Which type of reliability assesses the consistency of a person's scores across repeated administrations of an assessment?

Test-retest reliability measures the stability and consistency of a person's scores when the same assessment is administered multiple times under similar conditions. This type of reliability is pivotal in assessing whether a test yields similar results over time, assuming that the underlying attribute being measured has not changed. For example, if a client takes a measure today and then retakes it in a week, a high correlation between the two scores indicates strong test-retest reliability. This reinforces the idea that the instrument can reliably capture the same construct across different occasions.

In contrast, other types of reliability focus on different aspects of measurement. Inter-rater reliability examines the degree to which different raters or observers provide consistent scores for the same phenomenon. Internal consistency reflects how well items within a single assessment measure the same underlying construct. Criterion reliability assesses how well one measure correlates with an established benchmark or criterion. Each of these has its own context and importance, but they do not specifically target the consistency of scores over repeated test administrations like test-retest reliability does.