Relevance and Research Question: Surveys completed on mobile Web devices (smartphones) have been found to take longer than surveys completed on a PC. Several explanations have been offered for this finding: 1) slower connection speeds over cellular or Wi-Fi networks, 2) the difficulty of reading questions and selecting responses on a small device, and 3) the increased mobility of mobile web users, who have more distractions while answering Web surveys. Our analyses attempt to disentangle the sources of these differences.

Methods and Data: We use data from three iterations of a campus Web survey, administered to samples of students, faculty, and staff in 2012, 2013, and 2014. Of the 4,725 respondents who started the 2012 student survey, 10.8% used a smartphone. We have both server- and client-level times for all items (over 360,000 item-level observations) that permit us to disentangle between-page (transmission) times from within-page (response) times. We have detailed information on the types of questions asked (e.g., grid questions versus single-item questions) and client-side paradata on other behaviors (such as scrolling or backing up). Using these data, we plan to build multi-level models (items nested within respondents) to explore correlates of response time by device.

Results: Our initial analyses on the 2012 student survey found that significantly more mobile than PC users broke off (28% versus 13%) and significantly more of those who completed the survey did so in multiple sessions (28% versus 10%). Mobile respondents also took significantly longer to complete the survey (median of 839 seconds) than PC respondents (median of 951 seconds). The majority of the difference is due to within-page times.

Added Value: Understanding why differences in response times between PC and mobile users occur and attempting to minimize them is an important step in reducing the higher nonresponse rates and breakoff rates observed for respondents completing Web surveys on small mobile devices.