Placement, wording, and interviewers: Identifying correlates of consent to link survey and administrative data.

In a telephone setting, better to place linkage consent requests at the beginning of the survey; cognitive load gets higher as the survey goes on, so it is important to ask earlier. Interviewer effects can also be quite strong on consent requests, and can depend on interviewer attitudes to linkage consent. Interviewers who themselves would consent tend to have higher consent rates.