Decent graph from NYT showing quintiles over time, in this case, the declining portion of government benefits the poorest 20% of the population receives.

These sorts of graphs are very in right now, as the format is perfect for showing change of distribution over time, and so much of our political discourse is dealing with questions of distribution. I used to see these relatively rarely, but in the last couple of years  they are all over the place. Which is good! It’s an extremely compact way to show a trend and control for it.

One note on teaching graphs — I think there is a tendency with students to fall back on the idea that “Percentages should be done in pie charts”. As this shows, nothing could be further from the truth. Pie charts are a lousy form which people expect now, but there are so many more elegant was to deal with part whole relationships, especially ones we track over time.