Almost 50 years ago I had the misfortune to take two statistics classes at the same time. One was a required introduction to statistics and the other was econometrics. Don’t ask why I took them both — I don’t remember. But I do remember one day in the Intro to Statistics class when another student asked about this distribution plot (below).

 “What was it? What did it indicate? What could it be used for?” they asked.

“It’s nothing,” said the TA. “It’s useless.”

But I had seen that shape before, in econometrics, where they called it a split normal distribution. that was said to […]