 From 1965 to 1967 he directed the International Computing Center in Rome.He was also associated with the Centre d'Analyse et de Mathématique Sociales (CAMS), a research center of École des hautes études en sciences sociales.He held visiting positions at Princeton University in 1957, Pennsylvania State University in 1968, and New York University in 1985, and was a frequent visitor to the Indian statistical institute, Calcutta.