Abstract

Social proof as a psychological concept of compliance states that individuals are likely to follow the behavior of other individuals. This study investigates the effectiveness of social proof treatments in email invitations within a German online probability panel (OPAL) using an experimental design. Social proof, using a wording emphasizing either the actual number of respondents (e.g., 3600) or as a response rate percentage (e.g. 34%), was incorporated into the subject line and body of three reminder emails. We analyzed the impact on email opening, survey access, and overall response rates. Contrary to expectations, our results revealed that neither social proof treatment had a statistically significant effect on any of the outcomes. Furthermore, no differences emerged between the two wordings, and there was no evidence that social proof had variable effects across reminder stages. Additionally, social proof was not more effective for individuals who had not participated in a previous survey wave. These findings suggest that social proof wordings may have limited applicability in increasing survey participation within online panels.