Using subpopulation invariance to assess test score equity

Score equity assessment (SEA) is introduced, and placed within a fair assessment context that includes differential prediction or fair selection and differential item functioning. The notion of subpopulation invariance of linking functions is central to the assessment of score equity, just as it has been for differential item functioning and differential prediction. Advanced Placement (AP) data are used for illustrative purposes. The use of multiple-choice and constructed response items in AP provides an opportunity to observe a case where subpopulation invariance of linking functions does not hold (U.S. History), and a case in which it does hold (Calculus AB). The lack of invariance for U.S. History might be attributed to several sources. The role of SEA in assessing the fairness of test assembly processes is discussed.