Which term refers to the method of selecting subjects based on extreme scores to study specific variables?

The method of selecting subjects based on extreme scores to study specific variables is accurately referred to as statistical regression. This practice is grounded in the concept of regression towards the mean, where individuals with extreme scores (either high or low) tend to score closer to the average on subsequent measurements. When researchers intentionally select subjects with extreme scores, they can better analyze the effects of certain variables on outcomes and understand how these extremes may behave differently compared to more average participants. This approach is beneficial in identifying the relationships between variables and can provide insights into how extreme cases might respond in a given study, thereby enhancing the overall interpretation of the data.

Other terms provided do not specifically describe this selection method. Maturation refers to changes in subjects that occur naturally over time during a study, often affecting the results. Attrition pertains to the loss of participants over time, which can introduce bias if not accounted for. Instrumentation relates to changes in measurement tools or procedures that may influence results, rather than how subjects are selected. Each of these terms addresses different aspects of research methodologies but does not encompass the practice of selecting participants based on their extreme scores.