Abstract:Item response theory ( IRT ) methods are alternatives to classical test theory ( CTT ) approaches to scale construction, analysis, and scoring. A differentiating feature of IRT modeling is the estimat...Item response theory ( IRT ) methods are alternatives to classical test theory ( CTT ) approaches to scale construction, analysis, and scoring. A differentiating feature of IRT modeling is the estimation of a mathematical function that relates individual differences on a continuous latent variable to the propensity to respond to a scale item (e.g., respond correctly to a multiple‐choice aptitude item, or respond in category 3 on a five‐point ordered rating scale). Commonly applied IRT models appropriate for dichotomous and polytomous item response data are described. Assumptions underlying these models and interpretation of indices derived from model parameters are presented. Finally, popular applications of IRT models, such as computerized adaptive testing, are summarized.Read More