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
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---
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