Some statistical concepts are both easy to understand and easy to forget. Regression to the mean is one of them. Let’s say the average height of men is five feet eight inches. Now imagine a man who is six feet tall and then picture his adult son. Your initial System 1 hunch may be that the son is also six feet. That’s possible, but unlikely. To see why, we have to engage in some strenuous System 2 reasoning. Imagine that we knew everyone’s
