What does internal consistency reliability assess?

Internal consistency reliability assesses the extent to which test items that are intended to measure the same construct yield similar results. This measurement is crucial when evaluating the reliability of assessments, as it indicates how well the individual items in a test correlate with one another. A reliable test should have items that are coherent and assess the same underlying concept, providing measurements that are consistent across the board.

When a test has high internal consistency, it assures the user that each of the items is contributing to an overall understanding of the concept being measured, thus reinforcing the validity of the test. Examples of methods to measure internal consistency include Cronbach's alpha and split-half reliability, which both aim to quantify this coherence in test items.