regression toward the mean
Noun: - A statistical phenomenon: Regression toward the mean describes the tendency for an extreme or unusual measurement, score, or performance to be followed by a measurement that is closer to the average or mean when the measurement is repeated. It occurs due to the role of random variation or chance.
This term is used primarily in statistics, psychology, and scientific research to explain why exceptional results are often not sustained. - It is often invoked to caution against attributing causality where simple statistical fluctuation is at work. - The phrase is typically used in its full form, "regression toward the mean."
- After an exceptionally high score on the first test, her score on the second test showed regression toward the mean, returning to her usual average.
- The coach warned that the player's outstanding performance was likely an outlier and that regression toward the mean should be expected in the next game.
- When studying the effects of a new teaching method, researchers must account for regression toward the mean to avoid falsely crediting the method for improved scores.
- The Law of Regression: Sometimes referred to informally as "the law of regression," highlighting its predictable nature in statistical analysis.
- Misinterpretation: A common error is to interpret regression toward the mean as a causal force (e.g., "he failed because he did too well last time"). It is not a causal mechanism but a statistical artifact.
- Regression to the mean: An alternative, synonymous phrasing.
- Regression effect: A more general term for the observed phenomenon.
- Regression analysis: The broader statistical method for modeling relationships between variables, of which regression toward the mean is a key concept.
- Statistical regression
- Regression effect
- Reversion to the mean
While not idioms, these related phrases are common in discussion: - "What goes up must come down": A popular saying that sometimes captures the intuitive idea behind regression toward the mean, though it implies gravity or causality, not statistics. - "Return to normalcy": A general phrase describing a similar return to an average state, but without the specific statistical foundation.
- the relation between selected values of x and observed values of y (from which the most probable value of y can be predicted for any value of x)