The Interaction of Ability Differences and Guessing When Modeling Differential Item Functioning With the Rasch Model: Conventional and Tailored Calibration.In educational testing, differential item functioning (DIF) statistics must be accurately estimated to ensure the appropriate items are flagged for inspection or removal.  This study showed how using the Rasch model to estimate DIF may introduce considerable bias in the results when there are large group differences in ability (impact) and the data follow a three-parameter logistic model.  In terms of practical implications, results suggest that measurement practitioners should not trust the DIF estimates from the Rasch model when there is a large difference in ability and examinees are potentially able to answer items correctly by guessing, unless data from examinees poorly matched to the item difficulty are coded as missing.
Rasch
The Interaction of Ability Differences and Guessing When Modeling Differential Item Functioning With the Rasch Model: Conventional and Tailored Calibration.In educational testing, differential item functioning (DIF) statistics must be accurately estimated to ensure the appropriate items are flagged for inspection or removal.  This study showed how using the Rasch model to estimate DIF may introduce considerable bias in the results when there are large group differences in ability (impact) and the data follow a three-parameter logistic model.  In terms of practical implications, results suggest that measurement practitioners should not trust the DIF estimates from the Rasch model when there is a large difference in ability and examinees are potentially able to answer items correctly by guessing, unless data from examinees poorly matched to the item difficulty are coded as missing.
the Rasch model