SIMPOLYCAT: An SAS program for conducting CAT simulation based on polytomous IRT models

Abstract

A real-data simulation of computerized adaptive testing (CAT) is an important step in real-life CAT applications. Such a simulation allows CAT developers to evaluate important features of the CAT system, such as item selection and stopping rules, before live testing. SIMPOLYCAT, an SAS macro program, was created by the authors to conduct real-data CAT simulations based on polytomous item response theory (IRT) models. In SIMPOLYCAT, item responses can be input from an external file or generated internally on the basis of item parameters provided by users. The program allows users to choose among methods of setting initial , approaches to item selection, trait estimators, CAT stopping criteria, polytomous IRT models, and other CAT parameters. In addition, CAT simulation results can be saved easily and used for further study. The purpose of this article is to introduce SIMPOLYCAT, briefly describe the program algorithm and parameters, and provide examples of CAT simulations, using generated and real data. Visual comparisons of the results obtained from the CAT simulations are presented.