There is interest in population statistics for the built-up areas in Scotland as they are generally more identifiable as the traditional towns and cities of Scotland than administrative areas such as Council areas, much of which consists of land that is not built up. The General Register Office for Scotland (GROS) uses information about postcodes (some 140,000 in Scotland) to define 'settlements' and 'localities' as good approximations to built up areas.
GROS maintains data on unit postcodes, including a boundary enclosing all of the addresses assigned to the postcode. These postcode areas are used as "building bricks" in the definition of settlements.
GROS produces Small Area Population Estimates at data zone level on an annual basis. These, together with information from the Royal Mail Postcode Address File, are used to classify unit postcodes as either 'high density' or 'low density'. A postcode is defined as high density if it meets one or more of the following threshold conditions:
Once the postcodes are defined as high or low density, the population estimates in contiguous high density postcodes are joined together to form the built-up areas of Scotland. Where the population is 500 or more, the area is defined as a 'settlement'.
Localities are intended to be more representative of the towns and cities in Scotland. Some settlements cover an extensive area, and consist of more than one distinct town or city. For example, the settlement of Glasgow consists of many towns, such as Paisley, as well as the city of Glasgow itself. So, some settlements are divided into constituent towns and cities ('localities'). However, in most cases a settlement is exactly equivalent to the locality of the same name. Where settlements consist of two or more localities, the settlement is suffixed by the words "Settlement of" in the tables.
It is recommended that users exercise caution when comparing the settlement or locality population estimates with previous years. Whilst an increase in population may be due to new build, it may also be due to the inclusion of existing housing which had previously been seperated from the settlement by a low density postcode (and vice versa for a population decrease).
The sum of the settlement (or locality) population estimates will not add up to the total mid-year estimates for Scotland for the same year as the populations outside settlements (or localities) are not included.
The population estimate for each settlement (or locality) is rounded to the nearest 10. For the small number of settlements (or localities) that cross local authority boundaries, the population estimate for each part is reported and also rounded to the nearest 10. As a result, the overall population figure for some of these settlements (or localities) may not exactly equal the sum of its parts.