Presentation given by Chris Gale on Friday 13th April at GISRUK 2012. For more information on GISRUK 2012: www.lancs.ac.uk/gisruk2012 For further research by Chris Gale: mapblog.in

1. UCL DEPARTMENT OF GEOGRAPHY
Geodemographic Output Area
Classifications for London, 2001-2011
Chris Gale* Paul Longley
mapblog.in paul-longley.com
@geogale
* Conference attendance kindly supported by RGS-IBG funded QMRG bursary
UCL Department of Geography, Gower Street, London, WC1E 6BT

2. UCL DEPARTMENT OF GEOGRAPHY
Outline
• Geodemographic Classifications
• The 2001 Output Area Classification
• London and the 2001 Output Area Classification
• Change since 2001
• Uncertainty and the 2001 Output Area Classification
• Summary

3. UCL DEPARTMENT OF GEOGRAPHY
Geodemographic Classifications
• A Geodemographic Classification:
– Simplifies a large and complex body of information about a
population, where and how they live and work.
– Based on premise that similar people live in similar
locations, undertake similar activities and have similar
lifestyles and that such area types will be distributed in
different locations across a geographical space
• Clustering algorithms partition demographic data into
groups sharing similar characteristics
• Commercial (MOSAIC, ACORN) and free (OAC)
classifications available

4. UCL DEPARTMENT OF GEOGRAPHY
The 2001 Output Area Classification (OAC)
• Groups the UK population
into:
– 7 Supergroups
– 21 Groups
– 52 Subgroups
• Only data source used is the
2001 Census
– 41 Variables
• Variety of organisations use it
including local government
and commercial companies

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6. UCL DEPARTMENT OF GEOGRAPHY
OAC Cluster Distributions - UK and London
Supergroup OAC - UK OAC - London
Blue Collar
16.1% (35837) 2.5% (606)
Communities
City Living 7.5% (16637) 21.4% (5174)
Countryside 12.4% (27681) 0.1% (21)
Prospering Suburbs 21.2% (47250) 7.4% (1782)
Constrained by
14.9% (33165) 2.5% (592)
Circumstances
Typical Traits 18.3% (40769) 10.1% (2430)
Multicultural 9.7% (21721) 56.1% (13535)
Counts in brackets

7. UCL DEPARTMENT OF GEOGRAPHY
OAC Cluster Distributions - UK and London

8. UCL DEPARTMENT OF GEOGRAPHY
2001 London Output Area Classification
• Same methodology as the 2001 OAC
• Uses same Census variables as the 2001 OAC - but
includes only data for London
• 24,140 OAs cover London - instead of the 223,060 OAs
that cover the UK
• London contains 9.24% of UK’s OAs and 12.5% of UK’s
population
• 7 Supergroups created – Groups and Subgroups levels
were not clustered
• Based on Petersen et.al. 2010 paper

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10. UCL DEPARTMENT OF GEOGRAPHY
2001 LOAC Cluster Distributions
Supergroup OA Count OA Percentage (%)
Suburban 2506 10.4
Council Flats 3678 15.2
Asian Quarters 2716 11.3
Central District 3409 14.1
Blue Collar 3114 12.9
City Commuter 3542 14.7
London Terraces 5175 21.4

11. UCL DEPARTMENT OF GEOGRAPHY
2001 OAC vs. 2001 LOAC Cluster Profiles
• 2001 LOACs clusters significantly different to those of
the 2001 OAC
– Difference meant using same cluster names and profiles as
OAC was not possible for LOAC
• Cluster names and profiles for 2001 LOAC created by
Petersen et.al.
• Illustrates different results can be created by a regional
classification compared to a national alternative
• 2001 LOAC better representation of London compared
to the 2001 OAC - but lacks compatibility and
comparability with rest of the UK

12. UCL DEPARTMENT OF GEOGRAPHY
Bespoke Geodemographic Classifications
• Being able to easily create bespoke classifications
without any expert knowledge is one possible solution
to unsatisfactory cluster assignment
• Using tools like ‘GeodemCreator’ classifications could
have (but not limited to):
– The variables modified
– The geography changed
– Different standardisation techniques and clustering
algorithms used
• In the case of the 2001 OAC this could resolve a
problem when used at a regional level (e.g. London)

13. UCL DEPARTMENT OF GEOGRAPHY
Change and OAC Uncertainty
• Change happens across the UK – but this change
happens at different rates for different areas
• The 2001 OAC uses Census data that is now 11 years
old
• How much uncertainty in the 2001 OAC since 2001?
• This uncertainty will vary depending on the amount of
change that has occurred in a particular area over time
• A measure can be calculated to indicate how reliable
the 2001 OAC becomes over time

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17. UCL DEPARTMENT OF GEOGRAPHY
Uncertainty in London: 2001 OAC Case Study
• Uses Mid-Year Population Estimates from 2002 to
2010 at Output Area level
• Assumption:
– The greater the population change from 2001 the greater
the uncertainty
• Allows for the uncertainty of different OAC
Supergroups to be compared over time
• Different methods can be used to visualise this
uncertainty

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24. UCL DEPARTMENT OF GEOGRAPHY
Uncertainty in London: 2001 OAC Case Study
• Current lack of data at Output Area level makes
creating a more comprehensive measure of
uncertainty difficult
• Assumes the greater the population change the more
uncertain the classification – BUT population change
could also be reaffirming OAC Supergroup allocation
• Should be used as more of a note of caution when
using the 2001 OAC rather than a definite answer to if
the classification is now ‘wrong’
• The uncertainty of the uncertainty measure needs to
be taken into account

25. UCL DEPARTMENT OF GEOGRAPHY
Summary
• The 2001 OAC does not classify London well
• The 2001 LOAC was created by Petersen et.al is one
solution to this
• A measure of uncertainty gives some understanding
how reliable geodemographic classifications (that do
not employ updating of variables) become over time
• The uncertainty measures themselves have a level of
uncertainty
• Uncertainty measure does not quantify how much the
OAC Supergroup assignment is ‘wrong’– BUT does
allow for areas of possible change to be identified

26. UCL DEPARTMENT OF GEOGRAPHY
Any Questions?
Chris Gale
mapblog.in
areaclassification.org.uk
@geogale
c.gale.10@ucl.ac.uk