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Common Person Equating With The Rasch Model, Geoff Masters

Prof Geoff Masters AO

Two procedures, one based on item difficulties, the other based on person abilities, were used to equate 14 forms of a reading comprehension test using the Rasch model. These forms had no items in common. For practical purposes, the two procedures produced equivalent results. An advantage of common person equating for testing the unidimensionality assumption is pointed out, and the need for caution in interpreting tests of common item invariance is stressed.