Things That Can Be Explained by the Bell Curve

My previous post on Ed Lazear brings to mind a lecture I often give in class on the Bell curve. The tails of the Bell curve never touch the axis. So, if intelligence is measured on the axis and a pretty intelligent person is two standard deviations above the mean, there are still some people farther out--three, four, five standard deviations. In percentage terms, the probability of someone being five standard deviations above the mean is small, but when you consider that we live in a country of 300 million people, there can be a number of people at that level of intelligence. No matter how smart I may think I am, there are lots of people a lot smarter.

What if we measure something like sexual deviency on the axis? In a country of 300 million people there may only be five or six people at five or more standard deviations away from the mean. But that is enough people to fill up an episode of Jerry Springer. And, they all want to be on TV. So, some of these TV shows don't prove that the country is going to pot; they just verify the Bell curve.