Database Reference
In-Depth Information
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Change in height (column charts, prism charts)
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Change in position (scatter plots)
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Change in area (bubble charts, tree maps)
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Change in angular width (pie charts, donut charts)
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Change in length (radar charts)
Combinations of these formats to add data—for instance, color to show a
change, and size of a bubble to show the absolute value—are very common.
ProBlems wITh PoInT-In-TIme ComPArIsons
The most common problem with comparison visualizations in popular
media is that, despite being a snapshot of the comparison at a point in
time, the time period is not listed. This can lead to confusion later on when
the comparison has changed.
Figure 12-1 shows an example from VizWorld (
http://www.vizworld.
com/2009/11/bad-infographic-mapping-emissions-country/
) that
compares emissions. It has some of the problems mentioned in Chapter 2
with regard to the area of the bubbles (i.e., that the radius rather than the
area has been used, and it hasn't been labelled).
F I g u R e 12 -1
A comparison visual with several problems
