Participation in a Mobile App Survey to Collect Expenditure Data as Part of a Large-Scale Probability Household Panel: Coverage and Participation Rates and Biases

This paper examines non-response in a mobile app study designed to collect expenditure data. We invited 2,383 members of the nationally representative Understanding Society Innovation Panel in Great Britain to download an app to record their spending on goods and services: participants were asked to scan receipts or report spending directly in the app every day for a month. We examine coverage of mobile devices and participation in the app study at different stages of the process. We use data from the prior wave of the panel to examine the prevalence of potential barriers to participation, including access, ability and willingness to use different mobile technologies. We also examine bias in who has devices and in who participates, considering socio-demographic characteristics, financial position and financial behaviours. While the participation rate was low, drop out was also low: over 80% of participants remained in the study for the full month. The main barriers to participation were access to, and frequency of use of mobile devices, willingness to download an app for a survey, and general cooperativeness with the survey. We found extensive coverage bias in who has and does not have mobile devices, and some bias in who participates conditional on having a device. In the full sample, biases remain in who participates in terms of socio-demographic characteristics and financial behaviours. Crucially, however, we observe no biases for several key correlates of spending.