Classical Test Theory

Classical test theory (CTT) is an approach to measurement that considers the relationship between the expected score (or “true” score) and observed score on any given assessment. The word classical is used in the sense that the theory is considered to be the first practical application of mathematics to describe this relationship. CTT offers a relatively parsimonious, elegant, and intuitive way to scale individuals according to some theorized latent construct. This entry further describes CTT and its basic principles and estimation procedures, then discusses its framework for determining a measure’s proportion of true score variance, standard error of measurement, item analysis, and validity. Finally, it looks at the limitations to the theory.

Although more contemporary, model-based approaches to measurement, such as item response theory (IRT), have ...