The comparability of scores on test forms that are constructed through examinee item choice is examined in an item response theory framework. The approach is illustrated with data from the College Board's Advanced Placement Test in Chemistry taken by over 18,000 examinees. (SLD)

When an examination consists, in whole or in part, of constructed response items, it is a common practice to allow the examinee to choose among a variety of questions. This procedure is usually adopted so that the limited number of items that can be completed in the allotted time does not unfairly affect the examinee. This results in the de facto…