Topic overview

Start with the big picture

Validity and reliability are distinct concepts for thinking about epidemiological tests. Validity concerns whether a test supports an appropriate assessment of the condition or characteristic it is intended to evaluate. Reliability concerns the consistency of test results when measurement is repeated or assessed under comparable conditions. Considering both helps frame how test performance may be evaluated in screening and diagnostic contexts. This introduction establishes the central distinction without prescribing particular metrics or procedures. The full lesson develops the concepts further; details such as named measures, examples, and practical applications are not provided in the source snapshot.