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

Jonathan Crowe blogs about maps at The Map Room. His essays and reviews have been published by AE, Calafia, The New York Review of Science Fiction, the Ottawa Citizen, Strange Horizons and Tor.com. He lives in Shawville, Quebec.