Brandon Walker

Data Scientist

Tutorial: Why you should NEVER use a pie chart

1 minutes
November 17, 2018

Plotting is a big part of getting your point across in data science. Even if you know how to create plots, selecting the right plot is often not done when I think it should be. Take a look at the three pie charts I made with R. See if you can tell if the red or blue section is bigger in each chart.

Here is the same data, displayed as a bar chart. See if you can tell which is larger or smaller now.

Sure, I made them intentionally close together, but it is way easier to understand when it’s in a bar chart. Humans are worse at estimating areas (2 dimensions) than they are at estimating lengths (1 dimension). Generally, whenever it is possible to remove a dimensions from a visualizaion, you should. Anything that can be in a pie chart can be in a barchart, so usually you should make a barchart!