Bill Wolff's Composing Spaces

I recently came across several interactive maps on the interactive graphics section of the Philadelphia Inquirer website while looking up some information on the number of Philly homicides in 2007 (as of October 10, 318). Three that caught my attention are: “Philadelphia Shootings in 2007,” “Philadelphia Homicides in 2007,” and “Philadelphia Median Home Prices.” The maps, designed by Alan Baseden, John Duchneskie, and Robert West, are wonderful examples of what Edward Tufte calls beautiful evidence (click image to see full-size)

And yet, despite the wonderful mapping, sparklines, and comparative features that make these maps so meaningful, I felt that something is missing. Can we see a trend between the median home price and the number of homicides? So, I used what little Fireworks skills I have to merge the median income and homicide maps:

My point here is not to enter into a debate on the relationship between poverty and homicide (I know better than to do that). Rather, I am more interested in the comparative aspects of mapping, how what we choose to present affects how we understand the spaces in which we live. From this new map, most homicides seem to be concentrated in areas with lower median home sales. The question I leave up to the sociologists is why.