A City-Wide Experiment Testing the Impact of Geographically-Targeted, High-Payoff Vaccine Lotteries

66 Pages Posted: 16 Aug 2021 Last revised: 7 Jul 2022

See all articles by Katherine L. Milkman

Katherine L. Milkman

University of Pennsylvania - The Wharton School

Linnea Gandhi

University of Pennsylvania

Sean Ellis

University of Pennsylvania

Heather Graci

University of Pennsylvania

Dena Gromet

University of Pennsylvania

Rayyan Mobarak

University of Pennsylvania

Alison Buttenheim

University of Pennsylvania

Angela Duckworth

University of Pennsylvania - Department of Psychology

Devin G. Pope

University of Chicago - Booth School of Business

Ala Stanford

Black Doctors COVID-19 Consortium

Richard H. Thaler

University of Chicago - Booth School of Business; National Bureau of Economic Research (NBER)

Kevin Volpp

University of Pennsylvania - Perelman School of Medicine, Department of Medicine

Date Written: August 13, 2021

Abstract

Lotteries have been shown to motivate behavior change in many settings, but their value as a policy tool is relatively untested. We implemented a pre-registered, city-wide experiment to test the effects of three, high-payoff, geographically-targeted lotteries designed to motivate adult Philadelphians to get their COVID-19 vaccine. In each drawing, residents of a randomly selected “treatment” zip code received half the lottery prizes, boosting their chances of winning to 50-100x those of other Philadelphians. The first treated zip code, which drew considerable media attention, may have experienced a small bump in vaccinations compared to control zip codes: average weekly vaccinations rose by an estimated 61 per 100,000 people per week (+11%). Pooling results from all three zip codes treated during our six-week experiment, however, we do not detect any overall benefits. Further, our 95% confidence interval provides a 9% upper bound on the net benefits of treatment in our study.

Note:
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

Milkman, Katherine L. and Gandhi, Linnea and Ellis, Sean and Graci, Heather and Gromet, Dena and Mobarak, Rayyan and Buttenheim, Alison and Duckworth, Angela and Pope, Devin G. and Stanford, Ala and Thaler, Richard H. and Volpp, Kevin, A City-Wide Experiment Testing the Impact of Geographically-Targeted, High-Payoff Vaccine Lotteries (August 13, 2021). Available at SSRN: https://ssrn.com/abstract=3904365 or http://dx.doi.org/10.2139/ssrn.3904365

Katherine L. Milkman (Contact Author)

University of Pennsylvania - The Wharton School ( email )

Philadelphia, PA 19104
United States

Linnea Gandhi

University of Pennsylvania ( email )

Philadelphia, PA 19104
United States

Sean Ellis

University of Pennsylvania ( email )

Philadelphia, PA 19104
United States

Heather Graci

University of Pennsylvania ( email )

Philadelphia, PA 19104
United States

Dena Gromet

University of Pennsylvania ( email )

Philadelphia, PA 19104
United States

Rayyan Mobarak

University of Pennsylvania ( email )

Philadelphia, PA 19104
United States

Alison Buttenheim

University of Pennsylvania

Philadelphia, PA 19104
United States

Angela Duckworth

University of Pennsylvania - Department of Psychology ( email )

3815 Walnut Street
Philadelphia, PA 19104-6196
United States

Devin G. Pope

University of Chicago - Booth School of Business ( email )

5807 S. Woodlawn Avenue
Chicago, IL 60637
United States

Ala Stanford

Black Doctors COVID-19 Consortium ( email )

Philadelphia, PA
United States

Richard H. Thaler

University of Chicago - Booth School of Business ( email )

5807 S. Woodlawn Avenue
Chicago, IL 60637
United States
773-702-5208 (Phone)
773-702-0458 (Fax)

National Bureau of Economic Research (NBER)

1050 Massachusetts Avenue
Cambridge, MA 02138
United States

Kevin Volpp

University of Pennsylvania - Perelman School of Medicine, Department of Medicine ( email )

Philadelphia, PA 19104
United States

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