ABSTRACT
Commonly, a test consists of separate items and the test score is a (possibly weighted) sum of item scores. In this case, statistics describing the test scores of a certain group of examinees can be expressed algebraically in terms of statistics describing the individual item scores for the same group [see Eq. (1-21) to (1-25)]. As already noted, classical item theory (which is only a part of classical test theory) consists of such algebraic tautologies.
