Validity and Reliability

Yuankun Yao

Reliability and validity are two basic concepts in test theory. Reliability refers to the consistency of measures. One type is the test-retest reliability. In this approach, a test is administered to the same group of people twice, with a certain interval between the two administrations. If most examinees get similar test results across the two occasions, evidence is established for high reliability. This type of reliability is also called temporal stability. There are a number of factors that may affect this type of reliability. One factor is the memory effect. If a test is given twice within a short period of time, the examinees will most likely remember their answers to the exam the second time they take the exam. This may result in unusually high correlations between two sets of test scores, hence high reliability. On the other hand, if there is too long a period between two The ...

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