TitleComparing methods of assessing differential item functioning in a computerized adaptive testing environment
Publication TypeJournal Article
Year of Publication2006
AuthorsLei, P-W, Chen, S-Y, Yu, L
JournalJournal of Educational Measurement
Publication Languageeng
ISBN Number0022-0655 (Print)
Accession Number2006-10742-004
Keywordscomputerized adaptive testing, educational testing, item response theory likelihood ratio test, logistic regression, trait estimation, unidirectional & non-unidirectional differential item functioning

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)