Representing Data - Data Points: Visualization That Means Something - page 439

FIGURE 3-5 Incorrect bar graph
on left and correct one on the right
The difference between the two values looks like a huge increase—the
length of the right bar is about five times the length as the other—because
the value axis starts at 34 percent. The chart on the right shows the change
when the axis starts at zero, which looks less dramatic. Of course, you can
always look at the axis to verify what you see (and you always should), but
that defeats the purpose of showing the values with length, and if the chart
is shown quickly on television, most people won't notice the misstep.
Angle
Angles range from zero to 360 degrees on a circle. There's the 90-degree right
angle, the obtuse angle that is greater than 90 degrees, and the acute angle
that is less than 90 degrees. A straight line is 180 degrees.