A method used to estimate the consistency of a test or measure, this approach involves dividing the test into two equivalent halves and correlating the scores on each half. The resulting correlation coefficient indicates the extent to which both halves measure the same construct. For instance, a questionnaire assessing anxiety might be split into odd-numbered and even-numbered questions. A high correlation between the scores on these two sets of questions suggests strong internal consistency, indicating that the items are reliably measuring the same underlying anxiety construct. This provides an estimate of the test’s reliability without requiring two separate administrations of the test.
This approach offers a practical way to assess reliability, particularly when time or resources are limited. It is beneficial in situations where repeated testing might lead to practice effects or participant fatigue, as it only requires a single administration of the instrument. Historically, it provided a computationally simpler alternative to more complex reliability assessments before the widespread availability of statistical software. The strength of this method lies in its ability to provide a single snapshot of internal consistency. However, its result is dependent on how the test is divided; different splits can yield different reliability estimates, highlighting a potential limitation.
