Period and Cohort Measures of Internal Migration

Migration is rarely analysed from a cohort perspective, which is not the case for the two other main demographic phenomena of fertility and mortality. This study shows how standard demographic methodology can be used to study internal migration from a combined period and cohort perspective at the population level. Age-specific migration rates and the total migration rate are presented for both period and cohort data. Administrative register data are used for the years 1970 to 2012 on all interparish migration events for the complete population of Sweden. The results show an overall increase in the concentration of migration events in early adulthood, while total migration frequencies over the life course remained stable since 1970, with a small decline in the 1980s. Cohort rates show less fluctuation than period rates. The study shows that a population-level approach is useful not only for migration but also for simultaneously examining cohort and period trends. These methods can easily be extended by decomposing data into different distance thresholds and according to migration order, given the available data.