This course provides an introduction to Item Response Theory (IRT) with a focus on theoretical foundations and basic applications to problems of test or scale development. Topics covered include:
(1) concepts, models & features of IRT models,
(2) ability and item parameter estimation,
(3) assessment of model data fit,
(4) the ability scale,
(5) test and item information, and
(6) test and/or scale construction issues.
For the topics above, dichotomous and polytomous item response models are presented with example applications and discussion. Introduction and use of state of the art IRT/Factor Analysis software (BILOG-MG, PARSCALE, and TESTFACT) is provided. To maximize learning, participants should bring a data set for use specific to their own research.