Dotplots II

Dot plots are particularly useful when presenting moderately-sized data sets with categorical variables having many groups. A famous example from William Cleveland depicts the yield of 10 different varieties of Barley at 6 different sites for two years (120 data points in total) and is shown in figure @ref(fig:Cleveland).

Figure 1: A dot plot of the barley data set popularised by William Cleveland. Three variables representing 120 data points are plotted.