What is the key concept behind regression to the mean?

The concept of regression to the mean refers to the phenomenon where extreme performances or behaviors tend to return to a more average state over time. This occurs because extreme outcomes are often influenced by variables that may not be consistent across time or situations, such as luck, random variation, or exceptional circumstances. Therefore, when an individual or group performs exceptionally well or poorly, future performances are likely to be closer to the average, as the outstanding influence of those extreme factors wanes.

This concept is applicable in various fields, including psychology, sports, and economics, where it is observed that after an unusually high or low performance, the average tendency will emerge over subsequent measurements or events. Understanding this principle helps in interpreting results without overreacting to anomalies, reinforcing the idea that short-term fluctuations may not be indicative of long-term trends.