Population and Migration

1. Centre for Demography Population and Migration Seeking your views Welcome and introductions

2. Centre for Demography Population and Migration Welcome and Introduction ONS Centre for Demography

3. Aims of the day • Communicate the latest work being carried out to improve population statistics through • the 2011 Census and • the Improving Migration and Population Statistics programme • Census • progress on planning and executing the 2011 Census • methodology for assessing coverage • quality assurance of the census population estimates • Improving Migration and Population Statistics • present the indicative impacts • explain user engagement process • provide chance to feedback on results

4. AGENDA am • 9.30 - 10.00 Registration and coffee • 10.00 Welcome and introduction to the day • 10.15 Census overview • This session will provide an overview of the census components that are key to producing Census population estimates • To provide an update on progress on recent events, such as the census rehearsal. • 10.45 Census coverage • This will cover the methodology being developed to assess census coverage • It will focus on improvements that address many of the lessons from 2001 • 11.15 – 11.30 Coffee break • 11.30 Census data quality assurance • To provide an update on Census data quality assurance plans • To summarise the processes and evidence to be used to validate Census local authority estimates • 12.00 Questions • 12.30 – 1.15 Lunch

5. Agenda pm • 12.30 – 1.15 Lunch • 1.15 Improving Migration and Population Statistics Session I • Introduction and Background • User engagement • Indicative Impacts • 2.30 – 2.45 Tea Break • 2.45 Improving Migration and Population Statistics Session II • Open discussion • 4:00 Close

6. High level timetable • 18 January 2010 • Final date for comments • 27 May 2010 • Revised 2002-08 population estimate for LAs • 2008-based Subnational Population Projections • 27 March 2011 • Census day

7. Domestics • Fire Exits • Fire Alarm • Refreshments • Tea and Coffee about 11:15 • Lunch at about 12:30 • Tea and Coffee about 2:30 • Close at about 4:00 • Toilets • Delegate Packs • Questions

8. 2011 Census Overview Garnett Compton ONS Demography Seminar - December 2009

9. Reminder – key design changes Where are we now? Census rehearsal Census address register Census legislation Census stakeholder engagement Census outputs Key milestones Introduction

10. Questions New Qs on population characteristics New Qs on population base Address register Field operation Distribution via post Distribution of field staff Questionnaire tracking Internet data capture What’s new since 2001?

11. Census rehearsal areas Rehearsal areas: • Lancaster – 62,000 • Newham – London – 40,000 • Isle of Anglesey – Wales 34,000 Small scale test: • Birmingham – 17,000 Objective: • To validate 2011 Census field procedures and supporting systems

12. Rehearsal systems/procedures • Recruitment of field staff • E-learning • Flexible deployment of field staff • Questionnaire Tracking • Publicity • Local Authority & Community engagement • Census coverage survey

13. Address register Printing Royal Mail delivery & collection Internet completion Public contact centre Online help systems Census Management Information System ‘best internet survey I’ve ever seen’ – Prof Phil Rees Rehearsal systems/procedures

14. Rehearsal publicity

18. Engaging Advertising • Reaching students and young people where they spent their time with some engaging advertising

19. Total Returns by Completion Method(up to 29 November)(provisional)

20. REHEARSAL RESPONSE • 35% overall (so far – 29/11) • Action taken to improve response • More staff in Newham • More community liaison • More advertising • Targeted letters/questionnaires • Possible reasons – logistical • postal delays (stuck in system?)? • time of year? • contact patterns? • Possible reasons – behaviour • lack of trust? • not important – voluntary? • lack of awareness? 21/1029/11 Anglesey 34% 42% Lancaster 30% 39% Newham 10% 21% Overall 25% 35% Birmingham 11% 21%

21. What worked well: Recruitment, pay and training Daily receipting Questionnaire tracking system Linking replacements/deactivating addresses Generating follow-up lists Internet data collection/Web self help Actions to improve response rates Rehearsal – some early thoughts (1)

22. What needs reviewing and refining: Understanding low response rates Targeting of initial field resource Mixture of full and part-time hours Training and doorstep messages Management information Specification of reports Improve awareness and routing to IDC Working with LAs to increase publicity Rehearsal – some early thoughts (2)

23. Where are we now

24. Data sent to suppliers for resolution (Royal Mail, Intelligent Addressing) Unmatched addresses sent to LAs Address check implementation started In the field May – Aug 2010 15% of postcodes targeted on mismatches and multi-occupation Strong focus now on communal establishments Prioritised for target populations – 3rd party suppliers Special address check staff covering all of E&W Address register

25. Number of mismatched addresses sent to LAs for resolution

26. Census legislation • White Paper - 11 December 2008 • Census Order – tabled 21 October 2009 • Debated by the Delegated Legislation Committee - 30 November • Full Lords debate – 2 December • Privy Council - likely 10 Feb • Census Regulations – March 2010 • EU legislation

27. LA engagement - foundations • Stakeholder website launched September • New LA engagement advisory groups initiated • Operational advisory group • Communication advisory group • Local authority partnership guide launched October • Local authority communication toolkit • Regional networks established by many census regional champions • Online communities of practice

28. What’s next for LAs? • Second round of regional meetings hosted by CRCs • Regional meetings for LA communication teams to launch toolkit and councillor handbook • Defining the ways of working during the operational phase • Local partnership plans to agree commitments by each party around • Media relations and publicity • Community liaison • Support with logistics • Ongoing contact mechanisms

29. Community liaison • Liaison with national organisations representing target population groups continues • Some good offers of help and support • Communication materials for community groups to use being developed for March 2010 • 40 Community advisors start September 2010 to liaise with black and ethnic minority target population groups • Partnership plan with LA will also cover community liaison activities

30. Census outputs - vision • Web as the primary dissemination route • Flexibility for end users to create own products • Bulk download of data via the web • Web functionality provided jointly with external partners • 2001 comparisons which exploit stable geography (OAs) • Microdata products provided via secure mechanisms • UK Wide Approach with common disclosure control

31. Outputs – next steps • Continue technical development • Demonstrate Prototype & agree partnership proposals Spring 2010 • Populate 2011 System with some 2001 data December 2010 • User Consultation Round • Main content consultation in Dec 2009 • Geography consultation in Dec 2009 • Publish Proposed 2011 Outputs Product set end- 2010 • Disclosure Control • UKSDC approach agreed September 2009 • Complete alignment of Disclosure Control/Technical constraints and User requirements Summer 2010 • Finalise proposals for • Microdata delivery • Analytical Uses

32. Census – milestones

33. Coverage adjustment Quality assurance Quality census relies on other key aspects: Address register Census Operations: Questionnaire tracking Publicity Recruitment Field operations and procedures Finally ……

34. Thank you Questions?

36. AGENDA – Census Coverage • Background • Coverage in the 2001 Census • 2011 Methodology overview • Key changes • Summary

37. WHAT IS THE PROBLEM? • Despite best efforts, census won’t count every household or person • It will also count some people twice • Users need robust census estimates - counts not enough • In 2001: • One Number Census (ONC) methodology was developed to measure undercount • estimated 1.5 million households missed • 3 million persons missed (most from the missing households but some from counted households) • Subsequent studies estimated a further 0.3 million missed • In 2011 we want to build on the ONC, as broadly it was successful

38. 2001 CENSUS UNDERCOUNT BY AGE-SEX

39. RESPONSE RATES BY LOCAL AUTHORITY

40. Census Coverage Survey 2011 Census Matching Quality Assurance Estimation Adjustment COVERAGE ASSESSMENT PROCESS OVERVIEW

41. AREAS OF IMPROVEMENT • Elements of CCS Design • Estimation methodology • Measuring overcount • Adjustments for bias in DSE • Imputation • Motivated by: • lessons learnt from 2001 • 2011 Census design e.g. use of internet

42. THE CCS DESIGN • Similar to 2001 CCS: • 300,000 Households • Sample of small areas (postcodes) • 6 weeks after Census Day • Fieldwork almost identical • Improvements: • Designed at LA level, not for LA groups • Refined Hard to Count index (5 levels) using up to date data sources • Use Output Areas as PSUs • Select 3 postcodes per OA • Revised allocation of sample (using 2001 patterns)

43. THE CCS DESIGN (2) • What does this mean? • Each LA will have its own sample – at least 1 OA for each hard to count level • Sample is more skewed to LAs with ‘hardest to count’ populations (with an upper limit of 60 OAs) • More LAs will have estimates based on their own data • Especially in London and for big cities • HtC index will be ‘up to date’ • Most LAs will have 3 HtC levels • Most London areas only had one in 2001 • Will be a 40%, 40%, 10%, 8%, 2% distribution

44. MATCHING AND ESTIMATION • Estimation based on Dual System Estimation • Used mainly for wildlife applications • Requires two ‘counts’ of the population • Requires the two counts to be matched • Use standard survey estimation techniques to generalise the DSEs to the whole population • Ratio estimator • Trout, Catfish & Roach provides a fishing example of the principles of the method – Available in delegate packs

45. ESTIMATION • Obtained lots of data from 2001 to be able to explore whether improvements can be made • One issue was at what level to estimate undercount to best fulfil the assumptions of the methodology (Postcode, Groups of Postcodes) • One key issue was whether we should group LAs by geography or by ‘type’ • Improvements: • Confirmed that using DSE at OA level is sensible • Confirmed that we should group LAs by geography • Use simple Ratio estimator • Confirmed that 2001 LA estimation method is still best

46. ESTIMATION (2) • What does this mean? • The estimation methodology is much the same as it was • Should be slightly easier to explain • We will group LAs that don’t have enough sample with their neighbours until that group has enough sample • More LAs will have enough sample to produce direct estimates

47. OVERCOUNT • In 2001, estimated around 0.4% overcount (duplication) • No adjustments made • Not integrated into methodology • For 2011, expecting overcount to be higher • More complex population • Use of internet in 2011 Census • Strategy is to: • A) Build a process to identify and remove obvious cases (multiple response resolution) • B) measure and make net adjustments on the remainder • i.e. for the latter we are NOT removing duplicates

48. OVERCOUNT (2) • Methodology: • Select targeted samples of census records • Second residences • Students • Children • Very large sample (~600,000k records) • Automatic matching algorithm to identify duplicates • Clerical checking of matches • expect to see ~13,000 duplicates • Also use the LS to QA the estimates • Estimation of duplication rates by GOR and characteristics • estimating which is the correct record • Why not do whole database and remove them? • High risk of making false positives and thus removing too many!

49. OVERCOUNT (3) • What does this mean? • Population estimates will be reduced where there is overcount • We will be able to say how much adjustment was made due to overcount • The duplicates will still be in the data, we just won’t impute as much for undercount

50. DSE BIAS ADJUSTMENTS • Assumptions underpinning DSE: • Homogeneity • Independence • Accurate Matching • Closure • DSEs usually have some bias, mostly due to failure of homogeneity assumption • In 2001 Census we made a ‘dependence’ adjustment • This showed that we need to have a strategy for measuring this