We develop an Easy Java Simulation (EJS) model for students to experience the physics of idealized one-dimensional collision carts. The physics model is described and simulated by both continuous dynamics and discrete transition during collision. In designing the simulations, we discuss briefly three pedagogical considerations namely (1) a…

The procedures required to obtain the approximate posterior standard deviations of the parameters in the three commonly used item response models for dichotomous items are described and used to generate values for some common situations. The results were compared with those obtained from maximum likelihood estimation. It is shown that the use of…

Accuracy of item parameter estimates is a critical concern for any application of item response theory (IRT). However, the necessary sample sizes are often difficult to obtain in practice, particularly for the more complex models. A promising avenue of research concerns modified item response models. This study both replicates and improves on an…

The mathematical derivation of the statistics used for inference in some linear models assumes that the values of the independent variables are measured without error. This assumption is often disregarded when these models are utilized in research. This study is an investigation of the consequences of the violation of this assumption for one…

This paper describes quantitative tests which show the sophisticated-guessing model to be better than the criterion bias model in its ability to predict the outcome of certain kinds of recognition experiments. (Author/RK)

The potential of the Rasch model to develop scores, on a ratio scale, suitable for interindividual comparisons, from intact groups with disparate distribution characteristics was investigated. The specific problems studied were: (1) the effects of skewed test score distributions on the ability parameter of the Rasch measurement model; (2) the…