Research for 2021 Census in England and Wales

Potential innovations . . . .

Garnett Compton, ONS

UNECE Census Meeting, 30 September – 2 October 2015

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?

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

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 money

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

Planning and supporting census collection

Supporting the collection

• Three key collection objectives:

1. Maximise response

2. Minimise variation in response

3. Efficient use of resources

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

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 internetNo access and/or do not use internet

Group 2 Group 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

Characteristics such as trust in Government/security concerns

Group 2

Group 3Group 4

Group 1

On-line response Paper response No response

Maximising online (electronic) response . . 2

What success might look like . . .

i. Prioritise field resourcesii. 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 predictorsiii. Impact on on-line first?

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

Building a simulation model . . . 1

• Low digital exclusion

• Response rate of 97.4%

Building a simulation model . . . 2

• Low digital exclusion

• Response rate of 97.4%

• High digital exclusion

• Response rate of 98.6%

Improving census coverage and population estimation

Framework for producing population estimates using a census

Dual System Estimation

Matching

Ratio estimation

Census

Quality Assurance

Census Coverage

Survey

Population estimates

Enhanced census coverage

Dual System Estimation

Matching

Ratio estimation

Census

Quality Assurance

Census Coverage

Survey

Population estimates

Admin Data

An example . . . Administrative data (filtered for activity)

Address register Census Enhanced 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

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

Age-Sex Distribution of Census and Administrative data records

All per

sons

age

d 0

Male

s 1-

4

Male

s 5-

9

Male

s 10

-14

Male

s 15

-19

Male

s 20

-24

Male

s 25

-29

Male

s 30

-34

Male

s 35

-39

Male

s 40

-44

Male

s 45

-49

Male

s 50

-54

Male

s 55

-59

Male

s 60

-64

Male

s 65

-69

Male

s 70

-74

Male

s 75

-79

Male

s 80

and

ove

r

Female

s 1-

4

Female

s 5-

9

Female

s 10

-14

Female

s 15

-19

Female

s 20

-24

Female

s 25

-29

Female

s 30

-34

Female

s 35

-39

Female

s 40

-44

Female

s 45

-49

Female

s 50

-54

Female

s 55

-59

Female

s 60

-64

Female

s 65

-69

Female

s 70

-74

Female

s 75

-79

Female

s 80

and

ove

r0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%Census records

CUE records

Pe

rce

nta

ge

of

rec

ord

s

Estimates and Confidence Intervals

Estimation Area

With CUE records Without CUE records

Estimate Variance Relative CI width1 Estimate Variance Relative

CI width1

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%

Belfast462,000 11,562,800 1.44% 452,500 21,540,600 2.01%

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

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

Email: garnett.compton@ons.gov.uk

Thank you

Any questions?

23

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. 1st July 2015.

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. 1st 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

•  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.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---