The effects of test dimensionality (one-or three-dimensional), distribution shape (normal, positively skewed, or platykurtic), and estimation program (BILOG, MULTILOG, or XCALIBRE) on the accuracy of item and person parameter estimates were assessed. The criterion was the root mean squared error of the difference between estimated and true parameter values. There was an interaction between program and dimensionality, indicating that the robustness of the unidimensionality assumption was a function of the estimation program. With the sample size and test length used, unidimensional estimation programs were insensitive to different shapes of the underlying. distribution. BILOG consistently produced the smallest root mean squared error under most conditions. However, MULTILOG and XCALIBRE showed less variance in parameter estimation due to the violation of unidimensionality, with the exception of estimating the discrimination parameter in MULTILOG. Guidelines for estimating parameters of multidimensional test items using unidimensional item response theory models are suggested.

No abstract

No abstract

The suitability of fitting a two-parameter logistic item response model to the Drug Use Screening Inventory (DUSI) was assessed. In a sample of 846 adolescents, each of the 10 domains was found to be unidimensional. Invariance of the item parameters across different groups was also observed. The reliability coefficient, based on item response theory, was found to be superior. The results of these analyses indicate that the DUSI has sound psychometric properties.

This paper describes a comprehensive system of microcomputer programs that was developed as a tool for teachers to use for (a) improving instruction and classroom tests, and (b) evaluating and reporting student learning. The programs implement many of the suggestions made in standard educational measurement textbooks for how to use data from tests to improve instructional decision‐making in the classroom and to improve quality of classroom testing. The paper describes the three main components of the system: (a) a student data‐base with associated information retrieval and computational programs, (b) a test item analysis and evaluation component that can be used for guiding instruction, and (c) a test item banking and test assembly component. In the course of the description, several microcomputer program design considerations are discussed.