1. Research for 2021 Census in England and Wales Potential innovations.... Garnett Compton, ONS UNECE Census Meeting, 30 September – 2 October 2015

2. This presentation will cover..... Planning and supporting Census collection Target population and digital inclusion Hard to Count Index Collection operation design and management Improving population estimation methods What next?

3. Census Transformation Programme Develop and implement a predominantly online census in 2021 Maximise overall and on-line response Increased use of administrative data 2021 Census is a stepping stone towards a mainly administrative data based approach Building towards a recommendation in 2023 on the future of Census and population statistics Develop new methods using admin data and surveys

4. Developing the 2021 Census Design Follow-up Deliver Process Analyse Collect Disseminate 4 Drivers for change Lessons learned from 2011 and internationally Changes in society, technology and user needs Improvements in administrative data sources Continue to deliver value for mon ey Main areas of change Online first Understanding propensities to respond Multi-mode follow-up of non-responding households Data Processing and outputs Use of administrative data

5. Planning and supporting census collection

6. Supporting the collection Three key collection objectives: 1.Maximise response 2.Minimise variation in response 3.Efficient use of resources

7. Supporting the collection Some initiatives: 1.Understanding digital inclusion/exclusion 2.Hard to count index in design and priorisitation 3.Collection simulation model Operation design and management Follow-up of non-responding householders

8. Maximising online (electronic) response.. 1 Group 1 Willing to use the internet to complete government processes online Not willing to use the internet to complete government processes online Access and use internet No access and/or do not use internet Group 2Group 1 Group 3Group 4 Characteristics such as elderly, language, financial Source characteristics from other gov’t services, surveys, and censuses Characteristics such as trust in Government/security concerns

9. Group 2 Group 3Group 4 Group 1 On-line responsePaper responseNo response Maximising online (electronic) response.. 2 What success might look like...

10. i. Prioritise field resources ii. Stratify PES and Coverage Assessment and Adjustment The Hard To Count (HTC) Index Used to: What is it? i. Index of predicted levels of non- response ii. Used successfully in 2011 In 2021, evolving strategy: i. Developing lower level targeting, address level? ii. Improved predictors iii. Impact on on-line first?

11. Building a collection simulation model Aim: To understand cost quality trade-offs of different follow-up scenarios Use: Allocation of field resources, Responsive design – who to follow-up, when to stop Model inputs: No. HH Date of each reminder letter and impact on response Maximum number of visits and impact of each visit on response Digital exclusion level Response prob of digitally excluded HH Model outputs: Final return rate Returns by internet/paper No. of contacts No of follow-up visits necessary Estimated costs

12. Building a simulation model... 1 Low digital exclusion Response rate of 97.4%

13. Building a simulation model... 2 Low digital exclusion Response rate of 97.4% High digital exclusion Response rate of 98.6%

14. Improving census coverage and population estimation

15. Framework for producing population estimates using a census Dual System Estimation Matching Ratio estimation Census Quality Assurance Census Coverage Survey Population estimates

16. Enhanced census coverage Dual System Estimation Matching Ratio estimation Census Quality Assurance Census Coverage Survey Population estimates Admin Data

17. An example... Administrative data (filtered for activity) Address registerCensusEnhanced Census 1 The High Street 2 The High Street 3 The High Street 4 The High Street 5 The High Street 6 The High Street 7 The High Street 8 The High Street 9 The High Street 10 The High Street 11 The High Street 12 The High Street 13 The High Street 14 The High Street 15 The High Street

18. Enhance census coverage This approach used by NISRA in 2011 Full evaluation by Ross (2015) Findings: Added 68k persons (3.9%) in 31k (4.5%) households Reduced Confidence Intervals widths by around 20% Gains in variance with small risk of additional bias

19. Age-Sex Distribution of Census and Administrative data records

20. Estimates and Confidence Intervals Estimation Area With CUE recordsWithout CUE records EstimateVariance Relative CI width 1 EstimateVariance Relative CI width 1 Eastern Northern Ireland 791,900 9,146,600 0.75%782,000 14,372,000 0.95% Western Northern Ireland 535,800 10,800,700 1.20%528,600 13,991,800 1.39% Belfast 462,000 11,562,800 1.44%452,500 21,540,600 2.01%

21. Improving census coverage This is the preferred approach for 2021: Fits within existing framework Improves quality Does not require large scale person level linkage Can evaluate through existing Census-CCS linkage Can link the administrative data to the address frame in advance Could be used to target census collection BUT Requires high quality activity data

22. What next? Further development and testing development Learning from experience/research elsewhere around the world Small scale tests to develop understanding of design and impacts Larger scale end to end test in 2017 Rehearsal in 2019

23. Email: garnett.compton@ons.gov.uk Thank you Any questions? 23

24. References... 1 Abbott, O. (2009) 2011 UK Census Coverage Assessment and Adjustment Methodology. Population Trends, 137, pp. 25-32. Abbott, O. and Compton, G. (2014) Counting and estimating hard-to-survey populations in the 2011 Census. In: R. Tourangeau, B. Edwards, T. Johnson, K. Wolter and N. Bates, eds. 2014. Hard-to-survey populations. Cambridge: Cambridge University Press. Ch.4. Abbott, O., Castaldo, A., Racinskij, V., Ross, H., Smith, P. and Brown, J. J. (2015) Developing a weighting-class approach for the 2021 Census. Government Statistical Service Methodology Advisory Committee Paper 29/3. Available at http://www.ons.gov.uk/ons/guide-method/method-quality/advisory-committee/previous- meeting-papers-and-minutes/mac-29-papers.pdf Brown, J. J. (2000) Design of a census coverage survey and its use in the estimation and adjustment of census underenumeration. PhD Thesis. University of Southampton, Southampton. Brown, J. J., Diamond, I.D., Chambers, R. L., Buckner, L. J. and Teague, A.D. (1999) A methodological strategy for a one-number census in the UK. Journal of the Royal Statistical Society A, 162, 247–267. Cabinet Office, (2014), Government Digital Inclusion Strategy, https://www.gov.uk/government/publications/government-digital-inclusion- strategy/government-digital-inclusion-strategy Fraser, O. and Ghee, C., 2015. Analysis of the characteristics of internet respondents to the 2011 Census to inform 2021 Census questionnaire design. Twentieth GSS Methodology Symposium, London. 1 st July 2015.

25. References... 2 Fraser, O. and Ghee, C., 2015. Analysis of the characteristics of internet respondents to the 2011 Census to inform 2021 Census questionnaire design. Twentieth GSS Methodology Symposium, London. 1 st July 2015. Grondin, C. and Sun, L., (2008). 2006 Census Internet Mode Effect Study. American Statistical Association Joint Statistical Meeting, Section on Survey Research Methods. 3-7 August, Denver. Available at https://www.amstat.org/sections/SRMS/Proceedings/y2008/Files/300977.pdf https://www.amstat.org/sections/SRMS/Proceedings/y2008/Files/300977.pdf Nowok, B, Raab, G. M. and Dibben, C. (2015) Synthpop: Bespoke Creation of Synthetic Data in R. CRAN vignette. Available at www.cran.r- project.org/web/packages/synthpop/vignettes/synthpop.pdfwww.cran.r- project.org/web/packages/synthpop/vignettes/synthpop.pdf Office for National Statistics, (2015), 2021 Census Design Document. Available on request. Ross, H., 2015. Using administrative data to enhance the quality of census population estimates. MSc.Thesis, University of Southampton. Steele F, Brown J and Chambers R (2002) A controlled donor imputation system for a one- number census. Journal of the Royal Statistical Society A. 165, 495–522. UK Statistics Authority, 2014, The census and future provision of population statistics in England and Wales, Available at http://www.statisticsauthority.gov.uk/news/statement--- census-and-the-future-provision-of-population-statistics-in-england-and-wales---http://www.statisticsauthority.gov.uk/news/statement--- census-and-the-future-provision-of-population-statistics-in-england-and-wales---