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ERIC Number: ED365707
Record Type: Non-Journal
Publication Date: 1993-Apr
Pages: 33
Abstractor: N/A
Reference Count: N/A
Evaluation of DTF and DIF in Two-Dimensional IRT.
Oshima, T. C.; And Others
In 1992 N. S. Raju and others proposed a general procedure for assessing differential test functioning (DTF) and item bias (differential item functioning or DIF) in tests developed with unidimensional, multidimensional, or polytomous item response theory (IRT) models. The purpose of this paper is to assess the adequacy and validity of their technique in the two-dimensional IRT setup. Following Raju and others, a chi square test is described for determining whether or not an observed DTF is significantly different from zero. When an observed DTF is statistically significant, one may begin the search for items that may be causing the significant chi square. After deletion of items with a high positive compensatory DIF, the DTF index and its chi square should be recomputed. The technique is illustrated with generated 40-item two-dimensional data sets. Once the multidimensional item parameters are given and differences in item parameters between the reference and focal groups are found, the new procedure identifies DTF and DIF as expected. Five tables present analysis results. (Contains 15 references.) (SLD)
Publication Type: Reports - Evaluative; Speeches/Meeting Papers
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A