Re-design of short term surveys at the UK Office for National Statistics

1. Re-design of short term surveys at the UK Office for National Statistics Myrto Miltiadou Methodology Directorate, ONS

2. Overview of presentation • Industrial Classification • Business Register • Monthly Business Survey • Survey re-design • Sample allocation • Estimation • Conclusion

3. Industrial Classification • Economic activity is classified by the Standard Industrial Classification (SIC) • Updates every 10-15 years to reflect changes in the economy • Revision of the current classification from SIC(2003) to SIC(2007) • Phased approach

4. Timetable for implementation • 2007 Dual coding of Business Register • 2008-9 Re-design of annual surveys • 2010 Re-design of short term surveys • 2011 National Accounts

5. Business Register • Sampling frame used for most Business Surveys in ONS • Information on the Register include: • Business classification • Turnover • Employment • Dual coded since January 2008

6. Monthly Business Survey • Short term surveys collecting similar information but cover different parts of the economy • Retail Sales Inquiry (RSI) • Monthly Production Inquiry (MPI) • Monthly Inquiry into Distribution and Services Sector (MIDSS) • Integrate into the Monthly Business Survey (MBS) • Improve efficiency of sample • Increase coherence of methods • Promote use of best practice

7. Survey re-design • Short term surveys re-designed for 2010 • Review of all methodological aspects • definition of industrial strata • definition of employment thresholds • estimation methods • Sample allocation • Establish customer requirements

8. Definition of industrial strata • Group of SIC codes form the stratum • Different level of detail for different strata • 185 strata on SIC(2007) and 355 strata on SIC(2003)

9. Definition of employment thresholds • Each stratum is assigned four employment bands • Cumulative root frequency method • Manageable number of combinations • MBS assigned seven different band combinations • 0-9, 10-149, 150-249, 250+ • 0-9, 10-99, 100-249, 250+ • 0-9, 10-49, 50-249, 250+ • 0-9, 10-49, 50-149, 150+ • 0-9, 10-19, 20-99, 100+ • 0-4, 5-19, 20-149, 150+ • 0-4, 5-19, 20-99, 100+

10. Survey re-design • Sub-sample for employment • Sampling a sub-set of the sample • Reduce respondent burden • Ratio estimation • Investigations to decide whether combined or separate estimation should apply. Decision on which method to use was made on a stratum by stratum basis. E.g. combined separate

11. Sample Allocation • Previously - Neymann allocation • top level optimisation • lower level adjustments • specify sample size • Currently - Multivariate macro • lower level optimisation – Neymann allocation • specify Coefficients of Variation • no sample size specified

12. Results

13. Estimation • Require historical and current-period estimates on both classifications • Methods • Macro approach – conversion matrices • Micro approach – domain estimation

14. Conclusion • Change in SIC(2007) provided an opportunity for improving the design of the short term surveys. • Joining the surveys enabled us to standardise the methodology used. • Balance between manufacturing and services sectors. • Review of allocation in a years time when data on SIC(2007) will be available.

15. Thank you…. Questions?