Effective Figures and Tables
8- 15
Bar Graphs
Bar graphs are 1-axis graphs used to compare amounts, frequencies, or magnitudes for categories of discontinuous data. Bar graphs may be vertical (a column graph) as in the example shown or horizontal (horizontal bar graph). The bars should all be the same width, and the space between bars should be less than the bar width. Each bar must be appropriately labeled.
Figure 11. Variations by physician specialty in performance of tests during typical office visits.
The legend for this bar graph is brief because all the information necessary for interpretation is found within the graph itself.
Pie Graphs
Pie graphs can be useful when you need to show the proportions of the components of a “whole.” A pie graph shows components as wedges of a circle. When the values of the individual segments are given in percentages, they should add up to 100%. Limit the segments to those large enough to be seen and labeled. Components too small to be shown individually can be grouped into 1 wedge labeled “other.” Each segment of the pie should be labeled. Because it is difficult to estimate the sizes of angular areas, include the percentage for each segment as part of the label. It is common but not necessary to distinguish the individual wedges with shading or color.
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