Why the Differential Item Functioning? Math Test Item Bias and the Role of Linguistic Item Characteristics

• In Event: Detecting and Explaining Differential Item Functioning

Abstract

This article examines linguistic item characteristics as sources of differential item functioning (DIF) for middle- and high-school English language learners (ELLs) and their non-ELL peers on a state math exam. Specifically, the relationships among grade level, linguistic item characteristics, and two-way grade*characteristic interactions with a DIF area measure were investigated. DIF areas were computed in R using 1-parameter item response theory (IRT) model estimates. Multiple linear regression results revealed that items with greater multiple-meaning math words contributed to better ELL performance, whereas items containing more common multiple-meaning math words contributed to worse ELL performance. Although not statistically significant, there was also a trend for greater DIF favoring non-ELLs for items with high numbers of unique words in their verb phrases.

Authors

• Yuan-Ling Linda Liaw, University of Washington

• Elizabeth A. Sanders, University of Washington