The risk of accommodations is that they may provide the wrong correction. They may provide too weak a correction, leaving the scores of individuals with disabilities lower than they should be, or they may provide an irrelevant correction or an excessive one, distorting or changing scores further and undermining rather than enhancing validity. This risk is explicitly recognized in the guidelines provided by some state education agencies for avoiding these errors, although their guidance is sometimes very general and limited. For example, Maryland's Requirements and Guidelines for Exemptions, Excuses, and Accommodations for Maryland Statewide Assessment Programs (Maryland State Department of Education, 1995) says that "accommodations must not invalidate the assessment for which they are granted" (p. 2, emphasis in the original). However, the only guidance it provides for meeting this standard is a single pair of examples (p. 3):
Addressing the issue of validity involves an examination of the purpose of test and the specific skills to be measured. For example, if an objective of the writing test is to measure handwriting ability, that objective would be substantially altered by allowing a student to dictate his/her response. On the other hand, if a writing objective stated that the student was to communicate thoughts or ideas, handwriting might be viewed as only incidental to achieving the objective. In the latter case, allowing the use of a dictated response probably would not appreciably change the measurement of the objective.
Unfortunately, many cases will be far less clear than this, and accommodations may not succeed in increasing validity even when they seem clear and logical on their face (pp. 173, 176–177).
Many approaches to the assessment of individuals with disabilities, particularly assessment accommodations, assume that disabilities are not directly related to the construct tested. Case law indicates that rights to accommodations do not apply when the disability is directly related to the construct tested (see Phillips, 1994). In other words, a student with a reading disability might be allowed help with reading (the accommodation) on a mathematics test, since reading is not in the construct being measured, but would not be allowed help with reading on a reading test, since the disability is directly related to the construct of reading.
However, the groups of students with clearly identifiable disabilities (such as motor impairments) that are largely unrelated to the constructs being tested constitute a small number of the identified population of students with disabilities. Most students with disabilities have cognitive impairments that presumably are related to at least some of the constructs tested.
Relationship between disabilities and assessed constructs have important implications for the validity of inferences based on test scores. For example, if a new assessment includes communication skills as an important part