A norm-referenced test is a standardized test that compares a student's test performance with that of a sample of similar students who have taken the same test. After constructing a test, the test developers administer it to a standardization sample of students using the same administration and scoring procedures for all students. This makes the administration and scoring "standardized." The test scores of the standardization sample are called norms, which include a variety of types of scores. Norms are the scores obtained by the standardization sample and are the scores to which students are compared when they are administered a test.

Once test developers standardize a norm-referenced test, examiners can administer it to students with similar characteristics to the norm group and can compare the scores of these students with those of the norm group. Norm-referenced standardized tests can use local, state, or national norms as a base. Because of the comparison of scores between a norm group and other groups of students, a norm-referenced test provides information on the relative standing of students.

When assessing students with disabilities, evaluators should employ caution before making comparisons or interpretations stemming from established norms. It is possible to use typical norms when making interpretations that draw from the relative performance of the students with disabilities and from the general population of students. However, when making comparisons or interpretations that use level or degree of disability, normative data should come from the sample population to which comparisons are made.

Test manuals should provide sufficient details about the normative group so that test users can make informed judgments about the appropriateness of the norm sample (American Educational Research Association et al., 1999).