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Article
| JAMA Network Open
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Forthcoming
Comparing Financial Incentive Structures for Promoting Physical Activity: A Randomized Controlled Trial
by
Chethan Bachireddy, Andrew Joung, Leslie K. John, Francesca Gino, Bradford Tuckfield, Luca Foschini and Katherine L. Milkman
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Abstract
Importance: Few adults engage in recommended levels of physical activity. Financial incentives can promote physical activity, but little is known about how their structure influences their effectiveness; for example, whether incentives are more effective if they are disbursed at a constant rate versus increasing or decreasing rates.
Objective: To determine if it is more effective to disburse fixed total incentives at a constant, increasing or decreasing rate to encourage physical activity.
Design: Two-week, four arm randomized controlled trial from June 2, 2014 to June 15, 2014. Data analyses finalized in 2018.
Setting: An online platform that automatically records daily steps of pedometer-wearing users and awards points redeemable for cash.
Participants: 3,515 users of the online platform in the lower 70th percentile of steps taken among all users pre-treatment.
Intervention: Participants were randomized to either a control group or to one of three intervention groups over two weeks. Control participants received a constant daily rate of $0.00001/step. The three intervention groups received a 20-fold incentive increase ($0.00020/step) distributed differently over two weeks—at a constant, increasing or decreasing rate. Reminder emails explaining incentive schedules were sent the day before the intervention and halfway through the two-week intervention.
Main Outcome and Measure: Change in mean daily steps during the two-week intervention and three weeks post-intervention. The study had 80% power to detect a difference of 280 steps/day during the intervention at α=0.05.
Results: During the intervention, compared to control, constant incentives generated 306.7 more steps/day (95% CI [91.5,521.9]; p=0.005), decreasing incentives generated 96.9 more steps/day (95% CI [15.3,178.5]; p=0.020), and increasing incentives generated no change (1.5; 95% CI [-81.6,84.7]; p=0.971). One week post-intervention, compared to control, only constant incentives generated significantly more steps/day (329.5; 95% CI [20.6,638.4]; p=0.037). Two and three weeks post-intervention, there were no significant differences compared to control. Overall, for each dollar spent, constant incentives generated 475.5 more steps than increasing incentives and 429.4 more steps than decreasing incentives.
Conclusions and Relevance: Financial incentives for physical activity are more effective during a payment period if offered at a constant rather than an increasing or decreasing rate. However, this effectiveness dissipates shortly after the incentives are removed.
Trial Registration: Clinicaltrials.gov identifier: NCT02154256
https://clinicaltrials.gov/ct2/show/NCT02154256.
Keywords: physical activity;
financial incentives;
Motivation and Incentives;
Money;
