Friday, November 19, 2010
The Modifiable Areal Unit Problem and Districting
So we recently released a Visual Fusion app that focuses on the gerrymandering (the practice of drawing Congressional district boundaries for unfair political advantage) of U.S. Congressional districts. This is (should be) an interesting topic, not only for map nerds, but for everyone.
What is the Modifiable Areal Unit Problem?
Any time you make a map that includes boundaries, you are subject to the Modifiable Areal Unit Problem, whether you are aware of it or not. Pretty much, it is the notion that how you slice up an area into zones has everything to do with what gets aggregated into them. Anybody who's seen a thematic map of States or Counties can appreciate that color coding those shapes depends a lot on their size and shape, let alone the classification system used to color-code them. This is a consideration for any client that wants to aggregate market data to zones like census tracts or neighborhoods or sales territories (pretty much most of them).
After every census it is the job of the blokes in charge to re-draw the congressional districts, from which the population of each will elect a representative to congress. How do you draw those boundaries? In the political realm its more like the Modifiable Areal Unit Opportunity. The shape of the districts has everything to do with the resulting aggregate votes. And there are some pretty spectacular districts.
Whoa, Whoa, Whoa
So we'll probably see some funny shapes in the near future, and hear a lot of debating back and forth around some of the funnier examples, but gerrymanders have a long rich history so you may or may not have some amount of fun taking a look at what these things currently look like.
Link to the Gerrymander App...
Posted by john.nelson