internet access to uk census interaction data: that's wicid! john stillwell centre for...
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Internet access to UK Census interaction data: that's WICID!
John Stillwell
Centre for Computational Geography
University of Leeds, Leeds LS2 9JT
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