Which statement best describes independent and repeated-measures designs?

• A. Independent uses the same participants across conditions; repeated uses different participants.
• B. Independent uses different participants per group; repeated uses the same participants across conditions.
• C. Both designs use identical data and tests.
• D. Repeated measures designs always reduce power.

Answer: (B)

The main idea being tested is how participants are used across conditions. In an independent or between-subjects design, different participants are assigned to each condition, so each person contributes data from only one condition. In a repeated-measures or within-subjects design, the same participants are measured in every condition, so each person provides data across all conditions. This is why the correct statement describes independent designs as using different participants per group and repeated designs as using the same participants across conditions. The other descriptions miss this essential distinction: swapping who participates in each design, claiming all designs use identical data and tests, or asserting that repeated-measures always reduce power. In reality, repeated measures often increase power by reducing error variance, though they can introduce order or carryover effects that need to be managed.