Say NO to Pie (Charts)

I couldn’t say no to my colleague’s Kentucky bourbon pecan pie that he made for our annual potluck. (It is delicious!) I do, however, say no to using pie charts after learning there are better chart types to visualize your data.

Although pie charts have the ability to show a part-to-whole relationship, data visualization experts are not fans of them. Here are a few articles highlighting the problems with pie charts:

• Few, S. (2007). Save the Pies for Dessert, https://www.perceptualedge.com/articles/visual_business_intelligence/save_the_pies_for_dessert.pdf
• Feinberg, L. (2014). 10+ Ways to Leave Your Pie Chart, https://www.decisionviz.com/category/10-ways-to-leave-your-pie-chart/ (Start with 1.)
• Brown, T. (2011, February 8). Sorry Sir, we’re all out of pies…., https://www.theinformationlab.co.uk/2011/02/08/sorry-sir-were-all-out-of-pies/

The takeaways from these articles are:

1. Pie charts are more difficult for our brains to process based on visual perception science (Gestalt Principles). Comparing areas and angles takes time and is something we do not do accurately.

2. There are better chart types to tell a story. Experts recommend horizontal ranked bar charts, stacked bar charts, and other chart types that are easier to interpret. Here are resources to help you pick the right chart:

• Visual vocabulary: https://public.tableau.com/profile/andy.kriebel#!/vizhome/VisualVocabulary/VisualVocabulary
• Periodic table of visualizations http://www.visual-literacy.org/periodic_table/periodic_table.html

There is good news for those who cannot leave their pie charts. Authors of the Big Book of Dashboard, have found that bar charts can live in harmony with pie charts. Here is a recent post:  

• swexler. (2018, December 3). A Bar Chart and a Pie Chart Living in Harmony, https://www.datarevelations.com/barchartpiechart_harmony.html

If you still love pie charts, you may also like this cookie pie chart https://flowingdata.com/2011/09/09/girl-scout-cookie-pie-chart/, but be sure to pair it with a quality bar chart (and a glass of milk).

Comments

[Tim Drexler]

Great post! Almost every time I read about or take a class in data visualization, there is a special mention of why not to use pie charts (the Girl Scout cookie chart is a good exception, though!).