This paper will report on the results of a sequential mixed-mode experiment that took place in the UK alongside the main round of ESS 2012. The study aims to test the feasibility of data collection for a long interview using a web followed by face-to-face design in a country where the only credible general population sample frame is an address-based list.

The experiment involved sampling 2,000 addresses from the Postcode Address File and contacting them by letter. The letter invited potential respondents to complete the survey online. After a reminder process, a proportion of non-respondents were followed up by visits from an interviewer who attempted a face-to-face interview. Different incentive values and approaches to respondent selection were also tested.

The paper would explore the following questions:

1. How does the total response rate (online and face-to-face) compare to the response rate achieved in equivalent areas on the main ESS survey?
2. What impact did different value incentives have upon online response? What impact did the initial web phase have on response to the subsequent face-to-face interview?
3. What impact did the sequential mixed-mode design have on survey cost?
4. How did people complete a long interview online? How long did the interview take, did they tend to answer questions in one 'sitting', and what proportion dropped out?
5. What is the best approach to carrying out random respondent selection when no interviewer is present?