Data Visualization’s ‘Dirty Little Secret’ and Choropleth Maps

The Washington Post’s Christopher Ingraham compares two choropleth maps of U.S. population growth: while they look rather different, they use the same data. “The difference between my map and Pew’s—again, they both use the exact same data set—underscores a bit of a dirty little secret in data journalism: Visualizing data is as much an art as a science. And seemingly tiny design decisions—where to set a color threshold, how many thresholds to set, etc.—can radically alter how numbers are displayed and perceived by readers.” [Andy Woodruff]

(Worth mentioning that this is exactly the sort of thing dealt with in Mark Monmonier’s How to Lie with Maps.)

Author: Jonathan Crowe

I blog about maps at The Map Room, review books for AE: The Canadian Science Fiction Review, and edit a fanzine called Ecdysis.