the index is built to be internationally comparable see the pisa technical report oecd a students are considered socioeconomically advantaged if they are among the of students with the highest escs in their country or economy socioeconomically disadvantaged students are those among the of students with the lowest escs schools are defined as socioeconomically advantaged disadvantaged if the average escs of students in the school is statistically significantly above below that of the average school these patterns reflect in part the inherent advantages in resources that relatively high socioeconomic status provides