Quetelet, Adolphe (ädôlf' ketulā') [key], 1796–1874, Belgian statistician and astronomer. He was the first director (1828) of the Royal Observatory at Brussels. As supervisor of statistics for Belgium (from 1830), he developed many of the rules governing modern census taking and stimulated statistical activity in other countries. Applying statistics to social phenomena, he developed the concept of the “average man” and established the theoretical foundations for the use of statistics in social physics or, as it is now known, sociology. Thus, he is considered by many to be the founder of modern quantitative social science. A Treatise on Man (1835; tr., 1842) is his best-known work.
