1. The impact of using web in The Danish LFS
Labour Force Survey workshop 2018, Reykjavik
Tine Cordes

2. Background – changes i 2016
Core individual survey: Approx responses quarterly out of a sample of about individuals.
Changes in data collection in 2016
Multimode data collection – from pure CATI to a combination of CATI and CAWI.
New data supplier from 2016.
Could not reach our target response rate of 60 % of the net-sample.
Termination of contract with supplier with effect from 2017.

3. Background – changes in 2017
The data supplier from resumed data collection from 2017.
Increased response rate, reaching our target of percent of net sample.
Changed the share of CATI and CAWI to most CATI.
Invitation letter send to digital mailbox instead of by ordinary post.
Breaks in time series in 2016 and again in 2017.

4. Analysis: The impact of CAWI
1) Are CAWI-respondents different from CATI-respondents?
Looking at essential background characteristic for CATI- and CAWI-respondents.
2) Does the survey mode affect the way people answer the questions about employment in the reference week?
Benchmarking LFS-employees in CAWI and CATI with register-employees from our register based statistics on employees (RSE).

5. 1) Are CAWI-respondents different from CATI-respondents?

6. 1) Are CAWI-respondents different from CATI-respondents?

7. 2) Bias in survey mode - method
Statistics Denmark’s register based statistics on employees (RSE) contains information on all employees in Denmark.
Objective benchmark to check employee status in LFS with RSE.
Limit my population of analytical interest to employees according to the LFS and checking their correspondence with RSE.
Use information from part 1 to make subgroups where CAWI- and CATI-respondents are much more alike.

8. 2) Bias in survey mode

9. 2) Bias in survey mode

10. 2) Bias in survey mode – time aspect

11. 2) Bias in survey mode – time aspect

12. 2) Employed students – a looser attachment to the labour market

13. Conclusion
The CAWI-set-up inspires to far more voluntariness in the participation to the survey. The largest part of these respondents answer within the first two days; they are older, more educated and to a larger extent women compared to CATI-respondents.
Even when controlling for these differences the results from the different subgroups all point in the same direction: that CAWI gives more accuracy in measuring employee-status than CATI.
The difference between CAWI- and CATI-employees in their correspondence with RSE was bigger for groups with a looser attachment to the labour market (students and young people).
Being presented to a calendar in CAWI highlighting the reference week must play a significant role for these differences. Especially the calendar must be helpful the looser attachment the respondent has to the labour market and the longer time gap there is between reference week and completion of questionnaire.

14. Thank you for your attention!
Tine Cordes