Text Messages to Facilitate the Transition to Web-First Sequential Mixed-Mode Designs in Longitudinal Surveys

This article is concerned with the transition of a longitudinal survey from a single-mode design to a web-first mixed-mode design and the role that text messages to sample members can play in smoothing that transition. We present the results of an experiment that investigates the effects of augmenting the standard contact process of letters and emails with text messages, inviting the sample members to complete a web questionnaire and reminding them of the invite. This experiment was conducted in a subsample of Understanding Society, a household panel survey in the United Kingdom, in the wave that transitioned from a CAPI-only design to a sequential design combining web and CATI. In the experiment, a quarter of the sample received the usual letters and emails, while the rest received between one and three text messages with a personalized link to the questionnaire. We examine the effects on response rates, both at the web phase of a sequential design and at the end of the fieldwork after a CATI follow-up phase, exploring various mechanisms that might explain the increase in response rates. We also look at the effects on the device used to complete the survey and field efforts needed at the CATI stage. The findings indicate that text messages did not help significantly increase response rates overall, although some subgroups benefited from them. Text messages were effective in reaching panel members who had not provided an email or postal address before. Likewise, the text messages increase web completion among younger panel members and those with an irregular response pattern. Moreover, we only observed a slight and nonsignificant effect on smartphone use and no effect on the web household response rate, which is a proxy for fieldwork efforts.