reliability coefficient
(symbol: rxx) an index describing the consistency of scores across contexts (e.g., different times, items, or raters). Its value, ranging from 0 to 1, provides an estimate of the amount of obtained score variance that is due to true variance rather than to error. The larger this coefficient, the more confident a researcher may be that scores obtained at different times under similar conditions with the same participants will be alike. Typically, reliability coefficients are considered to be acceptable if they are above .80. Also called coefficient of reliability; index of reliability; reliability index.