An experimental design that uses the same participants in both the experimental and control conditions is called which?

• A. Repeated Measures Design
• B. Between-Subjects Design
• C. Matched Pairs Design
• D. Factorial Design

Answer: (A)

This question hinges on within-subjects experimental design, where the same participants experience both the treatment and the control condition. That structure is called a repeated measures design. By having participants serve in both conditions, individual differences become part of the baseline, which reduces error and increases statistical power, so you can detect effects with fewer participants. However, this approach can introduce order effects or carryover, so researchers counterbalance the order of conditions or include washout periods to minimize these issues.

The other designs don’t fit this scenario. A between-subjects design uses different people in each condition, so the same participants aren’t exposed to both. A matched-pairs design uses pairs of individuals matched on key characteristics but still assigns different people to the conditions. A factorial design concerns multiple independent variables and can be implemented in either within-subjects or between-subjects formats, but the core distinction here is that the same participants appear in both conditions, which defines a repeated measures (within-subjects) approach.