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Accuracy Of Rasch Model Item Parameter Estimation, Luc T. Le, Ray J. Adams

Professor Ray Adams

This study used Monte Carlo simulations to evaluate the item parameter recovery from ACER ConQuest 3 software (Adams, Wu, & Wilson, 2012) for the dichotomous Rasch model. The authors’ primary focus was the comparison of its estimation methods, joint maximum likelihood (JML), marginal maximum likelihood (MML) with a normal distribution assumption and MML with a discrete distributions assumption when the populations were in fact non-normal. The simulation data sets were generated with two test lengths (10 and 50 items) and four alternative true population distributions for the abilities: normal, bimodal, uniform, and chi-square. As expected, results showed that MML-Normal was …