the consistency, stability, and repeatability of a research method, measurement, or instrument. A reliable procedure produces the same or very similar results when applied repeatedly under the same conditions. High reliability indicates that the findings are dependable and not due to random error or chance.
Synonyms: Consistency
Example
A questionnaire designed to measure fatigue in patients with arthritis is administered to the same group of participants two weeks apart. If the scores remain highly similar, the instrument demonstrates strong test–retest reliability, indicating that it consistently measures fatigue over time.