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Exact Small‐Sample Differential Item Functioning Methods for Polytomous Items With Illustration Based on an Attitude Survey
Author(s) -
Meyer J. Patrick,
Huynh Huynh,
Seaman Michael A.
Publication year - 2004
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.1745-3984.2004.tb01169.x
Subject(s) - polytomous rasch model , differential item functioning , sample (material) , psychology , item response theory , differential (mechanical device) , psychometrics , item analysis , statistics , mathematics , clinical psychology , chromatography , chemistry , engineering , aerospace engineering
Exact nonparametric procedures have been used to identify the level of differential item functioning (DIF) in binary items. This study explored the use of exact DIF procedures with items scored on a Likert scale. The results from an attitude survey suggest that the large‐sample Cochran‐Mantel‐Haenszel (CMH) procedure identifies more items as statistically significant than two comparable exact nonparametric methods. This finding is consistent with previous findings; however, when items are classified in National Assessment of Educational Progress DIF categories, the results show that the CMH and its exact nonparametric counterparts produce almost identical classifications. Since DIF is often evaluated in terms of statistical and practical significance, this study provides evidence that the large‐sample CMH procedure may be safely used even when the focal group has as few as 76 cases.