Financial Incentives, Personal Information and Drop Out in Online Studies

Abstract

Whereas in a classical laboratory setting participants often feel compelled to stay and finish the experiment, participants in online studies can leave the session at any time. Though, from an ethical point of view this is an advantage of online studies, it might pose methodological problems. Of course, web experimenters would like their participants to stay until the end of the experiment. To ensure this they use special techniques. One such technique is to make web pages shorter and more attractive the further the participant gets. If a web page has a long loading time at the beginning participants with small interest or little time leave right away without even starting the experiment. This “high hurdle technique” is particularly effective in combination with a warm-up phase (Reips, 1996, 1999). A second frequently used technique to prevent participants from leaving is to initially announce a lottery with prizes, in which only those who finish the experiment can take part. Whether or not this procedure is a successful method to reduce the drop-out rate has never been examined experimentally. One might argue that promising financial incentives is negligible in reducing drop-out or might even reduce the intrinsic motivation of the potential participant (Deci, 1975). A survey among 21 web experimenters recently conducted by Musch and Reips (in press) suggests that this is not the case. In contrast to the expectation of a purely intrinsic motivation to participate in online studies they found a clear link between lack of financial incentives and drop-out rate. A monetary prize might diminish dropout tendency whenever intrinsically motivating factors are not sufficient. The web experiment at hand has been conducted to further investigate the causal nature of the relationship between financial incentives and drop-out. The experiment was also designed to test the hypothesis that asking participants for personal information early in the experiment would lead to increased drop-out as well as different answering behavior in questions that are likely to be influenced by social desirability. Participants’ answers might be more strongly influenced by social norms, if they believe they could be identified (e. g., by their e-mail address). Or they might discontinue participation in the experiment if they realize that their behavior would force them to answer contrary to what is usually desired or accepted. The question whether personal or demographic data should be assessed at the beginning