Item Response Theory Methods

Abstract

The use of item response theory (IRT) in testing applications has grown considerably over the past 15 years. This growth has been reinforced by the many publications in the area (e.g., Baker, 1992a; Hambleton and Swaminathan, 1985; Hambleton et al., 1991; Lord, 1980; 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 it explicitly modeling 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.