Completing web surveys on mobile devices: Does screen size affect data quality?

Using data from a non-mobile-optimised survey in the UK, this paper compares the quality of survey data from mobile devices with different screen size. The findings suggest that data quality mainly differs between small smartphones with a diagonal screen size of below four inches and larger mobile devices. Users of small smartphones are significantly more likely to drop out of the survey, to provide shorter responses to open-ended questions, and to straight-line in grid questions. There are no significant differences between screen size groups in completion times, response distributions, and number of items selected in check-all-that-apply questions.