Migration as a factor of population reproduction

Dalkhat M. Ediev, Vienna Institute of Demography
David A. Coleman, University of Oxford
Sergei Scherbov, International Institute for Applied Systems Analysis and Vienna Institute of Demography

Completed Net Migration is introduced as an expected number of net migrants to join the original birth cohort through its life span. In the context of population reproduction, Migratory Fertility is introduced as a measure of migrants’ addition to the reproduction of population birth cohorts. Robust estimating procedures are suggested which reflect the differential fertility of migrants and also significant links between migrations at different ages. Combined Fertility, which is approximated by the sum of conventional Total Fertility and of Migratory Fertility, characterises the reproduction regimen of a population with the migratory impact on reproduction explicitly taken into account. The concept of stable equivalent population is also adjusted to include the migratory impact on population growth and structure, which provides a sound basis for studying the prospects of population ageing.