The definition of differential item performance (DIP), often referred to as item bias, is discussed. DIP is suggested as a comprehensive term to encompass item bias (item invalidity which is unfair to certain population subgroups) and instructional bias (a valid reflection of group differences in instruction or background). This study investigated…

A procedure for the detection of differential item performance (DIP) is used to investigate the relationships between characteristics of mathematics achievement items and gender differences in performance. Eight randomly equivalent samples of high school seniors were each given a unique form of the ACT Assessment Mathematics Usage Test (ACTM).…