In theoretical cognitive science, there is a tension between highly structured models whose parameters have a direct psychological interpretation and highly complex, general-purpose models whose parameters and representations are difficult to interpret. The former typically provide more insight into cognition but the latter often perform better.…

A multilevel latent transition analysis (LTA) with a mixture IRT measurement model (MixIRTM) is described for investigating the effectiveness of an intervention. The addition of a MixIRTM to the multilevel LTA permits consideration of both potential heterogeneity in students' response to instructional intervention as well as a methodology for…

We examined whether strategies of memorization, transfer through elaboration, and metacognition accounted for reading, science, and mathematics achievement across 34 countries. 158,848 fifteen-year-olds completed a reading literacy test and a questionnaire. Of these students, 88,401 completed a science test, and 88,590 completed a mathematics…

An ability-based guessing model is formulated and applied to several data sets regarding educational tests in language and in mathematics. The formulation of the model is such that the probability of a correct guess does not only depend on the item but also on the ability of the individual, weighted with a general discrimination parameter. By so…

The methodological implications of using instructional information combined with the usual test item responses are discussed as they affect the linkage of achievement measurement and instruction. Models that expand those of standard Item Response Theory (IRT) are illustrated using achievement data from the United States sample of the Second…