Speaking Stata: Spineplots and their Kin

Abstract

The term spineplot has been applied over the last decade or so to a type of bar chart used particularly for showing frequencies, proportions, or percentages of two cross-classified categorical variables. The principle is that the areas of rectangular tiles are proportional to the frequencies in the cells of a contingency table. Often both coarse and fine structure are easy to see, including departures from independence. The main idea has, in fact, been rediscovered repeatedly over at least the last 130 years. In its most general form, it has been widely publicized under the name mosaic plots. This column introduces, discusses, and exemplifies a Stata implementation of spineplots. It is noted that a restriction to two variables is more apparent than real, as either axis of a spineplot can show a composite variable defined by cross combinations of two or more variables.