ERIC Number: EJ897866
Record Type: Journal
Publication Date: 2010
Abstractor: As Provided
A Comparison of Item Fit Statistics for Mixed IRT Models
Chon, Kyong Hee; Lee, Won-Chan; Dunbar, Stephen B.
Journal of Educational Measurement, v47 n3 p318-338 Fall 2010
In this study we examined procedures for assessing model-data fit of item response theory (IRT) models for mixed format data. The model fit indices used in this study include PARSCALE's G[superscript 2], Orlando and Thissen's S-X[superscript 2] and S-G[superscript 2], and Stone's chi[superscript 2*] and G[superscript 2*]. To investigate the relative performance of the fit statistics at the item level, we conducted two simulation studies: Type I error and power studies. We evaluated the performance of the item fit indices for various conditions of test length, sample size, and IRT models. Among the competing measures, the summed score-based indices S-X[superscript 2] and S-G[superscript 2] were found to be the sensible and efficient choice for assessing model fit for mixed format data. These indices performed well, particularly with short tests. The pseudo-observed score indices, chi[superscript 2*] and G[superscript 2*], showed inflated Type I error rates in some simulation conditions. Consistent with the findings of current literature, the PARSCALE's G[superscript 2] index was rarely useful, although it provided reasonable results for long tests.
Descriptors: Test Length, Goodness of Fit, Item Response Theory, Simulation, Sample Size, Models, Error of Measurement, Scores
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Publication Type: Journal Articles; Reports - Research
Education Level: N/A
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