How Mobile Device Screen Size Affects Data Collected in Web Surveys

More and more respondents answer web surveys using mobile devices. Different authors argue that the smaller screen size (particularly for smartphones) could lead to lower data quality. However, only a few studies have taken into consideration the screen size as a factor that can affect data quality. In this frame, this chapter aims at evaluating the effect of screen size for mobile respondents on four indicators: completion times, rate of failures in answering an Instructional Manipulation Check (IMC), answer consistency across waves, and survey experience. We use data from a cross-over experiment implemented in 2015 by means of a two-wave web survey that involved panelists of the Netquest online access panel in Spain. In each wave, respondents were randomly assigned to one survey condition: participation through PCs; participation through smartphones with a mobile-optimized version of the questionnaire; or participation through smartphones with a non-optimized version of the questionnaire. In this chapter, we use a subset of the entire dataset, since our interest is exclusively respondents who participated using smartphones. Overall, our findings suggest that screen size affects completion times, mostly if devices have very small screens. However, optimization of the questionnaire helps in reducing this effect. Moreover, screen size does not significantly affect failure in answering an IMC, whereas optimization of the questionnaire plays a key role in these terms. In addition, the level of answer consistency observed between the two waves is not affected by screen size, nor by changes in size across waves, nor by questionnaire optimization. However, both screen size and optimization affect the survey experience.