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 discusses the use of the LISREL computer program to compare two groups of Ontario students who studied French as a second language in either a regular or an immersion program. Longitudinal data on growth in mathematical ability, from grade 4 to grade 6, are analyzed using seven different mathematical models. The paper illustrates the…