Type I error rates and rejection rates for three-dimensionality assessment procedures were studied with data sets simulated to reflect short tests and small samples. Results show that the G-squared difference test (D. Bock, R. Gibbons, and E. Muraki, 1988) suffered from a severely inflated Type I error rate at all conditions simulated. (SLD)

The usefulness of a goodness-of-fit index proposed by R. P. McDonald (1989) was investigated with regard to assessing the dimensionality of item response matrices. The m subscript k index, which is based on an estimate of the noncentrality parameter of the noncentral chi-square distribution, possesses several advantages over traditional tests of…

The use of indices and statistics based on nonlinear factor analysis (NLFA) has become increasingly popular as a means of assessing the dimensionality of an item response matrix. Although the indices and statistics currently available to the practitioner have been shown to be useful and accurate in many testing situations, few studies have…