What does test-retest reliability measure?

Test-retest reliability refers to the measure of consistency of test scores when the same test is administered to the same group of individuals at two different points in time. When evaluating test-retest reliability, it is crucial to determine whether the results remain stable and consistent across these different administrations. If individuals score similarly upon retesting, this indicates high reliability, suggesting that the test effectively measures a stable trait or ability over time.

This concept is vital in psychological assessments and educational testing, as it helps to ensure that the test accurately reflects the measured characteristics rather than random fluctuations or errors. Other options, while relevant to the testing process, do not relate directly to the concept of test-retest reliability; they address aspects like the clarity of instructions, ease of administration, or difficulty of the test, which are not about consistency of scores over time.