ABSTRACT
Graphs must be displayed in two dimensions either on paper or on a computer screen. It is therefore straightforward to show one variable plotted on a vertical axis against a second variable plotted on a horizontal axis. For example, Figure 3.1 shows the alar extent plotted against the total length for the 49 female sparrows measured by Hermon Bumpus in his study of natural selection (Table 1.1). Such plots allow one or more other characteristics of the objects being studied to be shown as well. For example, in the case of Bumpus’s sparrows, survival and nonsurvival are also indicated.
