Due to rising mobile device penetration, Web surveys are increasingly accessed and completed on smartphones or tablets instead of desktop computers or laptops (i.e., unintentional mobile respondents). Mobile Web surveys are also gaining popularity as an alternative self-administered data collection mode among survey researchers. There might exist mode effects as different cognitive mechanisms might be at play when respondents answer surveys on mobile devices compared to PCs. In addition, the limited amount of space for displaying questions and scales on mobile screens poses new challenges for survey researchers.
Methods & Data:We conducted a methodological experiment with iPhone owners recruited on Amazon Mechanical Turk. Respondents who started the survey on a PC (n=1,511) were randomly assigned to one of two groups; they were asked to either switch from PC to iPhone to finish the short questionnaire (“switch to iPhone”) or to proceed with the survey on PC (“no switch PC”). Respondents who started the survey on an iPhone (n=109) finished the survey on the iPhone (“no switch iPhone”). We compared these three groups in terms of their demographic composition and response behavior (break-offs, item missing, response times, response distribution, and satisficing behavior). 
Results: We found that respondents who completed the survey on PC were more likely to be male, to have a lower educational level, and to have more experience with Web surveys than mobile Web respondents. Mobile Web respondents had more missing data and took longer to complete the survey than respondents who answered the questions on a PC but they also showed less straightlining behavior. However, there are only minimal mode effects on answers obtained from both devices.
Added Value: Our experimental study adds to the survey literature on mode effects by showing that very short mobile Web surveys are a viable alternative to Web surveys. Given the increasing interest in self-administered data collection through mobile devices, the results of the study will be of high relevance and significance to academic and non-academic survey researchers who consider collecting data through mobile devices.