Look at these two maps. They’re based on the same data: population gain or loss by county. But they tell vastly different stories.
In the first map, the graphic artist started with the two extreme values in the data set (-6.3% and +28.7%) and divided the color scale into 5 equal pieces. As a result, all of the counties losing population are lumped together with counties that had no change or that posted slight gains.
The map tells us that a lot of counties lost population or held steady, several counties added population, and exactly two (one in the top middle and one near the bottom middle) added a lot of population. Frankly, it’s not much of a story.
Now look at what the Washington Post‘s Christopher Ingraham did with the same data. Ingraham changed the color scheme: blue counties gained population and red counties lost. The color intensity changes for counties that gained or lost more than 1% or 2%.
Now you can see a story. Continue reading