The Bell Curve and Why It Shows Up Everywhere

Measure the height of every adult in your city. Plot how many people are at each height. Short on the left, tall on the right, count of people on the vertical axis. You get a bell. Narrow at the extremes, wide in the middle. Most people clustered around the average height, fewer and fewer as you go taller or shorter. Now measure reaction times in a psychology study. Plot them. Bell. Measure the weight of apples coming off a production line. Plot them. Bell. Measure the errors in any careful scie