Examining Differential Distractor Functioning in Reading Assessments for Students with Disabilities. CRESST Report 743

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. If different groups, such as students with disabilities and students without disabilities, selected different incorrect responses to an item, then the item could mean something different to the different groups. 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. (Detailed DDF Results are appended. Contains 14 tables.)