LSAT Dimensionality Analysis for the December 1991, June 1992, and October 1992 Administrations. Statistical Report. LSAC Research Report Series.

An extensive nonparametric dimensionality analysis of latent structure was conducted on three forms of the Law School Admission Test (LSAT) (December 1991, June 1992, and October 1992) using the DIMTEST model in confirmatory analyses and using DIMTEST, FAC, DETECT, HCA, PROX, and a genetic algorithm in exploratory analyses. Results indicate that the LSAT displays a moderate amount of multidimensionality. There appear to be two dominant dimensions. The larger seems to be created by the combination of Logical Reasoning (LR) and Reading Comprehension (RC) items. The other dimension is created by the Analytical Reasoning (AR) items. As is consistent with the apparent unidimensionality of the combination of LR and RC items, the LR and RC sections display highly correlated section scores. There is some evidence that the LR and RC sections are dimensionally distinct. DETECT indicated in two of the three administrations that the entire LSAT is three-dimensional. The LSAT also appears to have several moderately strong and easily detectable secondary dimensions, with some weaker and less easily detectable secondary dimensions associated with the LR section. It is apparent that these particular secondary dimensions introduce only weak multidimensionality relative to the entire test. (Contains 12 tables and 27 references.) (Author/SLD)