title: Performance of the likelihood ratio difference (G2 Diff) test for detecting unidimensionality in applications of the multidimensional Rasch model.
abstract: Previous research has investigated the influence of sample size, model misspecification, test length, ability distribution offset, and generating model on the likelihood ratio difference test in applications of item response models. This study extended that research to the evaluation of dimensionality using the multidimensional random coefficients multinomial logit model (MRCMLM). Logistic regression analysis of simulated data reveal that sample size and test length have a large effect on the capacity of the LR difference test to correctly identify unidimensionality, with shorter tests and smaller sample sizes leading to smaller Type I error rates. Higher levels of simulated misfit resulted in fewer incorrect decisions than data with no or little misfit. However, Type I error rates indicate that the likelihood ratio difference test is not suitable under any of the simulated conditions for evaluating dimensionality in applications of the MRCMLM.
authors.affiliation: Edward W. Wolfe, Pearson, 3974 Roberts Ridge, NE, Iowa City, IA 52240, USA, ed.wolfe@pearson.com.
authors.forename: Leigh
authors.initials: L
authors.lastname: Harrell-Williams
authors.forename: Edward W
authors.initials: EW
authors.lastname: Wolfe
mesh_terms: D003198:Computer Simulation; D006801:Humans; D016013:Likelihood Functions; D016015:Logistic Models; D008432:Mathematical Computing; D015233:Models, Statistical; D011581:Psychological Tests / Q000706:statistics & numerical data*; D011594:Psychometrics / Q000706:statistics & numerical data*; D018401:Sample Size