Detection of Differential Item Functioning Using Item Response Theory in Aptitude Test Data Implemented Multiple Countries

Abstract

The methodological and applied studies of differential item functioning (DIF) have been accumulated, but the study focused on three or more groups and polytomous item data is not enough. The purpose of the present study was to detect DIF using IRT in polytomous item data with four ordered categories of the four scales measuring extroversion, leadership, autonomy and adjustment. As a result, the authors detected DIF in extroversion and leadership scale. In addition, the authors compared standard error before and after item purification and confirmed that they did not significantly differ. The need for further study of the effect of multidimensionality on DIF was discussed at the end.