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Based on the limitations of an exclusive focus on group averages, explain why the researcher's conclusion might be false. Describe the specific individual differences that could be hidden within the treatment group's average score of 50.
Case context: A developmental psychologist tests a new spatial reasoning training program using a traditional between-subjects experiment. After a month, the control group scores an average of 50 on a standardized test. The treatment group, who completed the training program, also scores an average of 50. The researcher concludes the training had absolutely no impact on spatial reasoning skills.
Question: Based on the limitations of an exclusive focus on group averages, explain why the researcher's conclusion might be false. Describe the specific individual differences that could be hidden within the treatment group's average score of 50.
Sample answer: The researcher's conclusion might be false because focusing only on the group mean of 50 can obscure important individual differences. The training program could have had a strong positive effect on some participants (raising their scores well above 50) and a strong negative effect on others (lowering their scores well below 50). These opposing effects would statistically cancel each other out in the group average, creating the false appearance of no overall effect.
Key points:
- The group average obscures individual responses to the training program.
- Some participants may have experienced a strong positive effect from the training.
- Other participants may have experienced an equally strong negative effect.
- These opposing individual effects statistically cancel each other out, falsely implying no impact.
Rubric: The student must demonstrate comprehension of the concept by identifying that a mean of 50 does not necessarily indicate no effect, and specifically describe how opposing positive and negative effects on different individuals cancel each other out.
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Research Methods in Psychology - 4th American Edition @ KPU
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