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Panel Conditioning in a German Probability-Based Longitudinal Study: A Comparison of Respondents with Different Levels of Survey Experience

Learning effects due to repeated interviewing, which are referred to as panel conditioning, are a major threat to response quality in later waves of a panel study. Up to date, research has not provided a clear picture regarding the circumstances, mechanisms, and dimensions of potential panel conditioning effects. Especially the effects of conditioning frequency, that is, different levels of experience within a panel, on response quality are underexplored. Against this background, we investigated the effects of panel conditioning by using data from the GESIS Panel, a German mixed-mode probability-based panel study. Using two refreshment samples, we compared three panel cohorts with differing levels of experience with respect to several response quality indicators related to the mechanisms of reflection, satisficing, and social desirability. Overall, we find evidence for both negative (i.e., disadvantageous for response quality) as well as positive (i.e., advantageous for response quality) panel conditioning. Highly experienced respondents were more likely to satisfice by selecting mid-point responses or by speeding through the questionnaire. They also had a higher probability of refusing to answer sensitive questions than less experienced panel members. However, more experienced respondents were also more likely to optimize the response processes by needing less time compared to panelists with lower experience levels (when controlling for speeding). In contrast, we did not find significant differences with respect to the number of “don’t know” responses, non-differentiation, the selection of first response categories, and the number of non-triggered filter questions. Of the observed differences, speeding showed the highest magnitude with an average increase of 5.9 percentage points for highly experienced panel members compared to low experienced panelists.