Over the past decade, the number of high-achieving students at Australia's most advantaged schools has increased, while other schools have been left stranded.
The gap between high and low socioeconomic high schools is widening as struggling schools are left to support the most disadvantaged students, a new report has found.
Research from the Centre for Policy and Development, released on Wednesday, reveals that high achievers are increasingly populating the most advantaged schools while achievement levels for students in low SES schools are declining.
“We’ve long known that the results coming out of schools reflect who they enrol, but increasingly we are seeing growing clusters of high-achieving students in the most advantaged schools, leaving other schools stranded,” author of the report and former school principal Chris Bonnor said.
He told SBS News that while schools always vary in quality, the results go beyond the innate qualities of the school and teachers, and are instead more dependent on the socioeconomic status of the cohort.
“The reality is, sadly, that there is a peer effect,” Mr Bonnor said.
“It’s very complicated. Parents tend to think about it as if you go to a high-achieving school the competition will be good for him or her and it’s not quite like that.
“In schools that are chock-a-block full of aspirational kids, teacher expectations are higher, the curriculum is more diverse and deeper, the resources are more easily available. There are a number of things that interact with each other to create a positive effect at the top end of schools and a residual effect at the lower SES end of schools."
In the last decade, the research - which looks at data from NSW, Victoria, and Queensland - found that the number of high achievers enrolled in high SES schools had increased in each state, while falling in their lower SES counterparts.
In the NSW research, a high achiever was defined any student who received at least one HSC subject result in the highest band possible (Band 6 or Band E4 for an extension course).
According to the data, in 2017 the percentage of high-achieving students in NSW schools within the highest Index of Community Socio-Educational Advantage (ICSEA) range (1150 and over) was 18.49 per cent, compared to only 1.22 per cent in the lowest ICSEA range (up to 949). This is a jump of more than 5 per cent in the higher SES bracket since 2009, while at the lower end, the percentage dropped by 0.37 per cent.
The ICSEA school rating takes into account parental education levels, parental occupation, the school's geographical location and the proportion of Indigenous students to calculate a score for each school, with the average score sitting at 1000.
For Victoria, the data considered scores above 40 in the Victorian Certificate of Education (VCE) as high achieving and found, similar to NSW, that at schools with high educational advantage, the percentage of high achievers had increased by 0.9 per cent over the last decade, while in the lowest ICSEA group, the number had decreased by 0.7 per cent.
In Queensland, schools in the top group of ICSEA ratings also saw an increased number of high achievers between 2009 and 2017.
"This paper shows what happens to student achievement when we segregate our student population, with the strugglers ending up in 'a class of their own' in the schools with a declining capacity to lift them."
How did we get here?
Mr Bonnor told SBS News that schools have a "smorgasbord of discrimination devices" available to ensure as many high achievers are enrolled as possible in a process he calls "enrollment discrimination".
On the minor end of the spectrum, government schools might ensure classes are full so they are able to reject students after the school year has already started, while private schools can offer vast amounts of bursaries and scholarships to selected students. For selective and religious schools, what students are enrolled is based on their results and achievements.
School fees at non-governmental schools are also a way to control enrollments.
"Even a high demand public school, has a greater capacity to choose its enrollment because schools are able to take enrollments from out of area if they have vacancy," he said.
But on the other end of the spectrum, parents are also driving the shift as they shop around for schools with higher educational advantage.
Going forward, Mr Bonnor said in order to create a more equitable system we have to "curtail school choice".
"That would involve, for example, reducing funding for non-government schools," he said.
"But at the same time, you don’t do that in isolation. The system has to double its efforts to make every local school a preferred school by parents."
"You have to stop rewarding schools for discriminating enrollments."