This is just a quick post today to answer my question yesterday - "Are the locations of victim addresses random if population density is taken into account?" I have not bothered with legends because if you have been following my discussion (if not look back) a quick sentence or two will explain what is being represented.
By the way I did mention that I am experimenting with this form of representation and now realise that showing about the top twenty grid squares for each category and using only three shades seems to provide the simplest and therefore the least confusing map.
The red shades show the known home locations of suspects for street robberies in the London borough and the blue shades victims living in the borough who were victims of street robberies in the borough.
The two maps look very similar because only four of the squares a have both colours. This shows that suspects and victims though living close to each other live in distinctly different locations.
If victims and suspect home locations are random taking population density into account then it would be logical to expect a greater overlap between the two. The lack of overlap also suggests differences in geodemographic characteristics of the two groups.