Minimising attrition in UK longitudinal EU-SILC

1. Minimising attrition in UK longitudinal EU-SILC Matthew Minifie Research Officer EU-SILC UK E-mail: EUSILC@ons.gsi.gov.uk

2. Presentation overview • Challenges faced in preventing attrition of households in EU-SILC • Existing methods in place to minimise attrition in UK longitudinal EU-SILC • Recent analysis into various factors affecting attrition • Latest developments introduced to reduce attrition • Next steps

3. Challenges faced in keeping households in EU-SILC • Declining willingness to participate in social surveys Labour Force Survey Quarterly Survey Wave specific response rates, GB, excluding imputed households, December 1999 – February 2000 (D99F) to April-June 2015 (AJ15) Source: UK LFS Performance and Quality Monitoring Report April to June 2015

4. Challenges faced in keeping households in EU-SILC • Reasons for dropping out of EU-SILC

5. Challenges faced in keeping households in EU-SILC • Why households refuse to participate

6. Challenges faced in keeping households in EU-SILC • Mobile population Source: Part of 2011 Census Analysis; A Century of Home Ownership and Renting in England and Wales Release (ONS) Source: Divorces in England and Wales, 2012 (ONS)

7. Existing methods in place to reduce attrition in UK longitudinal EU-SILC • Collection of multiple contact details • Likelihood of moving checked • Contact details of nominated persons • Financial incentive • Keep In Touch Exercise (KITE) • Interviewer identification of local and distant movers

8. Existing methods in place to reduce attrition in UK longitudinal EU-SILC Contact details provided by adults in households agreeing to be followed up in 2013 EU-SILC W2-3 in UK • Collection of multiple contact details • Name(s) and title(s) • Address (including postcode) • Landline telephone number(s) • Mobile telephone number(s) • E-mail address(es)

9. Existing methods in place to reduce attrition in UK longitudinal EU-SILC • Likelihood of moving checked (and new address if applicable)

10. Existing methods in place to reduce attrition in UK longitudinal EU-SILC • Contact details of nominated persons

11. Existing methods in place to reduce attrition in UK longitudinal EU-SILC • Incentives for participation • For W1 cases: • £10 (€14) redeemable voucher per household on an unconditional basis • For W2-4 cases: • £10 voucher offered to all adults who successfully participate in the survey • Option of £10 e-voucher (sent via e-mail) or £10 gift voucher (sent via post)

12. Existing methods in place to reduce attrition in UK longitudinal EU-SILC • Keep In Touch Exercise (KITE) • Short telephone interview (<5 minutes) conducted with households 4 months prior to main interview • Address details checked • Landline phone numbers (if missing/incorrect) are obtained from Directory Enquiries using names and addresses • Movers out of household identified and new address and telephone details collected • Likelihood of household moving in the next few months checked and new address collected in applicable

13. Existing methods in place to reduce attrition in UK longitudinal EU-SILC • Interviewer identification of local and distant movers • During field period, if an interviewer identifies any local movers then the same interviewer will attempt to follow up these people • If an interviewer identifies distant movers within the UK then the new address is allocated to a different interviewer within the area where the movers have gone to

14. Recent work on identifying ways to reduce attrition • Review on best practices in UK longitudinal surveys to reduce attrition • Review of tracking process and data analysis • Field interviewer focus group

15. Recent work on identifying ways to reduce attrition: Review of Best Practices in UK Wealth and Assets Survey • Biennial longitudinal survey run by ONS Social Survey Division • Collects data on household wealth (divided into 4 components: property, physical, financial, and private pension wealth) • Referred to for respondent purposes as “Household Assets Survey” • Change of Address cards • Launched July 2010 • Low cost / time commitment • Approx 33 responses per month in first 3 years • Email KITE • Launched April 2014 • Low cost / time commitment • Approx 5 responses per month in first 6 months • Effectiveness likely to increase as more email • addresses collected

16. Recent work on identifying ways to reduce attrition: Review of Best Practices in UK Understanding Society • Annual UK Household Panel Survey – 40,000 households at W1 (2009) • Includes “Innovation Panel” specifically funded to research methods • Do not ask permission to recall question • 75% of W1 respondents successfully interviewed at W2 • Interactive responder webpages • Appealing layout, easy to navigate • Interesting content • Facility to update details online • Financial incentive for updating address • £5 voucher for supplying new address online or by post • Use of administrative data to track responders • Use commercially available address information by contract • Exploring options to gain access to NHS data • Have not found social media to be viable for tracing

17. Recent work on identifying ways to reduce attrition: Review of Best Practices in UK • Actions resulting from Review of Best Practices • Launched recently: • Email KITE (July 2015) • Change of Address cards(August 2015) • Ongoing work: • Exploring the possibility of removing the consent to follow up question asked in the longitudinal survey • Next steps: • Improve responder webpages (including mover address collection form) • Investigate administrative data sources which could be used for tracking • Analyse effectiveness of different incentives • Monitor impact of Email KITE and Change of Address cards • Expand review to look at best practices in other EU member states

18. Recent work on identifying ways to reduce attrition: Process Review and Data Analysis Number of proxy interviews in previous wave • Higher proportion of proxies tends to decrease chances of a successful interview in next wave • More proxies results in less people being able to agree to follow up W2 outcome for in-scope households in 2013 EU-SILC UK by proportion of proxy interviews in W1 Percentage of W1 households Permission to recall rates in 2012 EU-SILC UK W1 households containing two adults Percentage of W1 households

19. Recent work on identifying ways to reduce attrition: Process Review and Data Analysis Interviewer continuity across waves Using the same interviewer across waves tends to increase response * Movers between W1 and W2 have been excluded from the analysis

20. Recent work on identifying ways to reduce attrition: Process Review and Data Analysis Nominated persons 2013 EU-SILC UK W3 and W4 household field response rates by whether nominated person details were collected in previous wave Percentage of households Cases providing details of a nominated person are more likely to respond in the next wave

21. Recent work on identifying ways to reduce attrition: Process Review and Data Analysis Interviewer calling patterns ONS interview cases only; data recorded at person level There is a significant relationship between the timing of the successful W1 interview and that of the successful W2 interview There is no significant relationship between the timing of the successful W1 interview and that of the first call at W2

22. Recent work on identifying ways to reduce attrition: Process Review and Data Analysis Re-issuing of mover cases • Non-contacts and soft refusals in the initial scheduled interview month are re-allocated • Local and distant movers are included as part of the re-issued pool of cases but are not flagged as movers to the interviewer • Movers are not treated differently and are not prioritised above other non-contact and refusal re-issued cases

23. Recent work on identifying ways to reduce attrition: Process Review and Data Analysis Processing and questionnaire issues • Difficulties in identifying movers on data files • Questionnaire allows contradictory responses for current location of sample members • Lack of paradata available for non-responding cases

24. Launched recently Recent work on identifying ways to reduce attrition: Process Review and Data Analysis Actions resulting from Process Review and Data Analysis • Launched recently • Minor questionnaire changes (e.g., refine address info collected) • Modification of interviewer briefings • Ongoing work • Mover re-issues to be flagged as special cases • Expanding collection of nominated person contact details • Individual interviewer performance monitoring to be improved • Tracking of movers in production of register and data files to be refined

25. Recent work on identifying ways to reduce attrition: Process Review and Data Analysis Actions resulting from Process Review and Data Analysis • Next steps • Increase proportion of cases allocated to same interviewer as at previous wave • Explore making better use of previous wave calling information • Conduct review of tracking questions • Collect additional paradata (e.g., use of nominated person) • Investigate whether a telephone proxy conversion exercise could be worthwhile • Explore whether limiting KITE to only those households which are are more likely to move might be advantageous (allocate resource elsewhere)

26. Recent work on identifying ways to reduce attrition: Field Interviewer Focus Group Focus Group (April 2015) • 6 interviewers experienced in interviewing at all waves of UK-SILC • Topics covered included: • Techniques for persuading respondents to take part / agree to follow-up • Processes for tracing movers in the field • Many conclusions in line with other research: • Increasing interviewer continuity across waves • Collecting nominated person information for all cases • Using Change of Address cards • Additional ideas: • Sending advance letters closer to interview date (i.e.: later) • Using Electoral Roll data to trace movers • Lots of practical tips: • Will inform “best practice” to be shared with all interviewers

27. Summary (1/3) • There are many obstacles to keeping households in the longitudinal EU-SILC sample in the UK - Declining willingness to participate in surveys - Mobile population - Increase in renting and societal changes • Many of the recommended good practices to prevent attrition are currently in place - Multiple contact details collected - Likelihood of moving checked - Nominated persons - Financial incentives - Keep In Touch Exercise (KITE)

28. Summary (2/3) • Recently implemented procedures • - Email KITE • - Change of address cards • - Minor questionnaire changes (e.g., refining address details collected) • - Modified interviewer briefings • Procedures currently being implemented • - Flagging of re-issue cases which have moved • - Expanding collection of nominated person contact • details • - Improved interviewer performance monitoring • - More accurate identification of movers in datasets

29. Summary (3/3) • Recommended developments • - Increased interviewer continuity across waves • - Better use of previous interview calling patterns • - Collection of additional paradata (e.g., use of • nominated persons) • Procedures under investigation • - Removal of permission to follow up question • - Telephone proxy conversion • - Selective KITE • - Delaying sending of advance letter • Future work • - Improve responder webpage • - Investigate use of administrative data sources • - Analyse effectiveness of different incentives

30. Questions/Comments? Recommendations from other EU member states welcomed