What does test-retest reliability assess?

• A. Stability of test scores over time.
• B. Correlation between different test forms.
• C. Consistency among scorers.
• D. Difficulty of items.

Answer: (A)

Test-retest reliability measures the stability of test scores over time. By administering the same test to the same group on two separate occasions and looking at the correlation between the two sets of scores, you can see how consistently the measure behaves when the underlying trait is supposed to be stable. A high correlation indicates that the test yields similar results across time, suggesting good temporal stability. Keep in mind the interval between tests matters: too short can inflate reliability due to memory of items, too long can reflect real changes in the trait. This concept is distinct from parallel-forms reliability (consistency between different test versions) and inter-rater reliability (consistency among scorers), and it’s not about item difficulty.