Exploring the relation between socio-economic status and reading achievement in PISA 2009 through an intercepts-and-slopes-as-outcomes paradigm

• In the analyses done using hierarchal (multilevel) models the impact of within school differences in SES on performance was overshadowed by the impact of between school differences in SES.
• The impact of study orientation is systematic across countries; students in schools with a general orientation perform better than students in schools with a vocational orientation.
• The main effect of study orientation on the students’ achievement remains after accounting for SES in some countries while in others it almost disappears.
• With regard to the type of school, the private schools do not convey an academic advantage over public schools. In approximately half of the countries, the average score for the public schools is higher.
• In the remaining countries the difference in the average scores of private school over public schools virtually disappears after taking into account the SES attributes of their respective student populations.

In some countries more than others, factors like parental socio-economic status (SES) can cause inequalities in educational achievement. Here we show how the mechanisms leading to such inequalities can be scrutinized by involving background variables which impact the relation between SES and achievement. We use the intercepts-and-slopes-as-outcomes paradigm which recognizes that the outcomes of schooling systems are not only characterized by average achievement (the intercept) but also by the achievement–SES regression slope. We show how certain background variables moderate the relationship between SES and achievement. As an illustration, we examine the relationship between reading achievement and SES, and how this is moderated by school funding and curriculum. This is done for several countries that participated in the PISA 2009 cycle.