Most of the time bar graphs seem to be superior to circle and line graphs for presenting information. However, divided-circle graphs (Fig. 3.4), also called pie charts, are well suited for showing the relationship of a number of parts to the whole.
Although divided-circle graphs make a striking visual display, they present a fundamental problem - the impossibility of comparing areas. They are generally used best as attention-getting devices, and even then, only when comparing five or
fewer items. Pie charts are most effective when the segments are arranged by size, with the largest slice beginning at twelve o'clock. Continue placing progressively smaller segments clockwise. Note that some graphics software programs generate counterclockwise charts. Combine or exclude slices smaller than about 5% (18 degrees).
Was this article helpful?