Chapter 1 Generalizability Theory and Item Response Theory

Item response theory is usually applied to items with a selected-response format, such as multiple choice items, whereas generalizability theory is usually applied to constructed-response tasks assessed by raters. However, in many situations, raters may use rating scales consisting of items with a selected-response format. This chapter presents a short overview of how item response theory and generalizability theory were integrated to model such assessments. Further, the precision of the estimates of the variance components of a generalizability theory model in combination with twoand three-parameter models is assessed in a small simulation study.