the difficulty of linking two differently aggregated spatial datasets using a look up table to link postal sectors and 1991 census enumeration districts daniel vickers school geography university leeds ls2 9jt united kingdom e mail d geog ac uk january 2003 contents section title page abstract iii acknowledgement iv list figures v tables viii 1 introduction 2 postcode development postcodes as areal output units their changing role in 4 applications through data linkage 6 3 gis postcoding 7 experian sector 8 england wales 9 nature 11 ecological fallacies aggregation effect modifiable unit problem 13 consequences 14 5 how well does reflect 18 descriptive statistics correlations between within
