Regression Fallacy

The fallacy rests on a statistical phenomenon discovered by Francis Galton in the 1870s. Studying inherited height across generations, Galton observed that unusually tall or short parents tended to have children closer to the average — a natural fluctuation he called regression toward the mean (initially "regression toward mediocrity"). The fallacy arises when this natural statistical drift is mistakenly attributed to an external cause — as when speed cameras installed after accident spikes appear to "work" simply because extreme values naturally moderate over time.