Lazarsfeld, Paul F. (läˈzərsfĕltˌ) [key], 1901–76, American sociologist, b. Vienna. After beginning as a mathematician, he established a research center for social psychology. Emigrating to the United States in 1933, he taught at Columbia Univ. (1949–69), where he founded the Bureau of Applied Social Research. Lazarsfeld has been the most important influence on quantitative sociological research in the 20th cent. He developed social survey research, and made major contributions to mathematical sociology, methodology, and the study of mass communications and voting behavior. His studies indicated that voters follow informal media-wise leaders among family and friends rather than the media itself.