Pie Chart
Shows how a whole splits across a few categories — the right choice only for very few sectors.
Also known as: pie chart, circle chart
A pie chart displays shares of a whole as circular sectors; each sector's angle is proportional to its share, and all sectors together make 100 %. It answers exactly one question: how does the whole split up?
- Sector — angle and area proportional to the share, usually sorted from largest to smallest
- "Other" — many small categories get pooled; a readable pie chart rarely has more than five to seven sectors
The limitation is established in perception research: Cleveland and McGill (1984) show that people decode lengths considerably more accurately than angles and areas. As soon as two sectors are of similar size, or more than a handful of categories appear, a bar chart is read faster and more correctly.
See also
Used in
Sources
- Cleveland, W. S. & McGill, R. — Graphical Perception: Theory, Experimentation, and Application to the Development of Graphical Methods, JASA 79 (387), 1984
- Tufte, E. R. — The Visual Display of Quantitative Information, 2nd Edition, Graphics Press, 2001
- Few, S. — Show Me the Numbers: Designing Tables and Graphs to Enlighten, 2nd Edition, Analytics Press, 2012