Two structural laws for intelligence tests are discussed: one law concerns the sign of correlation coefficients and gives conditions under which all correlations between test items will be positive; and one law concerns the relative sizes of the correlation coefficients between intelligence items. A cylindrical structure extends these laws. (SLD)

Sources of observed differences in difficulty between items in graph comprehension performance were studied using 132 items from the Psychometric Entrance Test, an Israeli college entrance examination. Results indicate that item difficulty can be predicted successfully on the basis of item characteristics and task demands. Implications for graph…

It has previously been shown by M. Beller (1990) that an additive tree (Addtree, a hierarchical tree representation of similarity data developed by S. Sattath and A. Tversky in 1977), may be useful for representing the structure between tests and items through the similarity among them as measured by their intercorrelations. In this study, the…

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)