1. Modified Achievement Tests for Students with Disabilities: Basic Psychometrics and Group Analyses Ryan J. Kettler Vanderbilt University CCSSO’s National Conference on Student Assessment June 2008

2. Reliability and Concurrent Validity with a Proficiency Tests CAAVES Item Mod Data 20082

3. Concurrent Validity with Participation Criteria CAAVES Item Mod Data 20083

4. 4 Reading: Descriptive Statistics for Unmodified and Modified Tests

5. Distributions by Group and Condition in Reading CAAVES Item Mod Data 20085 Students without Disabilities, Ineligible Students with Disabilities, Ineligible Students with Disabilities, Eligible

6. Effect Sizes of Modifications on Reading Performance CAAVES Item Mod Data 20086

7. Group Improvement by Condition in Reading CAAVES Item Mod Data 20087

8. Mean Item Difficulty by Group and Condition in Reading CAAVES Item Mod Data 20088 * Student abilities were equated using a Rasch model.

9. CAAVES Item Mod Data 20089 Math: Descriptive Statistics for Unmodified and Modified Tests

10. Distributions by Group and Condition in Math CAAVES Item Mod Data 200810 Students without Disabilities, Ineligible Students with Disabilities, Ineligible Students with Disabilities, Eligible

11. Effect Sizes of Modifications on Math Performance CAAVES Item Mod Data 200811

12. Group Improvement by Condition in Math CAAVES Item Mod Data 200812

13. Mean Item Difficulty by Group and Condition in Math CAAVES Item Mod Data 200813 * Student abilities were equated using a Rasch model.

14. Upcoming Analyses: Difficulty Change on Individual Items CAAVES Item Mod Data 200814 Students without Disabilities, Ineligible Students with Disabilities, Eligible

15. Conclusions Assessments can be made more accessible for eligible students (with disabilities who have persistent academic difficulties). Modifications can change the difficulty of tests and items without invalidating the resulting scores. Much more work needs to be done! CAAVES Item Mod Data 200815