ERIC Number: ED410288
Record Type: Non-Journal
Publication Date: 1997-Mar
Reference Count: N/A
Application of a Polynomial Loglinear Model to Assessing Differential Item Functioning for Common Items in the Common-Item Equating Design. ACT Research Report Series 97-1.
Hanson, Bradley A.; Feinstein, Zachary S.
Loglinear and logit models that have been suggested for studying differential item functioning (DIF) are reviewed, and loglinear formulations of the logit models are given. A polynomial loglinear model for assessing DIF is introduced that incorporates scores on the matching variable and item responses. The polynomial loglinear model contains far fewer parameters than loglinear models which treat the matching variable and item response as nominal. Compared to logit models that have been presented for investigating DIF, the polynomial loglinear model is easier to generalize to the case of more than two groups and more than two response categories, and can model more complex forms of DIF. The use of DIF methodology to investigate whether common items in the common-item equating design are functioning differently across test forms is discussed. Examples are given of using the polynomial loglinear model to investigate DIF for a test containing dichotomous and polytomous items and for investigating DIF for common items in a common-item nonequivalent groups equating design. (Contains 6 tables, 12 figures, and 20 references.) (Author/SLD)
ACT Research Report Series, P.O. Box 168, Iowa City, IA 52243-0168.
Publication Type: Reports - Evaluative
Education Level: N/A
Authoring Institution: American Coll. Testing Program, Iowa City, IA.