A method of estimating conditional standard error of measurement at specific score/ability levels is described that avoids theoretical problems identified for previous methods. The method focuses on variance of observed scores conditional on a fixed value of an observed parallel measurement, decomposing these variances into true and error parts.…

To provide an introduction to item-response theory (IRT) for individuals with modest statistical and mathematical skills, the book emphasizes a conceptual approach to understanding IRT concepts. The book fills the gap between mathematically detailed studies and summary chapters on IRT in general texts. (SLD)