TitleThe implications of the use of non-optimal items in a Computer Adaptive Testing (CAT) environment
Publication TypeJournal Article
Year of Publication2002
AuthorsGrodenchik, DJ
JournalDissertation Abstracts International: Section B: the Sciences & Engineering
Publication Languageeng
Keywordscomputerized adaptive testing

This study describes the effects of manipulating item difficulty in a computer adaptive testing (CAT) environment. There are many potential benefits when using CATS as compared to traditional tests. These include increased security, shorter tests, and more precise measurement. According to IRT, the theory underlying CAT, as the computer continually recalculates ability, items that match that current estimate of ability are administered. Such items provide maximum information about examinees during the test. Herein, however, lies a potential problem. These optimal CAT items result in an examinee having only a 50% chance of a correct response. Some examinees may consider such items unduly challenging. Further, when test anxiety is a factor, it is possible that test scores may be negatively affected. This research was undertaken to determine the effects of administering easier CAT items on ability estimation and test length using computer simulations. Also considered was the administration of different numbers of initial items prior to the start of the adaptive portion of the test, using three different levels of measurement precision. Results indicate that regardless of the number of initial items administered, the level of precision employed, or the modifications made to item difficulty, the approximation of estimated ability to true ability is good in all cases. Additionally, the standard deviations of the ability estimates closely approximate the theoretical levels of precision used as stopping rules for the simulated CATs. Since optimal CAT items are not used, each item administered provides less information about examinees than optimal CAT items. This results in longer tests. Fortunately, using easier items that provide up to a 66.4% chance of a correct response results in tests that only modestly increase in length, across levels of precision. For larger standard errors, even easier items (up to a 73.5% chance of a correct response) result in only negligible to modest increases in test length. Examinees who find optimal CAT items difficult or examinees with test anxiety may find CATs that implement easier items enhance the already existing benefits of CAT. (PsycINFO Database Record (c) 2003 APA, all rights reserved).