Widely considered to be among the founding fathers of modern statistics, Leo died Dec. 22, 2020, of a COVID-19-related lung infection in Berkeley, Calif. 

Leo was born Aug. 7, 1928, in Brooklyn. He earned a bachelor’s degree in sociology and mathematics from Syracuse University and a Ph.D. at Princeton at age 22. His passion for statistics was ignited by mentors Sam Wilks and John Tukey *39.

In 1950 he joined the University of Chicago faculty as one of the nation’s youngest professors. After a year at Stanford’s Center for Advanced Study in the Behavioral Sciences, Leo began a 30-year tenure as UC Berkeley’s Class of 1938 Professor of Sociology and Statistics.

By addressing the intrinsic difficulty of studying categorical distinctions like race, religion, and gender with statistics designed for continuous variables like time and distance, Leo revolutionized the study of poverty, inequality, and other social phenomena. Techniques he developed are considered a gold standard in sociology scholarship worldwide. 

Three statistics used in software — Goodman-Kruskal Lambda, Gamma, and Tau — are named after Leo and his Chicago colleague William Kruskal.

Leo is survived by sons Andy and Tom; sister Janice; five grandchildren; and his former wife, Ann Hayes.

Graduate memorials are prepared by the APGA.