The extent to which the test scores or responses measure the attribute(s) that they were designed to measure. Several types of validity are described below. See Generalizability, Validation, Validity Coefficient.
* Concurrent: the relationship of one measure to another simultaneous measure or variable assessing the same or a related attribute.
* Consequential Basis of Validity: the assemblage of information on the theoretical and value implications of the way that the results of testing are used, and the appraisal of both the potential and actual social consequences of the testing, including side effects.
* Construct: the degree of fit of a measure and its interpretation with its underlying explanatory concepts, theoretical rationales, or foundations.
* Content: (1) the appropriateness of the domain definition and the sampling of content. (2) the extent of congruence between the scope of a content area that an instrument or process claims to cover and what it actually does cover. Both definitions are aspects of construct validity.
* Criterion-Related: the correlation or extent of agreement of the test score from an assessment with one or more external variables that measure the attribute being assessed.
* Curricular: the extent to which the items on the assessment or test measure the content of a local curriculum, or the extent of agreement between the test coverage (topics, breadth and depth, skills, cognitive complexity) and the goals and objectives of the curriculum.
* Evidential Basis of Validity: the assemblage of information about the construct validity of the test scores and measurements, as well as the relevance of the measurement to its applied purpose and its utility in an applied setting. Construct validity, in this case, includes information collected from content and criterion-related validation procedures.
* Face: the perceived extent of acceptability or legitimacy of an instrument or process to teachers, administrators, policymakers, students, parents, the general public, and other stakeholders concerned with teacher evaluation and the quality of teaching.
* Instructional: the degree to which the items on a test measure: (a) what is actually being taught, and (b) what the individuals being assessed have had an opportunity to learn.
* Predictive: the relationship of a measure to performance in a future context such as a new work setting or to the results obtained on a future measure assessing a similar or a different (but presumably related) attribute.
* Systemic: the negative and positive consequences of testing that should be monitored in order to evaluate the long-range value of the test.

This definition is in context to Teacher Evaluation. See more contextual defintions for Validity.