Because of their efficiency and ability to keep many other factors constant, twin studies have a special appeal for investigators. Just as with any teaching dataset, a "matched-sets" dataset used to illustrate a statistical model should be compelling, still relevant, and valid. Indeed, such a "model dataset" should meet the…

There are many well-known data sets that can be used to illustrate Simpson's Paradox. The Stand Your Ground data presented here shows Simpson's Paradox. In these data, race plays the key role--and not in the way that some students expect.