Item Response Theory Methods

Abstract

Item response theory (IRT) methods are used in many testing applications, and the use of IRT has been reinforced by many book-length treatments (e.g., Baker, 1992a; Hambleton and Swaminathan, 1985; Hambleton et al., 1991; Lord, 1980; van der Linden and Hambleton, 1997; Wright and Stone, 1979). Applications of IRT include test development, item banking, differential item functioning, adaptive testing, test equating, and test scaling. A major appeal of IRT is that it provides an integrated psychometric framework for developing and scoring tests. Much of the power of IRT results from the fact that it explicitly models examinee responses at the item level, whereas, for example, the focus of classical test models and strong true score models is on responses at the level of test scores.