Pie charts are a regular feature of most dashboards and reports, but that doesn't make them great for displaying data. Here are 5 reasons why you should stop using pie charts in your analysis.
1. It’s hard to visually compare segments
If you have two segments on a pie chart that are similar in value, it’s not easy to tell which is the larger value. In the below chart, for example which of France and Italy is larger?
An alternative is to use a column or bar chart, which makes it much easier to distinguish between similar values.
2. More than 2 categories makes a mess
Pie charts are just about passable if you’re just trying to show 2 data values against each other, but any more than this just makes hard work for the reader to guess values and proportions.
If this is the case you should question if a pie chart is really the best way to display your data. A simple bar chart may be a much better solution.
3. They are unable to show trending
A pie chart can only show a metric at a specific point in time - and to show another time period would require showing two pie charts side by side. This is a huge waste of space on the page, and makes hard work for the reader to tell the difference between the two time periods.
Much better is to either use a clustered bar/column chart (for a small number of data points), or a line chart where there’s a longer data trend to analyse.
4. Pie charts are one dimensional
It might seem obvious - but a pie chart can only show a single measure across different categories. If you have 2 metrics to show, a scatter diagram can be a more effective way to show two metrics across multiple categories.
5. They're a waste of valuable space
Above all, pie charts take up a large amount of space on any report or dashboard, but offers very little data insight in return. You can easily show clearer, more informative charts using other chart types
This view that pie charts are not a great way to visualise data is widely shared across the analytics community, and in a professional environment we’re seeing pie charts used less and less in corporate data analysis.