Question

When subjects who are treated in the same way differ in performance, what accounts for their measured difference? group of answer choices

O between-groups variation
O within-groups variation
O total variation
O treatment variation

Answer 1

Within-groups variation accounts for the differences in performance among subjects treated in the same way, reflecting individual differences and random variation within the group.

Step-by-step explanation:

When subjects who are treated in the same way differ in performance, the measured difference can be attributed to within-groups variation. This variation occurs because individuals in a group will naturally vary due to factors unrelated to the experimental conditions. In a properly designed study, participants are randomly assigned to either a control or a treatment group to control for lurking variables, and any significant differences in performance are ideally attributed to the treatment itself, known as treatment variation.

However, when individuals within the same group show different outcomes, it reflects the personal differences and random variations that are always present in any group of subjects. To statistically analyze these differences, researchers use techniques such as the one-way ANOVA test, which can distinguish between within-groups and between-groups variation by comparing the variance in performance within each group to the variance between the groups.