Which of the following describes the tendency for extreme or unusual scores to revert to the average?

The concept of regression toward the mean is a statistical phenomenon that describes how extreme or unusual outcomes in a data set tend to move closer to the average upon subsequent measurements or observations. This means that if a score is significantly higher or lower than the average, the next score is likely to be closer to that average. This tendency is observed in a variety of situations, such as sports performances, test scores, and many other scenarios where variability exists.

For instance, if an athlete has a particularly outstanding performance (an extreme score), their next performance is more likely to be closer to their typical performance level (the mean), rather than another exceptional result. This principle highlights that in repeated measurements, extreme values often do not continue to occur at the same frequency but rather move towards the average, illustrating a natural balancing process in random variables.

Understanding this concept is essential for accurately interpreting data and recognizing that not all anomalies or extremes are indicative of long-term trends. It is a key component in the analysis of variability and prediction in statistics.