ABSTRACT
This chapter provides a conceptual basis for understanding the important role of validity in item development. First, basic terms are defined. Validity refers to a logical process we follow in testing where what we measure is defined, measures are created, and evidence is sought and evaluated pertaining to the validity of interpreting a test score and its subsequent use. This logical process applies equally to tests and the units that make up tests, namely, test items. This process involves the validity of test score interpretations and uses and the validity of item response interpretations and uses. In fact, a primary source of evidence in validating a test score interpretation or use comes from item development. Thus, we should think of the validation of item responses as a primary and fundamental source of validity evidence for test score interpretation and use.
