A Method for Studying the Homogeneity of Test Items with Respect to Other Relevant Variables

Drawing on recently developed methodology for structural equation modeling with categorical data, this article proposes a new approach for investigating the behavior of a set of dichotomously scored test items in relation to a set of other relevant (observed) variables. This is achieved by considering a linear structural model relating the latent ability variable to a set of observed scores. The approach gives information on hypothesized unidimensionality and homogeneity of items with respect to these other variables. Some examples are given where a set of biology anchor items is related to a set of other related test scores obtained from the examinees.