bwplot

Available with the lattice package, a bivariate trellis plot (bwplot, or box and whisker plot) displays multiple box plots based on a category in the dataset. Lattice describes bwplot on the same page as several other plots, so you have to go down the page to find info on it. It has over 20 options, but you only need the dataset name, the parameter to count, and the grouping parameter.

Plot comparisons are low in detail, but allow you to compare many items at a glance. In the case of bwplot, you are comparing the IQR of a dataset grouped by some category.

R Example

This example depicts the distribution of chicken weights, grouped by the type of feed. A comparison lets you judge with feed might be optimal to provide your hens.

> library(lattice)
> bwplot(~weight | feed, data = chickwts)

Looking at this, we might want to use sunflower, because it has the most predictable value. Or we might choose casein, because you may want to produce chickens of greater variance in size and weight.