The pie chart

Each segment (slice) of a pie chart should be proportional to the frequency, or more helpfully the percentage of the category it represents.

The first segments start at 12 o'clock, which is a good practice, and helps if you are comparing two or more pie charts.

Incidentally, using the appropriate software, a good many charts can be formatted in 3D.

Examples:

Some things you should know about pie chart

- Easy to understand
- Can be used for either nominal or ordinal data and occasionally for discrete metric data
- Limited by being able to display only one variable. You will therefore need a separate pie chart for each variable you want to chart
- When comparing two or more pie charts, the area of each pie chart should be proportional to its frequency
- Pie charts expressed in percentage frequency terms can all be drawn in the same size
- A pie chart can lose clarity if it is used to represent more than a small number of categories (four or five or thereabouts)