Content and Objectives

Ex-post model calculations are used in this project to quantify the demographic effects of (internal and external) migration which additionally arise through impacts on the age stocks (e.g. potential children who have immigrated or emigrated with their parents), and which come about as a result of differing age structures of the resident and migrant populations. This takes place for the period from 1991 until the point in time which is currently possible for all Federal Länder, broken down by internal, external and total migration. In addition to the possibility to calculate these effects in absolute and relative population sizes, it is possible to measure the acceleration of ageing that is induced through migration using the resulting changes in the median age.

The effect caused by the internal migration of the years from 1991 to 2006 reveals that the birth figure for Eastern Germany (not including Berlin) would be roughly 12 percent higher without internal migration, whilst it would have been just over one percent lower in Western Germany (not including Berlin). Further, the effect of ageing in Eastern Germany is amplified by up to one-third (women) and one-quarter (men), this also applying in Lower Saxony, the Saarland and Schleswig-Holstein. This effect has been weakened by internal migration in the rest of Western Germany, and in the city states in particular.

External migration effectively has a positive impact on the population size and on the birth figures in all Federal Länder, and acts as a brake on ageing. For instance, the age structure effect created by external migration has reduced ageing in Eastern Germany by one-eleventh, and in Western Germany by one-seventh.

Furthermore, a new demographic rate, namely the ‘Total Migration Effect Rate’ (TMER), was developed within this project. This rate makes it possible to determine the additional demographic effect of migration which is always caused when the resident and the migrant populations differ in terms of their age composition and their demographic conduct. Put simply, this rate expresses what percentage of the difference in the stock sizes between two points in time is caused solely by these differences in age structure between resident and migrant populations. It is therefore revealed amongst other things that the internal emigration of primarily younger people from the Eastern German Federal Länder from 1991 to 2006 has an additional effect on the age structure of the population size of the year 2006. The age structure effect is positive in the three city states, as well as in Bavaria and in Hesse, so that these Länder have benefited from internal migration in terms of age structure (with regard to their population size). It is negative in Eastern Germany, but also in the other Western German Länder. The population size of Saxony in 2006 for instance would be +1.8 percent larger without the age structure effect of internal migration, this effect however being largely caused by the birth figures which emigrated with the younger women, and were hence reduced. The age structure effect of external migration on the population size is negative in Eastern Germany, Lower Saxony and the Saarland, that is, it causes an additional ageing and shrinking impact; the other Länder have benefited from external migration in terms of their age structure.