Cohen, A. S., Gregg, N., & Deng, M. (2005). The role of extended time and item content on a high-stakes mathematics test . Learning Disabilities Research & Practice , 20 (4), 225–233. https://doi.org/10.1111/j.1540-5826.2005.00138.x

Two studies were conducted to investigate the influence of extended-time and content knowledge on the performance of students tested with and without accommodations.

A random sample of 2,500 grade 9 students was drawn from the statewide assessment scores in Florida (U.S.), including 1,250 students with learning disabilities (LD) and 1,250 students without disabilities. Demographic characteristics were reported, including sex and ethnicity. Students with limited English proficiency were excluded from these studies.

The dependent variable was the mathematics section of the Florida Comprehensive Assessment Test (FCAT).

Results indicate that students for whom items were functioning differently were not accurately characterized by their accommodation status but rather by content knowledge. In other words, knowing accommodation status contributed little to test performance difference, and the more likely explanation is that mathematics competency differentiated the groups of learners.