This dataset portrays the boundaries of ‘Localities’ in Scotland as at the 1991 Census.. There is widespread interest in statistics for the built-up areas in Scotland as most of the population lives in a built-up environment. When the former two-tier local government structure of regions and districts came into being in May 1975, the small local authorities known as large and small burghs were lost. However, Census users stated that there was a need to know the population (and characteristics) of built-up areas. For 1991 Localities, information on the area of a postcode was available from the digitised postcode boundaries and also on the postcode’s population from the 1991 Census. The method used to identify localities in 1991 was basically to classify a postcode as either urban or rural based on population density. Groups of urban (high population density) postcodes were identified where the number of residents in all the postcodes in the group was 500 or more. The final stage was to ask the local authorities to suggest any changes which might refine the boundaries of the identified settlements. This method identified 603 localities, 448 of which contained 1,000 residents or more, with the remainder containing a population of 500 or more but less that 1000.
This dataset shows the 1991 Census Output Areas (OAs) Household Weighted Centroids. An individual Output Area generally covers a sufficiently small area (subject to meeting minimum population / household counts) so that user defined or ad-hoc areas can be created while maintaining a sufficient level of quality. National Records of Scotland (NRS) produces only one set of OAs and creates all other output geographies using the OA as the building brick. Each OA is assigned to an area in a higher geography by first selecting one of the postcodes in the OA as a ‘master’ postcode. The OA inherits all of the characteristics of the master postcode including its assignments to higher areas and its grid reference. The master postcode was selected using an algorithm which calculates the postcode centroid within an OA which has grid references closest to the household-weighted centre of the OA. Revisions and Corrections Correction to 1991 Output Area Household Weighted Centroids An anomaly was discovered when converting the Ordnance Survey Tile Reference to easting and northing where for some records, the centroid for the Output Area was not falling within the boundary of the Output Area.
NRS first created Output Areas (OAs) for the 1991 Census to allow comparability with small area statistics output from 1971 and 1981. NRS used postcodes to plan 1981 Census enumeration districts and 1991 postcode based OA generally fell within 1981 ED. 1971 small area statistics were retabulated for 1981 Enumeration Districts thus provided an degree on continuity over 3 censuses. OAs are the lowest level for which small area statistics for the 1991 Census are available. For confidentiality purposes each OA has at least 16 households and 50 usual residents. There are 38,254 Census 1991 OAs in Scotland. Of the 38,254 1991 output areas, 38,098 have polygons, the remaining 156 are special output areas. Revisions and Corrections Correction to 1991 Output Area boundaries An anomaly was discovered in the 1991 Output Area boundaries where the boundaries for Output Areas 6341DX13 and 6341DX16B were not following the postcodes that they were built up from.