Spotting Differences - Data Points: Visualization That Means Something - page 244

Starry Night
Instead of using faces to show multivariate data, you can use the same
idea but abstract on it by using a different shape. Instead of changing facial
features, you can modify the shape to match data values. This is the idea
for star charts, also known as radar or spider charts.
As shown in Figure 7-14, you can draw several axes, one for each variable,
starting from the middle and equally spaced in a circle. The center is the
minimum value for each variable, and the ends represent the maximums.
So if you draw a chart for a single unit, start at a variable and draw a con-
necting line to the corresponding spot on the next axis. Then you end up
with something that looks like a star (or a radar or spider web).
FIGurE 7-14 Star chart framework
You can represent several units on a single chart, but it'll become useless
in a hurry, which makes for a poorly told story. So stick to separate star
charts and compare.