Facts about Regression to the Mean
- 07
A 1989 study of professional golfers found that players with unusually low scores in one tournament regressed toward their career average in the next event, yet commentators attributed the decline to psychological pressure rather than statistical mean reversion.
- 06
Extreme weather events like record-breaking temperatures regress toward historical averages in subsequent years, causing meteorologists to incorrectly attribute the return to normal conditions as evidence of climate stabilization rather than statistical mean reversion.
- 05
Therapists treating severely depressed patients often see dramatic improvements in the first week that partially fade afterward, a phenomenon explained by regression to the mean rather than treatment efficacy alone.
- 04
Stock market analysts frequently misattribute mean-reverting price movements to their own forecasting skill, leading to overconfidence that erodes after initial lucky predictions regress toward market averages.
- 03
Medical students scoring in the top 10 percent on exams typically score closer to the class average on subsequent exams, misleading instructors into believing initial high performance resulted from luck rather than regression to the mean.
- 02
Athletes who score exceptionally high in one season typically perform closer to average the following year, a pattern known as regression to the mean that confuses coaches attributing decline to strategy changes.
- 01
Francis Galton first documented regression to the mean in 1886 when studying how children's heights averaged closer to the population mean than their parents' heights.