Survey incentives: Cash vs. in-kind; face-to-face vs. mail; Response rate vs. nonresponse error

Experiments on incentives have a long history in survey research, particularly in mail surveys but increasingly in other modes too. Most of this work has focused on variations in incentive type, timing, and amount on response rates. There has been relatively little research examining the effect of different incentives on nonresponse error. Furthermore, most of the studies on incentives have been within a single mode. No studies, to our knowledge, have examined the effect of incentives in a study using more than one mode. This paper adds to the methodological literature on incentives in several ways. Although we compare a cash incentive vs. an in-kind incentive, which has been done several times, we examine these effects in both a face-to-face and mail survey. The cash incentive yielded higher response rates than the in-kind incentive in the mail survey. Furthermore, the in-kind incentive was related to one of the topics of a metropolitan area survey, permitting us to examine possible effects of the incentive on the composition of the resulting sample as an indicator of potential nonresponse error. Specifically, the in-kind incentive was a set of passes to regional parks, and the survey included a variety of questions on behavior and attitudes related to park use. We found that, although there were demographic differences between incentive groups, the response distributions on key related variables did not vary by incentive type.