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In experiments that utilize both manipulated and non-manipulated independent variables, why are researchers restricted to drawing causal conclusions only about the manipulated variable? Describe the primary methodological reason and the resulting nature of the findings for the non-manipulated variable.
Question: In experiments that utilize both manipulated and non-manipulated independent variables, why are researchers restricted to drawing causal conclusions only about the manipulated variable? Describe the primary methodological reason and the resulting nature of the findings for the non-manipulated variable.
Sample answer: Causal conclusions can only be drawn for the manipulated variable because researchers systematically control it and randomly assign participants to its conditions. For a non-manipulated variable (such as a personality trait), participants are not systematically controlled or randomly assigned, meaning any observed effects could be caused by an unmeasured third variable. Consequently, the findings for the non-manipulated variable are strictly correlational.
Key points:
- Causal conclusions can only be drawn for manipulated variables.
- Non-manipulated variables lack systematic control and random assignment of participants.
- Observed effects of non-manipulated variables may be due to an unmeasured third variable.
- Findings regarding the non-manipulated variable are strictly correlational.
Rubric: Assess the response based on the following three criteria: 1. Mentions the presence of systematic control or random assignment for the manipulated variable but its absence in the non-manipulated variable. 2. Identifies the threat of an unmeasured third variable as the reason causal claims are invalid for non-manipulated variables. 3. Correctly states that non-manipulated variable findings are strictly correlational.
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Research Methods in Psychology - 4th American Edition @ KPU
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