Investigating self-selection bias of online surveys on COVID-19 pandemic-related outcomes and health characteristics from a cross-sectional and longitudinal perspective
GESIS – Leibniz-Institut für Sozialwissenschaften
The coronavirus SARS-CoV-2 outbreak has stimulated numerous online convenience surveys. The results are, however, often generalized to the general population. Using a probability-based sample that includes online and mail-mode respondents, we will tackle the following research questions assuming that the sample of online respondents mimics respondents of an online convenience survey: (1) Do online respondents systematically differ from offline respondents regarding COVID-19- related outcomes and health characteristics? (2) Do internet users (in both modes) systematically differ from non-internet users with respect to COVID-19-related outcomes and health characteristics? (3) Do we find any differences with regard to research questions (1) and (2) from a longitudinal perspective? The analyses utilize data from the GESIS Panel, a probability-based panel study that includes online and mail-mode respondents. Since data collection on the coronavirus outbreak started in March 2020, five additional waves have been fielded, allowing cross-sectional and longitudinal comparisons between the two survey modes (CAWI/PAPI) and groups (internet vs. non-internet users), respectively. Preliminary analyses reveal small differences concerning behavioral and attitudinal outcomes among the two modes/groups. Larger differences can be reported for health characteristics (e.g., "belong to a risk group"). Further analyses will be conducted focusing on differences among internet vs. non-internet users.