Capitalization on item calibration error in computer adaptive testing

In adaptive testing, item selection is sequentially optimized during the test. Since the optimization takes place over a pool of items calibrated with estimation error, capitalization on these errors is likely to occur. How serious the consequences of this phenomenon are depends not only on the distribution of the estimation errors in the pool or the ratio of the test length to the pool size, but also on the structure of the item-selection criteria used. A simulation study demonstrated the existence of the phenomenon empirically. It also showed that its effect on the errors in the ability estimates interacts strongly with the distribution of the items in the pool.