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The Analysis Of Measurement Equivalence In International Studies Using The Rasch Model., Wolfram Schulz, Julian Fraillon

Julian Fraillon

This paper outlines how Rasch modelling can be used for testing assumption about measurement equivalence in international studies. Based on the Rasch model (Rasch, 1960) for dichotomous items and the Partial Credit model for polytomous items (Masters & Wright, 1982), so-called item-by-country interactions can be estimated that provide useful information about the level of measurement invariance in parameter estimates. It should be noted that item-by-country interactions are one form of differential item functioning (DIF) where groups vary in their probability of answering questions even after controlling for their levels of ability (see Hambleton, Swaminathan and Rogers, 1991). Item-by-country interactions can …