Chart and table of population level and growth rate for the Cologne, Germany metro area from 1950 to 2025.

The study programme “FReDA – The German Family Demography Panel” is a cooperative project of the German Federal Institute for Population Research (BiB), GESIS – Leibniz Institute for the Social Sciences, and – as representatives of the pairfam consortium – the University of Cologne and the Friedrich Schiller University Jena. FReDA is a longitudinal study on family and demography with an international perspective and a dyadic multi-actor design. As part of the international Generations and Gender Programme (GGP), the German Generations and Gender Survey (GGS) sample (FReDA-GGS) allows for comparisons with around 14 other European countries as well as five countries or territories in Asia and South America. From FReDA wave 2 onwards, the pairfam sample – which had existed in large part since 2008 – was integrated into the FReDA panel as the FReDA-pairfam sample and will be followed with a joint FReDA survey instrument.

Regular FReDA waves comprise two subwaves, which are collected biannually: subwave A (e.g., W1A) and subwave B (e.g., W1B). Every four years, an additional recruitment/refreshment wave is conducted, which is marked with the letter R (e.g., W1R). The main survey is conducted with the anchor persons. In addition, the anchors´ partners are also surveyed – once in wave 1, bi-annually from wave 2 onwards. In addition, from wave 2 onwards, anchors´ ex-partners are also surveyed. Although the survey programme for (ex-)partners is based on the main survey, it differs in scope and content, and it is designed cross-sectionally – that is, anchors are asked in each subwave for their consent to their (ex-)partners being contacted with a request to participate in the FReDA partner survey.

For the recruitment of the FReDA-GGS sample, a probability-based sample of 108,256 anchor persons aged between 18 and 49 years resident in Germany was drawn from the population registers of municipalities in Germany in 2020. In wave 1, the Interviews were conducted in a self-administered mode – either web-based (CAWI) or paper-based (PAPI) – by the infas Institute for Applied Social Sciences. From wave 2 onwards, the interviews are conducted in a self-administered mode (CAWI or PAPI) by GESIS – Leibniz Institute for the Social Sciences. Also with effect from wave 2, the probability-based pairfam sample was integrated into FReDA as the FReDA-pairfam sample if anchors consented to participate in the FReDA study. Consent could be given either during the pairfam wave 14 interview or by telephone or postal mail (postcard). Hence, pairfam anchors who did not take part in pairfam wave 14 could also be integrated into FReDA if they gave their consent. The FReDA-pairfam sample includes randomly selected individuals from the birth cohorts 1971–73, 1981–83, and 1991–93. In addition, it includes a younger cohort (2001–03), which was recruited in pairfam wave 11. Furthermore, "step-up respondents" – that is, former participants in the pairfam children´s survey who transitioned to the main pairfam anchor survey on reaching the age of 15 years – also became part of the FReDA-pairfam sample if they consented to be re-interviewed.

FReDA focuses thematically on family life and intimate relationships. The FReDA questionnaires have a modular design and comprise the following main topics: • Family planning and fertility • Couples’ relationships and partnerships • Parent–child and intergenerational relationships • Sociodemographics • Health, well-being, and personality • Work and income • Attitudes and values • Aspects of the COVID-19 pandemic

A comprehensive overview of the methodological and conceptual principles of the FReDA study is provided in the FReDA reference paper (Schneider et al. (2021)) and in a recent data brief by Hank et al. (2024).

A comprehensive overview of the methodological and conceptual principles of the pairfam study can be found in the pairfam reference paper (Huinink et al. (2021)) and in the pairfam Studiendokumentation.