Measuring the need of the neediest − An investigation of PISA for Development’s Family Resources Index at the extremes of the distribution

International large-scale assessments (ILSAs) use proxy variables and scales to gain a sense of a student’s family background and socioeconomic status (SES). Historically, ILSAs have helped quantify how inputs influence outputs in educational systems, to compare systems of education, to yield educational trends, and to guide policymakers and other stakeholders to improve education quality. However, when those indicators and scales have flaws, we make incorrect assumptions, create faulty models, and derive erroneous conclusions. More importantly, because results of ILSAs inform policy, we risk engaging in decision-making inequitably with real human consequences. In this study, we trace the history of SES scales, discuss existing critiques, and review solutions and innovations. We then place a spotlight on one of those problems, the poor targeting of SES scales at the extremes of the distribution (i.e., high and low SES), and investigate whether items from PISA for Development’s student contextual questionnaire adequately target the Family Resources Index (FRI) scale across the seven countries that participated in Strand B. Although we find that items reasonably target the FRI scale, the nature of targeting varies across countries and appears to depend on the level of national economic development. Further, we challenge researchers to shift their focus from exclusively measuring the background and identities of students and their families to also measuring how systems and structures themselves cause inequities.