ERIC Number: ED563094
Record Type: Non-Journal
Publication Date: 2005
Abstractor: As Provided
Reference Count: 16
Using DIF Dissection Method to Assess Effects of Item Deletion. Research Report No. 2005-10. ETS RR-05-23
Zhang, Yanling; Dorans, Neil J.; Matthews-López, Joy L.
Statistical procedures for detecting differential item functioning (DIF) are often used as an initial step to screen items for construct irrelevant variance. This research applies a DIF dissection method and a two-way classification scheme to SAT Reasoning Test™ verbal section data and explores the effects of deleting sizable DIF items on reported scores after re-equating. The DIF dissection approach and the two-way classification scheme may yield new and detailed insight into item functioning at the subgroup level. Two hypotheses are studied: (1) whether or not the deletion of a sizeable DIF item that is the most disadvantageous to a particular subgroup will affect the scores for that subgroup the most; and (2) whether or not the effects of item deletion on scores can be predicted by the standardization method. Both hypotheses are supported by the results of this research. The following are appended: (1) Summary of Two-Way "STD FS-DIF" Effects and Unrounded Observed Scaled Score Differences for the Subgroups after DIF Item Deletion; and (2) The Local Approximation Algorithm.
Descriptors: Test Bias, Test Items, Statistical Analysis, Classification, College Entrance Examinations, Verbal Tests, Scores, Equated Scores
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Publication Type: Reports - Research
Education Level: Higher Education; Postsecondary Education
Authoring Institution: College Board; Educational Testing Service
Identifiers - Assessments and Surveys: SAT (College Admission Test)