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Simulation Studies Applying Posterior Predictive Model Checking for Assessing Fit of the Common Item Response Theory Models IRT

Sinharay, Sandip; Johnson, Matthew S.
Publication Year:
Report Number:
ETS Research Report
Document Type:
Page Count:
Subject/Key Words:
Unidimensionality (Tests), Speededness (Tests), Discrepancy Measures, Bayesian Methods, Odds Ratio, Item Response Theory (IRT)


useful insight about the fit of the models. The "odds ratios," corresponding to the responses of the examinees to pairs of items, appear to be powerful discrepancy measures in detecting several types of misfits of the IRT models. The observed score distribution and biserial correlation coefficients are also found useful as discrepancy measures on a number of occasions. A companion article applying the posterior predictive method to real data examples shows that the method has the potential to become very useful in psychometrics.

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