When visualizations go wrong, part 2

Here's part 2 of my continuing series of visualizations gone wrong (part 1 was about a viz on web browser market share).

The idea of metaphor is a good one. It's one of the oldest communication tools we have. It's clever and wise to use something people understand to help explain something they don't.

There's even a good argument to be made that much of all learning is done through some kind of metaphor.

But using any metaphor at all, or a well known one from a context that is unknown or feared ...