How is reliability defined in the context of psychological testing?

Reliability in the context of psychological testing refers to the consistency of a measure across time and contexts. It is critical because it ensures that the results of a test are stable and repeatable. If a test yields different results under similar conditions or at different times, its reliability is compromised, making it less useful for accurately assessing psychological constructs.

For example, if a person takes a personality test today and receives a certain score, they should ideally receive a similar score if they take the same test again in the future, assuming that their psychological state hasn't significantly changed. This consistency speaks to the reliability of the measure, which is essential for establishing trust in the test results and their interpretation.