Unconditional Lotteries in Web Surveys—Evidence from a Large-Scale Experiment

Extensive research suggests that upfront unconditional payments boost response rates compared to a promised payment conditional upon completion. However, we do not know whether the benefits of unconditionality also apply to lottery incentives, which are now commonly used. This study examines how unconditional lotteries affect response rates by randomly allocating sample members in a large web-survey of Norwegian master’s graduates (N = 11,291) to three groups—no-incentive, unconditional lottery, and conditional lottery—during the winter 2021/2022. Comparing response rates across treatments, we find that the unconditional lottery incentive does not outperform the conditional lottery incentive, but both types of lottery incentives modestly boost the response rate compared to no incentive. Moreover, although respondents differ from the population on some background characteristics, the lottery incentives neither alleviate nor increase this bias.