Case Study

Explain why and how Dr. Aris can utilize the data from his learning-change study to assess the test-retest reliability of the motivation survey, even if an overall change in motivation occurred. In your response, address the timing, the required statistical relationship, and the visual representation used.

Case context: Dr. Aris is developing a new survey to measure students' motivation. Standard research designs in his department only test participants once, making it difficult to assess test-retest reliability directly. However, Dr. Aris is also conducting a longitudinal study where he administers this new motivation survey at the beginning and the end of a semester to detect learning-related changes. Even if an overall change in students' motivation occurs over the course of the semester, Dr. Aris hopes to utilize this study's data to evaluate the test-retest reliability of his new survey.

Question: Explain why and how Dr. Aris can utilize the data from his learning-change study to assess the test-retest reliability of the motivation survey, even if an overall change in motivation occurred. In your response, address the timing, the required statistical relationship, and the visual representation used.

Sample answer: Dr. Aris can use data from his longitudinal study because it administers the survey to the same group of students at two separate times (beginning and end of the semester). To assess test-retest reliability, he needs to calculate the correlation (rr) between the two sets of scores and plot them on a scatterplot. This assessment is valid even if an overall change in motivation occurred, because test-retest reliability measures the consistency of the relative rankings of students' scores over time (correlation) rather than whether their average scores remained identical.

Key points:

  • Data from a study designed for a different question can be used if the measure is administered multiple times.
  • The evaluation requires calculating the correlation between the scores from the two administrations.
  • A scatterplot is used to visualize the statistical relationship of the scores.
  • Test-retest reliability can be assessed even if an overall change in the construct occurred.

Rubric: To receive full credit, the response must: 1. Explain that test-retest reliability is possible because the study measures the same participants at two separate times. 2. Identify that he must calculate the correlation between the scores from the start and end of the semester. 3. Mention that the relationship is visualized using a scatterplot. 4. Comprehend that reliability can still be assessed even if an overall attitude/motivation change occurred.

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Updated 2026-05-26

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Research Methods in Psychology - 4th American Edition @ KPU

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