Personal and nonpersonal incentives in mail surveys: Immediate versus delayed inducements

A mail survey was conducted to empirically investigate contributions to charity as a method of stimulating responses to a mail survey. The research design included a control group and four experimental groups with the following treatments: a prepayment of $1.00 enclosed with the questionnaire (immediate personal reward), $1.00 promised upon return of the questionnaire with the respondent identified (delayed personal reward, no anonymity), $1.00 promised upon return of the questionnaire with no identification of the respondent (delayed personal reward, anonymity), and the promise of $1.00 contribution to a respondent-selected charity (delayed non-personal reward). The $1.00 prepayment yielded a statistically significant higher response rate than the $1.00 promised to charity or $1.00 promised upon return of the questionnaire. This study generally supports existing empirical foudnations of equity theory. An immediate personal reward yields a higher response rate than a delayed personal or non-personal reward.