Which of these reliability measures assesses stability over time?

Test-retest reliability is a measure used to evaluate the consistency of a test or assessment over time. It involves administering the same test to the same group of participants at two different points in time and then correlating the scores from the two assessments. A high correlation indicates that the test produces stable and consistent results over time, making it a crucial aspect for research looking to ensure that the results are not affected by external variables or changes in individual participant circumstances.

In comparison, Cronbach's alpha assesses internal consistency or the degree to which items in a test measure the same construct, not stability over time. Parallel reliability involves comparing two different forms of the same test, while split-half reliability focuses on the consistency of the results obtained from two halves of a single test. Both of these measures evaluate different aspects of reliability and do not specifically concentrate on the temporal stability of scores, which is the hallmark of test-retest reliability.