How to encourage a face-to-face household panel to go online? Timing isn't everything but money talks!

The fifth wave of the UK Household Longitudinal Study Innovation Panel included a sequential mixed mode design to evaluate the possibility for saving costs by collecting a significant portion of both household and individual data by web rather than face-to-face interviewing. The panel also included an experiment to test whether it would be possible to manipulate certain design features to boost response to the web questionnaire, thus further increasing cost savings. Two design features were selected for experimentation using a fully crossed 2×2 factorial design: (1) day of first contact and (2) a bonus for web completion. In this presentation we will present the results of the experiment, looking at web response rates and final response rates for individuals and whole households. We will also discuss the possible implications for the UK Household Longitudinal Study.