Proportions

The topic of this chapter is the visualization of proportions, that is, part-to-whole relationships. We are in the situation where the data can be partitioned into a set of classes, for instance gender, nationality, age group, etc. The classes are usually expressed as a categorical variable; the proportion values are expressed as continuous variables with values in [0, 1] or, equivalently, as percentages. The general goal is to emphasize the relative importance of the categories while also bringing the reader’s attention to each category’s portion of the total. We present different tools for visualizing proportions; these include pie charts, doughnut charts, waffle charts, hundred percent stacked bar charts, hundred percent divergent stacked bar charts, and tree maps.