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Relative effectiveness of generalized Mantel-Haenszel, simultaneous item bias test and logistic discriminant function analysis for detecting differential item functioning in ordinal test items


Ibrahim Abdul-Wahab

Abstract

The study compared the power of Differential Item Functioning (DIF) detection for ordinal test items among Generalized Mantel Haenszel (GMH), Simultaneous Item Bias Test (SIBTEST), and Logistic Discriminant Function Analysis (LDFA) methods. It also determined the relationship between the proportions of test items that function differentially in ordinal test items when the different methods were used. These were with a view to improving the quality of ordinal test items construction. The study employed the descriptive-comparative research design. The population consisted of all undergraduate students who registered for EFC 303 (Tests and Measurement) at Obafemi Awolowo University during 2011/2012 Harmattan Semester. The sample consisted of an intact class of 457 Part 3 undergraduate students who registered for the course. The instrument used in the study was the “Teacher Efficacy Scale (TES).” The TES consists of 24-item in Likert format designed by Faleye (2008) to measure efficacy of teachers’ activities. A total of 445 copies of the TES were found properly completed. Data collected were analysed using Generalized Mantel Haenszel, Simultaneous Item Bias Test, and Logistic Discriminant Function Analysis. The results showed that there was a significant difference in the performance of the GMH, SIBTEST, and LDFA methods in detecting DIF in ordinal test items. Further, a non significant relationship existed between the proportions of test items that functioned differentially in the ordinal test items when the different methods were used. The study concluded that there was a high degree of correspondence among the three methods across ordinal test items but complement one other in their ability to detect DIF in ordinal test items.

Keywords: Ordinal test, Differential Item Functioning, psychological instrument, test fairness, and psychometric measures


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eISSN: 1117-1421