Bella had been very sad and fatigued,and when she first started treatment,she scored very highly on a measure of depression.A few months later,her therapist gave her the same test again and reported that the therapy must be working because Bella's scores were lower,even though she does not feel much different.What is the best alternate explanation for this outcome?

Question

Quizplus · Accepted Answer

Regression to the mean is a statistical phenomenon where extreme scores on a measure tend to move closer to the average score when measured again. Bella's high initial score may have been an outlier and her lower score on the second test may just be a statistical correction towards the mean score. This does not necessarily mean that therapy is working or that Bella's symptoms have improved.

Bella Had Been Very Sad and Fatigued,and When She First