“Coefficient Alpha and the Internal Structure of Tests“

Lee Cronbach's 1951 Psyckometrika article “Coefficient Alpha and the Internal Structure of Tests” established coefficient alpha as the preeminent estimate of internal consistency reliability. Cronbach demonstrated that coefficient alpha is the mean of all split-half reliability coefficients and discussed the manner in which coefficient alpha should be interpreted. Specifically, alpha estimates the correlation between two randomly parallel tests administered at the same time and drawn from a universe of items like those in the original test. Further, Cronbach showed that alpha does not require the assumption that items be unidimensional. In his reflections 50 years later, Cronbach described how coefficient alpha fits within generalizability theory, which may be employed to obtain more informative explanations of test score variance.

Concerns about the accuracy of test scores are ...