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Scottish Settlements Urban and Rural Areas in Scotland

Annex B - History of Definition of 'Urban' Areas at the General Register Office for Scotland

For 2000

12. We have created a new set of settlements by the following two-stage process. First, we identify 'urban' postcodes. A postcode is 'urban' if at least one of the following applies:

• it has more than 2.1 residential addresses per hectare; or
• it has more than 0.1 non-residential addresses per hectare (Note that any large user postcode which falls into a small user postcode counts as 2 non-residential addresses).

These density thresholds are revised downwards for some Council Areas (generally those with crofting communities) in order to ensure that at least 95 per cent of postcodes in 1991 localities are selected as 'urban'. This downward revision is largely to achieve some level of continuity with the low density localities added in 1991 (see paragraph 7). For more information about the address densities used for 2000, see Annex C, paragraphs 6-9.

13. GROS determines the number of 'non-residential' addresses in a postcode by examining the text recorded by Royal Mail for each address. This method has been tested in Census tests where Census enumerators have to check addresses on the ground. As for 'large user postcodes', these are postcodes each containing one address that receives a large number of items per day. Royal Mail make special arrangements for delivery. GROS do not attempt to map these postcodes. Instead we link each one to a small user postcode by locating the address of the large user on our map and assigning it to the small user postcode within whose boundary it falls.

14. Having identified urban postcodes we will then identify any clump of neighbouring urban postcodes containing more than 210 residential addresses. A clump is made to include any 'holes' i.e. non-urban postcodes entirely surrounded by urban ones.

15. We ran this process on the 2000/1 version of the postcode index and boundaries available last January. The allocation of postcodes to settlements and assignment of urban-rural codes was complete in March when we issued a postcode index to supplement the 2000/1 index. Users can combine the two indexes and, with the 2000/1 boundary set, create settlement boundaries with population estimates. We also issued a settlement index giving the name, code and number of residential addresses of each settlement.

16. Compared with that for 1991 localities, this method:

• uses addresses to create population estimates, which ensures the exercise can be repeated outside Census years;
• uses two densities rather than one; adding a density for non-residential development helps ensure that unpopulated urban areas are picked up and classified appropriately; and
• provides continuity with the previous exercise by, for some council areas, adjusting standard density thresholds rather than automatically including urban postcodes from the previous exercise.

17. We now aim to refine our methodology further and will be interested in the views of users
(see Annex C, paragraph 18).