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ERIC Number: EJ828147
Record Type: Journal
Publication Date: 2009
Pages: 12
Abstractor: As Provided
ISBN: N/A
ISSN: ISSN-0731-1745
EISSN: N/A
An NCME Instructional Module on Using Differential Step Functioning to Refine the Analysis of DIF in Polytomous Items
Penfield, Randall D.; Gattamorta, Karina; Childs, Ruth A.
Educational Measurement: Issues and Practice, v28 n1 p38-49 Spr 2009
Traditional methods for examining differential item functioning (DIF) in polytomously scored test items yield a single item-level index of DIF and thus provide no information concerning which score levels are implicated in the DIF effect. To address this limitation of DIF methodology, the framework of differential step functioning (DSF) has recently been proposed, whereby measurement invariance is examined within each step underlying the polytomous response variable. The examination of DSF can provide valuable information concerning the nature of the DIF effect (i.e., is the DIF an item-level effect or an effect isolated to specific score levels), the location of the DIF effect (i.e., precisely which score levels are manifesting the DIF effect), and the potential causes of a DIF effect (i.e., what properties of the item stem or task are potentially biasing). This article presents a didactic overview of the DSF framework and provides specific guidance and recommendations on how DSF can be used to enhance the examination of DIF in polytomous items. An example with real testing data is presented to illustrate the comprehensive information provided by a DSF analysis.
Blackwell Publishing. 350 Main Street, Malden, MA 02148. Tel: 800-835-6770; Tel: 781-388-8599; Fax: 781-388-8232; e-mail: customerservices@blackwellpublishing.com; Web site: http://www.blackwellpublishing.com/jnl_default.asp
Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
IES Funded: Yes
Grant or Contract Numbers: R305C050052