Supplementary material: Health promotion through monetary incentives: Evaluating the impact of different reinforcement schedules on engagement levels with an mHealth app

<b>Introduction</b>mHealth apps can be employed to promote health behavior, for example through financial rewards. However, the optimal reinforcement schedule (with maximum impact on health behavior change, at lowest costs) remains unclear.<br><b>Methods</b>We have evaluated the impact of different reinforcement schedules on engagement levels with an mHealth app in a six-week, three-arm randomized intervention trial. Participants (i.e., university staff members and students, N = 61) were awarded virtual points for performing health-related activities. They kept track of their performance via an individual dashboard, social leaderboard, and newsfeed. Additionally, participants could win financial rewards. These rewards were distributed according to a fixed ratio schedule in the first study arm, and a variable schedule in the other arms. The payouts of the first and second study arm were immediate, whereas the payout of the third arm was delayed.<br><b>Results</b>No single reinforcement schedule had a more profound impact on engagement levels. However, we found that a preference for monetary incentives in general seems to be personal. Particularly, individuals that were triggered by financial rewards could better defer gratification and were less intrinsically motivated.<br><b>Conclusion</b>Monetary incentives can stimulate mHealth app engagement and health behavior, particularly in individuals that are generally triggered by financial incentives.<br><b>List of files</b>`0-intervention-design.pdf` includes visualisations of the mHealth application.<br>`0-list-of-variables.pdf` includes an overview of different variables within the dataset.<br>`1a-intervention-data.csv` includes data that was recorded from the intervention mHealth tool.<br>`1b-pre-test-survey-data.csv` includes data that was recorded form a pre-test survey.<br>`1c-post-test-survey-data.csv` includes data that was recorded form a post-test survey.<br><br>`1d-monetary-incentives-data.csv` includes data on the financial rewards that were distributed throughout the program.<br>`2-data-analysis.Rmd` includes the R-script that was used to perform the data analyses.<br>`2-data-analysis.pdf` is the PDF output that is produced when the R Markdown script is run.<br>`3-figures.zip` is a folder with figures (in PDF format) that are output by the R-script, and that are used in the article.<br>`4-email-templates.zip` is a folder with email templates that were used throughout the health promotion program.<br>