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Using Estimated Item Observed-Score Regressions to Test Goodness-of-Fit of IRT Models IRT

Wingersky, Marilyn S.; Sheehan, Kathleen M.
Publication Year:
Report Number:
ETS Research Report
Document Type:
Page Count:
Subject/Key Words:
College Board, Goodness of Fit, Item Response Theory (IRT), Mathematical Models, Regression (Statistics), Statistical Analysis


This paper presents an investigation of a method for assessing the goodness-of-fit of IRT models using estimated item-observed score regressions. An advantage of this method is that examinees are assigned to cells on the basis of an observed quantity, their number-right score. The method for assessing goodness-of-fit currently used assigns examinees to cells on the basis of an estimated quantity, their estimated ability. Comparisons are made between the two methods using simulated and actual data. A disadvantage of the new method is that it cannot easily handle tests where many examinees do not finish. (68pp.)

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