Data Geography

Postcodes, census districts, wards and constituencies – neighbourhoods don’t necessarily follow the units of area that are used by public agencies to collect and present data…

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Postcodes, census districts, wards and constituencies – neighbourhoods don’t necessarily follow the units of area that are used by public agencies to collect and present data...

In more detail

The most common way we have of saying where something is the postcode.  Most neighbourhood statistics are, however, collected and made available on the basis of areas which are not directly related to postcodes but to census districts.  Other bits of information are only available based on areas made up of multiple OAs – lower super output areas and middle super output areas.  Some locally gathered statistics are collected for local authority wards and Parliamentary constituencies.   Although these different areas are not directly related, you should be able to use the government’s neighbourhood statistics website and your local council data to put together many different statistics for your neighbourhood.

Postcodes

Postcodes are made up of letters and numbers in four parts:

Title:

 

Represented in the code by: Example:
POSTCODE AREA

 

 

First one or two letters B is Birmingham
POSTCODE DISTRICT Next one or two numbers (sometimes the second is a letter)

 

B13 is the town of Moseley in Birmingham
POSTCODE SECTOR The following number B13 8 – the part of Moseley to the west of the Cross City rail line including the main shopping area and Moor Green
POSTCODE UNIT The final two letters B13 8JP – the area around the Post Office and Moseley Community Development Trust in Moseley High Street

Each postcode unit covers between 1 and 100 addresses (households and businesses).  On average a postcode unit applies to 15 addresses.  There are over a million postcode units in use in England.  They do not share the same boundaries as the output areas used in government statistical geography.

Although postcodes are very widely used (in SatNav applications for example) and understood by the general public, they are not a suitable basis for data collection and analysis because: they are very variable in terms of the number of residents in each unit; the units are changes and move around; and the lowest level (unit) is so small that data collected on this basis would not be anonymous.

Above all, postcodes are designed to ensure the efficient delivery of the mail – addresses which receive more than 500 pieces of mail a day get their own postcode unit, for example.  They are not designed for collecting or representing data.  They are, however, translatable into the geography which is used for this – output areas.  You can find postcode to output area translators online.

Small Area Statistics

Government neighbourhood statistics are based not only postcodes but on output areas.  The predecessor to output areas was the enumeration district.  This is an area which is defined in terms of the mechanics of collecting censuses.

Enumeration District – this, now mainly out-of-date term, was the area covered by a census collector (each census collector might actually be allocated many EDs, but the ED was the basic unit for census collection and analysis up to 2001).  On average, an ED covered 200 households (450 people) – more in urban areas, fewer in rural ones.  At the 2001 census (the last time EDs were used) there were about 100,000 of them in England.  Census information was only ever presented down to the level of the ED – reports were constructed based on statistics relating to EDs rather than individual households etc.   Because they are no longer defined, in a sense EDs no longer matter – except that they help explain the idea of having a lowest block of data on which analysis was based.  Nowadays, this block is the ‘output area’ which is roughly equivalent to the ED; and the ED was originally based on the patch covered by a census collector.

Output Area – this is the smallest area for which census information is made available.  Output areas are the building blocks, not only for higher level census information, but for larger geographical areas (eg Super Output Areas) which are used to aggregate other non-census data – things like benefit claimant data etc.  There are about 150,000 OAs in England – typically made up of about 150 households (350 people).  Since the census in 2011, the boundaries of some OAs have changed and the total number of OAs has gone up as population has increased.  When an OA exceeds more than 250 households or 650 residents, it is split up to make new OAs.

Super Output Areas – census information is available at the level of Output Areas (above), but most other government neighbourhood statistics are available at the level of Super Output Areas.  These come in three sizes, only two of which are used in England:

Lower Super Output Areas (LSOAs) – these are made up of neighbouring OAs – usually 5 or 6 OAs make up an LSOA.  The average population is about 1500 people but they vary a bit even though the aim is that they should be roughly equal in population.  In urban areas, LSOAs are geographically small areas (because urban places are densely populated) and in country areas LSOAs are much bigger (in terms of area, but not population).  The LSOA is the most common unit of neighbourhood area you will hear talked about by local councils.  A typical neighbourhood might consist of 2 or 3 LSOAs, but LSOAs do not necessarily follow the borders of what local residents would consider to be neighbourhoods.  There is an LSOA for each postcode.

Middle Super Output Areas (MSOAs)  - are made up of LSOAs (and therefore of OAs).  The average population of an MSOA is 7000 people.  There are usually between 3 and 8 LSOAa in an MSOA.  MSOAs are less often talked about by local councils and other service providers, but they are the lowest level on which some bits of neighbourhood information (like air quality data, VAT information, fire and rescue statistics and statistics relating to county court judgements on personal debt cases) is made available.

Upper Super Output Areas (USOAs) aren’t used in England.

Electoral and Administrative areas

Electoral areas are the areas we use to elect representatives – councillors who are elected by wards and MPs who are elected by constituencies.  Administrative areas are the areas over which decisions about public services are taken – council areas, parish council areas etc.  They are related but not the same.  A council may choose to base decision making committees on the geography of wards and constituencies, but they don’t have to.

Some neighbourhood statistics are collected and presented on the basis of wards.  They tend to be things which are collected by local councils and the agencies which work with them locally (the police, local NHS bodies and schools etc).  So, you may find information on things like the number of empty properties, teenage pregnancies, enrolments in further and higher education etc are available for wards rather than MSOAs or LSOAs).

Although LSOAs often follow ward boundaries, they don’t exactly match up.  Wards are, in any case, of variable size in different parts of the country – a few hundred people per ward in a village or small town and tens of thousands of people per ward in a large city.

Key Facts:

Postcodes and wards are ways that are commonly used to describe where a neighbourhood is.  Most (but not all) of the data about your neighbourhood and its people and businesses that you will want to look at when you are doing a community plan, however, is held on the basis of 'output areas'.  You can find out what wards and postcodes are in terms of output areas and get hold of a lot of statistis about your patch, for free, from the government's neighbourhood statistics website.

Page Links from here

See the Office for National Statistics Neighbourhood Statistics site

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BIRMINGHAM COMMUNITY PLANNING TOOLKIT DEFINITION SHEET This sheet may be reproduced in paper or electromic or any other form but please mention it was made by Chamberlain Forum Limited for Birmingham City Council supported by Department for Communities and Local Government.

created: 2016-07-22 14:52:10 by: admin status: f published