Public Health Wales 6:12
Localities and
statistical
geographies
Author: Ciaran Humphreys, Consultant in Public Health/Health
Intelligence
Date: 5 March 2010
Version: 1
Publication/ Distribution:

Directors of Planning and Service Development, Public Health Wales

Chief Executive, Public Health Wales

Director of Corporate Health Information Programme
Purpose and Summary of Document:
Localities have been proposed as the building block for primary and
community services across Wales. The existing statistical geography
(USOA) in Wales covers a population size similar to that required for
locality purposes. Development of separate geographies which do not take
account of existing statistical geographies could have serious implications
for the development of population based information to support service
development.
Public Health Wales Observatory
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Localities and statistical geographies
Purpose of this document
This document is intended to highlight
statistical geographies when developing
services. In particular it draws attention
for primary and community services in
areas.
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the need to consider existing
geographical units for planning
to the development of localities
relation to upper super output
Localities for primary and community
services
The Primary and Community Services Strategic Delivery Programme has
outlined the co-ordination of services on the basis of localities. Their
requirements include:
o indicative populations of 30,000-50,000 and
o boundaries agreed between health and social care sectors, and be
meaningful in terms of geography, natural communities and
functions such as patient flows.
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Statistical geographies below Local
Authority level
Health information below local authority level is usually presented at one
of the super output level geographies. These are based on census output
areas, and are intended to reflect populations of similar size. Lower super
output areas (mean population of 1,500) and middle super output areas
(population typically 7,500) are official UK geographies now in common
use in Wales.
Upper super output areas (USOAs) were developed for use in Wales in
2008 (figure 1). There are 94 Upper Super Output Areas in Wales. They
have a mean population of approximately 31,000, with a range from
24,000 to 48,000. They were developed by local authorities and they
enable the release of data that is not suitable for publication at lower
levels of geography (particularly useful for health data). Information is
currently made available at Upper Super Output Area by the Public Health
Wales Observatory, the Welsh Local Government Data Unit and Health
Maps Wales (provided by Health Solutions Wales).
Electoral divisions (wards) can be used to display information; however,
they have a number of deficiencies. In particular, the boundaries are reassessed on a regular basis making analyses over time more difficult.
Further, their population size varies greatly from less than a thousand to
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Public Health Wales Observatory
Localities and statistical geographies
over 15,000 persons; and the number of health events in any one
electoral division may be too few to be meaningful.
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Public Health Wales Observatory
Localities and statistical geographies
Figure 1. Upper super output areas of Wales
Source: 2001 Census, Output Area Boundaries. Crown copyright 2003. Crown
copyright material is reproduced with the permission of the Controller of HMSO
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Public Health Wales Observatory
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Localities and statistical geographies
Local data to support localities
Population based information is required to inform population based
planning at locality level. Currently the closest geography in use for health
data to ‘locality’ area in terms of population size is the USOA.
If new areas are developed that are similar to, but different from USOAs
this will have implications for producing information at the locality level.
Key implications are:
o Many central agencies make data available at output based
geographies (including USOA). These will not be usable for locality
purpose if they bear no relation to these localities.
o Inefficient use of information resources is likely, duplicating
information provision at different, but similar, geographies.
o Potentially it will be impossible to publish some information at both
levels. This is due to contractual arrangements and information
governance requirements which preclude the release of certain
‘small number data’ at a local level. If data is published at two
similar but different geographies, small numbers can potentially be
deduced leading to ‘disclosure by subtraction’.
o If boundaries are made that do not align to amalgamations of official
geographies (i.e. either output area based or electoral division
based) then it may not be possible to provide information for these
areas.
It should be noted that if localities are considered to describe the
populations attending specific clusters or networks of GP practices, then
some information on their registered population could be accessed
through registration data. This would not ‘map’ directly to physical
geographies due to the variable catchment of practices.
A number of areas have progressed some way to defining ‘locality’ areas.
In many cases this work has been ongoing for some time.
Example 1.
Within Gwynedd three localities
Meirionnydd. There are four USOAs.
are
in
use:
Arfon,
Dwyfor
and
o Meirionnydd is identical to one USOA, except that it appears to
include Penrhyndeudraeth Electoral Division.
o Dwyfor is identical to another USOAs except that it appears to
include Clynnog Electoral Division.
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Public Health Wales Observatory
Localities and statistical geographies
o Arfon is very similar to, but not quite the same as the amalgamation
of the remaining two USOAs.
Example 2.
There are six localities proposed for Cardiff. These are based largely on
electoral divisions. Cathays Electoral Division, however, is divided between
two of the localities. The division does not appear to follow the lines of any
existing official geography boundary, but does relate to the divisions
defined by the police between residential and central business district
areas. This could frustrate straightforward and consistent production of
population based information for these localities.
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Conclusions
Locality based planning for primary and community services must occur
along lines that are meaningful and sensible to local service providers.
Over time it is likely that there will be a requirement for population based
information at locality level. This would be most easily achieved if localities
were matched directly with USOAs, or at least an amalgamation of the
largest super output based areas suitable for the purpose. If geographies
(localities) are defined that do not take account of existing statistical
geographies then the provision of population based information for
localities could be seriously hampered.
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