This post has the base R code (pasted after the jump below, and available here) to produce the boxplot graphs shown at right. Why base R graphics? I certainly have nothing against ggplot2, lattice, or other graphics packages, and used them more in the past. I've found it easier, though (as in the demo code), to specify the values and location for each boxplot instead of generating complex conditioning statements. This may be a bit of the opposite of the logic of the Grammar of Graphics, but...