What phenomenon describes the tendency for extreme scores to revert back towards the average upon retesting?

The phenomenon described is known as regression toward the mean. This concept reflects the tendency for individuals with extreme scores—whether high or low—on a measure to have scores that are closer to the average upon subsequent measurements.

When conducting tests or observations, it is common to see that those who perform exceptionally well or poorly are likely to have more average performances in later assessments. This occurs because extreme scores can be influenced by various factors, such as situational specifics or measurement errors.

Regression toward the mean is significant in interpreting test results because it helps to indicate that not all changes in scores are due to genuine changes in ability or performance; rather, some changes might be due merely to statistical probability. Understanding this principle can help practitioners avoid misinterpreting the effects of interventions based solely on one-time measurements, particularly in clinical settings or research studies where repeated measures are common. This statistical phenomenon underscores the importance of context and variability when assessing individuals’ performance over time.