What is a Pie Chart?
A Pie Chart is a common type of visualization that demonstrates parts of a whole. Each section represents a value in relation to the entire composition. The slices should be proportionate to the amount in each data set so that the viewer can compare each section by size to determine its value.
When should I use a Pie Chart?
A Pie Chart is a great visual for a part-to-whole relationship. It should be used when displaying the “percent of…” or “part of…” something. StorytellingWithData provides two primary use cases for a pie chart:
- having a general sense of the part-to-whole relationship is more important than comparing the precise sizes of the slices
- to convey that one segment is relatively small or large in comparison
The percentages should sum to 100% so that the visual is relative in size to its value.
The Perfect Pie
I created the “perfect pie” in Excel using 2024 Coffee Statistics by DriveResearch. I will break down what makes this a perfect use case as well as design tips for creating an effective pie. You can click on the image below to open my Excel spreadsheet.
The data in this set is great for a pie chart because it equals 100% and one value is significantly larger than the others. It is also split up into 2-5 categories which is not too overwhelming for the viewer. The coffee preferences are all parts of a whole, making a pie chart the best choice over bar charts and other visualizations. To make it aesthetically pleasing to look at, I used different shades of brown throughout the entire chart which correlates with the coffee theme. I deleted the legend for a more minimalistic appearance, which the author of our textbook reiterates throughout each chapter. Because the values for Light Preference and No Preference are very similar, I added data labels to each segment so it is easy to comprehend. I also increased the font size for the numbers to make them stand out. Stephanie D.H. Evergreen suggests “unwrapping the pie” by making the largest slice start at noon and run clockwise in descending order (as seen above). When creating this chart, I was sure to avoid 3D and exploding effects in order to increase legibility. For more information, I suggest checking out this article on Tableau, which provides more examples of effective and ineffective pie charts.