Regression to the mean is a statistical concept based on evidence that a sample of data representing extreme values from the population mean will likely be close to the mean the next time a sample is taken.
In psychological testing, people who obtain extreme scores on a test tend to obtain scores closer to the mean on a second testing. That is, high scorers tend to earn lower scores and low scorers tend to earn higher scores.
The term, Regression to the Mean is sometimes referred to as RTM. The concept appears in a paper by British scientist Sir Francis Galton (1886).
I originally published this post in the Sutton (2024) location referred to in references. This is a copy of that post.
I created the image in Microsoft designer.
Galton, F. (1886). Regression towards mediocrity in hereditary stature. The Journal of the Anthropological Institute of Great Britain and Ireland, 15, 246-263.
Sutton, G. W. (2024, January 5). Regression to the mean. Psychology Concepts and Theories. Retrieved from https://suttonpsychology.blogspot.com/2024/01/regression-to-mean.html
Geoffrey W. Sutton, PhD is Emeritus Professor of Psychology. He retired from a clinical practice and was credentialed in clinical neuropsychology and psychopharmacology. His website is www.suttong.com
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