Type I Error Rates for Generalized Graded Unfolding Model Fit Indices
Type I error rates were examined for several ﬁt indices available in GGUM2000: extensions of Inﬁt, Outﬁt, Andrich’s χ2, and the log-likelihood ratio χ2. Inﬁt and Outﬁt had Type I error rates much lower than nominal α. Andrich’s χ2 had Type I error rates much higher than nominal α, particularly for shorter tests or larger sample sizes. The log-likelihood χ2 had Type I error rates near or below nominal α for small samples or longer tests but had inﬂated error rates with large samples and shorter tests. For conditions in which the log-likelihood ratio χ2 did not perform well, alternative ﬁt indices or modiﬁcations to these procedures should be considered in future studies.
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DeMars, C. E. (2004). Type I error rates for generalized graded unfolding model fit indices. Applied Psychological Measurement, 28, 48-71.