In this article, we use a probability-based, 30-minute web survey on political behavior to test effects of QR codes in mail invitations. As expected, we find a strong increase in mobile phone use compared to computer use. However, there is no difference in response rates, sample composition, response speed or response quality. This suggests that part of the sample is switching from computer to mobile phone, with no device effect. Importantly, the use of a QR code, which may give the impression of a short survey, led mobile phone users to perceive the survey as too long. This mismatch between …

Invitation letters to web surveys often contain information on how long it will take to complete a web survey. When the stated length in an invitation of a survey is short, it could help to convince respondents to participate in the survey. When it is long respondents may choose not to participate, and when the actual length is longer than the stated length there may be a risk of dropout. This paper reports on an Randomised Control Trial (RCT) conducted in a cross-sectional survey conducted in the Netherlands. The RCT included different version of the stated length of a survey …