Participant dropout as a function of survey length in internet-mediated university studies: implications for study design and voluntary participation in psychological research.

Internet-mediated research has offered substantial advantages over traditional laboratory-based research in terms of efficiently and affordably allowing for the recruitment of large samples of participants for psychology studies. Core technical, ethical, and methodological issues have been addressed in recent years, but the important issue of participant dropout has received surprisingly little attention. Specifically, web-based psychology studies often involve undergraduates completing lengthy and time-consuming batteries of online personality questionnaires, but no known published studies to date have closely examined the natural course of participant dropout during attempted completion of these studies. The present investigation examined participant dropout among 1,963 undergraduates completing one of six web-based survey studies relatively representative of those conducted in university settings. Results indicated that 10% of participants could be expected to drop out of these studies nearly instantaneously, with an additional 2% dropping out per 100 survey items included in the study. For individual project investigators, these findings hold ramifications for study design considerations, such as conducting a priori power analyses. The present results also have broader ethical implications for understanding and improving voluntary participation in research involving human subjects. Nonetheless, the generalizability of these conclusions may be limited to studies involving similar design or survey content.