A Procedure for Controlling General Test Overlap in Computerized Adaptive Testing

Abstract

To date, exposure control procedures that are designed to control test overlap in computerized adaptive tests (CATs) are based on the assumption of item sharing between pairs of examinees. However, in practice, examinees may obtain test information from more than one previous test taker. This larger scope of information sharing needs to be considered in conducting test overlap control. The purpose of this study is to propose a test overlap control method such that the proportion of overlapping items encountered by an examinee with a group of previous examinees (described as general test overlap rate) can be controlled. Results indicated that item exposure rate and general test overlap rate could be simultaneously controlled by implementing the procedure. In addition, these two indices were controlled on the fly without any iterative simulations conducted prior to operational CATs. Thus, the proposed procedure would be an efficient method for controlling both the item exposure and general test overlap in CATs.