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Regression to the Mean: A Simple Intro
Take a few minutes to earn an important mental model from math
Introducing one of the greats of the discipline of statistics — Sir Francis Galton! He brought us many crucial concepts including this mental model — Regression to the Mean (RTM).
This one fools many on a daily basis, and can feel a little counterintuitive at times — which makes it all the more important to internalize into your personal latticework of mental models! 🧠
What is Regression to the Mean?
The phenomenon that if a variable is extreme on its first measurement, it will tend to be closer to the average on its second measurement.
Huh? What does that mean?
To understand this, let’s look at Sir Galton’s original study in 1886 — which compared heights of children to their parents. He measured the heights of hundreds of children who’d reached adulthood and the average height of their parents. He was surprised by what he saw when he plotted the data:
It appeared from these experiments that the offspring did not tend to resemble their parents in size, but always to be more mediocre than they — to be smaller than the parents, if the parents were large; to be larger than the parents, if…
