Analysis of School Context Effects on Differential Item Functioning Using Hierarchical Generalized Linear Models

Abstract

This article considers and illustrates a strategy to study effects of school context on differential item functioning (DIF) in large-scale assessment. The approach employs a hierarchical generalized linear modeling framework to (a) detect DIF, and (b) identify school-level correlates of the between-group differences in item performance. To illustrate, I investigated (a) whether any of the civic skills items used in the U.S. Civic Education Study of the International Association for the Evaluation of Educational Achievement displayed ethnic–racial DIF, and (b) the extent to which the ethnic–racial DIF was related to teacher-reported opportunity to learn (OTL) major civic-related topics. The results indicated that 3 of the 13 items displayed ethnic–racial DIF. After adjusting for OTL, two of the three flagged items ceased to exhibit DIF. Implications of this approach are discussed.