Donut Charts are a derivative of the pie chart, and are used in the same manner for displaying contributions to a total.
Panopticon Designer (Desktop) can produce standard Donut Charts in which the donut slice represents a numeric variable that is proportional to the total size of the donut. The color variable can represent either a category or another numeric variable.
Donut Charts can be flat, showing a single set of slices. They can also be hierarchical and display multiple levels of data in a variant called a Multilevel Donut Chart.
A recommended alternative to the Donut Chart is the Treemap, which can display a larger number of data points, and is easier to compare constituent data points.
Figure 1. A typical Donut chart.
Figure 2. A multilevel Donut chart
Figure 3. A multilevel Donut chart with deeper hierarchy, and numeric color variables