Differential Validity and Differential Prediction of Cognitive Ability Tests: Understanding Test Bias in the Employment Context

Substantial mean score differences and significant adverse impact have long motivated the question of whether cognitive ability tests are biased against certain non-White subgroups. This article presents a framework for understanding the interrelated issues of adverse impact and test bias, with particular focus on two forms of test bias especially relevant for personnel selection: differential validity and differential prediction. Ethical and legal reasons that organizations should be concerned about differential validity/prediction are discussed. This article also serves as a critical review of the research literature on differential validity/prediction. The general conclusion is that available evidence supports the existence of differential validity/prediction in the form of correlation/slope and intercept differences between White and non-White subgroups. Implications for individuals and organizations are outlined, and a future research agenda is proposed highlighting the need for new, better data; new, better methods of testing for differential validity/prediction; and investigation of substantive factors causing differential validity/prediction.