Reliability

Reliability refers to the consistency of measures and measuring methods. Reliability ensures that a test measures equally well, irrespective of the circumstances. The test should be reliable at two different points in time (test-retest reliability), and irrespective of who evaluates the test (inter-rater reliability). It should also be reliable compared to a different test measuring the same construct (parallel-forms reliability) and it must have internal consistency, with items that measure the same construct.