Investigation of Equating Error in Tests with Differential Item Functioning

Meltem Yurtçu, Cem Oktay Güzeller


In this study purposes to indicate the effect of the number of DIF items and the distribution of DIF items in these forms, which be equalized on equating error. Mean-mean, mean-standard deviation, Haebara and Stocking-Lord Methods used in common item design equal groups as equalization methods. The study included six different simulation conditions. The conditions were compared according to the number of DIF items and the distribution of DIF items on tests. The results illustrated that adding DIF items to tests were equated caused an increase in the errors obtained by equating methods. We may state that the change in errors is lowest in characteristic curve transformation methods, largest in moment methods depending on the situations in these conditions.


Equation error,DIF,IRT equation methods,Large Scale Exams

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