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Regression to the Mean

Regression to the Mean

Regression to the mean is a statistical phenomenon where extreme results tend to be followed by results closer to average. After your worst day, things usually improve a bit — and after your best day, things tend to settle back to normal.

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What Is Regression to the Mean?

Regression to the mean is a statistical phenomenon first discovered by Francis Galton in the 19th century. It means that when a measurement of some variable is extremely high or low, the next measurement is likely to be closer to the average.

Why Does Regression to the Mean Happen?

Mindy can explain this simply. Any outcome involves both skill (a stable factor) and luck (a variable factor). When an extreme result occurs, luck likely played a big role — and the next time around, as luck shifts, the result naturally drifts back toward average.

Regression to the Mean in Everyday Life

  • If you did much better than usual on an exam, your next exam score is likely to be somewhat lower
  • The 'sophomore slump' in sports is partly explained by this phenomenon
  • A new employee whose first month is outstanding may gradually perform more averagely afterward
  • Common Misconceptions and Causal Illusions

    Failing to understand regression to the mean makes it easy to draw false causal conclusions:

  • Concluding that scolding is effective because grades improved afterward
  • Believing a health supplement cured your cold because you recovered after taking it
  • Assuming a new treatment is working simply because symptoms improved after starting it
  • In reality, what may have happened is a natural return to average from an extreme state.

    Connection to Mental Well-Being

    This concept can be a great source of comfort when you're going through a difficult time. If you're at your lowest point right now, statistically speaking, things are more likely to improve from here. On the flip side, keeping realistic expectations even when everything feels perfect helps maintain emotional balance. Mindy wants you to know that even if today is hard, tomorrow has a good chance of being a little better.

    💡 Real-Life Example

    After the worst week of your life, the following week feeling somewhat better may not be due to any special effort — it could simply be regression to the mean.

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    This content is for educational purposes and does not replace professional medical diagnosis.

    Regression to the Mean (Regression to the Mean) | 마음스캔 심리학 용어사전