Examining the Effectiveness of Test Accommodation Using DIF (Differential Item Functioning) and a Mixture Item Response Theory Model

• In Event: Psychometric Issues in Assessment in the Schools

Abstract

This study examined the validity of test accommodation using differential item functioning (DIF) and mixture IRT models to explore DIF between accommodated students with disabilities and non-accommodated students without disabilities on math assessment items. One data set was used to determine whether item types and features were associated with DIF characteristics. A second data set was used to test the relationship of DIF with student accommodation status, student characteristics and latent academic ability. Story items were not always more difficult than explanation or straightforward items. Item types and features were related to item difficulty, but not to DIF characteristics. Observed DIF was partially explained by an interaction of accommodation and academic ability. Limitations and implications of this study are discussed.

Authors

• Hyun-Jeong Cho, The University of Kansas

• Hongwook Suh, The University of Kansas

• Neal M. Kingston, The University of Kansas