It’s not what you look at that matters, it’s what you see.
Chapter 4 looks at visualising single categorical variables, nominal, ordinal, or discrete.
Compared to the range of plots proposed for visualising single continuous variable data, there have been few suggestions for visualising single categorical variable data. Barcharts (horizontally or vertically) and piecharts are the commonest options. You could argue that both are area plots where cases are represented by an area proportional to group size rather than being plotted individually. However, since the bars in a barchart always have the same width, you compare lengths, not areas, which is much easier.