• nonrespondents;
  • self-selection;
  • participation;
  • personality


We evaluated Big Five personality factor differences between research volunteers and nonvolunteers. In the first study, 158 military officers were asked to participate in a mail survey. The personality scores of the officers were available from an archival data set. In our second study, adult siblings from large families were invited to participate in extensive clinical epidemiological evaluations. The personality scores of volunteers (N = 55) and nonvolunteers from the same families (N = 29) were estimated from sibling ratings made by those who participated in the study. In both studies, respondents, compared to nonrespondents, were found to be significantly lower in Neuroticism and higher in Conscientiousness. The second study further indicated respondents as being higher in Extraversion and Agreeableness. Copyright © 2007 John Wiley & Sons, Ltd.