Applying DIF-free-then-DIF strategy on PHGLM to Assess Differential Item Functioning.

• Main Authors: Chia-Yi Lin, 林佳誼
• Other Authors: Ching-Lin Shih
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/61844365827139900817

碩士 === 國立臺中教育大學 === 教育測驗統計研究所 === 99 === In Williams and Beretvas’ (2006) study, confirmed the relationship between PHGLM and item response theory under the polytomous items situations, But they didn’t discuss that when there are impact between two groups. Chen Chen and Shih 's (2010) research has confirmed that when use the Hierarchical Generalized Linear Model to detection the differential item functioning would let the power inaccurate, but can use DIF-free-then-DIF strategy (DFTD strategy) to improve this problem. In the study demonstrated the use DIF-free-then-DIF strategy on PHGLM to assess differential item functioning. Two different DIF assessment methods, “PHGLM with standard procedure” and “PHGLM with DFTD strategy” was compared in assessing DIF under the Hierarchical Generalized Linear Modeli for polytomous items. Four independent variables were manipulated in the simulation study, the impact between two groups, including the ability difference of subjects, the percentage of DIF items in the test and the DIF patterns. The dependent variables were Type I error and power of DIF assessment. It was recommended that the DFTD strategy should be included into the PHGLM when assessing DIF for polytomous items.