Statistical graphs present data and the results of statistical analysis, assist in the analysis of data, and occasionally are used to facilitate statistical computation. Presentation graphs include the familiar bar graph, pie chart, line graph, scatterplot, and statistical map. Data analysis employs these graphical forms as well as others. Computational graphs ("nomographs") sometimes display data but usually show theoretical quantities such as power curves for determining sample size. Computational graphs are convenient when statistical tables would be unwieldy, but computer programs are even more convenient, and so nomographs are used with decreasing frequency. This article emphasizes the role of graphs in data analysis, although many of the considerations raised here also apply to graphical presentation.

Although it generally is recognized that the pictorial representation of information is a particularly effective mode of communication, statistical graphs seldom appear in sociological publications. Figure 1, from Cleveland (1984), shows the relative...