Relevance & Research Question: The number of respondents accessing web surveys using a mobile device (smartphone or tablet) has rapidly been increasing over the last few years. Compared to desktop computers, mobile devices have smaller screens, different input options, and are used in a larger variety of locations and situations. The suspicion that data quality may suffer when respondents access surveys using mobile devices has stimulated a growing body of research that has mainly focused on paradata and web survey design. The question whether there are mode effects on the validity of web survey data, however, has been examined in only a few studies. To add to this research, we compared the quality of responses produced by mobile and desktop users responding to a political online survey. To examine data quality, we determined the consistency of the participant’s responses, and validated them against various internal and external criteria.

Methods & Data: We collected the data of a large sample of participants in a political online survey conducted on the occasion of the 2013 German federal election. The internal-consistency reliability of a political knowledge test was used as an indicator of data quality. As additional indicators, we determined the consistency between self-reported voting intention for the German federal election in 2013 and party preference, coalition preference, and self-reported voting behavior in the previous election. Moreover, we examined the agreement between self-reported voting intention and the actual outcome of the election.

Results: We found no difference between mobile users and desktop users for any indicator of data quality. In fact, the agreement between self-reported voting intention and the actual election result was larger for mobile users than for desktop users.

Added Value: The present investigation adds to the ongoing discussion whether there are mode effects leading to a poorer quality of data submitted by respondents using mobile devices. Our findings suggest that the participation of mobile users does not compromise data quality, and that researchers do not need to worry about the participation of mobile respondents in web surveys.