Internet Internet Access to Access to Census Census

Migration and Migration and Journey-to-Journey-to-Work DataWork Data

John Stillwell and Oliver Duke-WilliamsJohn Stillwell and Oliver Duke-WilliamsCentre for Computational GeographyCentre for Computational Geography

University of Leeds, Leeds LS2 9JTUniversity of Leeds, Leeds LS2 9JT

Paper presented at the 32Paper presented at the 32ndnd Annual Conference Annual Conference

of the Regional Science Association International of the Regional Science Association International

British and Irish Section (Session on Migration British and Irish Section (Session on Migration Analysis)Analysis)

Dudley Hotel, Brighton and Hove, 21-23 August 2002Dudley Hotel, Brighton and Hove, 21-23 August 2002

FocusFocus

• The provision and development of a The provision and development of a Census Interaction Data Service (CIDS) Census Interaction Data Service (CIDS)

• The development of a web-based The development of a web-based information system (WICID) that allows information system (WICID) that allows researchers to extract data on researchers to extract data on interaction flows between sets of interaction flows between sets of origins and destinationsorigins and destinations

PresentationPresentation• The challenge: aims and objectivesThe challenge: aims and objectives

• Census-based interaction data setsCensus-based interaction data sets

• System architecture System architecture

• Metadata structureMetadata structure

• Features of the interfaceFeatures of the interface

• Some examples of data extraction and Some examples of data extraction and analysisanalysis

• Conclusions - next stepsConclusions - next steps

AcknowledgementsAcknowledgements• Funded by ESRC and JISC under the 2001 Funded by ESRC and JISC under the 2001

Census of Population Programme Census of Population Programme

(Award number H507 255177)(Award number H507 255177)

• Began: 1 August 2001Began: 1 August 2001

• Ends: 31 July 2006Ends: 31 July 2006

• Paul Boyle and Zhiqiang Feng, St Paul Boyle and Zhiqiang Feng, St AndrewsAndrews

The ChallengeThe Challenge

• To increase the use of the Origin-To increase the use of the Origin-Destination (interaction) data sets Destination (interaction) data sets that will be produced as outputs that will be produced as outputs from the 2001 UK Census from the 2001 UK Census

(as well as the equivalent special (as well as the equivalent special migration and commuting data sets migration and commuting data sets produced from 1991 and 1981 produced from 1991 and 1981 Censuses)Censuses)

Objectives Objectives • To provide users with access to existing To provide users with access to existing

census based interaction data sets (for census based interaction data sets (for 1991 and 1981) via the Internet1991 and 1981) via the Internet

• To maintain and develop an ‘user-friendly’ To maintain and develop an ‘user-friendly’ interface for query building and data interface for query building and data extractionextraction

• To develop a flexible system that allows To develop a flexible system that allows new data sets (e.g. 2001 Census new data sets (e.g. 2001 Census interaction data) to be added without any interaction data) to be added without any major system redesign major system redesign

Objectives Objectives

• To allow users the option of To allow users the option of constructing queries that involve the constructing queries that involve the selection of origin and destination areas selection of origin and destination areas at different spatial scales at different spatial scales

• To produce a library of popular sub-sets To produce a library of popular sub-sets of interaction data for quick extraction of interaction data for quick extraction and downloadingand downloading

• To provide facilities to download the To provide facilities to download the data in alternative formatsdata in alternative formats

Interaction Data Sets for Interaction Data Sets for 19911991Original data setsOriginal data sets

• SMS Set 1 (2 tables, 12 counts, wards)SMS Set 1 (2 tables, 12 counts, wards)

• SMS Set 2 (12 tables, 93 counts, districts)SMS Set 2 (12 tables, 93 counts, districts)

• SWS Set C (9 tables, 274 counts, wards)SWS Set C (9 tables, 274 counts, wards)

• Table 100 (2 tables, 47 counts, districts)Table 100 (2 tables, 47 counts, districts)

Derived data setsDerived data sets

• SMS Set 1 Tables 3-10 (adjusted by Rees and SMS Set 1 Tables 3-10 (adjusted by Rees and Duke-Williams) so-called SMSGAPSDuke-Williams) so-called SMSGAPS

• SMS Set 1 Table 3 (adjusted by Simpson and SMS Set 1 Table 3 (adjusted by Simpson and Middleton) so called SMS-MIGPOPMiddleton) so called SMS-MIGPOP

Interaction Data Sets for Interaction Data Sets for 19811981• 1981 SMS Set 2 (Male and female 1981 SMS Set 2 (Male and female

migrants between wards in 1991)migrants between wards in 1991)

• 1981 SWS Set C (Five tables - 172 1981 SWS Set C (Five tables - 172 counts - of journey to work flows counts - of journey to work flows between wards in 1991)between wards in 1991)

• all re-estimated for 1991 ward all re-estimated for 1991 ward geography by Boyle and Feng as part of geography by Boyle and Feng as part of a Census Development Programme a Census Development Programme projectproject

System ArchitectureSystem Architecture

MetadataMetadataStructureStructure

CIDS HomepageCIDS Homepage

Features of the WICID Features of the WICID InterfaceInterface

Login in screenLogin in screen

General Query ScreenGeneral Query Screen

Area Selection ToolsArea Selection Tools

List Area Selection ToolList Area Selection Tool

Data Selection ToolsData Selection Tools

Data Selection OptionsData Selection Options

Table Selection for 1991 SMS 2Table Selection for 1991 SMS 2

Variable Selection with Table 4 of the 1991 SMS 2

Variable Selection with Table 4 of the 1991 SMS 2

Off the shelf facilityOff the shelf facility

Data extractionData extraction

WICID Output PlannerWICID Output Planner

WICID Output PreviewerWICID Output Previewer

Some examples of data Some examples of data extractionextraction

What were theWhat were the migrant flows to migrant flows to Brighton from elsewhere in 1990-91?Brighton from elsewhere in 1990-91?

Need to designa set of zonesthat are suitable:- districts in Sussex- counties in SE- other GB regions- NI and Eire- overseas

Query: Extraction of SMS data on migration to Brighton, 1990-91

Query: Extraction of SMS data on migration to Brighton, 1990-91

Source: 1991 CensusCrown Copyright: ESRC/JISC Purchase

Migration flows to Brighton, 1990-91Migration flows to Brighton, 1990-91 North 52 Hampshire 177

Yorkshire and Humberside 160 Hertfordshire 68East Midlands 151 Isle Of Wight 19East Anglia 118 Kent 149South West 294 Oxfordshire 70West Midlands 176 Surrey 198North West 174Wales 111 Eastbourne 74Scotland 99 Hastings 39Northern Ireland 16 Hove 1609

Lewes 433Irish Republic 56 Rother 21Total inflow from overseas 1643 Wealden 87

Adur 139Inner London 611 Arun 76Outer London 532 Chichester 28Bedfordshire 33 Crawley 102Berkshire 81 Horsham 90Buckinghamshire 48 Mid Sussex 231Essex 106 Worthing 101

Query: SMS data on age-specific migration to Brighton from rest of GB and from overseas, 1990-91

Query: SMS data on age-specific migration to Brighton from rest of GB and from overseas, 1990-91

0

500

1000

1500

2000

2500

Age group

Nu

mb

er o

f in

-mig

ran

ts

Inflows from GB

Inflows from overseas

Age profiles of in-migrants to Brighton from rest of GB and from overseas, 1990-91

Age profiles of in-migrants to Brighton from rest of GB and from overseas, 1990-91

Query: Students aged 19-21 Query: Students aged 19-21 with term-time residence in with term-time residence in Sussex and usual residence Sussex and usual residence

by countyby county

Query: Students aged 19-21 Query: Students aged 19-21 with term-time residence in with term-time residence in Sussex and usual residence Sussex and usual residence

by countyby county

Source: 1991 Census Crown Copyright: ESRC/JISC Purchase

Main county origins with term-time addresses in Sussex

Main county origins with term-time addresses in Sussex

Source: 1991 Census Crown Copyright: ESRC/JISC Purchase

Main county destinations of students with term-time address outside Sussex

Main county destinations of students with term-time address outside Sussex

Query: Migration flows in life course ages for DTLR modelling system

Query: Migration flows in life course ages for DTLR modelling system

Spatial Interaction Modelling

dDOBAM ijjijiij

Power function model:

Exponential function model:

eDOBAM ijjijiij

d

Intra-area flows included Intra-area flows excludedAge Power Exponential Mean mig Power Exponential Mean mig

group parameter parameter distance parameter parameter distance

1-14 2.66 0.045 45.1 1.47 0.011 122.415-19 2.56 0.040 51.4 1.41 0.011 129.120-24 2.33 0.034 53.0 1.24 0.010 116.925-29 2.48 0.041 45.8 1.46 0.013 98.230-44 2.49 0.039 49.6 1.50 0.012 110.945-59 2.61 0.041 51.1 1.66 0.013 119.760+ 2.83 0.049 45.8 1.71 0.013 121.6

Decay parameters and mean migration distances

Parameters and MMLs for matrices that exclude intra-area flows

Parameters and MMLs for matrices that include intra-area flows

0

0.5

1

1.5

2

2.5

3

1-14

15-1

9

20-2

4

25-2

9

30-4

4

45-5

9

60+

Age

Gen

eral

ized

par

amte

r

0

20

40

60

80

100

120

140

Dis

tan

ce (

km)

Decay parameterMean migration length

0

0.5

1

1.5

2

2.5

3

1-14

15-1

9

20-2

4

25-2

9

30-4

4

45-5

9

60+

Age

Gen

eral

ized

par

amte

r

0

20

40

60

80

100

120

140

Dis

tan

ce (

km)

Decay parameterMean migration length

Social structure of Leeds and surrounding districts using 1991

SWS

Social structure of Leeds and surrounding districts using 1991

SWS

Query: Journey to work flows Query: Journey to work flows between zones by social class, between zones by social class,

19911991

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

I II III (NM) III (M) IV V

Social class structure of commuters in Leeds and between Leeds and surrounding

districts, 1991

Social class structure of commuters in Leeds and between Leeds and surrounding

districts, 1991

Source: 1991 Census Crown Copyright: ESRC/JISC Purchase

% of flow in Class II

56.436.233.428.413

%of flow in class I

2110.4

8.36.20

Source: 1991 Census Crown Copyright: ESRC/JISC Purchase

Proportions of commuters to Central Leeds from other wards and surrounding districts by social class, 1991

Proportions of commuters to Central Leeds from other wards and surrounding districts by social class, 1991

Professional

Managerial and Technical

% in class III (M)

24.115.312.811

1

% in class III (NM)

46.432.53028.318

Source: 1991 Census Crown Copyright: ESRC/JISC Purchase

Skilled Non-manual

Skilled Manual

% in class V

12.83.832.50

Source: 1991 Census Crown Copyright: ESRC/JISC Purchase

Partly Skilled

Unskilled

Conclusions/Next stepsConclusions/Next steps• CIDS now up and running CIDS now up and running

• Flexible metadata structure of WICID will Flexible metadata structure of WICID will allow 2001 Census results to be included in allow 2001 Census results to be included in the systemthe system

• WICID will be used to verify the 2001 data in WICID will be used to verify the 2001 data in 20032003

• Mapping option for geographical area Mapping option for geographical area selection now being developedselection now being developed

• Analysis and modelling facilities intended Analysis and modelling facilities intended but raise difficult questionsbut raise difficult questions