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Based on this scenario, explain how switching to a within-subjects design addresses the researcher's concerns about individual participant differences, and describe the impact of this design choice on their overall participant recruitment needs.
Case context: A researcher is planning a study to compare the effectiveness of two memory retrieval strategies on exam performance. The researcher is concerned that differences in participants' baseline intelligence and prior academic achievement will heavily influence exam scores and obscure the actual effects of the retrieval strategies. To address this concern, the researcher decides to implement a within-subjects design instead of a between-subjects design.
Question: Based on this scenario, explain how switching to a within-subjects design addresses the researcher's concerns about individual participant differences, and describe the impact of this design choice on their overall participant recruitment needs.
Sample answer: By switching to a within-subjects design, the researcher will test the same participants under both memory retrieval strategies. This naturally controls for extraneous participant variables like baseline intelligence and prior academic achievement since each participant acts as their own control. Consequently, this reduces statistical noise, making the true effect of the retrieval strategies on exam performance easier to detect. Furthermore, this design choice means the researcher will need fewer overall participants compared to a between-subjects design to detect a treatment effect of the same size.
Key points:
- Testing the same individuals in all conditions controls for extraneous participant variables like baseline intelligence and prior academic achievement.
- Reducing participant-related differences minimizes statistical noise, making the true effect of the retrieval strategies easier to detect.
- The change in design decreases the total number of participants the researcher needs to recruit to detect an effect of the same size.
Rubric: The response should demonstrate comprehension by explaining that: (1) testing the same participants under all conditions controls for extraneous participant variables (intelligence, prior achievement), (2) this control reduces statistical noise, making it easier to detect the true effect of the independent variable, and (3) the design reduces the overall number of participants required to detect an effect of the same size.
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Research Methods in Psychology - 4th American Edition @ KPU
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Based on this scenario, explain how switching to a within-subjects design addresses the researcher's concerns about individual participant differences, and describe the impact of this design choice on their overall participant recruitment needs.