The Influence of Incremental Increases in Token Cash Incentives on Mail Survey Response: Is There an Optimal Amount?

Abstract

The research reported is fr om a large-scale, national, mixed-mode survey (N = 49,675 addresses), in which token incremental, noncontingent incentives used in the second (mail) stage of the survey were tested in an experimental design. The levels of the incentives tested ranged from $0 to $10, in one-dollar increments, with the excep- tion that there was no $9 condition. Furthermore, the experiment was conducted using three types of household addresses that originally were sampled in the first stage of the mixed-mode survey via a random digit dial (RDD) frame: (1) households that agreed to participate in the mail stage of the survey; (2) households that were never contacted in the RDD stage despite numerous contact attempts; and (3) households that had refused to participate when co ntacted in the RDD stage. It was determined that among those households that had previously agreed to participate, even those that receive d no cash incentive ($0) were more likely to return completed surveys than the groups of previously non- contacted and previously refusing households that received $10. It was also found that the nature of the outcome of the prior contact with the household mediated (that is, interact ed with) the proportional effects of the incremental incentives, in ways only partially consistent with Dillman's social exchange theory. The findings, which are consistent with leverage-salience theory, suggest that if there is an optimal amount for an incentive to use in a mail survey , then it is a variable amount best targeted to the individual household.