Examination of Gender-Related Differential Item Functioning Through Poly-BW Indices

Area of Science:

• Educational Measurement
• Psychometrics
• Item Response Theory

Background:

• Traditional differential item functioning (DIF) detection methods focus on item difficulty and discrimination, limiting understanding of DIF item characteristics.
• Minimizing DIF is crucial in test construction, yet teachers and practitioners lack insights into DIF item associates.
• Existing DIF detection methods often lead to items being deleted or ignored, potentially losing valuable information.

Purpose of the Study:

• To investigate the contribution of Poly-BW indices (power, defenselessness, disturbance, hint) to understanding gender-related DIF in a mathematics achievement test.
• To provide teachers and testing practitioners with practical information on DIF item associates.
• To explore the predictive accuracy of Poly-BW indices for DIF measures.

Main Methods:

• Utilized data from a 34-item teacher-made mathematics achievement test administered to 1,439 seventh-grade students in Taiwan.
• Employed the Poly Simultaneous Item Bias Test (Poly-SIBTEST) procedure to estimate DIF measures.
• Calculated and analyzed Poly-BW indices, specifically defenselessness (mp) and power (cp), comparing male and female student groups.

Main Results:

• Differences in defenselessness (mp) and power (cp) indices between genders significantly predicted DIF measures obtained via Poly-SIBTEST.
• The Poly-BW indices demonstrated satisfactory accuracy in predicting DIF.
• Items with higher defenselessness for males indicated male-favoring DIF, while items with higher power for males suggested female-favoring DIF.

Conclusions:

• Poly-BW indices, particularly defenselessness and power, offer valuable insights into the nature of gender-related DIF.
• These indices provide practical directions for modifying test items to reduce bias.
• The findings support the use of Poly-BW indices as a tool for enhancing fairness in educational assessments.