Distance to Work and Distance Moved
A note on the method of calculation
Ed Fieldhouse, Census Microdata Unit
Both the Household SAR and the Individual SAR contain variables measuring the distance people travel to work (DISTWORK) and the distance moved by migrants (DISTMOVE).
DISTWORK is banded into seven distance groups with other categories for people working at home, people working outside Great Britain and those who did not state their place of work. People not in paid work in the week prior to census day were not assigned a value.
The distance to work is measured as a straight line distance between the postcode of residence and the postcode of place of work. For England and Wales, this calculation is based on the grid reference of the first address in the postcode as listed in the Central Postcode Directory (CPD). This is normally accurate to 100m. For Scotland, the calculation is based on the centroid of the populated part of the postcode and is given to the nearest 10m.
The accuracy of the calculation is dependent on the accuracy of the grid references in the CPD and postcodes of the place of residence (supplied by the enumerated person) and the place of work. The latter is entered by OPCS using information supplied on address of workplace and, where this information is incomplete, from lists of workplace establishments from the 1989 Census of Employment and other appropriate sources.
DISTMOVE measures the distance moved by individuals who had changed address in the previous twelve months. This is banded into 13 distance categories with top coding above 200km. There are separate categories for people migrating from outside the Great Britain and those who failed to state an address of origin. Persons who have not moved or who are under one year of age are not assigned a value. Distances are calculated on the basis of postcodes, as for DISTWORK, between the address of origin and destination.
"We can't distinguish between those taking the high road and those taking the low road."