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Detecting DIF for Polytomously Scored Items: An Adaptation of the SIBTEST Procedure
Author(s) -
Chang HuaHua,
Mazzeo John,
Roussos Louis
Publication year - 1996
Publication title -
journal of educational measurement
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.917
H-Index - 47
eISSN - 1745-3984
pISSN - 0022-0655
DOI - 10.1111/j.1745-3984.1996.tb00496.x
Subject(s) - polytomous rasch model , statistics , type i and type ii errors , item response theory , mathematics , computer science , econometrics , psychometrics
Shealy and Stout (1993) proposed a DIF detection procedure called SIBTEST and demonstrated its utility with both simulated and real data sets'. Current versions of SIBTEST can be used only for dichotomous items. In this article, an extension to handle polytomous items is developed. Two simulation studies are presented which compare the modified SIBTEST procedure with the Mantel and standardized mean difference (SMD) procedures. The first study compares the procedures under conditions in which the Mantel and SMD procedures have been shown to perform well (Zwick, Donoghue, & Grima, 1993). Results of Study I suggest that SIBTEST performed reasonably well, but that the Mantel and SMD procedures performed slightly better. The second study uses data simulated under conditions in which observed‐score DIF methods for dichotomous items have not performed well. The results of Study 2 indicate that under these conditions the modified SIBTEST procedure provides better control of impact‐induced Type I error inflation than the other procedures.