Monitoring Internal Migration in the United Kingdom

1. Monitoring Internal Migration in
the United Kingdom
John Stillwell
School of Geography, University of Leeds
Presentation at the BSPS Annual Conference,
University of Leeds, 7-9 September 2015

3. Importance of internal migration
• Underpinned the processes of urban and rural
change (urbanisation, rural exodus,
suburbanisation, counterurbanisation,
reurbanisation) that have defined the UK’s
settlement pattern
• Critical component of population dynamics for
local areas – magnitude and composition
provide evidence of what services are required
• In recent years, tendency for attention to
focus more on international migration

4. Presentation
1. Internal migration change in the UK 2001-11:
based on data from the Census and annual
estimates from administrative sources
2. Internal migration distance in England: based
on a sample of data from a large commercial
survey in mid-2000s
3. International comparison of internal
migration: based on data from the IMAGE
repository

5. Research questions
• How has migration changed in the UK over the
decade between 2000-01 and 2010-11?
• What distance did internal migrants actually
travel within England in the mid-2000s?
• How does the migration intensity and distance
of migration compare with other countries?
• How important is scale in the analysis of
migration indicators?

6. Key dimensions
Intensity – Migration rates
Impact – Migration effectiveness (MEI)
MEI = Net migration / (In-migration + Out-migration )*100
Distance – Mean migration distance
Scale – Various
Key data sets
Census – 2001 and 2011
Administrative – PRDS/NHSCR/Estimates
Survey – Acxiom Research Opinion Poll

7. Acknowledgements
• ESRC: UK Data Service-Census Support grant
• ESRC: PhD Case studentship with ONS for Nik Lomax
– collaboration with Phil Rees and Paul Norman
• ESRC: PhD for Michael Thomas (supervised jointly
with Myles Gould) under the TALISMAN programme
and Acxiom Ltd for providing the data for this project
• ARC: IMAGE project and collaboration with
researchers in Australia, Poland and China led by
Martin Bell
• Kostas Daras, Nikola Sander, Carl Bradbrook, Claire
Woodvine

8. 1. Internal migration change in the UK between
2000-01 and 2010-11
District Ward Output Area
1991 11 tables (94 counts) 2 tables (12 counts)
2001 10 tables (996 counts) 5 tables (96 counts) 1 table (12 counts)
2011 83 tables (2,551 counts) 50 tables (2,171 counts) 50 tables (2,189 counts)
Open: 5 tables
(83 counts)
Safeguarded: 39 tables
(916 counts)
Safeguarded: 9 tables
(353 counts)
Safeguarded: 3 tables
(3 counts)
Secure: 39 tables
(1,552 counts)
Secure: 41 tables
(1,818 counts)
Secure: 47 tables
(2,186 counts)
Evolution of Census Origin-Destination Migration data

9. How has migration changed in the UK over the
decade between 2001 and 2011?
• Use set of 404 consistent
areas:
Districts
England 324
Wales 22
Scotland 32
Northern Ireland 26

10. Levels of migration in the UK
(those aged over 1)
2000-01 2010-11 Change
%
Change
Inter-district 2,443,964 2,768,632 +324,668 13.3
Intra-district 3,627,034 4,046,769 +419,735 11.6
Internal 6,070,998 6,815,401 +744,403 12.3
But there were an additional 458,000 migrants with unknown
usual residence at the beginning of the period in 2000 – these
can be allocated proportionately
Immigrants 401,174 687,174 +286,000 71.3
Total 6,472,172 7,502,575 +1,030,403 15.9

11. Adjusted levels of migration in the UK
2000-01 and 2010-11
(Migrants aged over 1)
2000-01 2010-11 Change
%
Change
Inter-district 2,616,807 2,768,632 151,825 5.8
Intra-district 3,883,547 4,046,769 163,222 4.2
Internal 6,500,354 6,815,401 315,047 4.8
Immigrants 429,546 687,174 257,628 60.0
Total 6,929,900 7,502,575 572,675 8.3

12. Migration intensities (%) in the UK
2000-01 and 2010-11
2000-011 2001-11 Change % Change
Inter-district 4.50 4.44 -0.06 -1.3
Intra-district 6.68 6.49 -0.19 -2.8
Internal 11.18 10.92 -0.26 -2.3
Immigrants 0.74 1.10 0.36 48.7
Total 11.92 12.03 0.10 0.9
Note: 2000-01 intensities adjusted for origin not stated

13. UK migration intensities by age group,
2000-01 and 2010-11
Note: 2000-01 intensities adjusted for origin not-stated

14. Changes in UK migration intensities
between 2000-01 and 2010-11
Note: 2000-01 intensities adjusted for origin not-stated

15. Net migration by district, 2000-01 and 2010-11

16. Migration effectiveness by district,
2000-01 and 2010-11

17. MEI by district, ages 15-19,
2000-01 and 2010-11

18. MEI by district, ages 45-59,
2000-01 and 2010-11

19. MEI by district, ages 60-64,
2000-01 and 2010-11

20. MEI by district, ages 65-74,
2000-01 and 2010-11

21. Internal churn rates, 2000-01 and 2010-11
y = 1.1554x - 2.2889
R² = 0.8976
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0
Churnrate2011(per100)
Churn rate 2001 (per 100)
y = 0.6096x + 6.4362
R² = 0.1718
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0
Immigrationrate20011(per1000)
Immigration rate 2001 (per 1000)
Immigration rates, 2000-01 and 2010-11

22. Time series change
• Census is problematic:
- those with origin unknown in 2001
- periodic nature
• Use of administrative data from NHSCR/PRDS to build time
series for the UK at district scale from 2001-02 to 20110-11

23. Spreadsheet information system

24. Inter-district migration intensity during the 2000s

25. Changes in inter-district migration
intensities between 2001-02 and 2010-11

26. Different aggregations of districts
e.g. City regions
and their
component parts:
Metropolitan:
- Core
- Rest
Non-metropolitan
- Near
- Coast & Country

27. Circular plots showing migration flows of over 280 migrants
between and within city regions in 2001-02 and 2010-11
http://nikolasander.com/uk-migration/
2001-02 2010-11

28. Changes in migration between metro and non-
metro aggregations of districts: time-series indices
Source: Stillwell, J., Lomax, N. and Sander, N. (2015) Monitoring and visualising sub-national migration
trends in the UK, In Geertman et al. (eds) Planning Support Systems and Smart Cities, Springer

29. 2. Internal migration distance in
England, 2005-2007
Source: Stillwell, J. and Thomas M. (2015) How far do internal migrants in England
really move?, Working Paper 15/1, School of Geography, University of Leeds
Acxiom ROP – voluntary lifestyle
survey household respondents
aged 18 and over
In 3 years (2005, 06 and 07), asked
question about when did you move
and where was previous residence
950,658 cases (movers and stayers)
over 3 years
Subset 1: 125,494 migrants
Subset 2: 26,688 migrants in
previous 12 months
Subset 3: 43,390 migrants in
previous 36 months
Key benefit: Postcodes of origin and
destination available
Using Subset 1, how far do
people move?

30. Using Subset 2, how does distance moved vary
by migrant type?
Source: Thomas, M, Stillwell, J. and Gould, M. (2015) Modelling multilevel variations in distance moved
between origins and destinations in England and Wales, Environment and Planning A, 47, 996-1014

31. Using Subset 3, how does
postcode distance
compare with centroid
distance? 9 areas 27 areas 324 areas 6,793 areas
(i) Inter-area migration

32. (ii) Intra-area migration
Intra-area distance calculated as the radius
of a circle equivalent to the area divided by
the square root of 2 (Batty, 1976)
How can we improve the measure of intra-area distance?

33. Use the relationship between inter-area migration
distance and area size at different spatial scales?
Distance measure: Inter-centroid
distances plus:
2000-01 2010-11
𝑅2 IoD MAPD 𝑅2 IoD MAPD
(i) Conventional estimate for intra 0.908 27.2 55.7 0.921 25.6 51. 5
(ii) Linear estimate for intra 0.963 19.5 39.2 0.960 18.6 37.5
(iii) Quadratic estimate for intra 0.978 17.2 34.6 0.977 16.5 33.3
What are the results of fitting constrained spatial interaction models?
Inter-areamigration
distance(km)
Linear model Quadratic model
Generate estimates of intra-area distance from area size using model equations
which can be used in modelling 2001 and 2011 Census migration flows

34. 3. International comparison of internal
migration
IMAGE is an international collaborative program which aims to
provide a robust basis for comparing internal migration between
countries around the world
http://www.gpem.uq.edu.au/image
IMAGE Inventory
Review of internal
migration data
collection practice in
the 193 UN member
states
IMAGE Repository
Global collection of
population and internal
migration data and GIS
boundaries for 135
countries
IMAGE Studio
Analytical software to
compute internal
migration measures
and address key
methodological issues
RESEARCH FRAMEWORK

35. Major problem with cross-national
comparison of internal migration
• Different shapes and sizes of the spatial units that are
used for counting migration flows
• Modifiable Area Unit Problem (MAUP) which has
identified two components (Openshaw, 1984):
- scale effect or the variation in results obtained when
data for one set of areal units is aggregated into larger
spatial units (i.e. where the number of regions changes)
- zonation or aggregation effect or the variation in
results obtained from different ways of subdividing
geographical space at the same scale (i.e. where the
number of regions remains the same)
• IMAGE Studio is software that tries to address these
effects

36. IMAGE Studio:
Framework and Sub-systems

37. Aggregation sub-system
Example of the IRA wave algorithm
This process can be repeated iteratively with different seed points

38. Example aggregation for the UK
0
500000
1000000
1500000
2000000
2500000
3000000
10
30
50
70
90
110
130
150
170
190
210
230
250
270
290
310
330
350
370
390
410
Meantotalinter-ASRmigrants
Scale (Number of ASRs)
Start: N = 420 BSUs
M= 2.5 million
CMI = 4.2%
End: n = 10 ASRs
M=1.1 million
CMI = 1.9%

39. Why is the Studio useful?
Example 1: Comparing Aggregate Crude Migration
Intensities (ACMI) between countries
Crudemigrationintensity
(CMI)
Ln (Households/Number of ASRs)
In some countries (Country A), CMI
maybe available from data at
different spatial scales, including
total migration which gives ACMI
Country ALinear relationship is known as
Courgeau’s k
In other countries (Country B), total
migration data are not available but
CMI may be available at one scale
(e.g. districts)
Studio can be used to generate CMI
at different spatial scales and
regression line used to identify ACMI
Country B

40. One-year migration
league table of
aggregate intensities UK
Source: Bell, M., Charle-Edwards, E.,
Kupiszewska, D., Kupiszewski, M.,
Stillwell, J. and Zhu, Y. (2015) Internal
migration and development:
comparing migration intensities
around the world, Population and
Development Review, 41(1): 33-58

41. Example 2: Comparing migration distance and
distance decay between countries
0 400000 800000
Mean ASR population
Mean migration distance (MMD)
Meanbeta
0123
Beta derived from model is as follows:
𝑀𝑖𝑗 = 𝐴𝑖 𝐵𝑗 𝑂𝑖 𝐷𝑗 𝑑𝑖𝑗−𝑏𝑒𝑡𝑎
4 6 8 10 12 14
Ln (Mean ASR area)
MeanMMD
050010001500
Distance decay parameter (Beta)

42. Example 3: Comparing migration distance and
effectiveness in the UK by age group, 2001 and 2011
70
90
110
130
150
170
190
210
230
10
50
90
130
170
210
250
290
330
370
404
2001
2011
50
100
150
200
250
300
10 40 70 100130160190220250280310340370400
2001
1 to 14
15 to 19
20 to 24
24 to 34
35 to 44
45 to 59
60 and up
50
100
150
200
250
300
10 40 70 100130160190220250280310340370400
2011
1 to 14
15 to 19
20 to 24
24 to 34
35 to 44
45 to 59
60 and up
Distance
Number of ASRs Number of ASRs
Number of ASRs

43. Example 3: Comparing migration distance and
effectiveness in the UK by age group, 2001 and 2011
National MEI = 100 ∑|Net migration| / ∑ (In-migration + Out-migration)
Effectiveness
2001 2011

44. Conclusions
• Census and administrative data suggest modest declines
in internal migration intensities in the UK over the
2000s, most marked for those in the latter half of the
age range (but impact of recession not that significant)
• Changes in net migration suggest spatial pattern of
waning counterurbanisation and increasing re-
urbanisation
• Inter-district migration distance decreasing
• Convergence of migration impact by age group at lower
level, but MEI increasing for 15-19 year olds (students)
• Compared with other countries for which one-year
data are available, UK has average aggregate
intensity

45. Take-away messages
Migration researchers should:
• make greater use the under-exploited origin-
destination migration data sets that have become
available from the 2011 Census
• investigate the potential of less conventional data
sources for migration analysis particularly in the event
of a possible shift away from census-taking after 2021
• attempt more cross-national comparative research on
internal migration (perhaps using data collected as part
of the IMAGE project)
• give more consideration to issues of scale and zonation
when doing migration research