Mobile apps are an attractive and versatile method of collecting data in the social and behavioral sciences. In samples of the general population, however, participation in app-based data collection is still rather low. In this article, we examine two potential ways of increasing participation and potentially reducing participation bias in app-based data collection: (1) inviting sample members to a mobile app study within an interview rather than by post and (2) offering a browser-based follow-up to the mobile app. We use experimental data from Spending Study 2, collected on the Understanding Society Innovation Panel and on the Lightspeed UK online access panel. Sample members were invited to download a spending diary app on their smartphone or use a browser-based online diary to report all their purchases for one month. The results suggest that inviting sample members to an app study within a face-to-face interview increases participation rates but does not bring in different types of participants. In contrast, the browser-based alternative can both increase participation rates and reduce biases in who participates if offered immediately once the app had been declined. We find that the success of using mobile apps for data collection hinges on the protocols used to implement the app.
