Differential Speededness and Item Omit Patterns on the SAT.

Two editions of the Verbal and Mathematical portions of the Scholastic Aptitude Test (SAT) were used to study differential speededness and differential omission and the relationships among differential item functioning (DIF), differential omission, and item difficulty for Asian-Americans, Blacks, Hispanics, and females. Consistent and replicable evidence of differential speededness was found for Blacks and Hispanics. Use of an unspeeded criterion for matching in place of the traditional total score, which contains speeded items, does not affect the DIF analyses of the speeded items. A strong artifactual negative relationship between DIF and differential omission was found. The relationship between differential omission and difficulty was consistently positive on the Verbal sections for all comparison groups except the Asian-American group, for whom it was consistently negative. On the Mathematical sections, this relationship was only consistently found for the female/male comparison, for whom it was negative. Finally, the relationship between difficulty and DIF was negative but smaller than previously observed.