Supplementary Material: Money talks: Evaluating the impact of virtual incentives and monetary rewards on user engagement levels in a health promotion context

The ongoing increase in obesity rates suggests that incorporating more physical activity in daily lifestyles and improving dietary intake remains challenging for people. The application of mHealth interventions can be utilized to promote physical activity and improve dietary intake, especially in cases where such interventions employ incentives. These incentives are typically categorized as either non-financial (e.g., virtual) rewards, or financial rewards.
In this study, we evaluated the impact on user engagement levels of virtual, non-financial rewards, implemented using a point-based system, and monetary rewards. During the course of a five-week, three-arm randomized intervention trial, participants (i.e., staff members and students of a Dutch university, N = 95) engaged in a health promotion program that was designed to promote physical activity and fruit intake. Through this program, subjects were suggested to perform a set of health-related activities every week. Subjects could self-track how many times they had performed each activity, and review the activities other participants had performed. Participants in the second and third study arm received virtual points for completing the suggested activities. Moreover, participants in the third study arm received a monetary reward in the third week of the campaign.
Results indicated that monetary incentives can be employed effectively to engage participants in a health promotion context, with little risk of crowding effects in the short run. The introduction of point-based incentives seemed to only have a small, non-significant impact on participant engagement levels, compared to a situation without any (non-)financial incentives.
List of files
`0-intervention-design.pdf` includes visualisations of the mHealth application.

`0-list-of-variables.pdf` includes an overview of different variables within the dataset.
`1a-intervention-data.csv` includes data that was recorded from the intervention mHealth tool.
`1b-survey-data.csv` includes data that was recorded form a post-test survey.
`2-data-analysis.Rmd` includes the R-script that was used to perform the data analyses.
`2-data-analysis.pdf` is the PDF output that is produced when the R Markdown script is run.
`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.