The Effects of Test Accommodation on Test Performance: A Review of the Literature

NICHCY’s Structured Abstract 74 describes the following:

Title | The Effects of Test Accommodation on Test Performance: A Review of the Literature

Authors | Sireci, S.G., Li, S., & Scarpati, S.

Source | Center for Educational Assessment, Research Report No. 485.  Amherst, MA:  School of Education, University of Massachusetts Amherst.

Year Published | 2006

Over 150 studies pertaining to test accommodations were identified in the literature and 40 studies that empirically studied the effects of test accommodations on the performance of students with disabilities or English language learners were reviewed. The results of these studies are discussed as are the internal and external validity of the authors’ conclusions. All studies were critiqued with respect to the interaction hypothesis that test accommodations should improve the test scores for targeted groups, but should not improve the scores of examinees for whom the accommodations are not intended. Data are provided regarding the types of accommodations studied. In general, consistent conclusions were not found across studies due to the wide variety of accommodations, the ways in which they were implemented, and the heterogeneity of students to whom they were given. However, a fairly consistent finding was that the accommodation of extended time improved the performance of students with disabilities more than it improved the performance of students without disabilities. In light of this finding and similar results in some studies focusing on other accommodations, a revision of the interaction hypothesis is proposed. Directions for future research and for improved test development and administration practices are also proposed.

In recent years, interest in the fairness of test accommodations has risen alongside the increase in standardized testing. Many people accept the administration of certain accommodations on standardized tests for students with disabilities while they question others. For example, if a student with a visual impairment is provided a standardized test in large-print or Braille most people will accept this accommodation because they do not feel such accommodations give students an advantage over other test takers. However, accommodations such as reading a test out loud to students or providing extra time on tests for students with learning disabilities are often questioned because of the belief that these accommodations would help anybody who was granted them and would give an unfair advantage to those students receiving them. The opposing argument is called the “interaction hypothesis.” The interaction hypothesis states that accommodations help students who need them but do not affect the scores of students who don’t. This review looks for evidence to support the interaction hypothesis.

Research Questions

  1. Do test accommodations affect the test performance of students with disabilities?
  2. What specific types of test accommodations result in valid score interpretations for specific types of students?
  3. Do test accommodations affect the test performance of students who are English Language Learners (ELL)?

Research Design
Review of the Literature

  • Number of Studies Included | 40
  • Number of Subjects | Not Specified
  • Years Spanned | 1986-2001

Research Subjects
Students taking standardized tests

Age/Grade of Subjects
Grades 3 to 12

Specified Disability

  • Visual Impairments
  • Hearing Impairments
  • Physical Disabilities
  • Learning Disabilities
  • English Language Learners (ELL)

Students with disabilities or who were learning English were provided with accommodations on standardized tests. The most common accommodations studied were:

  • oral test administration (31% of studies),
  • and extra time (20%).

Other accommodations which were studied less frequently included:

  • changes in test presentation (e.g. translating the test into Braille or sign language),
  • accommodations in test response methods (e.g. using a scribe or transcription),
  • and changes in settings (i.e. separate room for testing).

Duration of Intervention
Accommodations lasted for the length of the standardized test being administered, ranging from an hour to several days.


  1. All students benefit to some degree from accommodations such as extended time on tests or having the test read out loud to them. However, the gains for students with disabilities and English language learners (ELLs) were greater than the gains of their general education counterparts.
  2. There is a great amount of diversity among both students with disabilities and ELLs. This diversity among students coupled with variety of ways a single type of accommodation can be implemented make it difficult to make broad statements about the effects of a specific accommodation on a specific type of student.

Combined Effects Size
A limitation of many of the studies in this review was that they did not report effect sizes. Effect size is a statistical calculation, often represented as ES or d, that measures the impact of an intervention.The authors computed effect sizes for studies which provided enough information to do so, but it was not possible for all the studies so there was no combined effect size reported.

According to this review, all students benefit from certain accommodations such as extra time and oral presentation of exams. Students with disabilities, however, receive a greater benefit and demonstrate their true abilities more clearly when they are allowed to use accommodations. In fact, the authors suggest the fact that general education students benefit from accommodations may say more about overly stringent test conditions that plague standardized tests in general than it does about accommodations for students with disabilities being unfair.

One idea which the authors believe holds promise for providing an equitable testing experience for all students is the concept of Universal Design for Learning (UDL). UDL does not focus on accommodations for a subset of students, but instead strives to create tests that accommodate a wide spectrum of users in their basic design. UDL tests may allow for more flexible testing conditions without changing test results. For example, a UDL assessment may allow every student (not just those with testing accommodations listed in their IEPs) to take as much time as they need on tests because the tests would be assessing the students’ abilities in solving particular types of problems not their speed.

Though UDL as a concept holds promise for creating tests which would be equitable and accommodate a broad range of student abilities it has not been well researched. Hopefully, as UDL assessments are designed and implemented research will examine this new trend and discover if it lives up to the promise of providing assessments which are so universal that the need for accommodations is reduced or eliminated.


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