A diagram representing grouped numerical data in which cumulative frequency is plotted against upper class boundary, and the resulting points are joined by straight line segments to form a polygon. The polygon starts at the point on the x-axis corresponding to the lower class boundary of the lowest class. See also ogive; step diagram.

Cumulative frequency polygon. The diagram refers to the distances between the breeding colony and the point of recovery for a group of razorbills. The outline is typical, with slow increases at the left and right ends of the polygon indicating the scarcity of the corresponding values.