Once raw scores from The OECD Programme for International Student Assessment (PISA) were adjusted according to school and student SES backgrounds, children in all school sectors performed the same in scientific and reading literacies tests.

However, in mathematical literacy, the adjusted figures showed public school students were achieving at a higher level than Catholic school students.

The raw data paints a grimmer picture of the extent to which students' socio-economic background, and where they attend school, will affect their academic performance.

According to unadjusted figures, public school students lagged around one-and-a-half years behind those in independent schools, and around three-quarters of a year behind Catholic school students across all three tested areas.

Dr Sue Thomson, ACER Deputy CEO (Research) and PISA National Project Manager, said it was irrelevant if students attend a private or public school because the biggest factor that will determine their academic success at school is the SES profile they come from.

“Actually what it tells us is that there is a huge gap, but once you adjust it for socio economic background there is no gap - so that’s one of the important things to understand: the differences between the students in those schools, a lot of it comes down to socio-economic background.

“So if you have kids with the same background, same resources, same level of aspiration etcera, it really doesn’t matter whether they go to a private school - they are going to end up in a similar position educationally,” Thomson said.

Thomson believes that although the OECD might class Australia as a ‘high equity’ country, these findings suggest we are anything but, at least when it comes to education.

“…I don’t really think we are high equity at the moment.”

Notably, across the board in mathematical literacy, scientific literacy and reading literacy, students at independent schools showed the biggest decrease in average performance between 2009 and 2018 cycles.

“…private schools have actually gone down by as much, if not more than the government schools have…” Thomson notes.

Australian Education Union Federal President Correna Haythorpe said that the PISA report holds no surprises for teachers who work in disadvantaged settings. 

“Resource gaps are evident in the Morrison Government’s school funding architecture and this has a big impact at the school level in terms of staffing and learning programs,” Haythorpe said.

“The Morrison Government’s claims of record school funding belies the fact that there are huge equity gaps in school funding in Australia. The PISA 2018 results highlight the impact of six years of Federal Coalition failure when it comes to properly funding and resourcing public schools,” she added. 

“The Morrison Government’s policy of school funding inequity is short-changing a generation of Australian students by creating a system of ‘haves and have nots’.”

PISA is a major international measurement that assesses the reading, mathematics and science literacy of 15-year-old students and has been conducted every three years since 2000.

PISA 2018 was conducted in Australia by ACER, which publishes the latest results on behalf of Australian Government and state and territory governments.