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Based on the concepts of active manipulation, explain why this study cannot be classified as a true experiment, and diagnose how potential confounding variables could explain the differences in cognitive performance.
Case context: A researcher wants to study the effects of a new exercise program on cognitive function. She decides to compare a group of people who already regularly attend spin classes at a local gym with a group of people who do not engage in regular exercise. She measures their cognitive performance on a standardized test and finds that the spin class group scores significantly higher.
Question: Based on the concepts of active manipulation, explain why this study cannot be classified as a true experiment, and diagnose how potential confounding variables could explain the differences in cognitive performance.
Sample answer: This study is not a true experiment because the researcher did not actively intervene and manipulate the independent variable (exercise program); instead, she compared pre-existing groups of exercisers and non-exercisers. The groups likely differ in confounding ways, such as baseline physical health, motivation, stress levels, or daily habits, which could serve as alternative explanations for the higher cognitive performance.
Key points:
- Explain that the study is not an experiment because it lacks active manipulation/intervention by the researcher.
- Clarify that comparing pre-existing groups (exercisers vs. non-exercisers) is not manipulation.
- Identify potential confounding variables (e.g., motivation, baseline health) that offer alternative explanations for the results.
Rubric: The response must explain that the study lacks active manipulation because the researcher is merely comparing pre-existing groups rather than intervening. It must also identify at least one plausible confounding variable (such as motivation, conscientiousness, or baseline fitness) that could act as an alternative explanation for the cognitive scores.
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Research Methods in Psychology - 4th American Edition @ KPU
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