Case Study

Explain why the co-author's reasoning is incorrect and justify how Dr. Aris should decide which graph version to select.

Case context: Dr. Aris is preparing a bar graph for a 2 × 2 factorial experiment examining the effects of Therapy Type (Cognitive vs. Behavioral) and Treatment Duration (Short vs. Long) on depression scores. Dr. Aris drafts two versions of the graph. Version A places Therapy Type on the xx-axis and uses different bar colors for Treatment Duration. Version B places Treatment Duration on the xx-axis and uses different bar colors for Therapy Type. Dr. Aris's co-author claims that Version A must be used because Therapy Type was introduced first in the methodology section, but Dr. Aris feels Version B makes the interaction effect much easier for a reader to interpret.

Question: Explain why the co-author's reasoning is incorrect and justify how Dr. Aris should decide which graph version to select.

Sample answer: The co-author's reasoning is incorrect because there is no strict rule, such as methodology order, that determines which variable goes on the xx-axis and which is represented by bar color. Dr. Aris should select the graph version based on visual clarity and ease of communication. Since Version B makes the interaction effect easier to interpret, Dr. Aris should choose Version B because it most clearly communicates the study's findings to the audience.

Key points:

  • Rejects the co-author's claim of a strict rule based on methodology order.
  • Explains that there is no rigid rule for assigning variables to the xx-axis versus formatting features.
  • Identifies that the main decision criterion is clarity of communication.
  • Concludes that the version making the interaction easier to interpret (Version B) is the correct choice.

Rubric: The response must explain that: 1. Order of introduction or other arbitrary standards do not dictate variable placement because there are no strict rules. 2. The decision should be made based on which arrangement communicates findings most clearly and effectively. 3. Justifies choosing Version B because it makes the interaction effect easier to interpret.

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Updated 2026-05-26

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Research Methods in Psychology - 4th American Edition @ KPU

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