Reconsidering the Fundamental Contributions of Fisher and Neyman on Experimentation and Sampling Author(s): Stephen E. Fienberg and Judith M. Tanur Source: International Statistical Review / Revue Internationale de Statistique, Vol. 64, No. 3 (Dec., 1996), pp. 237-253 Published by: International Statistical Institute (ISI) Stable URL: http://www.jstor.org/stable/1403784 Accessed: 19/10/2008 12:47 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. 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InternationalStatisticalInstitute the Fundamental Contributions Reconsidering on and of Fisher Experimentation Neyman and Sampling Stephen E. Fienberg1 and Judith M. Tanur2 1Departmentof Statistics, CarnegieMellon University,Pittsburgh,PA 15213-3890, USA 2Departmentof Sociology, State University of New Yorkat StonyBrook,Stony Brook,NY 11794-4356, USA Summary R.A. Fisher and Jerzy Neyman are commonly acknowledged as the statisticians who provided the basic ideas that underpin the design of experiments and the design of sample surveys, respectively. In this paper, we reconsider the key contributions of these great men to the two areas of research. We also explain how the controversy surrounding Neyman's 1935 paper on agricultural experimentation in effect led to a split in research on experiments and on sample surveys. Stratification. Designof samplesurveys;Randomization; Designof experiments; Key words:Clustering; 1 Introduction The 1920s and 1930s marka criticalperiodin the developmentof statistics.Much of the modern theory of estimationand statisticaltesting emergedfrom paperspublishedduringthis period by two of the most importantstatisticiansof the century,RonaldAylmerFisherandJerzyNeyman. In many ways, the theoreticalwork of these two greatmen was stimulatedby practicalproblemsthey encountered in their day-to-day statisticalwork of agriculturalexperimentationand, later for Neyman, the sampling of humanpopulations.Moreovermany believe that their greatestaccomplishmentswere not in the realmof theoriesof inferencebutratherin theirarticulationof theoryand principlesunderpinning the two key modernmethods for the scientific collection of data-randomized experiments and randomsampling. In connection with a largerprojecton experimentsand sample surveys, and in partstimulatedby the recent occasion of the 100th anniversaryof Neyman's birth,we have rereadmuch of the work of both Fisher and Neyman in the areasof samplingand experimentation.Ourstory for both Fisher and Neyman begins with the work thatled to their 1923 paperson agriculturalexperimentation.For Neyman, this workcontinuedlargelyin the directionof samplingand culminatedin his now famous 1934 paper on the topic. Despite the many contributionsof others to the technical developmentof sampling in the period from 1900 to 1925, Neyman's 1934 paper played a pivotal role in turning the dry mathematicsof expectations into real sampling plans for actual randomly selected large scale surveys. For Fisher,his 1923 paperled to furtherpioneeringwork in experimentaldesign that culminatedin the publicationof his 1935 book, The Design of Experiments.Fisher's book played a catalytic role in the actual use of randomizationin controlled experimentsthat is similar to the role Neyman's 1934 paperplayed in the use of methodsfor randomsampling.The year 1935 was a 238 and J.M. TANUR S.E. FIENBERG criticalone in the developmentsin the fields of experimentationand sampling,not simply because of the publicationof Fisher'sbook but also becauseof a majorcontroversybetweenFisherandNeyman engenderedby Neyman's (1935) paper on agriculturalexperimentation.Because of the bitterness that grew out of this dispute (and a related one between Fisher on the one hand and Neyman and Pearson on the other,over tests of hypotheses and then later over confidenceintervals),Fisher and Neyman were never able to bring their ideas togetherand benefit from the fruitfulinteractionthat would likely have occurredhad they done so. And in the aftermath,Neyman stakedout intellectual responsibilityfor samplingwhile Fisherdid the same for experimentation.It was in partbecause of this rift between Fisher and Neyman that the fields of sample surveys and experimentationdrifted apart. In the next section, we begin with Neyman'simportant1923 paperon agriculturalexperimentation, and we remind the reader of the interrelatednature of fundamentalideas on experiments and surveys and the pivotal role that randomizationplayed in both areas. Then our narrativeproceeds by interweaving accounts of the work by Fisher and Neyman on experimentationand sampling, and controversiesthat surroundedthem. Our accountculminateswith the clash between Fisher and Neyman over ideas in Neyman's 1935 paper.Throughoutwe include relevantbiographicalmaterial assembledfrom a varietyof sources includingBox (1978, 1980), Lehmann& Reid (1982) and Reid (1982). 2 Parallels between Surveys and Experiments: Innovations in Neyman's 1923 Work on Agricultural Experimentation JerzyNeyman was bornof Polish parentsin 1894, in Bendery,which has been variouslylabeledas Rumania,Ukraine,and Moldavia because of the vicissitudes of border-drawingin EasternEurope. In 1912 he enteredthe Universityof Kharkov(which laterbecameMaximGorkiUniversity)to study mathematics.Finishing his undergraduatestudies in 1917, Neyman remainedat the University of Kharkovto begin to preparefor an academiccareer;he also received an appointmentas a lecturer at the KharkovInstituteof Technology.In the fall of 1920 he passed the examinationfor a Masters degree and became a lecturerat the University.Thusuntilafterhis 27th birthdayNeymanwas doubly isolated-both by living in a provincial city and by being part of an ethnic minority in that city. In the spring of 1921, learning that he was to be arrested,Neyman fled to the country home of a relative,where he supportedhimself by teachingthe childrenof peasants.In the summerhe returned to Kharkovand thence to Bydgoszcz in northernPoland,as partof an exchangeof nationalsbetween Russia and Poland agreed to at the end of the Russian-Polish War.In Bydgoszcz, Neyman went to work as "senior statistical assistant"at the National AgriculturalInstituteand it was there that he wrote two long papers on agriculturalexperimentationthat were published in 1923 in Polish (Splawa-Neyman, 1990 [1923a], 1925 [1923b]). In this section we focus primarilyon the first of these papers,and we returnto the second in Section 4, discussing its 1925 republicationin English. An excerpt of the 1923 paper(Splawa-Neyman, 1990 [1923a]) on experimentationwas recently translatedfrom the Polish originaland publishedin StatisticalScience, and in it we were especially struckby the importancethatrepeatedrandomsamplingplayed in Neyman's thinking.This seemed to us to foreshadow,at the very least, the use of randomizationin experimentation.Reid (1982, p. 44) quotes Neyman considerablylateras denying his priorityhere: ". .. I treatedtheoreticallyan unrestrictedlyrandomizedagriculturalexperimentandthe randomizationwas consideredas a prerequisiteto probabilistictreatmentof the results. This is not the same as the recognitionthat without randomizationan experimenthas little value irrespectiveof the subsequenttreatment.The latterpoint is due to Fisherand I consider it as one of the most valuableof Fisher'sachievements." The FundamentalContributionsof Fisher and Neymanon Experimentationand Sampling 239 Since we see one of the majorpurposesof experimentalrandomizationas the necessary precondition for probabilisticinferencefrom the results, we wouldjoin Rubin (1990, p. 477) in saying that had Neyman later claimed priorityratherthan denying it, we would have had no reason to quarrel with that claim. Rubin (1990) also remindsus that the use of randomizationwas "in the air"in the early 1920s, citing Student(1923, pp. 281-282) and Fisher & MacKenzie(1923, p. 473). There is, however, anotherimportantfeatureof Neyman's first paperon the topic of agricultural experimentationwe think especially worthy of note. For a numberof years, we have pursuedthe parallels and linkages between surveys and experiments(e.g., see Fienberg & Tanur,1987, 1988, 1989) and, in particular,Fisher's and Neyman's roles as progenitorsof ideas in both areas.Although in fact surveys and experimentshad developed very long and independenttraditionsby the startof the 20th century, it was only with the rise of ideas associated with mathematicalstatistics in the 1920s thatthe tools for majorprogressin these areasbecame available.The key intellectualidea was the role of randomizationor randomselection, both in experimentationand in sampling, and both Neyman and Fisherutilized this idea, althoughin differentways. But then, as now, it is clear thatone can adaptthe ideas from one field to the otherand that one can profitablylink them, as in sampling embedded within experimentsor experimentsembeddedwithin surveys. Neyman's first 1923 paperon experimentaldesign embodies this sort of adaptation.He conceptualizes the assignmentof treatmentsto units in an experimentas the drawingwithoutreplacementof balls from urns, one urnfor each treatment.These urnshave the special propertythatthe removalof a ball (representingthe outcome of an experimentalunit) from one urn causes it to disappearfrom the otherurnsas well. Thus Neyman shows thatwhen thereis a finite pool of experimentalunits that need to be assigned to treatments,the randomassignmentof units to treatmentsis exactly parallel to the randomselection of a sample from a finite population.Hence, when the numberof units used in an experimentis a large fractionof the units in the population,a finite populationcorrectionmust be used in an experiment,just as it is in a sample survey. The parallel between experimentsand sampling is particularlyclose in this case. Nevertheless,all but a few moderninvestigatorshave lost sight of the paralleland fail to take advantageof insights offered in the parallelliterature. 3 Fisher's Initial Contributions to the Design of Experiments in the 1920s While it is only recently that statisticiansand othershave rediscoveredNeyman's early contributions to the design of experiments,Fisher has long been recognized for the innovationhe broughtto the field. Fisherwas bornin 1890 in Londonandit was duringhis undergraduate yearsat Cambridgethathis interestsin eugenics, genetics, and biometrystimulatedhis interestin probabilityand statistics.After graduationin 1913, he taughtmathematicsand physics at a series of schools but pursuedresearchin both genetics and statistics and publishedhis first majorpaperson these topics. This work led, six years later,to a temporarystatisticalposition in 1919 at RothamstedExperimentStation,where the director,Sir John Russell, wantedsomeone who would be preparedto examine the accumulateddata on wheat yields from BroadbalkFields in orderto elicit furtherinformationthat might have been missed. Russell quickly recognized Fisher's genius and set aboutconvertingthe temporaryposition to a more permanentone (see Box, 1978, pp. 96-97). In 1921, Fisherpublishedthe firstof a series of papersentitled"Studiesin crop variation"intendedfor the JournalofAgriculturalScience', in which he presentedsome of his reanalysesof the Broadbalkdata. But it was in the second in this series of papers,writtenwith W.A. Mackenzie(1923), thatFisher'snew ideas on agriculturalexperimentation emerged. Fisher & Mackenzie (1923) contains two key innovations for the design of experiments: the 'Actually the third paper in the series appearednot in the Journal of AgriculturalScience but in the Philosophical Transactionsof the Royal Society, and without the title, "Studiesin crop variation".Two later paperswith Thomas Eden in 1927 and 1929 are labelled as V and VI. 240 S.E. FIENBERGand J.M. TANUR introductionof the analysisof variance,adaptedfromFisher's 1918 paperon Mendelianinheritance, and randomization.In fact, in introducingthe analysis of variance, the authors argue that it is conditionalon randomization: "Further,if all the plots are undifferentiated,as if the numbershad been mixed up and writtendown in randomorder,the averagevalue of each of the two partsis proportional to the numberof degrees of freedomin the variationof which it is compared."(p. 315) The spirit of this statementis not unlike that in Splawa-Neyman (1990 [1923a]): "The goal of a field experimentwhich consists of the comparisonof n varietieswill be regardedas equivalentto the problemof comparingthe numbersal, a2, . . ., an or theirestimatesby way of drawingseveralballs from an urn."(p. 467) Both speak of randomization,but in hypotheticalterms.There are dramatic differences between Fisher's and Neyman's treatmentsas well, with Fisher focusing on the actual dataanalysisandNeymanputtingmuchemphasison the mathematicalformulationof finitesampling and expectations. Neither Fisher nor Neyman actually wrote about the implementationof randomizationin 1923, however.In fact, as Cochran(1980, p. 18) notes in connectionwith the 2 x 12 x 3 factorialexperiment describedby Fisher & Mackenzie(1923): "No randomizationwas used in this layout. Following the procedurerecommendedat thattime, the layoutapparentlyattemptsto minimizethe errorsof thedifferencesbetween treatmentmeans by using a chessboardarrangementthat places different treatments near one another as far as is feasible. This arrangementutilizes the discovery from uniformitytrialsthatplots nearone anotherin a field tend to give closely similaryields. A consequenceis, of course, thatthe analysis of varianceestimateof the errorvariance perplot, which is derivedfromdifferencesin yield perplots receivingthe sametreatment, will tend to overestimate,since plots treatedalike are fartherapartthanplots receiving differenttreatments.Fisherdoes not commenton the absenceof randomizationor on the chessboarddesign. Apparentlyin 1923 he had not begun to think about the conditions necessaryfor an experimentto supply an unbiasedestimateof error." A furtherproblem with Fisher's 1923 analysis was his failure to recognize the split-plot structure of the actual experimentwith respect to a thirdfactor,potassium.This he correctedin Statistical Methodsfor Research Workers(1925). Thus, in 1923, we see both Fisherand Neyman as having arrivedat similarpositions with respect to randomization,althoughFisher alreadyhad moved aheadin his thinkingabout otherfeaturesof design. Box (1980) argues, that the statementin Fisher & Mackenzie on the analysis of variance rested heavily on Fisher's appreciationof the requirementsof underlying theory for the normal distributionupon which hereans, reld in his analysis,as well as upon Fisher's"geometricrepresentation that by then was second natureto him. He could picture the distributionof n results as a pattern in n-dimensional space, and he could see that randomizationwould produce a symmetry in that patternratherlike thatproducedby a kaleidoscope,and which approximatedthe requiredspherical symmetryavailable,in particular,from standardnormaltheoryassumptions"(p. 2). While we agree thatFisher's geometricalintuitionwas highly refined,we see little supportin the 1923 paperfor this conclusion. But by the publicationof StatisticalMethodsin 1925, Fisherclearly had a deeperappreciationof the function of randomizationin experimentation: "Thefirstrequirementwhich governsall well-plannedexperimentsis thattheexperiment should yield not only a comparisonof differentmanures,treatments,varieties,etc., but also a means of testing the significance of such differences as are observed .... For our test of significance to be valid the differences in fertility between plots chosen as The FundamentalContributionsof Fisher and Neymanon Experimentationand Sampling 241 parallels must be truly representativeof the differences between plots with different treatment[s];and we cannotassume thatthis is the case if our plots have been chosen in any way accordingto a prearrangedsystem."(p. 248) According to Fisher,valid tests resultif treatmentsare assigned to plots wholly at random,and here we have a clear departurefrom the 1923 papers. The treatmentof experimentationin StatisticalMethods,which follows this discussion of randomization, consists of only a few pages. Fisherintroducedblocking as a device to increasethe accuracy of treatmentcomparisons and he illustratedits use in both randomizedblock experiments and in Latin squares. He described the split-plot structureof the experimentanalyzed in the 1923 paper, which should have requiredtwo levels of randomizationfor its validity, but Fisher did not discuss this point in the original or subsequenteditions of the book. Later embellishmentsto the theory of experimentaldesign came in Fisher (1926) where he laid out in a more systematicfashion the principlesunderlyingfield experimentation,including the need for replication,and in which he expoundedupon the notion of factorialdesigns with new insights, including the role of confounding.The example used in this paperwas from a real experimentbeing runby a colleague, ThomasEden, and Eden & Fisher(1927), presentsa more detaileddescriptionof the experimentand an analysis of its results.Factorialstructures,Fisher(1952) would later observe, had their roots in the "simultaneousinheritanceof Mendelianfactors". Throughoutthis period, Fisher continuedto work with colleagues at Rothamstedand elsewhere in the design and analysis of experimentsthatimplementedhis ideas on randomizationand factorial structures.But not all of his Rothamstedcolleagues had fully accepted Fisher's insistence on randomization as the foundationof experimentatiion (Box, 1980). In fact, Fisher's 1926 article was at least in part a response to an articleby Sir John Russell, directorof Rothamsted,on the state of the artin experimentaldesign. In his paper,Russell had noted Fisher's argumentfor randomizationbut said that it was impossible to use in practice!Despite this disagreement,Russell allowed Fisher and Eden to runtheircomplex randomizeddesigns on fields at Rothamstedand this ultimatelyconvinced many others of the value of Fisher's innovativeideas (Box, 1980). 4 Neyman's Initial Contributions to the Theory of Sampling in the 1920s In 1924, Neyman obtainedhis doctorsdegree from the Universityof Warsaw,using as a thesis the work done in Bydgoszcz, and in 1925, he obtaineda governmentgrantto study for a year in London with KarlPearson.Before his arrivalin London,Neyman had shippedto KarlPearsonseveral of his statisticalpublications,includingthe two 1923 paperson agriculturalexperimentation,and Pearson suggestedthatNeymanrepublishpartof the secondpaperin Englishin Biometrika(Splawa-Neyman, 1925 [1923b]). But Pearsonbelieved thatNeyman'sstatementat the end of the paper,thatit is only in samplingfrom a normalpopulationthatthe samplemean and samplevarianceare independent,to be mistaken.When Neyman tried to explain to Pearsonhis confusion between independenceand lack of correlation(in haltingEnglish and in frontof severalotherPearsonstudents),Pearsoninterrupted: "Thatmay be true in Poland, Mr. Neyman, but it is not true here."(Reid, 1982, p. 57) Dismayed at having offended Pearson and at perhapshaving lost a chance to publish in English-his Polish mentorshad sent Neyman to Englandas a kind of test to see if his ideas were worth anything,and a publicationin English would go a long way towardssettling that matter-Neyman searchedfor a way to communicatehis explanationto Pearson.He finallyofferedhis explanationto J.O. Irwin,who communicatedit to Egon Pearson,who finally convinced his fatherthatNeyman was not mistaken. Thus the Biometrikaversion does contain this observationfrom the Polish version. In the resulting 1925 Biometrikapaper, Neyman gave the higher moments of the means and variancesof samples from finite populations.The paperis succinct and to the point. He begins by deriving formulas for moments of the sampling distributionof the mean of samples of size n from 242 and J.M. TANUR S.E. FIENBERG a finite population of size m, where the sample members are drawn without replacement,and he relates these to the moments of the underlyingfinite population.Then he focuses on the variance, skewness, and kurtosis, of the sampling distribution,i.e., M2, B1 = M/M23, and B2 = M 2/M2, where M2, M3, and M4 are the centralmomentsof the samplingdistribution,and he expresses these in terms of /,2, P1 = ,LlJ/,t3, and P2 = 4/ 1A2 where u2>,/3, and 14 are the centralmoments of the finite populationof m elements. He explains how the momentsof the samplingdistributiontend to the usual ones for sampling with replacementwhen we let m - 0oo.He then turnsto the first and second moments of the sample variance,expressingthem in terms kL2 and B2, and to the correlation between the squareof the samplemean andthe samplevarianceas well as to the correlationbetween the sample mean and the sample variance,expressingthe firstin termsof P2 and the second in terms of P31and B2. In the final paragraphof the paper, by letting the finite population size m -+ 0o, Neyman uses the correlationformulasto argue that the independenceof the sample mean and the sample varianceholds only for normaldistributions,the point originallyin dispute with Pearson. The 1925 papermight have passed unnoticed,butfor the fact that,in 1927, MajorGreenwoodand Leon Isserlis publisheda complaintaboutit in the Journalof the Royal StatisticalSociety, pointing out that Neyman had failed to acknowledgethe publishedpapersof the recently deceased Russian statistician,AlexanderAlexandrovitchTchouproff2. Greenwood & Isserlis (1927, p. 348) quote Neyman as writing of the formula for the second moment of the variance"[t]hisresult, being a generalizationof formulaegiven by otherauthors,is, I believe, novel and of considerableimportance".Indeed, after that statementon page 477 of his 1925 paper,Neyman did actuallycite one of Tchouproff's1918 Biometrikapapersas well as a 1925 paper by Church.Greenwoodand Isserlis neverthelesstake him to task for failing to cite works by Karl Pearson,Isserlis, and Edgeworthbesides those of Tchouproff.In their view, Neyman's felony was compoundedby the work of A.E.R. Church,especially a 1926 paperpublishedin Biometrika, which cited Neyman for some of the formulasfor momentsratherthan citing Tchouproff.There is little question but that Neyman's results can be found at least in some form in the sea of formulas in Tchouproff's 1923 papers. What appearsto have been happeningin these and other papers by Tchouproffis the alternativealgebraicderivationandexpressionof a varietyof momentexpressions, most of which were quitecomplex. One of the nice featuresof Neyman(1925) is the relativelyclean derivationsand succinct formulas. By the time the Greenwood-Isserliscritiquewas published,Neyman had returnedto Poland. In obvious distress at the accusation,he wrote to Egon Pearsonsoliciting advice. The reply, it turned out, was handledby KarlPearson(1927), who editorializedin Biometrikain Neyman's defense (as well as Church's). He arguedthat Neyman's original publicationin Polish in 1923 was certainly contemporaneouswith Tchouproff'spair of 1923 articlesin Metron,and perhapsactuallypredated those Tchouproffpublicationsbecause delays in the publicationof Metroncaused it to appearlater than its cover date. But it seems to us that this argumentfrom Pearson,while it may well be true, is irrelevantto the controversy-Greenwood and Isserlis were accusingNeyman of ignoringnot these specific papers of Tchouproffbut a whole body of literaturethat originatedsome 20 years earlier with work by Pearson himself. PerhapsPearsonwas in some sense defending himself as editor of Biometrikafor his laxness in failing to urgeNeyman, the young foreigner,to updatehis work for an English-readingaudiencewith citationsto the literaturein English.ThatNeymancould haveprofited by such urgingseems clear from anotherfacet of Pearson'seditorialdefense-he cites a letterfrom Dr. K. Bessalik, Professor of the University of Warsaw,who in 1922 was Director of the State Instituteof AgriculturalResearchin Bydgozcz. In that letter,Bessalik certifies that Neyman wrote his paperin Bydgozcz in 1922 and that "no English Journals"were accessible to him. Had Pearson urgedNeyman to place the republicationof his results in the historicalcontext about which he had 2This was the transliterationof Tchouproff'sname, as it appearedin the 1918 Biometrikaarticles. We use the spelling Tchouproffthroughout,even though when he publishedin Metron,the editor used Tschuprow,and elsewhere he is referred to as Chuprovand Chouprow,but we referto specific papersusing the spelling used in connectionwith them. The FundamentalContributionsof Fisher and Neymanon Experimentationand Sampling 243 presumablybeen ignorantduringthe time he was writing the original paper in Poland, we believe thatNeyman would undoubtedlyhave agreed.He had, afterall, come to London with the expressed purpose of studying with Pearson, whose Grammarof Science had served as an inspirationsince Neyman discovered it in 1916. Since Neyman's 1923/1925 paper did not representa conceptual breakthroughin the theory of sampling from finite populations, we are left with two questions of historical interest. The first is to ask how the isolated scholar arrivedat what may well be an independentderivationof some key results in finite sampling and the second is to ask why Neyman's results, in particular,seem to have had a more profoundinfluence than did similarones obtainedby others. Perhapsthe answerto the firstquestionis that,while surelyout of the mainstreamof earlytwentieth centurystatistics, neitherin Russia nor in Polandwas Neyman completely isolated. Neyman studied probabilitytheory in Kharkovunder the direction of the Russian mathematicianS.N. Bernstein as early as 1915 or 1916. Although these activities had been forgottenby Neyman by the time he was describing his early career to Constance Reid in 1978 (and perhapsthis forgetfulness in his later life contributesto our image of Neyman's early years as totally isolated), in the mid 1920s Neyman describedhimself as havingcontinuedhis studiesunderBernsteinthrough1921. He also notes thathe worked in 1920 underBernsteinto apply the theory of probabilityto experimentationin agriculture (Reid, 1982, p. 30). ThroughBernstein,Neyman became familiarwith Markov'swork, which also influencedTchouproff(see also Seneta, 1982, 1985). We know that,before he left Poland,Neyman workedwith a ProfessorIsseroff on statisticalanalysis of agriculturalexperimentsand even lectured to the AgriculturalDepartmentat the Universityof Kharkovon the applicationof probabilitytheory to experimentalproblemsin agriculture.These activitieswere clearlyprecursorsto the papersdealing with experimentaldesign in agricultureand his paper on finite sampling theory which appearedin Biometrikain 1925. Just as Fisher was stimulatedby the challenges of real experimentationat Rothamstedto gather together ideas that were "in the air" to make his masterly synthesis of the design of experiments and the analysis of variance, so Neyman could well have been stimulated by the challenges of experimentationat the Institutein Poland to synthesize ideas of sampling from finite populations that were "in the air".And that would lead rathernaturally,given the variablecitation practices at the time, to the kind of papersNeyman wrote in 1923, papersthathad little referenceto the work of others. The lack of referencesto work in English is particularlyunderstandable,since as his advisor certifiedto Pearson,Neyman had no access to Englishjournalswhile he was in Poland. To answer the second question, that of Neyman's profoundinfluence, we need to look not at the 1923 paper (nor at its 1925 republication),but at Neyman's watershed1934 paper,in which he was able to capturethe essential ingredientsof the problemof sampling,synthesizehis own contributions and those of others, and effectively demolish the idea of purposivesampling. Neyman arrivedin London in 1925, shortly after the publicationof Fisher's Statistical Methods for Research Workers.But the pathsof the two seem not to have crossed duringthe entire academic year. In March of 1926, Gosset passed throughLondon and met with Neyman, who expressed an interest in visiting Fisher at Rothamsted.Gosset wrote to Fisher warninghim that Neyman "holds a letter from me to you asking you to show him anythingthat you think might be useful to him. I daresay offprints would be useful to him if you could spare them as he finds it hard to trace your work. I gatherthathe will write to you in April".FisherandNeyman actuallymet for the firsttime in July in Rothamsted,althoughthereis no recordof what they discussed. Neyman then spent a year in Paris,after which he returnedto Poland.The next recordof interactionbetween Neyman and Fisher is linked to Neyman's work in 1932 with Egon Pearsonon the theory of statisticaltests. and J.M. TANUR S.E. FIENBERG 244 5 The 1925 and 1927 ISI Discussions on Sampling Before Neymanreturnedto the problemsof samplingfroma finitepopulationthathe hadaddressed in 1923, major developments in sampling were presented at the 1925 and 1927 sessions of the InternationalStatistical Institute (ISI), and published in 1926 and 1928, respectively. Kruskal & Mosteller (1980) give a relatedand somewhatmore detaileddiscussion. A substantialportionof the 1925 ISI Meeting was taken up with discussions of the "methodof representativesampling".In 1924, the Bureau of the ISI appointeda Commission, consisting of ArthurBowley, CorradoGini, Adolph Jensen, Lucien March, VerijnStuart,and Frantz Zizek, to study the representativemethod. Jensen served as rapporteurand leader of the discussion at the meeting. The Commission Report (Jensen, 1926a) contains a descriptionof two methods:random sampling(with all elementsof the populationhavingthe sameprobabilityof selection), andpurposive selection of large groups of units (in modernterminologyclusters) chosen to match the population on selected control variates.The reportdoes not really attemptto choose between the methods. In one of severalannexesto the report,Bowley (1926) provideda lengthy theoreticaldevelopment,but failed to describefully how the statisticaltheoryof purposivesamplingworks.Whatis remarkableto us in this Reportand its Annexes, especially in light of the controversythatIsserlis and Greenwood were to ignite only the next year,is the singularlack of rto references the theoreticalworkon sampling from finite populationsby Isserlis, Neyman, and Tchouproff,althoughthe referencelist in Jensen's (1926b) Annex did include one referenceto Tchouproff,his 1910 thesis! Tchouproffwas presentat the meeting but because he was ratherill he appearedto contributelittle to the discussion. He died soon afterthe meeting. Yates (1946), in reviewing these proceedings, notes the "lack of any clear conception of the possibility, except by the selection of units wholly at random,or by the inadequateprocedureof sub-dividingthe sample into two or moreparts,of so designing samplinginquiriesthatthe sampling errorsshould be capable of exact estimationfrom the resultsof the inquiryitself". (p. 13). He goes on to describethe developmentsin randomsamplingthattook place in Englandlinkedto agricultural experimentationbetween 1925 and 1935, stimulatedlargely by the elements of randomizationin experimentationand the analysis of variance,both of which he attributesto Fisher.We see this as anotherindication of the lack of impact of Neyman's early contributionsin these two interrelated fields. At the 1927 ISI meeting, CorradoGini presenteda paper on the application of the purposive methodto the samplingof recordsfromthe 1921 Italiancensus (see Gini, 1928, and Gini & Galvani, 1929), which was to play a pivotal role in the later work by Neyman. They needed to discardmost of the recordsof the 1921 census before taking the next one, and they proposedto retaina sample for futureanalyses and reference.To make theirsamplerepresentative,they chose to retainall of the datafrom 29 out of 214 large administrativedistrictsinto which Italy was divided. They appliedthe purposivemethod in orderto select the 29 througha process which attemptedto matchthe averages on seven importantcharacteristicswith those for the countryas a whole. When they did this, they discoveredthattherewere substantialdeviationsbetweenthe sampleandthe entirecountryfor other characteristics.This, they claimed, called into question the accuracyof sampling. It remainedfor Neyman to take up the challenge embodiedin this claim. 6 Neyman's 1934 Paper on Sampling Neyman took up the challenge in his classic 1934 paper presentedbefore the Royal Statistical Society, "Onthe two differentaspectsof the representativemethod".We review the paper'selements and emphasize how Neyman rescuedclusteringfrom the clutches of purposivesamplingand gave it a rightfulplace in the foundationsof randomsamplingmethodology. Neyman originally preparedthe paperin 1932 in Polish (with an English summary)as a booklet The FundamentalContributionsof Fisher and Neymanon Experimentationand Sampling 245 growing out of his practicalexperience. He had been working for the Institutefor Social Problems on a projectinvolving sampling from the Polish census to obtaindatato describethe structureof the working class in Poland.As he wrote to Egon Pearson,he used the opportunityand "pusheda little the theory"(Reid, 1982, p. 105). Publishedin 1933, the original Polish version of the paper traces a good deal of history (Neyman had clearly learnedhis lesson aboutcitationpractices and was now unquestionablyfamiliarwith the literature);the 1934 version publishedin the Journal of the Royal Statistical Society includes even more history and carefully cites many of the people who were to be in the room for the presentationbefore the Society. Neyman gives enormous credit to Bowley for his 1926 synthesis of the theory underpinningsampling methods, but also notes the hundreds of contributionsin the area on which his comparison between purposive and random sampling builds. There is, however,the curious presentationof optimal allocation with no reference back to Tchouproff(1923a, 1923b). The goal of the paper is to comparepurposiveand randomsampling. But elements of synthesis are prominentas well. Neyman describesstratifiedsampling,noting thatBowley considers only the proportionatecase but stating that such restrictionis not necessary.He gives a crisp descriptionof cluster sampling: "Suppose that the population n of M' individuals is grouped into Mo groups. Insteadof consideringthe populationn we may now consideranotherpopulation,say n, having for its elements the Mo groups of individuals,into which the populationf is divided .... If there are enormousdifficultiesin samplingindividualsat random,these difficultiesmay be greatlydiminished when we adoptgroups as the elements of sampling"(pp. 568-569). This is a new synthesis-earlier conceptualizationsof clustering had coupled it with purposivesampling. Indeed, Neyman quotes Bowley as maintainingthat"in purposiveselection the unit is an aggregate,such as a whole district, and the sample is an aggregateof these aggregates,while in randomselection the unit is a person or thing, which may or may not possess an attribute,or with which some measurable quantity is associated"(p. 570). Neyman goes on to explicitly uncouple clusteringand purposivesampling, saying, "Infact the circumstancethatthe elements of samplingare not humanindividuals,but groups of these individuals,does not necessarilyinvolve a negationof the randomnessof the sampling"(p. 571). He calls this procedure"randomsampling by groups"and points out that, althoughBowley did not consider it theoretically,he used it in practicein London, as did 0. Andersonin Bulgaria. Neyman also speaksof combiningstratificationwithclusteringto form"randomstratifiedsampling by groups".[Bowley, in his role as the lead discussantof Neyman's paper,notes the innovativeness of Neyman's suggestion of randomstratifiedsamplingof groupsand acknowledgesthatin fact it was what he had been drivento use in his work even thoughhe has not fully recognizedthe implications of what he had done]. Then Neyman refersto the full theoryfor best linearunbiasedestimation3of a populationaveragedeveloped in his 1933 Polish publication,and he gives the now familiarformula for the varianceof the "natural"weighted averageestimatorin stratifiedcluster sampling. In orderto compare Gini and Galvani's method of purposiveselection with his own method of randomstratifiedsampling by groups, Neyman imbues the purposivemethod with a structurethat allows one to treat it as if it were based on a special form of randomselection, even though this was clearly not the way Gini and Galvaniactually selected or conceived of their groups (districts)4 3There was an implicit assumptionin Neyman's work regardingthe uniquenessof the best linear unbiased estimate in samplingfrom finite populations.This assumptionturnsout to be false. Godambe& Thompson(1971, pp. 386-387) observe that "Neymanproposedthe use of the Gauss-Markofftechniqueto prove the optimality(UMV-ness)of the sample mean and othersimilarestimators.Indeed,duringthe discussion,Fisherconcurredin this method;andit appearsthatthe Gauss-Markoff technique, now known to be of doubtful validity in sampling theory (Godambe, 1955), was one of the very few points on which Neyman and Fisher were in agreement". 4Neymanenvisions a universeof districtsdividedup into strataaccordingto the values of one or morecontrolvariates,and then each stratumis subdividedinto substrataaccordingto the numberof units in the district.Then within each substratum he speaks of the randomselection of a preassignednumberof districts.Of course, because of the large size of the districtsin Gini and Galvani's situation, most stratawould contain zero or one district.This leads to the sampling bias which Neyman then illustrates. 246 S.E. FIENBERG and J.M. TANUR In doing so, Neyman constructsa sturdycoffin inwhich to burythe method of purposiveselection, and then he proceeds to slam the lid of the coffin tight and nail it shut, by presentingone statistical argumentafter another.First, he considersthe conditionsunderwhich the purposivemethod, which utilizes the regressionof groupmeans on a control variatey, producesunbiasedestimates. He then notes, on the basis of calculations from Gini and Galvani's own data, that the conditions appear not to be satisfied in practice.Neyman goes further,however,and points out that Gini and Galvani make the implicit assumptionthat the groups (clusters) are themselves randomsamples from the population,somethingthat is decidedly false. Neyman's own methodof randomstratifiedsampling by groupsdoes not have these deficiencies.Neymancarriesthe argumentone final step by exploring, using his varianceformula, whetherit is preferableto sample a small numberof large groups (in effect a varianton Gini and Galvani)or a large numberof smallerunits.The latterturnsout to be the clear choice and this providesNeyman with the final nail to hammershut the coffin of the purposive method. Shortly later,the coffin was buried,althoughthe ghost of the purposivemethod continues to rise until this day in the form of quota sampling. The immediateeffect of Neyman's paperws to establishthe primacyof the methodof stratified random sampling over the method of purposiveselection, somethingthat was left in doubt by the 1925 ISI presentationsby Jensen and Bowley. But the paper'slonger-termimportancefor sampling was the consequenceof Neyman'swisdom in rescuingclusteringfromthose who were the advocates of purposive sampling and integratingit with stratificationin a synthesis that laid the groundwork for modern-daymultistageprobabilitysampling. The heart of the 1934 paper, however, in terms of the amount of space Neyman devoted to exposition and in terms of emphasisin the discussion by othersat the presentationbefore the Royal StatisticalSociety, is the materialon confidenceintervals.Therewas much confusion as to whether this was just Fisher's fiducial method presentedin a slightly differentfashion or a new inferential approach.Neyman introducedthe idea of coverage in repeatedsamples, but the discussion did not pick up on its originality.It is somewhatironicthatin his discussionof Neyman(1934), Leon Isserlis, who only seven years earlierhad condemnedNeyman for not giving enough credit to Tchouproff, completely overlookedthe fact that Neyman failed to credit Tchouproffin this paper,this time for proposingthe notion of optimal allocation in stratifiedsampling.We speculatethat Isserlis' failure to questionthis point arose largely from the troublehe was havingunderstandingNeyman's concept of confidence intervals,the latterbeing the sole topic of Isserlis' discussion. Two decades later Neyman (1952a) acknowledgedTschouproff'spriorityin discovering these results: "I am obliged to Dr. DonovanJ. Thompsonof the StatisticalLaboratory,Iowa State College, Ames, Iowa, for calling my attentionto the article of A.A. Tschuprow,"On the mathematicalexpectationof the moments of frequencydistributionsin the case of correlatedobservations"publishedin Metron,Vol. 2, No. 4 (1923), pp. 646-680, which contains some resultsrefoundby me and published,withoutreferenceto Tschuprow,in 1933. The results in question are the generalformulafor the varianceof the estimate of a mean in stratifiedsampling and the formuladeterminingthe optimumstratificationof the sample. These formulaeappearedfirstin a Polish bookletAn Outlineof the Theory and Practice of RepresentativeMethod,Applied in Social Researchpublishedin 1933 by the WarsawInstituteof Social Problems.Lateron they were republishedin English in the Journal of the Royal StatisticalSociety, Vol. 97 (1934), pp. 558-625. Finally,the same formulae, again without a reference to ProfessorTschuprow,were given in the second edition of my book, Lecturesand Conferenceson MathematicalStatistics and Probability,Washington,D.C., 1952. The purposeof this note is, then, to recognize the priorityof ProfessorTschuprow, The FundamentalContributionsof Fisher and Neymanon Experimentationand Sampling 247 to express my regretfor overlookinghis results and to thankDr. Thompsonfor calling my attentionto the oversight." And in the 1970s, Neyman continued in this apologetic vein by reprintingthe recognition of priorityin an introductionto a book of correspondencebetween Markovand Tschouproff(Neyman, 1981). What seems clear today for those of us who go back for Tschouproff(1923a, 1923b) is thatif Neyman had read these papers,it would have been difficultto have missed Tschouproff'streatment of stratificationalthoughwe confess to having to searchto identify the result on optimal allocation. Thus, the simplestinterpretationfor us is thatwhen Neymanwas developingthe materialfor the 1934 paper in Poland he not only did not have easy access to Tschouproff'spaper,but simply presumed that everyone would accept the notion of stratification,especially in light of the ISI discussion and publicationson the topic. Fisher's lenghty discussion of the Neymanpaperis noteworthyin the presentcontext, not so much for his challenge that Neyman's confidence intervalswere in some senses fiducial intervalsundera differentname, butratherfor his observationson the importanceof the parallelismbetween sampling in economic researchand the role of samplingof finite populationsin agriculturalexperimentation. The majordistinction,he was reportedas saying, was that:"Ina well-designedexperiment,however, the mathematics were simplified, and all anxiety was avoided in respect to different systems of weighting"(p. 616). Of course, Fisher did recognize that Neyman's goal in creating confidence intervals was quite different from his own goal of inductive inferences from the sample at hand. As Edwards (1995) remindsus, Fisherexpessed his skepticismregardingthe value of the coveragepropertyof confidence intervalsand he remarkedin his discussion thatNeyman's generalization"was wide and handsome, but it had been erected at considerableexpense, and it was perhapsas well to count the cost" (p. 618). Our question of why the Neyman paper had such a profoundinfluence comparedto the earlier work of Tchouproffandothers,was also raisedby Bellhouse (1988) and Kruskal& Mosteller(1980). We believe that while Tchouproffhad clearly derived a numberof the technical results a decade earlier,and had droppedthe constraintof constantprobabilitiesof selection, his paperswere abstract and formal in nature,and his results were far removed from real-worldapplication.Neyman more clearly laid the groundworkfor statistical practice by his innovativeintegrationof clustering and stratification,and his clear and convincing exposition of the inferiorityof the purposive method. Neyman provided the recipe for others to follow and he continuedto explain its use in convincing detail to those who were eager to make randomsampling a standarddiet for practicalconsumption (e.g., see Neyman, 1952b, for a description based on his 1937 lectures on the topic at the U.S. Departmentof AgricultureGraduateSchool). 7 Fisher, Neyman, and The Design of Experiments in 1935 The year after Neyman presentedhis sampling paperto the Royal StatisticalSociety, three publications resolved all doubt about who was to gain full credit for the design of experimentsas an areaof statistics.To understandthese events surroundingthese publications,however,we move back several years and trace the interlockingdevelopmentsin this areainvolving Fisher and Neyman. Following Fisher's series of papers on experimentaldesign in the 1920s, those at Rothamsted such as Yates and Wisharthelped to propagatehis ideas and move them into actual agricultural practice, and Fisher temporarilyturned his focus to the completion of The Genetical Theory of Natural Selection, publishedin 1930, as well as relatedissues of genetics and eugenics and his ideas on inverse probability.But Fisher and others recognized the need to pull together the new ideas on statistics and experimentation.In 1930 he lectured on the topic at ImperialCollege in London and at Chelsea Polytechnic and then he spent the summerof 1931 at Iowa State University giving 248 S.E. FIENBERGand J.M. TANUR some related lectures. This was to be the beginning of notes that ultimatelyled to The Design of Experiments,in 1935. Meanwhile,Neyman was workingon a series of paperson hypothesistesting with Egon Pearson,and on some agriculturalexperimentationproblems. By the late 1920s, Fisher was becoming restless at Rothamstedand considered applying for positions at Britishuniversities(Box, 1978, pp. 202-203). Box (1978) andReid (1982) describesome of the correspondencebetween Fisher and Neyman in 1932 and 1933, primarilyabout Neyman's paperwith Egon Pearsonon tests of hypotheses.When KarlPearsonretiredfrom UniversityCollege in 1933, both his position and the departmentwere split in two, with Egon Pearsonbeing appointed as Reader in Statistics and head of the Departmentof Applied Statistics and Fisher being given the position of Galton Professorof Eugenics and responsibilityfor the GaltonLaboratory.A major issue between the two was responsibility for teaching of statistics. Pearson proposed that Fisher not teach statisticaltheory,and so Fisherrespondedby proposingto teach the logic and philosophy of experimentation(Box, 1978, p. 259 and Bennett, 1990, p. 192). Here we see anotherimpetus for Fisher to complete the book on experimentaldesign. In mid 1933, upon hearing of Fisher's appointmentat UniversityCollege, Neyman wrote to him asking aboutthe possibility of a position in the Laboratory.But Fisherhad nothingto offer specificallyin statisticsand, in 1934, Neymanleft Poland andjoined Pearson'sdepartmentfor a threemonthvisiting position, which ultimatelyturned into a permanentnt one. It was also at aboutthis time that FishernominatedNeyman for membership in the InternationalStatisticalInstitute.Thatfirsttermback in London,Neyman lecturedon interval estimationand Fisher on experimentation,with Neyman in attendance. In Marchof 1935, Neymanpresenteda paperbeforetherecentlyformedIndustrialandAgricultural Research Section of the Royal StatisticalSociety (Neyman, 1935) entitled "Statisticalproblemsin agriculturalexperimentation".The paperwas based on work done in Poland, in co-operationwith two junior colleagues, Iwasziewicz and Kolodziejczyk.In it, he presentedformal statisticalmodels for the analysis of randomizedblockanLatin and squaredesigns, and he claimed that "theapplication of the usual tests of significanceto the resultsof experimentsby the two methodsis not yet rigorously justified, thoug thteeffect of the inaccuracyinvolved may be negligible".In other words (but not those explicitly used by Neyman), Fisher's claims aboutthe validity of tests were wrong! Neyman gives the model explicitly; treatmentsaffect individualplots in a row-by-columnlayout differently (i.e., unit-treatmentnon-additivity).The model and Neyman'sdiscussion of it includes the notion of an infinite series of repetitionsof the experiment,and it is with respect to this long-rundistribution that he takes expectations.In an appendix,he shows that, if the averagetreatmenteffect over the entire experimentalarea is the same for all treatments,the usual estimate of the errorvarianceis unbiasedfor randomizedblocks whereasfor his Latin squaremodel there is a bias. He repeats the opening claim that this bias may not be substantial.This means that the F test (referredto by both Fisher and Neyman as the z test) for treatmenteffects in a Latin square"may ... cause a tendency to state significant differentiationwhen this, in fact, does not exist" (p. 154). Then Neyman goes on to examine the test of hypothesis that one treatmenthas a greatereffect than another and he demonstrates,in a series of examples, that Latin squaresare often less efficient than randomized blocks. Throughoutthe paper Neyman employed the notions of type I and type II errors he had developed with Pearson. Fisher was the lead discussantof the paperand he respondedwith greatsarcasmaboutNeyman's surprisingresultsnotingthatthose present"hadto thankhim, not only for bringingthese discoveries to their notice, but also for concealing them from public knowledge until such time as the method should be widely adopted in practice!"(p.155). Fisher questioned Neyman's apparentinability to grasp the very simple argumentby which the unbiased characterof the test of significance might be demonstratedand then he presenteda simple illustrationin the context of a 5 x 5 Latin square. Here Fisher states ratherobliquely one of his key differences with Neyman, the hypothesis to be tested, which in the Fisherianformulationis that treatmentshave no effect on yields whereasin the The FundamentalContributionsof Fisher and Neymanon Experimentationand Sampling 249 Neyman formulationit relates to zero treatmenteffects averagedover all plots. Then Fisher invokes the randomizationdistribution,which in effect assumes unit-treatmentadditivity.Yates and Wishart also contributedto the discussion in a more polite, but just as critical fashion, and when Neyman attemptedto respondbriefly,Fisher interruptedwith the final statement: "Ithinkit is clearto everyonepresentthatDr.Neymanhas misunderstoodthe intentionclearly and frequentlystated-of the z test and of the LatinSquareand othertechniques designed to be used with that test. Dr. Neyman thinks that anothertest would be more important.I am not going to arguethatpoint.It may be thatthe questionthatDr.Neyman thinksshouldbe answeredis moreimportantthanthe one I have proposedand attempted to answer.I suggest thatbeforecriticizingpreviousworkit is always wise to give enough study to the subject to understandits purpose.Failing that it is surely quite unusualto claim to understandthe purposeof previous work betterthan its author. Froma purelystatisticalstandpointthe positionis thatDr.Neymanwouldlike a different test to be made, and I hope he will invent a test of significance, and a method of experimentation,which will be as accuratefor questions he considers to be important as the Latin squareis for the purposefor which it was designed." Neyman laterrespondedat lengthin writingbut his relationwith Fisherhad been shatteredandmost presentat the presentationof the paperseemed to side with Fisher.The controversythat began with this exchange raged throughoutFisher's lifetime, and it included not only fundamentalaspects of experimentaldesign but also two very differentapproachesto testimonyand statisticalinference. The dispute that erupted over the Neyman paper was bound up in issues of estimation and hypothesis testing and the difference between the two types of inference. Even with Neyman's model, the usual F-test in the Fisherianapproachhas the correctnull distributionwhen there is "no treatmenteffect", because then there is no issue of whethertreatment-unitadditivityholds. Fisher correctly pointed this out in the discussion. Neyman was insisting on a different null hypothesis, that the treatmenteffect, throughits interactionwith plots, averages out over the complete set of plots used in the experiment.This is essentially estimatingthe treatmenteffect in the non-null case, however,and here it matterswhetherone allows for treatment-unitadditivityor not. Fisherdid allude to this difference,butin languagethatremainsdifficultto decipher.(Rhetoricwas at a premiumrather than statisticalclarity.)Nelder (1994) essentially arguesthat Neyman's errorwas in formulatingan uninterestingnull hypothesis,largely as a resultof the non-hierarchicalnatureof its construction.In such circumstancesone also needs to look at the alternatives.Thus Nelder arguesthatFisher's attack on Neyman was irrelevantbecause he dealt only with the null case. Further,the Neyman/Pearson approachto confidence intervals and tests of hypotheses, which Fisher was never to accept, was essential to the Neyman argumentin this paper;the ideas were still too new for most present to understand.Finally, we note thatrandomizationseemed to play little role in Neyman's argumentsin the 1935 paper whereas it was essential to Fisher's ideas, clearly structuringall of his thinking on models and the validity of relatedstatisticalmethodsfor the analysis of experiments. Just two months after Neyman's presentation,Fisher's successor at Rothamsted,Frank Yates (1935), presentedhis own paperon agriculturalexperimentationbeforethe same section of the Royal StatisticalSociety and the debate between Fisher and Neyman continued,with Yates becoming the target for Neyman's criticism. In a lengthy critique of Yates' exposition of the theory of factorial experimentation,submittedin writing afterthe meeting, Neyman again used his work with Pearson on tests of hypotheses to suggest that interactionshad low power of detection and that Yates' (and thus Fisher's) definitionof interactionswere fatally flawed.This discussion seems to have confused the natureof the contrastsused to estimateeffects in the Fisher-Yatesframeworkand Yates avoided the possibility of others being similarly confused by alteringslightly the definitions in the printed version of his paper(which followed Neyman's paperin the Journal).This minor alterationvitiated 250 S.E. FIENBERGand J.M. TANUR all of Neyman's analysis. Yatesalso respondedrathercausticallyin writingto Neyman'scritiqueand Neyman then submittedan addendumpointing out why he still thoughtthe Fisher-Yatesapproach was wrong. The controversybetween Neyman and Fisher (with Yates as an occasional surrogate) was now full-blown. The final of the trio of 1935 publicationson experimentation,Fisher'sTheDesign of Experiments, was the most significant.Fisher completedthe prefacethe month afterYatespresentedhis paper.In this book, Fisherpresentedan integratedperspectiveon the logic and principlesof experimentation. After a brief introductionin which he explains why for inferenceshe does not use Bayes' theorem in the book, Fisher turns to his famous example of "The Lady Tasting Tea", based on an actual experimenthe proposedmore than 12 yearsearlierat Rothamsted,in responseto the claim by Muriel Bristol, an algologist, who claimed thatshe could tell the differencebetween a cup of tea into which the milk had been poured first (her preference)and one into which the tea had been poured first (which Fisherhad offeredher). HereFishermade his strongestargumentsfor the need to randomize. In the next chapter he dealt with Darwin's data on cross- and self-fertilization(in which there was no randomization),introducingthe notion of matching,and this time he used the argumentof randomizationto "justify"the use of the t-distributionfor the key comparison.Subsequentchapters dealt with randomizedblocks, Latin squares,factorialdesigns, confounding,partialconfounding, and the analysis of covariance.The final pair of chaptersdealt with more theoreticalmaterialon estimation:fiducial inferenceand the measurementof information. Few of the ideas in the book were totally new, but their integrationand the power of Fisher's exposition of them helped to establishrandomizedexperimentationas basic to the scientist'stoolkit. The battle over randomizationcontinued to be waged in British journals, with Gosset, who still advocated the use of systematic designs such as Beavan's drill strip or sandwich design, being Fisher's main antagonist.The debateessentially ended with Gosset's deathin 1937, althougha final critiqueby Gosset appearedposthumouslyin Biometrikain 1938. On the otherside of the Atlantic, there was no such battle, and in 1936, on the occasion of its 300th anniversary,HarvardUniversity awardedFisheran honorarydegree at least in partfor this achievement.Justas with Neyman and his 1934 paperon sampling,Fisher's The Design of Experimentsprovideda recipe for othersto follow. 8 Conclusions Both FisherandNeymanmadefundamentalcontributionsto statisticalmethodologythatunderpins the modernapproachesto the design of experimentsand the design of sample surveys. In this paper we have retracedtheirworkon these topics, especiallyduringthe criticalyearsfrom 1921 to 1935, and we attemptto explainthe pivotalroles of Neyman's 1934paperon agriculturalexperimentationwhich ultimatelyled to a rift between the two men thatwas neverto be repaired.In the aftermath,Neyman stakedout intellectualresponsibilityfor samplingand Fisherdid the same for experimentation.The two fields subsequentlydriftedapart. Two issues were raised in the discussion of an earlierversion of this paperpresentedat the 50th ISI Session in Beijing, China. In this discussion, otherschallengedus regardingthe real reason for the separationof the design of experimentsandsamplesurveysafter 1935, andregardingthe original of Neyman's contributionsto sampling.We commenton each briefly. Some have arguedthat it was the fundamentaldifferences between experimentationand survey work that were truly responsible for the separationof the two fields within statistics and not the fued between Fisherand Neyman. Forexample,T.F.M.Smith(personalcommunication)arguesthat randomizationin an experimentsupportsinternalvalidity,to the collection of experimentalunits, whereas random selection in a survey setting supportsexternal validity, allowing generalization to those not in the sample. This is technically correct, but only in a narrowsense. The statistical tools used in the two fields are essentially the same and the real scientific goals of an experimenter The FundamentalContributionsof Fisher and Neymanon Experimentationand Sampling 251 involve generalizationbeyond the experimentalunits. This is exactly why we have emphasizedthe importanceof experimentsembedded in surveys and surveys embedded in experiments (Fienberg & Tanur,1988,1989). The recent interestin the common featuresof experimentationand sampling suggests that the technical links are important,as many of the early contributorsrecognized in the 1930s. Thus we do not believe thatthe differencesin perspectivebetweenexperimentationas surveys alone can account for the separation.The clash of two strongpersonalitieswho were determinedto gain recognition for their inferentialapproaches,in our view, was a majorcontributionto the split. Otherscontinueto raise the issue of the extentto which Neyman"stoodon the shouldersof giants". In particular,Chris Heyde (personal communication)raises the question of Neyman's debt to the Russian school of sampling led by Tschouproff.It is true thatNeyman was educatedin Karkovand studied probabilitywith Bernstein,as we note above, but he appearsto have had little or no contact with statistics and the sampling of finite populations.Thus, as we argued above, we believe that the contributionsin Neyman's 1923 paperrepresentindependent inen discovery.In the 1925 Biometrika version there is a reference to an earlier Biometrikapaper by Tschouproff,but no recognition of Tschouproff's 1923 Metronpaper.This appearssomewhatsloppy and even in 1934, Neyman did not single out Tschouprofffor recognition,eitherin generalor in connectionwith optimalallocation.But Neyman's purpose in 1934 was differentand he broughta new integrativeperspectiveto sampling in the paperthat differedfrom those who wrote on the topic previously. Thus while we believe that Neyman was influencedby the work of many others-few of whom he referenced-he broughtoriginalityto his paperson samplingand the clarityof his exposition was crucial to the subsequentdevelopmentof sampling.As a result, he rightly became one of the giants on whose shouldersothershave stood. We continue to see importantlinks between the fields of experimentationand sample surveys and we find their roots in the pioneering work of both Fisher and Neyman, during a time of great intellectual ferment in the 1920s and 1930s. We believe that the statisticalprofession has much to learn from their creativeideas. Acknowledgments A preliminaryversion of partsof this paperdealing with Neyman was presentedat the "International Conference on Statistics to Commemoratethe 100th Anniversaryof Jerzy Neyman's Birth", Jarchranka,Poland,November25-26, 1994, and appearedas Fienberg& Tanur(1995a). The present paperhas addedconsiderablyto the materialdrawnfrom thatearlierone. 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FisherandJerzyNeymansontbienreconnuscommeles statisticiensqui ont etabliles idees fondamentales qui soutiennent et le plandes enguetesparsondage,respectivement. le plandes experiences Danscet articlenousrevoyonsles contributions centralesde ces hommesfameuxdansles deuxdomainesde recherche.Nous adressonsaussil'effet d'une controverse a l'articlede Neyman(1935)ausujetde l'experimentation quia rapport agronome quia aboutia uneseparation dansle champsdesrecherches desexperiences et des6chantillonnages. [ReceivedMarch 1996, accepted July 1996]