Finch, H., Barton, K., & Meyer, P. (2009). Differential item functioning analysis for accommodated versus nonaccommodated students . Educational Assessment , 14 (1), 38–56. https://doi.org/10.1080/10627190902816264

Accommodations were not specified; however, details were reported on the proportion of students receiving 1, 2, or 3 or more accommodations.

Testing data for 3,550 students with disabilities completing a standardization of a national (U.S.) test were examined. These participants were reported to be drawn from throughout the nation. The participant group was relatively evenly drawn from grades 3 through 8. The study compared data from students with disabilities who either received or did not receive accommodations—the former numbered 1,798, about 51% of the participants, and the latter were 49% of the participants. Details were provided regarding the proportion of each group who had disabilities from the federal categories, including learning disabilities, speech and language disabilities, emotional disabilities, and the remaining categories (each of which had less than 5% of either group).

Scores on subtests of math and language arts from a national norm-referenced achievement test, TerraNova, administered to students in grades 3–8 comprised the dependent variable. The differential item functioning (DIF) was analyzed for performance scores of groups of students with disabilities who either received or did not receive accommodations.

The mathematics test demonstrated more uniform than nonuniform DIF; that is, students with disabilities not receiving accommodations tended to score higher than students with disabilities receiving accommodations. In other words, the accommodations did not provide students the needed support for success. The language test had a larger proportion of items which displayed nonuniform DIF. While students did not differ in scores in sixth grade and higher regardless of receiving or not receiving accommodations, there were complex patterns at the lower grade levels. Specifically, students in early grades not receiving accommodations scored better than those receiving accommodations. Put another way, students at lower proficiency levels in early grades seemed less able to benefit from accommodations in comparison with those who had higher proficiency. An unexpected finding was that DIF did not always favor students receiving accommodations: for items requiring heavy navigational load—such as charts and maps—it is suspected that accommodations may have involved distraction or interference.