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Differential Item Functioning on the Graduate Management Admission Test DIF GMAT

Author(s):
McPeek, W. Miles; O'Neill, Kathleen A.; Wild, Cheryl L.
Publication Year:
1993
Report Number:
RR-93-35
Source:
ETS Research Report
Document Type:
Report
Page Count:
84
Subject/Key Words:
Differential Item Functioning (DIF), Graduate Management Admission Test (GMAT), Item Analysis, Mantel-Haenszel Technique, Racial Differences, Sex Differences

Abstract

(84pp.) The purpose of this study was to identify differentially functioning items on operational administrations of the Graduate Management Admission Test (GMAT) through the use of the Mantel-Haenszel statistic. Retrospective analyses of data collected over a three-year period are reported for Black/White and female/male comparisons. Two tests are included in the analyses--Verbal and Quantitative. Data concerning the number of items identified as differentially difficult, the characteristics of the test questions associated with differential item difficulty, and the relationship of item difficulty to differential item functioning are discussed. In general, one percent to six percent of the items were identified as being differentially difficult per comparison with a greater number of items flagged in the female/male analyses than in the Black/White analyses. There was little overlap among the items flagged in the two analyses. Although the analyses suggested some content characteristics that may be related to differential item functioning, these findings about the GMAT items should be considered tentative since only a small number of items was studied and all investigations were post hoc analyses. Correlations between item difficulty and differential item functioning were generally low, with the exception of Quantitative items in the Black/White analyses. For these items, a moder- ately positive relationship existed between item difficulty and the differential item functioning statistic, showing that Black examinees performed differentially better than matched White examinees as item difficulty increased.

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