If you only read one thing this week…

As the Worldmapper group demonstrates, using cartograms to organize several hundred (or thousand) data points can be an effective method to see patterns and relationships: it leverages that large part of our cranial area devoted to visual processing.

These cartograms each plot one variable (over 350 in total). The method can be used to plot two variables, enabling somewhat more powerful analysis with comparable ease of comprehension. For cartograms of the 2004 US presidential election results, see

http://www.cscs.umich.edu/~crshalizi/election/

The first map shows the 48 states by geographic size, colored “red” if majority voted for the Republican candidate and “blue” if the majority voted for the Democratic one.

Compare with the cartogram at the end: this represents data at the county level, with the size of each county proportional to population size (more accurate if number of voters or number of registered voters) and the color depth (on a red-blue scale) proportional to the % Republican – % Democrat – the higher percentage R, the redder; the higher percentage D, the bluer.

Note:

1. The contrast between these two maps leads one to much different conclusions about the distribution and segregation of political voting (R v. D).

2. One could apply this method to other kinds of population differences or conflicts: ethnic or religious affiliation, economic status, extent of property destruction or damage in a disaster, etc.