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GPD Support

Geography

NHS National Services Scotland ISD Scotland & NHS National Services Scotland

Postcode Reference File

Created twice a year from the National Records of Scotland (NRS) postcode extract, the below file is the main geographical lookup file used by analysts in ISD.

The postcode file below is also used to update deprivation lookup files. A flow chart detailing the path that the data follows upon submission to ISD can be seen below:

ISD postcode processingDownload Powerpoint file [110Kb]


Lookup Files

The below postcode file comprises a list of live and deleted postcodes (small and large user) in Scotland, and acts as a lookup file to higher geographies such as Census Output Area, Data Zone, Intermediate Zone, Council Area, CHP, NHS board and other lesser used geographies.

Description of File Format Size Format Size
Scottish Postcode Directory 2016_1 SPSS 153 MB CSV 95 MB
SPD Bulletin 2016_1 PDF 282 KB    
Last Update: Files above were updated with the 2016_1 NRS Scottish Postcode Directory in April 2016
Next Update: Files above will be updated with the 2016_2 NRS Scottish Postcode Directory around October 2016
Source: National Records of Scotland (NRS)

This file can be used to match higher geographies onto your data via 7 or 8 character postcode. Please read the guidance below before using this file.

Important Information About This File

Postcodes can be decommissioned and recycled in another area by the Royal Mail, and are not static over time due to building development and demolition. Entire areas can be re-coded and codes can be re-used in a different place after just two years. Care should therefore be taken when undertaking analysis. The postcode lookup files used by ISD are based on the most recent version of a postcode. In most cases the postcode will be ‘live’ but some are historic and ‘deleted’ and retained on the files.

Postcodes may not be an exact 'fit' when matched with higher geographies. When unit postcodes span council areas they are split to reflect the council area that they fall into. To show this split they are coded as A, B or C postcodes:

  • ‘A’ coded postcodes represent either the largest part of a split postcode, or the whole of an unsplit postcode.
  • ‘B’ coded element of a unit postcode represents the smaller part of a split postcode. Those postcodes split between two council areas therefore have an ‘A’ and ‘B’ part.
  • ‘C’ coded element of a unit postcode represents the smallest part of a unit postcode split between three council areas (coded 'A', 'B', and 'C').

Please be aware that the ISD lookups include only the ‘A’ postcodes, so it appears that there is a direct match from postcode to council area.


Postcodes With Missing Geography

A number of postcodes do not have full geographical information attached to them. This can be the case if the postcode has been deleted or if the postcode is a large user postcode.

A large user postcode is one that has been assigned to a single address due to the large volume of mail received at that address, usually more than 50 items of mail daily. Large user postcodes are also assigned to mail receiving services such as PO Boxes and Business Reply.

Boundaries are not drawn for large user postcodes. Where possible the location of new large user postcodes is found on the map and it is linked to a small user postcode.

It is not always possible to do this. For small and large postcodes without grid references, the postcode of the local Royal Mail delivery office (each Royal Mail delivery office is assigned to a distinct set of postcode sectors in Scotland) is used to assign each postcode a Council Area, CHP and CHP subarea only.

This is shown below:

How NRS has allocated higher geographies to postcodes - procedure used up to 2012_2

Small User Postcodes with grid reference (digitised)

  • All higher geographies added automatically, e.g. Data Zone, NHS board, Council Area and Community Health Partnership.

Large User Postcodes with address

  • Link to a Small user link postcode.
  • All higher geographies added automatically, e.g. Data Zone, NHS board, Council Area and Community Health Partnership.

Small User Postcodes without grid reference (not digitised)

  • Only Council Area added, using the Council Area of a neighbouring postcode.

Large User Postcodes without address (unmapped PO boxes)

  • Only Council Area added, using the Council Area of a neighbouring postcode.

How NRS will allocate higher geographies to postcodes - procedure used from 2013_1

Small User Postcodes with grid reference (digitised)

  • All higher geographies added automatically, e.g. Data Zone, NHS board, Council Area and Community Health Partnership.

Large User Postcodes with address

  • Link to a Small user link postcode.
  • All higher geographies added automatically, e.g. Data Zone, NHS board, Council Area and Community Health Partnership.

Small User Postcodes without grid reference (not digitised)

  • Add NHS board, Council Area, Community Health Partnership and Community Health Partnership subarea only,
  • Based on postcode of the local Royal Mail delivery office. Each Royal Mail delivery office is assigned to a distinct set of postcode sectors in Scotland.

Large User Postcodes without address (unmapped PO boxes)

  • Add NHS board, Council Area, Community Health Partnership and Community Health Partnership subarea only,
  • Based on postcode of the local Royal Mail delivery office. Each Royal Mail delivery office is assigned to a distinct set of postcode sectors in Scotland.
Details of the numbers of postcodes involved
Notes
Numbers taken from latestpcinfowithlinkpc.sav
This file comprises a single record per postcode - either an entire postcode or the "A" part of a split postcode.
  Postcode File 2012_2 Postcode File 2013_1
Postcode Type Number of postcodes % of postcodes Number of postcodes % of postcodes
Small User Postcodes with grid reference (digitised) 176,688 81% 176,306 81%
Large User Postcodes with address 15,268 7% 15,764 7%
Small User Postcodes without grid reference (not digitised) 139 1% 191 <1%
Large User Postcodes without address (unmapped PO boxes) 24,886 11% 25,452 12%
Total 216,981 100% 217,713 100%

Geographical Fit

When using different geographies, care must be taken to ensure that the 'fit' of the geography is suitable for the purpose. Some geographies 'nest' exactly into others and some which do not are simply assigned as 'best fit'. Information about this 'degree of fit' is shown in the following table:

Geography Matrix for Key Scottish Geographies

As at 2001 Census
  2001 Census Output Area 2001 Data Zone Intermediate Zone Scottish Parliamentary Constituency Community Health Partnership Local Authority/ Council Area Health Board SG Urban/Rural 6-fold classification
Unit Postcode 100% 100% 100% <100% <100% <100% <100% <100%
2001 Census Output Area 100% 100% <100% <100% <100% <100% <100%
2001 Data Zone 100% <100% <100% <100% <100% <100%
Intermediate Zone <100% <100% <100% <100% <100%
Scottish Parliamentary Constituency <90% <100% <100% <50%
Community Health Partnership 100% <100% <50%
Local Authority/ Council Area <100% <50%
Health Board <40%

Changes since 2001 Census (Shown in Red)
* After the 2001 Census, slight anomalies appeared in the Glasgow City/North Lanarkshire LA area, and the Angus/Dundee City LA area, but since October 2012 "all CHPs should reflect LA boundaries". As at May 2013, each LA area is coterminous with one CHP, except Fife LA which comprises 3 CHPs.
  2001 Census Output Area 2001 Data Zone Intermediate Zone Scottish Parliamentary Constituency Community Health Partnership Local Authority/ Council Area Health Board SG Urban/Rural 6-fold classification
Unit Postcode <100% <100% <100% <100% <100% <100% <100% <100%
2001 Census Output Area 100% 100% <100% <100% <100% <100% <100%
2001 Data Zone 100% <100% <100% <100% <100% <100%
Intermediate Zone <100% <100% <100% <100% <100%
Scottish Parliamentary Constituency <90% <100% <100% <50%
Community Health Partnership <100%* <100% <50%
Local Authority/ Council Area <100% <50%
Health Board <40%

The figures in the matrix show the "percentage fit" of population covered by each geographical unit (as at the 2001 Census).

For example, when linking from Data Zone to Intermediate Zone, there is a perfect match (100% of the population in each DZ falling within one IZ). However, there is not a perfect match from DZ to CHP (less than 100% of the population in each DZ falls within one CHP).

Please note that if you want to link a list of patients' postcodes to a higher geography such as council area there is a many-to-one relationship i.e. less than 100% of the population in a unit postcode falls within one council area.


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