Jäckle, A., Burton, J., Couper, M. P., & Lessof, C. (2019). 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. Survey Research Methods, 13(1), 23–44. https://doi.org/10.18148/srm/2019.v1i1.7297