An Experiment Evaluating the Impact of Large-Scale, High-Payoff Vaccine Regret Lotteries
28 Pages Posted: 16 Aug 2021 Last revised: 27 Aug 2021
Date Written: August 13, 2021
We present a pre-registered experiment testing the effects of three, high-payoff (up to $50,000) vaccine regret lotteries in Philadelphia. In each drawing, residents of a randomly selected “treatment” zip code received half of the 12 lottery prizes (boosting their chances to 59-98x those of their neighbors). Our quasi-experimental results yield mixed estimates of the benefits of these lotteries for Philadelphia’s overall vaccination rate. Our experimental results, however, offer a causal estimate of the limited return on even high-odds vaccine lotteries. Difference-in-difference regressions estimate the first treated zip code experienced an insignificant 11% jump in vaccinations compared to control zip codes. Pooling results from all three, we do not detect significant benefits from treatment, and our 95% confidence interval bounds the benefits at 9%.
Funding Information: Funding for this project was provided by Flu Lab, the Behavior Change for Good Initiative at the University of Pennsylvania, and the Center for Health Incentives and Behavioral Economics at the University of Pennsylvania.
Declaration of Interests: Kevin G. Volpp is a part-owner of VAL Health, a behavioral economics consulting firm, all others have nothing to declare.
Ethical Approval Statement: Prior to implementation, the design for the Philly Vax Sweepstakes was reviewed and approved by the institutional review boards (IRBs) of the University of Pennsylvania and the City of Philadelphia. Our study’s analysis plan was pre-registered at osf.io/gxsa4.
Keywords: COVID-19, regret lottery, vaccination, vaccine hesitancy, field experiment, behavioral science, incentives
JEL Classification: D91, C93, I12, I18, Z18
Suggested Citation: Suggested Citation