Abstract

For a psychological test or instrument to function properly as intended, items in the test should measure respondents’ performance fairly across different groups of respondents such as male and female. In psychometric literature, the concept of differential item functioning (DIF) has been introduced to address the differential group performance on an item when the groups are equated at the same level of ability or latent trait status. This article introduces the concept of DIF while making a clear distinction of DIF from item bias and simple group performance difference since the civil rights error of the 1960’s in the United States, inequity has become a critical social issue. The area of educational and psychological testing is no exception. The use of testing as a sorting mechanism [1] has brought equity concerns to many people, specifically the testing enterprise.