Oscar Kempthorne (January 31, 1919 – November 15, 2000) was a British

statistician A statistician is a person who works with theoretical or applied statistics. The profession exists in both the private and public sectors. It is common to combine statistical knowledge with expertise in other subjects, and statisticians may wor ...

and

geneticist A geneticist is a biologist or physician who studies genetics, the science of genes, heredity, and variation of organisms. A geneticist can be employed as a scientist or a lecturer. Geneticists may perform general research on genetic processe ...

known for his research on randomization-analysis and the

design of experiments The design of experiments (DOE, DOX, or experimental design) is the design of any task that aims to describe and explain the variation of information under conditions that are hypothesized to reflect the variation. The term is generally associ ...

, which had wide influence on research in agriculture, genetics, and other areas of science. Born in St Tudy,

Cornwall Cornwall (; kw, Kernow ) is a historic county and ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people. Cornwall is bordered to the north and west by the Atlantic ...

and educated in England, Kempthorne moved to the United States, where he was for many decades a professor of statistics at Iowa State University.

Randomization analysis

Kempthorne developed a randomization-based approach to the statistical analysis of randomized experiments, which was expounded in pioneering textbooks and articles. Kempthorne's insistence on randomization followed the early writings of

Ronald Fisher Sir Ronald Aylmer Fisher (17 February 1890 – 29 July 1962) was a British polymath who was active as a mathematician, statistician, biologist, geneticist, and academic. For his work in statistics, he has been described as "a genius who a ...

, especially on randomized experiments. Kempthorne is the founder of the "Iowa school" of

experimental design The design of experiments (DOE, DOX, or experimental design) is the design of any task that aims to describe and explain the variation of information under conditions that are hypothesized to reflect the variation. The term is generally associ ...

and

analysis of variance Analysis of variance (ANOVA) is a collection of statistical models and their associated estimation procedures (such as the "variation" among and between groups) used to analyze the differences among means. ANOVA was developed by the statisticia ...

. Kempthorne and many of his former doctoral students have often emphasized the use of the randomization distribution under the

null hypothesis In scientific research, the null hypothesis (often denoted ''H''0) is the claim that no difference or relationship exists between two sets of data or variables being analyzed. The null hypothesis is that any experimentally observed difference is d ...

. Kempthorne was skeptical of "

statistical model A statistical model is a mathematical model that embodies a set of statistical assumptions concerning the generation of Sample (statistics), sample data (and similar data from a larger Statistical population, population). A statistical model repres ...

s" (of populations), when such models are proposed by statisticians rather than created using objective randomization procedures. Kempthorne's randomization-analysis has influenced the

causal model In the philosophy of science, a causal model (or structural causal model) is a conceptual model that describes the causal mechanisms of a system. Causal models can improve study designs by providing clear rules for deciding which independent va ...

Donald Rubin Donald is a masculine given name derived from the Gaelic name ''Dòmhnall''.. This comes from the Proto-Celtic *''Dumno-ualos'' ("world-ruler" or "world-wielder"). The final -''d'' in ''Donald'' is partly derived from a misinterpretation of the ...

; in turn, Rubin's randomization-based analysis and his work with Rosenbaum on

propensity score matching In the statistical analysis of observational data, propensity score matching (PSM) is a statistical matching technique that attempts to estimate the effect of a treatment, policy, or other intervention by accounting for the covariates that predic ...

influenced Kempthorne's

analysis of covariance Analysis of covariance (ANCOVA) is a general linear model which blends ANOVA and regression. ANCOVA evaluates whether the means of a dependent variable (DV) are equal across levels of a categorical independent variable (IV) often called a tre ...

Model-based analysis

Oscar Kempthorne was skeptical towards (and often critical of)

model A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin ''modulus'', a measure. Models c ...

-based inference, particularly two influential alternatives: Kempthorne was skeptical of, first, neo-Fisherian statistics, which is inspired by the later writings of Ronald A. Fisher and by the contemporary writings of

David R. Cox Sir David Roxbee Cox (15 July 1924 – 18 January 2022) was a British statistician and educator. His wide-ranging contributions to the field of statistics included introducing logistic regression, the proportional hazards model and the Cox pro ...

and

John Nelder John Ashworth Nelder (8 October 1924 – 7 August 2010) was a British statistician known for his contributions to experimental design, analysis of variance, computational statistics, and statistical theory. Contributions Nelder's work was inf ...

; neo-Fisherian statistics emphasizes

likelihood function The likelihood function (often simply called the likelihood) represents the probability of random variable realizations conditional on particular values of the statistical parameters. Thus, when evaluated on a given sample, the likelihood funct ...

s of parameters. Second, Kempthorne was skeptical of

Bayesian statistics Bayesian statistics is a theory in the field of statistics based on the Bayesian interpretation of probability where probability expresses a ''degree of belief'' in an event. The degree of belief may be based on prior knowledge about the event, ...

, which use not only likelihoods but also

probability distribution In probability theory and statistics, a probability distribution is the mathematical function that gives the probabilities of occurrence of different possible outcomes for an experiment. It is a mathematical description of a random phenomenon i ...

s on parameters.However, Kempthorne recognized that the planning of experiments used scientific knowledge and beliefs, and therefore Kempthorne was interested in

optimal design In the design of experiments, optimal designs (or optimum designs) are a class of design of experiments, experimental designs that are Optimization (mathematics), optimal with respect to some statistical theory, statistical objective function, ...

s, especially

Bayesian experimental design Bayesian experimental design provides a general probability-theoretical framework from which other theories on experimental design can be derived. It is based on Bayesian inference to interpret the observations/data acquired during the experiment. ...

The optimal design is dependent upon the unknown theta, and there is no choice but to invoke prior information about theta in choosing the design. I would like to say there has never been the slightest argument about this. In the design of experiments, one has to use some informal prior knowledge. (Folks, 334)

Kempthorne's skepticism towards

Bayesian inference Bayesian inference is a method of statistical inference in which Bayes' theorem is used to update the probability for a hypothesis as more evidence or information becomes available. Bayesian inference is an important technique in statistics, a ...

focused on the prior's use in analyzing data from randomized experiments; for analyzing data from randomized experiments, Kempthorne advocated using the objective randomization-distribution, which was induced by the randomization specified in the experimental protoocol and implemented in the actual experimental plan. Nonetheless, while subjective probability and

were viewed skeptically by Kempthorne,

was defended. In the preface to his second volume with Hinkelmann (2004), Kempthorne wrote,

We strongly believe that design of experiment is a Bayesian experimentation process, ... one in which the experimenter approaches the experiment with some beliefs, to which he accommodates the design. (xxii)

Bibliography

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Writings about Oscar Kempthorne

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Notes

External links