Analysis of Covariance; *Analysis of Variance;

Two analyses of valiance (ANOVA) models for item scores are compared. The first is an items by subject random effect ANOVA. The second is a mixed effects ANOVA with items fixed and subjects random. Comparisons regarding reliability, Cronbach's alpha coefficient, psychometric inference, and inter-item covariance structure are made between the models. When considering the inter-item covariance structures for the two ANOVA models, brief comparisons with factor analysis models are also made. It is concluded that inference from a sample of items to a population of items requires homogenous inter-item covariances, that reliability has different meanings under the two models, and that while cocfficient alpha is a lower bound for reliability under the second model, it is not under the first. (Contains 51 references and two tables). (Author/SLD) Reproductions supplied by EDRS are the best that can be made from the original document.