An assessment of surface and zonal models of population

The advantages of handling population data in GIS as a raster surface rather than as zonal attributes are discussed, and a technique for creating such surfaces briefly reviewed. Existing models created by this method using the 1991 UK Census are then compared with equivalent zonal data and some weaknesses identified, in particular the poor association between enumeration districts and 200 m grid cells. A refined version of the surface generation technique is presented in which population totals are constrained within zone boundaries, while residential geography is retained with considerable success.