Throughout the recruitment process, the GESIS Panel followed state-of-the-art recommendations for building a probability based online access panel. The reference population for the GESIS Panel is the German speaking population aged between 18 and 70 years and permanently resident in Germany. By the end of the recruitment phase in February 2014, the GESIS Panel comprised around 4900 panelists. All panelists were recruited from a random sample drawn from municipal population registers.
All persons in the sample were interviewed in personal house visits with a computer-aided personal interview (CAPI) (in German only) and asked to participate in the panel. Mail questionnaires were sent to those participants who were unable or unwilling to participate in online surveys. Each interviewed person was given an incentive to participate in the recruitment interview; participation in all subsequent waves was also incentivized.
Further details of the recruitment process can be found in the Executive Summary: Recruitment for the GESIS Panel and the GESIS Panel reference paper (Bosnjak et al., 2017). The executive summary of the recruitment process is based on the comprehensive report authored by TNS Infratest. Further details can be found in that report (in German only).
In order to compensate for panel attrition, a refreshment sample was drawn from the German General Social Survey (ALLBUS) in 2016. Now, the GESIS Panel comprises about 4400 panelists (June, 2018).