What is test retest reliability?

Test-retest reliability refers to the consistency of a measure or test when it is administered to the same subjects at two different points in time. It is assessed by calculating the correlation between the scores from the two administrations, indicating how stable the test results are over time. High test-retest reliability suggests that the test produces similar results under consistent conditions, while low reliability indicates potential issues with the test's stability or the influence of external factors. This concept is essential in validating the reliability of psychological assessments, educational tests, and other measurement tools.