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…

In spite of the challenges inherent in making dozens of comparisons across heterogeneous populations, a relatively recent interest in scale-score equivalence for non-achievement measures in an international context has emerged. Until recently, operational procedures for establishing measurement invariance using multiple-groups analyses were…

Karabatsos compared the power of 36 person-fit statistics using receiver operating characteristics curves and found the "H[superscript T]" statistic to be the most powerful in identifying aberrant examinees. He found three statistics, "C", "MCI", and "U3", to be the next most powerful. These four statistics,…

Tests of model misfit are often performed to validate the use of a particular model in item response theory. Douglas and Cohen (2001) introduced a general nonparametric approach for detecting misfit under the two-parameter logistic model. However, the statistical properties of their approach, and empirical comparisons to other methods, have not…