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

The research reported is from a large-scale, national, mixed-modesurvey (N = 49,675 addresses), in which token incremental, noncontingentincentives used in the second (mail) stage of the survey weretested in an experimental design. The levels of the incentivestested ranged from $0 to $10, in one-dollar increments, withthe exception that there was no $9 condition. Furthermore, theexperiment was conducted using three types of household addressesthat originally were sampled in the first stage of the mixed-modesurvey via a random digit dial (RDD) frame: (1) households thatagreed to participate in the mail stage of the survey; (2) householdsthat were never contacted in the RDD stage despite numerouscontact attempts; and (3) households that had refused to participatewhen contacted in the RDD stage. It was determined that amongthose households that had previously agreed to participate,even those that received no cash incentive ($0) were more likelyto return completed surveys than the groups of previously noncontactedand previously refusing households that received $10. It wasalso found that the nature of the outcome of the prior contactwith the household mediated (that is, interacted with) the proportionaleffects of the incremental incentives, in ways only partiallyconsistent with Dillman’s social exchange theory. Thefindings, which are consistent with leverage-salience theory,suggest that if there is an optimal amount for an incentiveto use in a mail survey, then it is a variable amount best targetedto the individual household.