Advances in Clinical Personality Measurement: An Item Response Theory Analysis of the MMPI-2 PSY-5 Scales

Item response theory (IRT) provides valuable methods for the analysis of the psychometric properties of a psychological measure. To date, however, these methods have not been used frequently by personality assessment researchers, in part because many researchers have not been introduced to the methods and in part because most of the development of IRT has taken place in applied education assessment settings, resulting in terminology that is ability focused rather than trait focused. The purpose of this article is twofold. First, an overview of IRT is presented, highlighting the concepts of the three-parameter IRT model, item and test information, and conditional standard error of measurement. Second, the psychometric properties of the (MMPI-2) PSY-5 scales are examined to demonstrate IRT's value.