Publication Date
2010
Document Type
Thesis
Committee Members
Gary Burns (Committee Member), David Lahuis (Advisor), Debra Steele-Johnson (Committee Member)
Degree Name
Master of Science (MS)
Abstract
This study examined two methods for detecting differential item functioning (DIF): Raju, van der Linden, and Fleer's (1995) differential functioning of items and tests procedure (DFIT) and Thissen, Steinberg, and Wainer's (1988) likelihood ratio test (LRT). The major research questions concerned which test provides the best balance of Type I errors and power and if the tests differ in terms of detecting different types of DIF. Monte Carlo simulations were conducted to address these questions. Equal and unequal sample size conditions were fully crossed with test lengths of 10 and 20 items. In addition, α and β parameters were manipulated in order to simulate DIF. Findings indicate that the DFIT and LRT both had acceptable Type I error rates when sample sizes were equal, but that DFIT produced too many Type I errors when sample sizes were unequal. Overall, the LRT exhibited greater power to detect both α and β parameter DIF than DFIT. However, DFIT was more powerful than LRT when the last two β parameters had DIF as opposed to the extreme β parameters. Therefore, it is recommended under most circumstances to use the LRT for DIF detection, unless there is reason to believe that the DIF is at the high end of the scale.
Page Count
52
Department or Program
Department of Psychology
Year Degree Awarded
2010
Copyright
Copyright 2010, all rights reserved. This open access ETD is published by Wright State University and OhioLINK.
