Surname Diversity in Great Britain

As part of my PhD research I recently produced the map below (high res. version) that shows the diversity of surnames in Great Britain. I wanted to demonstrate that surname diversity is not uniform across Great Britain. For example towns and cities (especially London) have relatively high surname diversities compared with rural areas because more migrants and single people live in them. Wales has a very low surname diversity due to its past naming conventions. The measure used is calculated by dividing the number of surnames by the total population of each Output Area (OA). There are over 200,000 OAs in Britain. Urban OAs are very small despite accounting for a large proportion of the total population, so I have scaled the size of each OA by their population (the map is therefore a cartogram). This creates the somewhat bloated appearance of Great Britain, but serves to emphasise the increased surname diversity (due to more single people and migrants) in towns and cities. The correct shape of Great Britain is shown in the inset. For more technical info please see below.

To create this map I used ArcGIS 10 and the Cartogram Geoprocessing Tool. The nice thing about the tool is that it is not dependent on VBA and therefore worked straight off in ArcGIS 10. There are over 220,000 spatial units in this map and the tool had no problems processing them. I have not found any alternatives that work for this volume of data.