The usual response from statisticians and data professionals to pie charts ranges from lofty disdain to outright snobbery. But sometimes I think they’re the right tool for communication with a particular audience. Like others I was struck by this image from New Zealand news site stuff.co.nz showing that nearly half the earthquake energy of the past six years came in one day (last Sunday night, and the shaking continues by the way). Pie charts work well when the main impression of relative proportions to the whole is obvious, and fine comparisons aren’t needed.
Here’s my own version of the graphic. I polished this up during a break while working at home due to the office being shut for earthquake-related reasons:
Consider me in the lofty disdain camp. That said, this is probably the best case scenario for a pie chart: when looking at relative percentage of one dominant element versus the remaining set.