Monday, April 29, 2019

Charts that lie

A few days ago skeptical environmentalist Patrick Moore published a chart of temperature change since 1880 on Twitter that ruffled some feathers. Eric William Lin and others asked me to chime in. Here's one interchange:

That's right. There's an entire section about this same type of chart in my upcoming How Charts Lie. It's in a chapter about how to reason about the X- and Y-axis in graphs, and about scales and legends in general.

Here are the pages mentioned in the tweet, in case you want to learn why that chart is bad —long story short: a variation of a few degrees Fahrenheit may sound tiny, but in reality it's very significant, so it ought to be emphasized. Moore's scale isn't “realistic”, quite the contrary: it doesn't make any sense. These pages come from the latest draft of How Charts Lie, which is still being copy-edited, so forgive typos and clunky grammar: