Case Study

Based on the case context, diagnose the error in the student's understanding of research designs. Explain why comparing these two occupational groups does not make the study an experiment, and identify the key feature that makes it a non-experimental correlational study instead.

Case context: A student researcher is reviewing Cacioppo and Petty's (1982) study on need for cognition. The student notes that the researchers compared the scores of two distinct groups (university professors and factory workers) and found a significant difference. The student concludes that because the researchers compared two groups to find a difference, they conducted an experiment with occupation as the manipulated independent variable.

Question: Based on the case context, diagnose the error in the student's understanding of research designs. Explain why comparing these two occupational groups does not make the study an experiment, and identify the key feature that makes it a non-experimental correlational study instead.

Sample answer: The student's error is assuming that comparing two groups automatically makes a study an experiment. In an experiment, the researcher must actively manipulate the independent variable and assign participants to different conditions. In this study, Cacioppo and Petty did not manipulate the participants' occupations or assign them to be professors or factory workers. Because they simply measured pre-existing occupational groups, the study is a non-experimental, correlational design.

Key points:

  • Diagnoses the error that group comparison is not sufficient to define an experiment.
  • Explains that the researchers did not manipulate the independent variable (occupation).
  • States that participants were not randomly assigned to the groups by researchers.
  • Identifies that the study measured pre-existing occupational groups, making it non-experimental.

Rubric: The response must explain that group comparison alone does not define an experiment, clarify that the researchers did not manipulate the occupation variable or assign participants, and define the study as non-experimental/correlational because it measured pre-existing groups.

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Updated 2026-05-27

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Research Methods in Psychology - 4th American Edition @ KPU

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