How do reliability and validity differ in testing?

Reliability and validity are fundamental concepts in psychological testing, and they serve different purposes in evaluating the quality of a test.

Reliability refers to the consistency of a test's results. A reliable test will yield the same results under consistent conditions, meaning that if a person were to take the same test multiple times, their scores would be similar each time. Reliability can be evaluated in various ways, such as through test-retest reliability, inter-rater reliability, and internal consistency.

Validity, on the other hand, pertains to the accuracy of a test—specifically, whether the test measures what it is intended to measure. A valid test captures the construct it claims to assess. For instance, if a test is designed to measure anxiety, a valid test would accurately reflect the level of anxiety in its subjects, rather than measuring something unrelated, such as general intelligence or mathematical ability.

The distinction between these two concepts is crucial; a test can be reliable (producing the same results consistently) without being valid (not measuring what it intends to measure). Conversely, a test cannot be valid unless it is reliable, as an inaccurate measure cannot consistently reflect a true score. Therefore, option B accurately encapsulates these definitions by stating that reliability assesses consistency, while validity