Prof. Emeritus R. Darrell Bock, an eminent scholar and teacher who helped revolutionize educational assessments, died Sept. 15 at the age of 93.
A longtime UChicago faculty member in the Departments of Psychology and Comparative Human Development, Bock was best known for his influential work on educational metrics and his many contributions to the statistical framework known as item response theory (IRT), a term that he introduced which is still widely used.
Over the course of his career, Bock greatly advanced the precision and accuracy of measurement in the social, behavioral and educational sciences. He also made significant contributions to numerous other areas of mathematical and statistical thinking, including linear algebra, multivariate statistics and quantitative genetics.
“Darrell was a leader in the rich University of Chicago tradition of quantitative thinking, dramatically raising the sophistication of quantitative inquiry in the fields of education and psychology,” said Robert Gibbons, PhD’81, a former student who is now the Blum-Riese Professor of Biostatistics at UChicago. “He was a brilliant scholar and a devoted and compassionate teacher.”
Born in Oakdale, Pennsylvania, on Sept. 17, 1927, Bock attended Carnegie Institute of Technology (now Carnegie Mellon University) with classmate John Nash, a mathematician who would later share a Nobel Memorial Prize in Economic Sciences.
After graduating with a chemistry degree in 1949, he came to the University of Chicago for graduate school, earning a master’s in 1950 and a Ph.D. in 1952, both in the study of educational practice.
After a brief military service as a psychology assistant in the U.S. Army, Bock returned to UChicago in 1955. He taught as a research associate and assistant professor in UChicago’s Department of Psychology until 1958, when he became an assistant professor at the University of North Carolina at Chapel Hill.
In 1964, he returned to the University of Chicago as a professor of psychology and education, remaining on the Hyde Park campus for the rest of his career. At UChicago, Bock founded the Committee on Research Methodology and Quantitative Psychology in 1984 and chaired it for nearly a decade.
That committee, said Prof. Guanglei Hong, “produced a generation of leading scholars. Among them were Robert Gibbons and Don Hedeker, who then helped with the reincarnation of this unique interdisciplinary research and training program.” Hong is the current chair of the committee, now known as the Committee on Quantitative Methods in Social, Behavioral, and Health Sciences.
Bock’s research, teaching and other professional activities have had far-reaching influence in educational measurement, psychology, statistics and linear algebra. He developed maximum marginal likelihood estimation to deal with the problem of increasing parameter space with an increasing number of subjects in both IRT model estimation and mixed-effects regression models. This led to multidimensional extensions of IRT and dramatic expansion of applications of IRT beyond educational measurement.
“Darrell Bock can be regarded as a co-inventor of this theory,” said Stephen Raudenbush, the Lewis-Sebring Distinguished Service Professor of Sociology. “More than any other, he put IRT on a rigorous mathematical-statistical foundation, and the methods he derived are nearly universally applied in the practice of IRT and have implications for a broad array of other scientific applications.”
Bock also made major contributions to the fields of behavioral genetics and auxology (the study of human growth). His landmark book Multivariate Statistical Methods in Behavioral Research (1975) revolutionized the practice of statistics in the behavioral and social sciences. He is credited with introducing the multinomial logit model, which was a milestone development in nonlinear statistical theory. His final book Item Response Theory, which he co-wrote with Gibbons, was published last month. Holding a copy of the book, Gibbons said, brought a smile to Bock’s face.
Bock’s accomplishments led to national and international recognition and a long list of honors and awards. He served as president of the Psychometric Society and received a lifetime achievement award from the organization in 2008. He was also a fellow of the American Statistical Association and the Royal Statistical Society.
In 1990, he received the National Council on Measurement in Education’s annual award, among the many honors that spoke to his renown and eminence in the field of educational testing and metrics.
Nevertheless, Bock’s friends recalled him as humble and unassuming. “Despite being a giant both intellectually and physically, Darrell kept his presence quiet on the campus,” Hong said.
In a 2006 interview, Bock mentioned an award-winning essay that he had written as an undergraduate, a copy of which he rediscovered during a move. In characteristic fashion, Bock remarked that his writing had changed little in the intervening years, despite ample opportunity for improvement: “As it is, I seem doomed to compose nothing but my straightforward academic prose.”
“Despite his statements to the contrary,” Gibbons said, “he was a brilliant writer whose works will remain an inspiration.”
Outside of academia, Bock loved theater, art and photography. He was a gifted black-and-white photographer whose work was exhibited in New York City galleries, including an exhibit with his daughter Monica entitled “Soft Touch/Wondering Eye.” Even in later years, Bock enjoyed discussing photography and passed his love of the hobby onto his children and grandchildren.
He is survived by his wife of 68 years, Renee Menegaz-Bock; three children, Conrad, Monica and Paul; and six grandchildren.