Edward Tufte hates pie charts. Edward Tufte is also the only chart theorist normal people have ever heard of. And so yesterday the Internet was gripped with anti-pie fervor. My friend Tom Lee sticks up for the much-maligned pie, but I would recommend this March post from Bruce Gabrielle as the best defense of the pie chart out there.
I was particularly taken with this example of how sometimes you want lots of pie charts:
Exactly as Tufte would tell you, this is not a very good way to convey precise information about the black population of Idaho as compared with Maine. But that's not the point. The idea is to illustrate the general theme that the black population share is highest in the Southeast. And it works.
Another good example of a useful pie chart comes from the Center on Budget and Policy Priorities, which is trying to show that we don't have an "entitlement society" in which able-bodied prime workers are loafing around rather than working. If the idea here was to get a rigorous comparison between the number of entitlement recipients who are non-elderly non-working disabled people versus the number who are working, pie would be a terrible choice.
But CBPP's point here is that the elderly, the disabled, and the working together combine to represent the vast majority of entitlement recipients. And it's right there in the pie chart. Delicious.
Now don't get me wrong, I see the merits in a blanket rule. When I was an editor in college, my rule was no semicolons ever. Not because a semicolon is never the right choice but because I thought it was simpler to have a blanket rule. So I can respect that idea. Maybe there are too many pie charts out there and in general people should give more serious consideration to other ideas. But it's by no means true that pies are never the right way to go.