outlined a full agenda of research into the effects of accommodations (National Research Council, 2002a). Two different NRC committees that addressed the educational needs and concerns of students with disabilities (National Research Council, 1997a) and English language learners (National Research Council, 2000b) both recommended programs of research aimed at investigating the performance of these groups in large-scale standardized assessments.

A substantial amount of useful and interesting research is already available on the effects of accommodations on test performance, and several extensive reviews of this literature have been conducted. The effects of accommodations on test performance have been reviewed by Chiu and Pearson (1999); Tindal and Fuchs (2000); and Thompson et al. (2002). However, much of the existing research focuses on whether or not the accommodation had an effect on performance and, in some cases, on whether the effect was different for students with and without disabilities. Little of the available research directly addresses the validity of inferences made from the results of accommodated assessments, yet it is this second kind of research that could really assist policy makers and others in making decisions about accommodations. In this chapter, we review the available research regarding accommodations and outline the current methods of conducting validity research. In Chapter 6 we present the committee’s view of the way the validity of inferences based on accommodated assessments can best be evaluated.

EFFECTS OF ACCOMMODATIONS AND THE INTERACTION HYPOTHESIS

The committee commissioned a review and critique of the available research on the effects of test accommodations on the performance of students with disabilities and English language learners in order to gauge both any discernible trends in this research and the thoroughness with which the issues have been studied. This review was conducted by Sireci et al. (2003).

The authors were asked to review and critically evaluate the literature on test accommodations, focusing on empirical studies that examined the effects of accommodations on individuals’ test performance. The authors began their review with the articles summarized in the NRC’s workshop report (National Research Council, 2002a), additional articles provided by NRC staff, and questions raised about the studies during the workshop. They supplemented the lists provided by searching two electronic databases, ERIC and PsychoInfo, and the web sites of the Center for Research on Evaluation, Standards, and Student Testing (CRESST) and the National Center on Educational Outcomes (NCEO). They also queried researchers whose work was frequently cited, sent the authors the list of citations they had, and asked the authors to forward any additional studies. Included in the review were studies conducted between 1990 and December of 2002; the ending time was specified to ensure that the literature review would be ready in time for the committee’s first meeting.



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