Mixed-format tests that include both multiple-choice (MC) and constructed-response (CR) items have become widely used in many large-scale assessments. When an item response theory (IRT) model is used to score a mixed-format test, the unidimensionality assumption may be violated if the CR items measure a different construct from that measured by MC…

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…