Many surveys link to administrative records, with respondent consent, and many surveys now use web as a primary mode of data collection. However, respondents are substantially less likely to consent when asked online than in person. In panel surveys, respondents who decline a request for data linkage once often do consent when asked again in a subsequent wave. Many longitudinal surveys therefore routinely re-ask consent questions of those who do not consent initially.

In this paper we examine the following research questions: Is this re-asking of non-consenters as effective in the web mode as it is in face-to-face interviews? Are web consenters just a smaller set, or are they also a different set of respondents than face-to-face consenters?

We analyse data from repeated consent requests made in different modes in a major UK household panel survey (Understanding Society: The UK Household Longitudinal Study). As well as raw differences by mode of completion — the ‘as-treated’ analysis — we can use experimental allocation to web-first or face-to-face-first in the Understanding Society Innovation Panel to calculate intention to treat (ITT) differences based on mode of allocation, and to estimate causal effects of mode. As consent to link to a variety of domains of administrative data have been (re)asked in Understanding Society, we replicate aspects of our analysis with consents relating to different domains.

Our initial findings suggest that while some non-consenters do provide consent when asked a second time in the web mode, the proportion who do so is lower than the proportion of non-consenters who consent when re-asked face-to-face. These findings mirror typical mode differences in initial data linkage consent requests. We will present further results related to our research questions at the conference.

Co-authors

Professor Annette Jäckle; Dr Jonathan Burton, University of Essex;

Professor Mick Couper; Professor Thomas Crossley, University of Michigan