1. JOINT UN-ECE/EUROSTAT MEETING ON POPULATION AND HOUSING CENSUSES GENEVA, 7-9 JULY 2010 A QUALITY ASSURANCE STRATEGY FOR THE 2011 CENSUS IN ENGLAND AND WALES IAN WHITE, Office for National Statistics, UNITED KINGDOM

2. STRATEGIC AIMS UN Department of Economic and Social Affairs One of the most basic decisions in a census operation, and indeed a key decision about the quality of census results, is the trade-off between timeliness and accuracy. This is particularly important in designing the output strategy, in that the decision affects not only the dissemination team but all the preceding stakeholders in the census programme. In general, it can be expected that the faster a process is undertaken the greater the level of inaccuracy in the results of that process. It is also a general rule that users of census data will expect a high level of accuracy in the information provided by an official census agency. The census agency will have to manage this trade- off

3. 2011 CENSUS DESIGN CHANGES TO IMPROVE DATA QUALITY Changes Address Register Questionnaire-tracking system Re-design of questionnaire Re-structuring field operation Improvements to - Census Coverage Survey - Census Quality Survey

4. 2011 CENSUS DESIGN CHANGES TO IMPROVE DATA QUALITY Changes Address Register Questionnaire-tracking system Re-design of questionnaire Re-structuring field operation Improvements to - Census Coverage Survey - Census Quality Survey Aims Maximise coverage and quality nationally Minimise differences between local areas

5. 2011 CENSUS DATA QUALITY STRATEGY Objectives Fit for purpose Understand differences Accurate characteristics Transparency Quality indicators Input into mid-year estimates

6. 2011 Census quality model Design Operational quality management Quality assurance Quality measurement and reporting High quality Population Statistics (as defined by the Critical Success Factors) Quality management team →→ → → ↑↑ ↑ ↑

7. DEMOGRAPHIC QUALITY ASSURANCE Census Coverage Survey Independent 6-10 weeks after Census 500,000 individuals Matched to census records Dual estimation Undercount and overcount Estimates by 5-year age- group for each Local Authority area Record imputation

8. DEMOGRAPHIC QUALITY ASSURANCE Comparator data sets Babies aged under 1 5-years age groups up to 85 Sex ratios by age-group Number of households Household size Fertility rates Mortality rates

9. TOPIC QUALITY ASSURANCE Population sub-groups Babies Young men Students Very elderly Armed Forces International migrants Non-English speakers Internal migrants Prisoners Staff in institutions Minority ethnic groups Same -sex couples Private renters Residents in second addresses

10. TOPIC QUALITY ASSURANCE Problem areas Holiday home Caravan sites Second homes High multi-occupancy Controlled access Regeneration areas

11. Thank you – Any questions ? More details of 2011 Census Data Quality Assurance Strategy at: www.ons.gov.uk/census/2011-census/process-info/data-quality-assurance/2011-census--- data-quality-assurance-strategy.pdf