APA Dictionary of Psychology

a set of test items that are developed to be similar to another set of test items, so that the two sets represent different versions of the same test. In order to demonstrate that one test is an alternate form of the other, a researcher usually must show that there is matching content (each test has the same number of each kind of item) and that factor loadings and measurement errors are approximately the same across the two versions. Alternate forms of a test can be used to measure its reliability (see alternate-forms reliability). Also called comparable form; equivalent form; parallel form.