Various applications of item response theory often require linking to achieve a common scale for item parameter estimates obtained from different groups. This article used a simulation to examine the relative performance of four different item response theory (IRT) linking procedures in a random groups equating design: concurrent calibration with…

This paper reviews the existing multidimensional item response theory (IRT) models and demonstrates how one of the models can be applied to estimation of abilities from a test measuring more than one dimension. The purposes of this paper were threefold. First, the fundamental concepts required when considering multidimensional models for the…

In this paper a quadratic curve equating method for different test forms under a random-group data-collection design is proposed. Procedures for implementing this method and related issues are described and discussed. The quadratic-curve method was evaluated with real test data (from two 30-item subtests for a professional licensure examination…