Fertility data for German speaking countries. What is the potential? Where are the pitfalls?

This paper gives an overview of fertility data for Germany, Austria and Switzerland. Particular attention is given to the availability of order-specific fertility data. We discuss the quality of data provided by the Statistical Offices, both birth registration data and censuses or microcensuses. In addition, we explore how social science surveys can be used to generate order-specific fertility indicators, and compare fertility estimates across surveys with estimates from vital statistics. Prior studies have shown that there is a ’family bias’ in most surveys, with the fertility of the younger cohorts being overstated, because respondents with young children are easier to reach by the interviewers. Our assessment of various types of surveys from the three different countries does mostly support this notion. However, the ‘family bias’ is most pronounced in family surveys while all-purpose surveys suffer from it to a lesser extent. Weighting the data does not fully cure the ‘family bias’, which we attribute to the fact that the number of children is usually not considered in the sampling weights that are provided by the survey agencies and the Statistical Offices. The confounding role of migration in the production of reliable and comparable fertility statistics is also discussed.