Comparative dotplot

Because every dot is still one observation, a comparative dotplot compares groups without summarizing anything away, so gaps, clusters, and repeated values stay visible. For example, group A with values 4, 5, 5, 6 and group B with values 3, 5, 5, 7 share the same mean of $20 / 4 = 5$, but B has a range of $7 - 3 = 4$ against A's $6 - 4 = 2$. A side-by-side boxplot would also show that difference in spread, but it would hide the fact that both groups pile up at 5. Comparative dotplots work best for small data sets, since with hundreds of points the stacks grow too tall to read.