Why I Hate Pie Charts

​If you have been in one of my BI classes, heard me speak at a conference or been in a meeting with me you know that I hate pie charts. There are so many reasons why, I thought I would take a few minutes and write them down. So let's begin with my top 3.

• Pie charts are frequently used without context. When you are looking at a slice and it says its 10%, how do you know what it's 10% of? Is it 1,000 or 1,000,000? That's a big difference. There is another way to leverage the same look and feel but by adding the context.  Try using a donut chart then use a single value object that you drag over the center of your donut.

• ​The slices are too small to make reasonable assumptions about the difference between your types or categories. The whole point of a pie chart is to show the difference between things so what could is it if you can't read it? What takes up the biggest % or the lowest %?  If there are so many options that it's a rainbow of slices, pie is not the best visualization option.  Try a treemap instead.  It allows you to see all the slices that are important.

• Viz experts hate them too! I read BI books and blogs. I know I'm a nerd but even the experts agree pie charts are bad. Stephen Few has been one of the most influential speakers on BI visualizations and a fellow hater of pie charts. So if you want to read about it from someone else's perspective, check out this site. If you want to nerd out even more check out this site.  It's a lot of examples of what not to do and how viz can be made to show just about anything!

There are many more reasons and this should be enough to get you started on the right path but ​If you still have your heart set on using one keep these things in mind:

• ​Did you give it proper context? Do you know what it's a % of?
• Can you see the variations in the slices or are some slivers that get lost?
• Do you have too many slices to make it readable?

Happy vizzing. If you have questions or comments I would love to hear from you.

-Bonnie, Enterprise Data Manager City of Raleigh