Spearman's factor-analytic model has been proposed as a unidimensional linear item response theory (IRT) model for continuous item responses. This article first proposes a reexpression of the model that leads to a form similar to that of standard IRT models for binary responses and discusses the item indices of difficulty discrimination and…

The Cartesian theory of dimensionality (defined in terms of geometric distances between points in the test space) and Leibnitzian theory (defined in terms of order-generative connected, transitive, and asymmetric relations) are contrasted in terms of the difference between a factor analysis and an order analysis of the same data. (Author/CTM)

Two sets of five items each from the Law School Admission Test were analyzed by two methods of factor analysis, and by the Krus-Bart ordering theoretic method of multidimensional scaling. The results indicated a conceptual gap between latent trait theoretic procedures and order theoretic procedures. (Author/CTM)

An analysis of self-report delinquency data using four non-metric procedures for structural analysis revealed support for the existence of a general delinquency factor. However, offenses of low seriousness and victimless offenses (drinking and drug-taking items) were only weakly related to this general factor. (Author/CTM)

Multidimensional scaling (MDS) and components solutions were compared using two balanced self-report item sets. Results suggest that when self-report items are balanced and negatively worded items are not reverse scored, MDS and components solutions can differ largely, due to a component associated with measures of acquiescence. (SLD)

Geometric approaches to representing interrelations among tests and items are compared with an additive tree model (ATM), using 2,644 examinees and 2 other data sets. The ATM's close fit to the data and its coherence of presentation indicate that it is the best means of representing tests and items. (TJH)