zeros from the scale and change the heading for the scale to read
"DOLLARS IN MILLIONS" (figure 13(B)). As you can see, this change
makes the chart's scale much easier for the reader to understand and
apply; therefore, the reader can apply the values to the data plotted
much quicker and easier. Another benefit of changing the chart's scale
is the scale is much clearer now and does not present a cluttered,
compressed look, which makes the chart more attractive and eye pleasing.
As previously stated, a chart's scale normally starts at zero. If you
do not start the scale at zero, the chart does not show the entire range
of the data plotted and gives the reader the wrong interpretation of the
data presented. In figure 14, columns A and C and B and D compare the
same quantities. However, when you look at the charts, the quantities
in columns A and C and B and D do not appear to have the same values.
Additionally, columns C and D present the proportions of two quantities
compared correctly; but, since columns A and B do not start at zero and
do not show the whole scale, they do not show the proportions correctly.
The righthand side of figure 14 illustrates the correct way to present
and use a scale. This is particularly important when you must have two
charts side by side and the reader must compare information from both
charts.
Figure 14. Poor selection of scale deceives the reader
Splitting the scale of the chart is another pitfall you must avoid.
Sometimes you see a scale divided near the top and starting again after
omitting part of the values, especially when the range of quantities
shown is large or there is a large interval between quantities. You can
avoid this pitfall by using a little imagination when designing the
chart's scale.
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