## Statistical Science

- Statist. Sci.
- Volume 22, Number 4 (2007), 621-636.

### A Conversation with Seymour Geisser

Ronald Christensen and Wesley Johnson

#### Abstract

Seymour Geisser received his bachelor’s degree in Mathematics from the City College of New York in 1950, and his M.A. and Ph.D. degrees in Mathematical Statistics at the University of North Carolina in 1952 and 1955, respectively. He then held positions at the National Bureau of Standards and the National Institute of Mental Health until 1961. From 1961 until 1965, he was Chief of the Biometry Section at the National Institute of Arthritis and Metabolic Diseases, and also held the position of Professorial Lecturer at the George Washington University from 1960 to 1965. From 1965 to 1970, he was the founding Chair of the Department of Statistics at the State University of New York, Buffalo, and in 1971, he became the founding Director of the School of Statistics at the University of Minnesota, remaining in that position until 2001. He held visiting professorships at Iowa State University, 1960; University of Wisconsin, 1964; University of Tel-Aviv (Israel), 1971; University of Waterloo (Canada), 1972; Stanford University, 1976, 1977, 1988; Carnegie Mellon University, 1976; University of the Orange Free State (South Africa), 1978, 1993; Harvard University, 1981; University of Chicago, 1985; University of Warwick (England), 1986; University of Modena (Italy), 1996; and National Chiao Tung University (Taiwan), 1998. He was the Lady Davis Visiting Professor, Hebrew University of Jerusalem, 1991, 1994, 1999, and the Schor Scholar, Merck Research Laboratories, 2002-2003. He was a Fellow of the Institute of Mathematical Statistics and the American Statistical Association.

Seymour is listed in World Men of Science, American Men and Women of Science and Who’s Who in America. He served on numerous committees for the National Institutes of Health, Food and Drug Administration, National Institute of Statistical Science and National Research Council. In addition, he was a National Science Foundation Lecturer in Statistics from 1966–1969; member of the National Research Council Committee on National Statistics from 1984–1987; Chair of the National Academy of Sciences panel on Occupational Safety and Health Statistics from 1986–1987; and he served on Program Review Committees for many universities. He delivered the American Statistical Association President’s Invited Address in 1991.

Seymour authored or coauthored 176 scientific articles, discussions, book reviews and books over his career. One of his articles, “On methods in the analysis of profile data,” which was coauthored by S. W. Greenhouse, and published in *Psychometrika* in 1959, is listed as a citation classic. He pioneered several important areas of statistical endeavor. He and Mervyn Stone simultaneously and independently invented the now popular statistical method called “cross-validation,” which is used for validating statistical models. Dr. Geisser’s paper on the subject, “The predictive sample reuse method with applications,” was published in the *Journal of the American Statistical Association* in 1975. He pioneered the areas of Bayesian multivariate analysis and discrimination, Bayesian diagnostics for statistical prediction and estimation models, Bayesian interim analysis, testing for Hardy–Weinberg equilibrium using forensic DNA data, and the optimal administration of multiple diagnostic screening tests.

Seymour was primarily noted for his sustained focus on prediction in Statistics. This began with his work on Bayesian classification. He gave an early exposition in his article, “The inferential use of predictive distributions,” published in *Foundations of Statistical Inference* in 1971. Most of his work in this area is summarized in his monograph, *Predictive Inference: An Introduction* published by Chapman and Hall in 1993. The essence of his argument was that Statistics should focus on observable quantities rather than on unobservable parameters that often do not exist and have been incorporated largely for convenience. He argued that the success of a statistical model should be measured by the quality of the predictions made from it. He pointed out that interest in model parameters often seemed to be based more on interest in ease of mathematical display than in their scientific utility.

Shortly after it was introduced, he gave his attention to forensic DNA profiling. He was involved as an expert witness in 100 litigations involving murder, rape, paternity, and other issues. His experiences in dealing with the FBI throughout these litigations are catalogued in his paper, “Statistics, litigation and conduct unbecoming,” published in *Statistical Science in the Courtroom* in 2000. His primary purpose in these litigations was to point out that statistical calculations displayed in court should be valid. It was his contention that the statistical methods then being used by the prosecution in DNA cases were flawed.

Finally, he was proud of his role in the development of the University of Minnesota School of Statistics and its graduate program. During his tenure there, he was responsible for hiring outstanding faculty who have since become leaders in their areas of expertise. Moreover, many of the students obtaining their Ph.D. degrees at the University of Minnesota have also become prominent in their respective fields. Seymour was substantially responsible for creating an educational environment that valued the foundations of Statistics beyond mere technical expertise.

Two special conferences were convened to honor the contributions of Seymour to the field of Statistics. The first was organized by Jack Lee and held at the National Chiao Tung University of Taiwan in December of 1995. The second was organized by Glen Meeden and held at the University of Minnesota in May of 2002. In conjunction with the former conference, a special volume entitled, *Modeling and Prediction: Honoring Seymour Geisser*, was published in 1996.

Most recently, Seymour compiled his lecture notes into a manuscript entitled, *Modes of Parametric Statistical Inference* [published by Wiley in 2006]. The book provides a broad view of the foundations of Statistics and invites discussion of the relative merits of different modes of statistical inference, method, and thought. His life’s work exemplifies the presentation of thoughtful, principled, reasoned, and coherent statistical methods to be used in the search for scientific truth.

Seymour Geisser died March 11, 2004.

The Department of Statistics at the University of Minnesota has established the **Seymour Geisser Lectureship in Statistics**. Each year, starting in the Fall of 2005, an individual will be named the Seymour Geisser Lecturer for that year and will be invited to give a special lecture. Individuals will be selected on the basis of excellence in statistical endeavors and their corresponding contributions to science, both statistical and otherwise. For more information or to see his curriculum vitae, visit the University of Minnesota, Department of Statistics web page, www.stat.umn.edu.

#### Article information

**Source**

Statist. Sci. Volume 22, Number 4 (2007), 621-636.

**Dates**

First available in Project Euclid: 7 April 2008

**Permanent link to this document**

http://projecteuclid.org/euclid.ss/1207580175

**Digital Object Identifier**

doi:10.1214/088342307000000131

**Mathematical Reviews number (MathSciNet)**

MR2420464

**Zentralblatt MATH identifier**

1246.01026

#### Citation

Christensen, Ronald; Johnson, Wesley. A Conversation with Seymour Geisser. Statist. Sci. 22 (2007), no. 4, 621--636. doi:10.1214/088342307000000131. http://projecteuclid.org/euclid.ss/1207580175.