Pie Charts: Infrequent Servings Are Best

Pie charts are a simple and popular way of visualizing data, but they have some major problems.

Generally Avoid Pie Charts

• The human eye is not very good at estimating area.
• You can only compare slices that are right next to each other.

Instead, use bars when making comparisons. Our eyes are much better at comparing height than area.

However, Pie Charts Can be Useful

• When the wedges represent a percent breakdown of a measure
• When the area of the pie is a measure (so the circumference is telling the story)
• When the pie is being used on a map.

The pie charts in the viz below fit the bill: