Trend estimation in international comparative large-scale assessments relies on measurement invariance between countries. However, cross-national differential item functioning (DIF) has been repeatedly documented. We ran a simulation study using national item parameters, which required trends to be computed separately for each country, to compare…

To design a series of assessments that could be used to compare the learning gains of high school students studying the cardiopulmonary system using traditional methods to those who used a collaborative computer simulation, called "Mr. Vetro". Five teachers and 264 HS biology students participated in the study. The students were in…

Performance in assessing the unidimensionality of tests was examined for four methods: (1) W. F. Stout's procedure (1987); (2) the approach of P. W. Holland and P. R. Rosenbaum (1986); (3) linear factor analysis; and (4) non-linear factor analysis. Each method was examined and compared with the others using simulated and real test data. Seven data…

More than a dozen statistical models have been developed for the purpose of cognitive diagnosis. These models are supposed to extract a much finer level of information from item responses than traditional unidimensional item response models. In this paper, a general diagnostic model (GDM) was used to analyze a set of simulated sparse data and real…