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A statistical term used to describe the consistency of a measuring instrument. The more reliable a test is, the less random error there is likely to be. In order to be reliable an experiment must be conducted under the same conditions and all the variables must remain constant. In order for an instrument to be reliable, it must be in good working order and must yield the same readings over the course of multiple tests (using the same conditions). Reliability is crucial in science and psychology to insure objectivity. describes reliability as, “The extent to which an experiment, test, or measuring procedure yields the same results on repeated trials.”

Example: A student takes a standardized test several times and scores similarly each time. Therefore, the test is reliable.

APA Reference
Fournier, G. (2018). Reliability. Psych Central. Retrieved on July 8, 2020, from