Case Study

Based on the provided context, identify which visual tool the researchers should use to detect if the program had opposite effects on different participants, what pattern they should look for, and explain how a factorial design could help them investigate if these differences vary systematically across participant subgroups.

Case context: A team of psychologists conducts a group-based study to test a new anxiety-reduction program. They find that the overall group mean difference in anxiety scores before and after the program is zero. The lead researcher believes the program did not work at all, but another researcher suspects the program might have reduced anxiety for some participants while actually increasing it for others.

Question: Based on the provided context, identify which visual tool the researchers should use to detect if the program had opposite effects on different participants, what pattern they should look for, and explain how a factorial design could help them investigate if these differences vary systematically across participant subgroups.

Sample answer: The researchers should examine the distribution of individual scores using a histogram to look for a bimodal distribution, which would indicate that some participants improved while others got worse. Additionally, they could implement a factorial design to systematically examine if these treatment effects differ across specific participant subgroups (such as introverts vs. extraverts) rather than relying only on the overall group mean.

Key points:

  • Examine distributions of individual scores using a histogram.
  • Identify a bimodal distribution to detect if some participants were affected positively and others negatively.
  • Employ a factorial design to test if treatment effects vary systematically across different participant subgroups.

Rubric: Assess if the student explains that (1) a histogram can reveal a bimodal distribution showing opposing effects that average to zero, and (2) a factorial design can show whether the treatment effects differ systematically between different participant subgroups.

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Updated 2026-05-26

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Research Methods in Psychology - 4th American Edition @ KPU

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