, Volume 78, Issue 1, pp 116-133
Date: 20 Oct 2012

How Should We Assess the Fit of Rasch-Type Models? Approximating the Power of Goodness-of-Fit Statistics in Categorical Data Analysis

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We investigate the performance of three statistics, R 1, R 2 (Glas in Psychometrika 53:525–546, 1988), and M 2 (Maydeu-Olivares & Joe in J. Am. Stat. Assoc. 100:1009–1020, 2005, Psychometrika 71:713–732, 2006) to assess the overall fit of a one-parameter logistic model (1PL) estimated by (marginal) maximum likelihood (ML). R 1 and R 2 were specifically designed to target specific assumptions of Rasch models, whereas M 2 is a general purpose test statistic. We report asymptotic power rates under some interesting violations of model assumptions (different item discrimination, presence of guessing, and multidimensionality) as well as empirical rejection rates for correctly specified models and some misspecified models. All three statistics were found to be more powerful than Pearson’s X 2 against two- and three-parameter logistic alternatives (2PL and 3PL), and against multidimensional 1PL models. The results suggest that there is no clear advantage in using goodness-of-fit statistics specifically designed for Rasch-type models to test these models when marginal ML estimation is used.

This research was supported by an ICREA-Academia Award and Grant SGR 2009 74 from the Catalan Government, and by Grants PSI2009-07726 and PR2010-0252 from the Spanish Ministry of Education awarded to the first author, and by a Dissertation Research Award of the Society of Multivariate Experimental Psychology awarded to the second author. The authors are indebted to the reviewers and to David Thissen for comments that improved the manuscript.