Type I error rates of Lord’s X² chi; test for differential
item functioning were investigated using monte carlo
simulations. Two- and three-parameter item response
theory (IRT) models were used to generate 50-item
tests for samples of 250 and 1,000 simulated examinees.
Item parameters were estimated using two algorithms
(marginal maximum likelihood estimation and
marginal Bayesian estimation) for three IRT models (the
three-parameter model, the three-parameter model
with a fixed guessing parameter, and the two-parameter
model). Proportions of significant X²s at selected
nominal α levels were compared to those from joint
maximum likelihood estimation as reported by
McLaughlin & Drasgow (1987). Type I error rates for
the three-parameter model consistently exceeded theoretically
expected values. Results for the three-parameter
model with a fixed guessing parameter and for the
two-parameter model were consistently lower than expected
values at the a levels in this study. Index
terms: differential item functioning, item response
theory, Lord’s X².
Kim, Seock-Ho, Cohen, Allan S & Kim, Hae-Ok. (1994). An investigation of Lord's procedure for the detection of differential item functioning. Applied Psychological Measurement, 18, 217-228. doi:10.1177/014662169401800303
Kim, Seock-Ho; Cohen, Allan S.; Kim, Hae-Ok.
An investigation of Lord's procedure for the detection of differential item functioning.
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