Strongly influenced by the works of Alfred James Lotka (1880-1949) and Pierre Depoid (1909-1968), the first INED demographers (mostly graduates of the prestigious École Polytechnique), developed original methods of demographic analysis that confirmed the Institute's independence and established its international reputation. A few names from that period stand out in particular:
• Jean Bourgeois-Pichat (1912-1990) who explored the notions of stable and quasi-stable populations and modelled relationship networks between demographic variables;
• Paul Vincent (1912-1979) who invented the concept of population growth potential;
• Sully Ledermann (1915-1967) who applied multivariate analysis methods to establish model life tables;
• Louis Henry (1911-1991) who founded historical demography and in 1953, used samples of Ancien Régime parish registers to reconstruct families and analyse the population dynamics of France ("Survey of the French population from 1690 to 1729" in collaboration with the archivist and palaeographer Michel Fleury).
The work of these pioneers was set down in the manuals and in the dictionary of demography written by Roland Pressat (who joined INED in 1953), which became essential reading for generations of students, and which spread the principles of demographic analysis far and wide, notably to Quebec, and to numerous countries in Eastern Europe and Africa.
The sociologist Jean Stoetzel (1910-1987) who founded the Institut français de l'opinion publique (IFOP) the French public opinion polling institute in 1938 after working briefly for Gallup in the United States, worked on numerous INED surveys together with Alain Girard (1914-1996) on such varied subjects as female labour, the ideal number of children, the choice of spouse, immigration, etc. This work was pursued by Louis Roussel in the 1970s and Henri Leridon in the 1980s.
The social history of populations was studied by Louis Chevalier (1911-2001), the Paris historian elected to the Collège de France in 1952. Jean-Noël Biraben researched the history of disease, while Jacques Houdaille focused on the history of minorities.
Population genetics were developed successively by Jean Sutter (1910-1970), Albert Jacquard, and André Chaventré.
A second generation of INED researchers took the reins after 1965, composed of École Polytechnique graduates (Daniel Courgeau, Henri Leridon, and Hervé Le Bras), as well as demographers from a variety of backgrounds (Jacques Vallin, Patrick Festy, Chantal Blayo, and Jean-Claude Chesnais).