We examined whether set-based items affected IRT model-data fit. We also evaluated fit after combining dependent items into composites and treating them as polytomous items. Analysis of the 2009 AP English Literature and Composition Exam showed that some of the item pairs had major violations of local independence. Model fit improved when we analyzed the data using composites. Our findings suggest that conducting IRT analyses on composites provides a viable approach to circumventing problems of local dependence for set-based items.
Liu, Liwen; Drasgow, Fritz; Reshetar, Rosemary; and Kim, YoungKoung Rachel, "Item Response Theory (IRT) Analysis of Item Sets" (2011). NERA Conference Proceedings 2011. Paper 10.