A method for constructing a bank of items scored in two or more ordered response categories is described and illustrated. This method enables multistep problems, rating scale items, question 'clusters', and other items using partial credit scoring to be calibrated and incorporated into an item bank, and it provides a mechanism for computer adaptive testing with items of this type. Procedures are described for calibrating an initial set of items, for testing the fit of items to the underlying measurement model, and for linking new items to an existing item bank. The method is illustrated using items from the Watson-Glaser Critical Thinking Appraisal. The psychometric method used to transform a collection of items into a coherent measuring system is perhaps the most important part of an item bank. The procedure described and applied in this article is based on a simple extension of Rasch's dichotomous measurement model to responses scored in more than two response categories.
- Item banks,
- Rasch model,
- Partial credit scoring,
- Watson-Glaser Critical Thinking Appraisal
Available at: http://works.bepress.com/geoff_masters/192/