Controlling Item Exposure Conditional on Ability in Computerized Adaptive Testing.

The interest in the application of large-scale adaptive testing for secure tests has served to focus attention on issues that arise when theoretical advances are made operational. Many such issues in the application of large-scale adaptive testing for secure tests have more to do with changes in testing conditions than with testing paradigms. One such issue is that of insuring item and pool security in the continuous testing environment made possible by the computerized administration of a test, as opposed to the more periodic testing environment typically used for linear paper-and-pencil tests. In the continuous testing environment of adaptive testing, methods have been developed in the past to use the computer to control the rate at which particular items are exposed to test-takers. These methods have typically employed randomization schemes, sometimes in reference to a particular target distribution of test-taker ability. This paper presents a new multinomial method of controlling the exposure rate of items conditional on the ability level of an individual test-taker. The properties of such conditional control on the exposure rates of items, when used in conjunction with a particular adaptive testing algorithm, are explored through five studies with simulated data. (Contains 1 table, 7 figures, and 17 references.) (Author)