Rainbow colors are pretty, and many of us like them. However, go to any visualization-related conference, and you’ll hear a lot of ‘rainbow-hate’. Where does that come from? Below is an excellent example that shows how rainbow color tables might mislead and make us see categories, or patterns, that might not be there. The image below is featured in a blog post titled “How The Rainbow Color Map Misleads” by Robert Kosara, in his wonderful visualization and visual communication blog eagereyes:
There is more to the art and science of choosing colors. Here is another informative post by Lisa Charlotte Rost: https://blog.datawrapper.de/colors/
Consider this infographic about imprisonment, from this article on the American Legislative Exchange Council blog. Most people would look at it and find it very engaging and attractive, which it is. But, as a visualization expert, one wonders if the odd coloring variations in the outer ring of the main figure and in the “Juvenile” block at right, which just show how the larger wedges (categories) divide up more finely (into sub-categories) wouldn’t be better shown in a Tree Map, using the ideas about showing hierarchical categories proposed by Ben Shneiderman in the 199os. A Tree Map version of these data would almost certainly show the area of sub-categories and categories relative to each other (context) better than the snazzy graphic shown here.