Mosaic plot

A mosaic plot is a segmented bar chart with one extra piece of information: the width of each bar is proportional to how many observational units are in that group, so a tile's area is the share of the whole data set sitting in that cell. For example, with 150 freshmen and 50 seniors, the freshman bar takes $150 / 200 = 0.75$ of the width, and if 90 of those 150 freshmen play a sport that segment is $90 / 150 = 0.60$ of the bar's height. The tile area is then $0.75 \times 0.60 = 0.45$, matching the 90 of 200 students, or 45 percent, who are freshmen athletes. Heights let you compare groups, and areas tell you how much data stands behind each comparison.