When you look at three pie charts and can’t tell much of a difference, the story isn’t that pie charts are bad, it’s that in those three instances, the composition is pretty similar! The poor pie chart did its simple and thankless job, you ingrates. No more, no less.

Unconvinced? Let’s look at the cold, hard numbers:

The largest overall difference is from graph A to graph C, and the largest shift in composition that occurred in a category is a whopping 6%!

In conclusion, the compositions remained very similar, so the pie charts look similar. The story that the pie chart told us holds up.

Of course, the aspiring intellectual will point out that sometimes, small changes matter too. A modest proposal: if you really want to show difference, why not plot difference?

I’m no artiste, but after two minutes with Excel, this chart seems much more effective at conveying small differences. With better data-to-ink ratio than the bar charts too!

However, looking only at this chart, you could be lead, perhaps, to believe that these five categories changed a lot in absolute terms from situation A to situation C. After all, look at how long the red bar is! Our ever-loyal friend, the pie chart, informs us otherwise.

What we’re seeing here is a design continuum. It’s a metaphorical line along which we can move, one way or another, to trade off one benefit for another. It’s up to us to decide the tradeoff we want to make to serve the purpose we want best served.

The pie charts say that nothing changed much overall from A to C. The difference bar chart (I made this name up) says that red and black changed the most, but in opposite ways. Both of these are different statements derived from the same data, and both are true at the same time. The regular bar charts in the middle say a bit of both, but tells each story a bit less clearly than the others.