Modeling multidimensional test data with a unidimensional model can result in serious statistical errors, such as bias in item parameter estimates. Many methods exist for assessing the dimensionality of a test. The current study focused on DIMTEST. Using simulated data, the effects of sample size splitting for use with the ATFIND procedure for…

Two factors, language difficulty and option set convergence, were experimentally manipulated and their effects on item difficulty assessed. Option convergence was found to have a significant effect on item difficulty while the effect of language difficulty was not significant. (Author/BW)