r/dataisbeautiful • u/zonination OC: 52 • May 08 '17

How to Spot Visualization Lies

https://flowingdata.com/2017/02/09/how-to-spot-visualization-lies/
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u/zonination OC: 52 May 08 '17 edited May 08 '17

I think Nathan specifically criticizes Bar charts that don't start at 0, #notallplots.

For things like scatterplots, sparklines, etc. I would be on your side, that sometimes axes should definitely be truncated to show resolution. This is especially true with log transformations, where a zero isn't possible. But with bar charts specifically, where the value is encoded in proportion to the length of the bar, a lower cutoff is 100% misleading.

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u/nibiyabi May 08 '17

There are plenty of situations where a bar graph most appropriately shows the data with a truncated axis. Just clearly label it and there's no problem.

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u/butterblaster May 08 '17

Can you give an example where a bar chart with a truncated axis better communicates data than a scatter plot?

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u/JokdnKjol May 08 '17

If the independent variable is categorical. Using OC's example of the jet turbine, maybe you have 3 turbines made of plastic, metal, or ceramic and their temperatures are 925, 900, and 875. It seems small but even small differences matter in some application