What distinguishes reliability from validity in psychological testing?

The distinction between reliability and validity in psychological testing is foundational for understanding how tests measure what they are intended to measure. Reliability is primarily concerned with consistency. When a test is reliable, it produces stable and consistent results over repeated administrations under similar conditions. For instance, if a person takes a reliable intelligence test multiple times, their scores should not fluctuate dramatically; this consistency indicates that the test is measuring something stable rather than being affected by random external factors or inherent test variability.

On the other hand, validity refers to the degree to which a test actually measures what it claims to measure. It assesses the accuracy of the test results in reflecting the concept or construct that it is intended to evaluate. Thus, while reliability can ensure that the test outcomes are stable, validity ensures that those outcomes are meaningful and interpretable in the context they are used.

While some other options may relate to these concepts, they do not accurately define the essence of reliability and validity in the context of psychological testing. For instance, validity does not measure consistency over time; instead, it involves the relevance and appropriateness of the test for its intended purpose. Understanding these distinctions helps not only in interpreting test scores but also in choosing appropriate assessments based on their psychometric properties.