Publications & Resources

Examining Differential Distractor Functioning in Reading Assessments for Students with Disabilities

Sep 2008

Jamal Abedi, Seth Leon, and Jenny C. Kao

This study examines the incorrect response choices, or distractors, by students with disabilities in standardized reading assessments. Differential distractor functioning (DDF) analysis differs from differential item functioning (DIF) analysis, which treats all answers alike and examines all wrong answers against the correct answer. DDF analysis in contrast examines only the incorrect answers. Our study results found items showing DDF for students with disabilities in Grade 9, but not for Grade 3. Results also suggest that items showing DDF were more likely to be located in the second half of the assessments rather than the first half of the assessments. Additionally, results suggest that in items showing DDF, students with disabilities were less likely to choose the most common distractor than students without disabilities. Results of this study can shed light on potential factors affecting the accessibility of reading assessments for students with disabilities, in an ultimate effort to provide assessment tools that are conceptually and psychometrically sound for all students. A companion report is available examining differential item functioning for students with disabilities.

Abedi, J., Leon, S., & Kao, J. C. (2008). Examining differential distractor functioning in reading assessments for students with disabilities (CRESST Report 743). Los Angeles: University of California, Los Angeles, National Center for Research on Evaluation, Standards, and Student Testing (CRESST).