%0 Journal Article %J Journal of Educational Measurement %D 2006 %T Comparing methods of assessing differential item functioning in a computerized adaptive testing environment %A Lei, P-W. %A Chen, S-Y. %A Yu, L. %K computerized adaptive testing %K educational testing %K item response theory likelihood ratio test %K logistic regression %K trait estimation %K unidirectional & non-unidirectional differential item functioning %X Mantel-Haenszel and SIBTEST, which have known difficulty in detecting non-unidirectional differential item functioning (DIF), have been adapted with some success for computerized adaptive testing (CAT). This study adapts logistic regression (LR) and the item-response-theory-likelihood-ratio test (IRT-LRT), capable of detecting both unidirectional and non-unidirectional DIF, to the CAT environment in which pretest items are assumed to be seeded in CATs but not used for trait estimation. The proposed adaptation methods were evaluated with simulated data under different sample size ratios and impact conditions in terms of Type I error, power, and specificity in identifying the form of DIF. The adapted LR and IRT-LRT procedures are more powerful than the CAT version of SIBTEST for non-unidirectional DIF detection. The good Type I error control provided by IRT-LRT under extremely unequal sample sizes and large impact is encouraging. Implications of these and other findings are discussed. all rights reserved) %B Journal of Educational Measurement %I Blackwell Publishing: United Kingdom %V 43 %P 245-264 %@ 0022-0655 (Print) %G eng %M 2006-10742-004 %0 Journal Article %J Applied Psychological Measurement %D 2005 %T Controlling item exposure and test overlap in computerized adaptive testing %A Chen, S-Y. %A Lei, P-W. %K Adaptive Testing %K Computer Assisted Testing %K Item Content (Test) computerized adaptive testing %X This article proposes an item exposure control method, which is the extension of the Sympson and Hetter procedure and can provide item exposure control at both the item and test levels. Item exposure rate and test overlap rate are two indices commonly used to track item exposure in computerized adaptive tests. By considering both indices, item exposure can be monitored at both the item and test levels. To control the item exposure rate and test overlap rate simultaneously, the modified procedure attempted to control not only the maximum value but also the variance of item exposure rates. Results indicated that the item exposure rate and test overlap rate could be controlled simultaneously by implementing the modified procedure. Item exposure control was improved and precision of trait estimation decreased when a prespecified maximum test overlap rate was stringent. (PsycINFO Database Record (c) 2005 APA ) (journal abstract) %B Applied Psychological Measurement %V 29 %P 204-217 %G eng