Contextualising the achievement gap: assessing educational achievement, inequality, and disadvantage in high-Income countries

We examine the disparities in educational outcomes for highincome countries as they are reported by the Programme for International Student Assessment (PISA), with a specific emphasis on a more nuanced exploration of SES-based achievement gaps. To explore differences in the educational inequality and disadvantages associated with SES-based achievement gaps by country, we analyze three measures: overall average performance, educational inequality (or achievement gaps), and educational disadvantage (comparative achievement gap patterns). We find that, when examined together, these three measures are instructive for understanding the differences in educational outcomes across countries. Our findings offer insight into the PISA results that go beyond average achievement. We recommend that country-level averages should not be emphasised or interpreted without also considering educational inequality and disadvantage.