Thursday, September 25, 2008

Let's not use 3D pie chart

From this blog,

This is a share of textbooks for Tokyo metropolitan high schools.

The share of Nichibun (brown, 14.5%) is twice as much as Keirincan (blue, 7.2%) but the center angle is smaller than Keirincan, and those look nearly the same in size.

I would like people teach students not to use 3D pie chart in their information literacy class.
Pie chart itself is not good, as is described in R help,

Pie charts are a very bad way of displaying information. The eye is good at judging linear measures and bad at judging relative areas. A bar chart or dot chart is a preferable way of displaying this type of data.

Cleveland (1985), page 264: “Data that can be shown by pie charts always can be shown by a dot chart. This means that judgements of position along a common scale can be made instead of the less accurate angle judgements.” This statement is based on the empirical investigations of Cleveland and McGill as well as investigations by perceptual psychologists.

3D pie chart is even worth than pie chart.

This document is licensed under the Creative Commons Attribution 2.1 Japan License.
copyright by Haruhiko Okumura

No comments: