Estimations des migrations répétées et des migrations de retour dans des sous-populations en France

Many people who have migrated internally move again, often back to their earlier location. This paper examines these well-known phenomena using a French administrative data source, a panel sample taken from employers? annual declarations of tax and social security data (DADS). Descriptive statistics on migration at ages 25-35 of cohorts born in 1966, 1968 and 1970 reveal the main characteristics of successive migrations. Using a ?mover-stayer? model, estimates are made of the proportions of the population exposed to the risk of migration or further migration, and of the probabilities of various types of migration occurring among the people exposed to that risk. Repeat and return migrations are observed to vary considerably by cohort and, within a given cohort, by population category. This variability must be taken into account when applying the relationship between number of migrants and numbers of migrations proposed by Daniel Courgeau in 1973, and used since then to establish series of internal mobility rates from population censuses.