You might now know that I’m not a huge hater of pie charts. They do have their place and they can have value. But, just like a bad column chart or a bad map, there are also bad pie charts. And I think this one from the USDA is one of them. A pie chart dropped inside a donut chart? It makes any comparison difficult—within the pie, within the donut, or, especially, between the two.
It’s especially difficult to make the comparison between the two graphics because the values differ between the two, which throws off the alignment. See what happens when I extend the edges of the pie chart outwards and how things go awry right away with the 11%-20% difference in the Europe and Central Asia group.
There are lots of alternatives to this graph, but I’ll just list a couple.
Anytime I want to compare two categories, one of my first go-tos is a slope chart. The chart on the left uses the original color scheme, giving each country its own color; the chart on the right uses blue for the 5 countries for which the values are staying the same or increasing, and the orange for the 3 series that decline. The downside of this approach is that the slope chart no longer helps us focus on the part-to-whole relationship, but the relative ranking and the change between the two.
Stacked Column/Bar Chart
One way to get back to visualizing the part-to-whole relationship is to use a stacked column or bar chart. In the examples below, I used the same color palette as the original and added linking lines so that it’s a bit easier to see how the values change. I also sorted the data from largest to smallest for the top/left category (1995-99 Average). One of the big challenges here is getting the labels to fit; in the stacked column chart, I started by putting the labels in between the two columns, but ended up putting them to the left (and adding color).
There are certainly other ways to visualize these data–pie chart pairs (no!), dot plot, column/bar chart–but these seemed like the most obvious, straightforward examples. If you have thoughts of other graph types, please share them below. You can download my Excel file here.