The effect of material incentives on Web survey completion: Evidence from three meta-analyses

The present study conducts three meta-analyses to examine the effects of material incentives, promised material incentives and contingent material incentives on Web survey completion, respectively. Although considerable variation exists across the studies, the results indicate that the material incentives, promised material incentives, and contingent material incentives can motivate potential respondents to complete Web surveys (Odds Ratio=1.16, 1.14, 1.12, respectively) even if the motivations are relatively small compared with those in offline surveys. Those surveys offering low-cost prepaid incentives and promised lottery incentives or offering promised certain (low-cost) and lottery incentives simultaneously engender the highest completion (OR = 1.79). Contingent incentives have the most stable effectiveness and contingency of incentives (certain, contingent, and combined) exert a moderate impact on effectiveness of material incentives. However, occasion of incentives (prepaid, promised, and combined) do not exert any large influence on the incentives´ effectiveness.