u r p r i s i n g t h a t t h e arboretum and b o t a n i c a l garden
formed one group, t h e c o n s e r v a t o r i e s formed a
second group, and t h e f o r e s t p r e s e r v e s made up t h e
t h i r d group. These groups were t h e n used t o s e t
up a n e s t e d c h o i c e p r o c e s s a s i n f i g u r e 4 . A t t h e
f i r s t d e c i s i o n l e v e l , t h e consumer f a c e s a c h o i c e
among c o n s e r v a t o r y , b o t a n i c a l garden, o r f o r e s t
p r e s e r v e . These r e p r e s e n t d i f f e r e n t a c t i v i t y
types, perhaps s e l e c t e d t o s a t i s f y d i f f e r e n t
o b j e c t i v e s . A t t h e second l e v e l t h e a l t e r n a t i v e s
depend on t h e outcome of t h e f i r s t .
In t h e e a r l i e r s t u d y , P e t e r s o n and o t h e r s
used a s i m u l t a n e o u s c h o i c e model t h a t f o r c e d
s u b s t i t u t i o n across those hypothetical decision
l e v e l s . When t h e mix was changed, t h e model had
t o change. L i n used t e s t s - d e v e l o p e d by McFadden
and o t h e r s (1976) t o r e j e c t t h e h y p o t h e s i s t h a t
DIRECTIONS FOR FUTURE RESEARCH
I,,;,,,,,,,,,1
Botancial Garden
(choice)
F i g u r e 4.--Lin's n e s t e d urban r e c r e a t i o n
s i t e c h o i c e model.
t h e 21 a l t e r n a t i v e s obey t h e I I A p r o p e r t y r e q u i r e d
by t h e s i m u l t a n e o u s c h o i c e model. He t h e n
e s t i m a t e d t h e n e s t e d l o g i t c h o i c e model w i t h t h e
s t r u c t u r e i l l u s t r a t e d i n f i g u r e 4 . The
e x p l a n a t o r y power was improved s i g n i f i c a n t l y and
t h e meaning of t h e model was improved. Within t h e
c o n d i t i o n a l g r o u p s , t h e I I A p r o p e r t y was obeyed.
Between t h e groups, d i f f e r e n t b u t meaningful
c h o i c e p r o c e s s e s were s e e n t o be o p e r a t i n g .
I n d i r e c t Evidence From a Wilderness S i t e Demand
Model
I n an e a r l i e r s t u d y , P e t e r s o n and o t h e r s
(1982) developed a site-demand model f o r t h e
Boundary Waters Canoe Area Wilderness (BWCAW).
The model was s t r a t i f i e d by 12 t y p e s of u s e
o c c u r r i n g i n t h e same w i l d e r n e s s . The d a t a
c o n s i s t e d of a census of t r i p s f o r th'e p e r i o d 1974
through 1977. No a t t e m p t was made t o i n c l u d e
s u b s t i t u t e s i t e s f o r any of t h e 12 t y p e s of u s e .
The model simply d i s t r i b u t e s t r i p s among o r i g i n s
under t h e assumption of no s u b s t i t u t e s .
The d i s t a n c e e l a s t i c i t y of demand ( p e r c e n t
change i n demand p e r c e n t change i n d i s t a n c e ) was
found t o d i f f e r by t y p e of u s e . These d i f f e r e n c e s
d e m o n s t r a t e t h a t d i f f e r e n t demand p r o c e s s e s a r e a t
work among t h e d i f f e r e n t t y p e s of u s e . The
d i f f e r e n t u s e r groups have d i f f e r e n t o b j e c t i v e s ,
t h e i r o n - s i t e a c t i v i t i e s have d i f f e r e n t i n p u t
r e q u i r e m e n t s , and t h e y f a c e d i f f e r e n t s e t s of
s u b s t i t u t e s i t e s . T h e r e f o r e , t h e y respond
d i f f e r e n t l y t o t r a v e l c o s t and, by i m p l i c a t i o n , t o
on-site a t t r i b u t e s .
I n t h i s p a p e r we have a t t e m p t e d t o expose and
m o t i v a t e i n t e r e s t i n a major problem i n r e c r e a t i o n
c h o i c e , t h a t of s u b s t i t u t i o n i n r e c r e a t i o n c h o i c e
behavior.
It i s an i m p o r t a n t q u e s t i o n i n many
a s p e c t s of r e c r e a t i o n r e s o u r c e management and
r e s e a r c h , y e t i t i s p o o r l y understood. Toward
c o r r e c t i o n of t h i s inadequacy, we have t r i e d t o
d e f i n e t h e q u e s t i o n and review v a r i o u s l i n e s of
r e s e a r c h t h a t seem t o b e converging on i t , a l b e i t
from d i f f e r e n t p o i n t s of view and w i t h d i f f e r e n t
languages. F i n a l l y , drawing on t h i s r e s e a r c h , we
have framed t h e s u b s t i t u t i o n problems i n terms of
n e s t e d c h o i c e s t r u c t u r e , which we i l l u s t r a t e w i t h
h y p o t h e t i c a l and e m p i r i c a l examples.
The problem of s u b s t i t u t i o n i s s t i l l f a r from
r e s o l v e d . Q u e s t i o n s a r i s e which p o i n t d i r e c t i o n s
f o r much-needed f u t u r e r e s e a r c h . One i m p o r t a n t
need i s f o r r e s e a r c h e r s and managers t o r e c o g n i z e
t h a t t h e d e c i s i o n s t h e y make about model
s p e c i f i c a t i o n s and s u b s t i t u t e s e t s i n demand and
p a r t i c i p a t i o n a n a l y s e s c a r r y some i m p o r t a n t
implied assumptions about c h o i c e b e h a v i o r . These
assumptions should be exposed and c h a l l e n g e d .
A second i m p o r t a n t need i s f o r b e t t e r
i n t e g r a t i o n of t h e r e l a t e d c o n c e p t s of s e v e r a l
d i s c i p l i n e s i n t o a t h e o r y of r e c r e a t i o n c h o i c e .
Well-developed b o d i e s of l i t e r a t u r e i n psychology,
geography, economics, and t r a n s p o r t a t i o n , f o r
example, p r o v i d e t h e b a s i s f o r a powerful
t h e o r e t i c a l framework. Once i n t e g r a t e d , such a
framework needs t o b e made o p e r a t i o n a l i n terms o f
p r a c t i c a l models and r e s e a r c h methods. F u r t h e r ,
t h e c o n c e p t s need t o b e t u r n e d i n t o f a c t s about
r e c r e a t i o n c h o i c e b e h a v i o r . What a r e t h e n e s t i n g
s t r u c t u r e s t h a t describe t h e a c t u a l choice
p r o c e s s e s of d i f f e r e n t t y p e s of people i n
r e c r e a t i o n c h o i c e s i t u a t i o n s ? What d e c i s i o n r u l e s
do t h e y f o l l o w ? What a r e t h e p r a c t i c a l c h o i c e
s e t s t h a t a r e c o n s i d e r e d when d e c i s i o n s a r e made?
Are t h e s e ad hoc q u e s t i o n s t h a t must be
e n c o u n t e r e d i n e v e r y p r a c t i c a l o r r e s e a r c h problem
o r can e m p i r i c a l r e s e a r c h b e g e n e r a l i z e d i n t o
u s e f u l r u l e s and p r i n c i p l e s ?
Depending on t h e o b j e c t i v e s , s t i l l more work
may be needed i n e x p l a i n i n g t h e d e c i s i o n p r o c e s s e s
t h u s r e v e a l e d . Are we s a t i s f i e d w i t h t h e
d e s c r i p t i v e approach of r e v e a l e d p r e f e r e n c e , o r i s
t h e r e a need t o d e l v e i n t o m o t i v a t i o n a l f a c t o r s
t h a t l i e behind and a r e t h e o b j e c t of r e c r e a t i o n
c h o i c e ? The work of Morishima (1959), L a n c a s t e r
(1966), and Becker (1965) p r e s e n t s a n i n t e r e s t i n g
e x t e n s i o n of t h e powerful and well-developed
t h e o r y of economics, which seems t o be r e a c h i n g
toward behavioral. r e s e a r c h i n t h e psychology of
r e c r e a t i o n choice.
A t f i r s t g l a n c e t h e r e a p p e a r s t o be l a c k of
consensus among r e s e a r c h e r s from d i f f e r e n t
d i s c i p l i n e s on t h e m e r i t s of f u r t h e r emphasis on
t h e s e b e h a v i o r a l a s p e c t s . For e s t i m a t i o n of
demand, t h e b e n e f i t s a t l e a s t i n c l u d e exposure of
t h e assumptions implied by v a r i o u s demand s p e c i f i cations.
I n g e n e r a l , though, t h e q u e s t i o n should
be asked i n t h e c o n t e x t of t h e purpose t o be
served. D i f f e r e n t purposes require d i f f e r e n t
k i n d s of i n f o r m a t i o n . The i n f o r m a t i o n n e e d e d t o
answer q u e s t i o n s a s k e d by e c o n o m i s t s , f o r example,
may b e d i f f e r e n t t h a n i s needed t o s a t i s f y
d e s i g n e r s o r p l a n n e r s . I n d e e d , t h i s may b e a n
example of t h e most s e r i o u s o b s t a c l e s t o
m u l t i - d i s c i p l i n a r y i n t e g r a t i o n o f a t h e o r y of
s u b s t i t u t i o n i n recreation choice. D i f f e r e n t
d i s c i p l i n e s , d i f f e r e n t s t u d i e s , and d i f f e r e n t
a p p l i e d c o n t e x t s seem t o b e a n s w e r i n g m i x t u r e s o f
d i f f e r e n t q u e s t i o n s which h a v e n o t b e e n a s k e d
c l e a r l y o r a d e q u a t e l y s e p a r a t e d . One o f t h e most
n e e d e d c o n t r i b u t i o n s may s i m p l y b e t o i d e n t i f y t h e
different questions being s t i r r e d i n the research
p o t , t h e a p p l i e d c o n t e x t s from which t h e y d e r i v e ,
and t h e k i n d s of a n s w e r s t h e y r e q u i r e .
C h r i s t i a n s e n , J . E . and D . R. Y o e s t i n g . The
s u b s t i t u t a b i l i t y concept: a need f o r f u r t h e r
d e v e l o p m e n t . J . of L e i s . Res. 9(3):188-207;
1977.
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