Bell ML, et al. (2007) Spatial and temporal variation in PM2.5 chemical composition in the United States for health effects studies. Environmental Health Perspectives 115:989-995, Figure 3

What's wrong with this one?

What's worse than one piechart? Try nine. This figure is intended to demonstrate that NO3 and SO4 change dramatically between winter and summer and that the change is consistent across geographic region. Unfortunately, it takes a couple of minutes of squinting to see this. Piecharts are bad because humans are notoriously poor at comparing areas. This figure is even worse because we are expected to compare areas across what appears to be a bake sale of piecharts.

What should have been done?

An easy fix would be to use barplots instead. However, because all that matters is the change from summer to winter, a couple of simple scatter plots (East and West), with winter and summer on the x- and y- axes, would do the trick.

Last modified: Sat Jan 19 08:54:45 2008