After the bar chart visualization guide, we are continuing with one of the most common charts. Pie charts are widely used in everyday statistics, in the business world, and in education. In this article, we will give you some tips about pie chart visualization even though we recommend that you use other charts if it is possible. If there is no other way to visualize your data, this article will be a good guide for you.
What Is a Pie Chart?
According to Wikipiedia: “Pie chart (or a circle chart) is a circular statistical graphic, which is divided into slices to illustrate numerical proportion. In a pie chart, the arc length of each slice (and consequently its central angle and area), is proportional to the quantity it represents. While it is named for its resemblance to a pie which has been sliced, there are variations on the way it can be presented. The earliest known pie chart is generally credited to William Playfair’s Statistical Breviary of 1801:
“A table is nearly always better than a dumb pie chart; the only worse design than a pie chart is several of them…” – Tufte, The Visual Display of Quantitative Information
Do not forget the Five common mistakes
Pie Charts and Donuts
Pie charts are mostly used to compare part-to-whole relationships in the case of discrete or linear data. We recommend using with a low number of slices. In addition to pie charts, donut charts are also a commonly used circle visualization method.
The biggest disadvantage of pie charts is that human eyes can only recognize friendly rates like 25%,-50%,-75%, or 100%. To read more, check out our previous article about circle visualization.
Standard Pie Chart: Used for Describing Whole-to-Part Relationships
Donut Chart: Can Contain Additional Information or Style Elements
Pie Chart Guide
Below you will read four tips about how to create pie charts.
- Don’t use pie charts for comparing. Instead of a pie chart, use a stacked bar chart.
- Use only two or three categories on one pie chart and a maximum five.
- The total value of the pie chart must be 100%.
- Order slices clockwise starting with the largest part.
Advantages and Disadvantages
- Popular and easy to understand if only using two or three categories
- Indicates a part-to-whole relationship between values
- Looks nice
- Angles are difficult to estimate
- Difficult to compare quantities
- Can’t visualize complex relationships
- Valid for one point in time only