The Lisrel-model with structured means was used to study similarities and differences in the development of mathematical ability between two student groups as measured by two tests on three successive occasions. Procedures for testing models to assess the contribution on an individual parameter to the goodness of fit are described. (Author/BS)

This paper reviews methods which have been used to identify and validate learning hierarchies. Specifically, three methods which reflect the notion of a relatively inviolate sequence are discussed and compared. Two of the psychometric methods compare pairs of skills, the ordering-theoretic method (Bart and Krus) and the test of inclusion (White…