Internet access to UK Census interaction data: that's WICID! John Stillwell Centre for...

Internet access to UK Census interaction data: that's WICID!

John Stillwell

Centre for Computational Geography

University of Leeds, Leeds LS2 9JT

john@geography.leeds.ac.uk

Focus

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

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

Presentation Population censuses CIDS challenge: aims and objectives Census based interaction data sets Importance of interaction data in planning System architecture and metadata structure Features of the interface Some examples of data extraction and analysis

Acknowledgements

Funded by ESRC and JISC under the 2001 Census of Population Programme

(Award number H507 255177)

Began: 1 August 2001 Ends: 31 July 2006

Paul Boyle and Zhiqiang Feng, University of St Andrews

Keith Cole and Justin Hayes, University of Manchester

Population censuses

reliable comprehensive small area scale very important for geographic research

but periodic not problem free

Problems Incorrect or missing information

e.g. origin or workplace unstated Measures taken to preserve confidentiality e.g.

minimum thresholds for persons and households

Underenumeration

e.g. missing million in 1991

2001 is first ‘One Number Census’ where underenumeration has been adjusted for by imputation

2001 Census population counts: male deficit in young adult ages: cause for concern?

0.90

0.92

0.94

0.96

0.98

1.00

1.02

1.04

1.060-

4

5-9

10-1

4

15-1

9

20-2

4

25-2

9

30-3

4

35-3

9

40-4

4

45-4

9

50-5

4

55-5

9

60-6

4

65-6

9

Age group

Mal

es/F

emal

es

Y&H ratioUK ratio

Parity

Digital data productsVarious different products of 1991 Census

- LBS: Local Base Statistics

- SAS: Small Area Statistics

- SMS: Special Migration Statistics

- SWS: Special Workplace Statistics

- SARs: Samples of Anonymised Records

- LS: Longitudinal Study

- DBD: Digital Boundary Data

Similar set of products for 2001 Census

Data Support Units Census Registration Service (CRS) (University of Essex) Census Dissemination Unit (University of Manchester) for CAS

(LBS/SAS) Geography Data Unit: UKBORDERS (University of Edinburgh) for

DBD Census Interaction Data Service (CIDS) (University of Leeds) for

SMS/SWS Census Microdata Unit, CCSR (University of Manchester) for SARs Centre for Longitudinal Study Information and User Support

(CeLSIUS) (University of London School of Hygiene and Tropical Medicine) for LS

CIDS Challenge

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

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

Objectives To provide users with access to existing

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

To develop an ‘user-friendly’ interface for query building and data extraction

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

Objectives

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

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

To provide facilities to download the data in alternative formats

Interaction Data Sets for 1991Original migration data setsSMS Set 1 (2 tables, 12 counts, wards)SMS Set 2 (12 tables, 93 counts, districts)

Interaction Data Sets for 1991

Original commuting and student data sets

SWS Set C (9 tables, 274 counts, wards) Table 100 (2 tables, 47 counts, districts)

Derived data sets

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

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

Suppression problem

Only flows for some origin-destination pairs are available

Can identify the extent of suppression using a raster image based on SMS Set 2 Table 1 (no flows suppressed)

Each cell shaded

- white when cell empty

- grey when flow is 1-9

- black when flow is 10+

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

between wards in 1991)1981 SWS Set C (Five tables - 172 counts -

of journey to work flows between wards in 1991)

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

Importance of interaction data in planning

Interaction data sets are very important because they provide information on migration and commuting flows between small areas (wards)

e.g. migration data used for population estimation and projection by central and local government agencies

e.g. commuting data used to define TTWAs and in transport planning

System Architecture

MetadataStructure

Features of the Interface: CIDS homepage

Login page

Welcome page

Different parts of the page

Status line

Feedback and Help

Part of each page where you will interact

Logout

Key Links

Off the shelf

Flow summaries

General query page

Area Selection Tools

List Area Selection Tool

Origins selected

Data Selection Tools

Data Selection Options

Table Selection for 1991 SMS 2

Variable Selection with Table 1 of 1991 SMS 2

Current query summary

Data extraction

Output Planner

Output previewer

Download file

Examples of data extractions

In-migrants to Cardiff Immigrants from Greece by age and sex Immigrants from Greece Net migration in Scotland Students to and from Sussex Social class of commuters in Leeds

Query: What were the in-migration flows to Cardiff district from various origins in 1990-91?

In-migration flow to Cardiff, using SMS Set 2, 1990-91

Source: 1991 Census Crown Copyright:

ESRC/JISC Purchase

Query: What is the age structure of migrants

from Greece to GB in 1990-91?

Age profile of migrants from Greece, 1990-91

0

100

200

300

400

500

600

1-4 5-10

10-14

16-19

20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

75-79

80-84

85+

5 Year age group

Migrants to GB from Greece, 1990-91

Male

Female

Source: 1991 Census

Crown Copyright: ESRC/JISC Purchase

Query: What is the distribution of migrants from Greece by district of GB in 1990-91?

Districts receiving most migrants from Greece, 1990-91

Source: 1991 Census

Crown Copyright: ESRC/JISC Purchase

Forest Heath 182Westminster,City of 152Manchester 91Camden 84Kensington and Chelsea 81Haringey 80Glasgow City 51Wandsworth 50Birmingham 49Barnet 48

What are the net migration balances of Scottish districts for (a) moves within Scotland and (b)

moves between Scotland and England and Wales?

Source: 1991 Census Crown Copyright: ESRC/JISC Purchase

Query: Where do universities in Sussex get their students from?

Main county origins with term-time addresses in Sussex

Source: 1991 Census Crown Copyright: ESRC/JISC Purchase

Social structure of Leeds and surrounding districts using 1991 SWS

Query: What are the journey to work flows

between zones by social class in 1991?

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

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

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 steps

CIDS now available and WICID stable Usage rates reasonable (particularly since

Athens One Stop Sign On was introduced by Census Registration Service)

Access available at

http://census.ac.uk/cids/

Next steps Flexible metadata structure of WICID will allow 2001

Census results to be included in the system

WICID will be used to verify the 2001 data in 2003

Next steps

Mapping option for geographical area selection now being developed

Next steps

Analysis and modelling facilities in WICID intended but raises difficult questions

Important to consider the research agenda for the future… what are the key research areas that should be investigated:

e.g. validation studies, comparative studies, empirical research, modelling work