Split-Half Reliability

Split-half reliability is a statistical method used to measure the consistency of the scores of a test. It is a form of internal consistency reliability and had been commonly used before the coefficient α was invented. Split-half reliability is a convenient alternative to other forms of reliability, including test–retest reliability and parallel forms reliability because it requires only one administration of the test. As can be inferred from its name, the method involves splitting a test into halves and correlating examinees’ scores on the two halves of the test. The resulting correlation is then adjusted for test length using the Spearman-Brown prophecy formula. This entry introduces the basic principles and estimation procedures for this method and discusses its limitations.