Lotteries as Incentives in Longitudinal Web Studies

Abstract

A longitudinal experiment examined the influence of a lottery of gift certificates on response and retention in a four-wave study conducted in an online panel. Independent of the lottery, people who responded in a given wave were more likely to respond in the next wave. This process was characterized to follow a first-order Markov chain. There was a direct positive effect of the lottery on response only at the first wave of the study. However, mediated by the Markov process, the positive effect of the lottery on response at the first wave was carried over into later waves. The lottery did not have any effect on retention. Furthermore, it was found that retention at a given wave is a reliable predictor for response at the next wave. This information could be used by survey managers to diagnose and act on any impending nonresponse.

Individual payments as a longer-term incentive in online panels

“…Replicating the results of many other longitudinal studies, the present study showed that people who stayed until the end of a given wave were more likely to stay until the end of the subsequent wave. We replicated a finding of Göritz and Wolff (2007) that dropout at an earlier wave is an early indicator for nonresponse at the next wave. Survey managers could act on this information.…”

“…We have addressed some of these open issues in an experiment parallel to the one presented here (Göritz, Wolff, & Goldstein, 2008). The two experiments intersect, in that they were conducted in the same university-based online panel, with comparable (but nonoverlapping) samples from all walks of life, on a similar topic, and with invitees who were offered an electronic payment for the first time since they had become panel members.…”

“…Second, in a four-wave experiment, Göritz and Wolff (2007) offered panelists either repeated inclusion in a gift certificate lottery or no incentive at all. Independent of the lottery, panelists who had responded in a given wave were more likely to respond in the next wave.…”

The Long-Term Effect of Material Incentives on Participation in Online Panels

“…This stability reflects individual panelists' general inclination to Göritz / MATERIAL INCENTIVES AND PARTICIPATION IN ONLINE PANELS 215 participate. This is a commonly encountered phenomenon in both offline (Brennan and Hoek 1992) and online panel studies (Göritz and Wolff 2007).…”

“…The only longitudinal incentive experiment conducted in an online panel so far (Göritz and Wolff 2007) examined the influence of a lottery of gift certificates on response and retention in a four-wave study. Independent of the lottery, people who responded in a given wave were more likely to respond in the next wave.…”