Cohort Fertility: A Comparison of the Results of the Official Birth Statistics and of the Microcensus Survey 2008
Data are available for the first time for the year under report 2008 on the biological number of children of women from the comprehensive Microcensus sample. Previously, only the ongoing birth statistics provided information on cohort fertility as a total fertility rate of the synthetic female cohorts. Since both benchmarks bear different types of insecurity, a comparison is to provide important information on the quality of these indicators.
This article shows that the average number of children per woman in the dataset of the Microcensus 2008 and the cohort fertility rate in the birth statistics show a highly similar course of cohort fertility. Whilst the agreement for the female cohorts in the new Länder (former GDR without Berlin East) and in Germany as a whole is almost complete, the values in the old Länder (Western Germany without Berlin West) are further apart. A major cause of this evidently lies in the high proportion of female immigrants in the old Länder. Some of the women who immigrated into the former territory of Federal Republic already gave birth to their children before entering Germany. These births could not be taken into account in the ongoing birth statistics, whilst the Microcensus provided information on all children born, regardless of where they were born. These survey-related deviations can be largely reduced if the comparison with the cohort fertility rate of the birth statistics is based not on the average number of children of all women, but only on the number of children of women who were born in Germany or who immigrated below the age of 26. The share of female migrants was low in the new Länder and did not impact cohort fertility. All in all, the comparison showed that both sets of statistics provide data with a good degree of concurrence on the fertility of the birth years from 1933 to 1992 for Germany as a whole, as well as for the old and the new Länder. This makes it possible to carry out detailed analyses of fertility in relation to comprehensive socioeconomic characteristics of the Microcensus.