What statistical phenomenon causes participants with extremely low pre-test scores to likely score closer to the average on a subsequent test, regardless of intervention?
Answer
Regression to the Mean.
Regression to the Mean describes the tendency for statistical outliers to move toward the average score upon retesting, an effect that a control group helps researchers filter out.

Related Questions
What is the primary function of a control group in research?What major issue arises when an experiment lacks a proper control group?Which confounding variable relates to biological or psychological changes that occur naturally over time?What is the specific purpose of using a Placebo Control group in research?In which scenario is an Active Control group comparison most scientifically rigorous?The principle of 'Dose Equivalence' in control design primarily requires what?What statistical phenomenon causes participants with extremely low pre-test scores to likely score closer to the average on a subsequent test, regardless of intervention?What is the fundamental concept established when an experimental group's outcome differs significantly from the control group?How does an Active Control group help mitigate the Hawthorne effect?What do control groups prevent when a city implements a new, expensive after-school tutoring program without one?