It’s often claimed private schools outperform public schools. In recent days, a media report revealed the Liberal Party candidate for the Melbourne seat of Macnamara had previously written in support of public funding of private schools. The report said the candidate, Kate Ashmor, wrote a newspaper letter in 2001 in which she said:

I was only able to attend a private school via a heavy subsidy due to the income restraints of my parents, and I firmly believe that I would never have achieved the high VCE score I did if it hadn’t been for my private school education.

But our analysis of MySchool data and Victorian Certificate of Education (VCE) results between 2014 and 2018 shows public schools have similar, or even better, VCE results than private schools with similar rankings of socioeconomic status. And these public schools achieve the results with far less funding per student.

Returns on investment

Those who argue in favour of public funding for private schools claim private schools are more efficient and academically outperform public schools.

The conservative side of politics believes there is no equity problem to address in Australian education. The current federal government relies on conservative researchers’ evidence denying any causal link between socioeconomic status and student academic outcomes.

Read more: What the next government needs to do to tackle unfairness in school funding

Our analysis compared the results of 229 private and 278 public schools. Schools with fewer than 20 students at Year 12 were excluded, as were select-entry public schools. The analysis compared both VCE results and school-based data including funding details available from MySchool and individual school websites. The analysis took into account the socioeconomic status of the schools, using the Index of Community Socio-Educational Advantage (ICSEA).

The ICSEA is a scale that allows a comparison of the levels of educational advantage or disadvantage students bring to their academic studies. The average ICSEA across all Australian schools is 1,000.

In Victoria the average ICSEA is 1,031, while in Tasmania and the Northern Territory the average is less than 1,000. Schools above that figure are deemed more advantaged than those below. The school with the highest ICSEA in Victoria is Presbyterian Ladies’ College in Burwood (1,210).

There are 38 other private schools at the top of the rankings before the first public non-selective school, Princes Hill Secondary (1,156). In Victoria 318 schools are above 1,000, while those below average include only eight non-government schools, either Islamic or Catholic. The lowest ICSEA among these eight is 926 while the lowest public school ICSEA is 876.

What we found

Even excluding select-entry schools, public schools equal or outperform private schools with similar ICSEA rankings. Table 1 (below) shows Victorian schools’ VCE results for similar or “like” private and public schools, their median scores and percentage of 40+ scores, (only 9% of students will get a score on or above 40), total government (federal and state) funding per student as shown on the MySchool website, and Year 12 fees found on individual school websites.

When it comes to Year 12 funding, private schools on average outspend public schools by almost A$8,000 per student to achieve a similar result. The average Year 12 fee in public schools is A$753 compared to A$12,374 in private schools.

Almost 50% of funding is from federal and state funds for independent schools and 80% or more for Catholic schools. The School Resource Standard (SRS) is an estimate of how much funding a school needs to meet the educational needs of its students.

In 2018, the SRS was A$13,764 for secondary students across Australia. More than half of Victorian public schools currently receive less than the SRS.

Socio-economic status and academic achievment

Conservative commentators claim socioeconomic status has little impact on student academic performance. This is contrary to peer-reviewed research.

This analysis of the 2014-2018 VCE results demonstrates school performance is strongly correlated to the socioeconomic index of the school. The higher the ISCEA generally, the better the school performs in VCE. Postcodes “don’t equal destiny”, however, as there are some exceptions in public schools as shown in Table 1.

For example, Narre Warren South P-12 College, with more than 55% of children from non-English-speaking backgrounds and 81% of its enrolment from disadvantaged homes, outperforms most private schools with a median study score of 32 (including 32 for English and 36 for Physics). Almost 11% of its study scores are over 40%.

What about money?

Can we imagine how much better our public schools could be with the extra resources that would be available if governments transferred the A$13.7 billion spent on private schools to their public counterparts?

Spending more money on students and school buildings, well-being centres, international campuses, playing fields, equestrian facilities, rowing sheds, music centres and swimming pools seems to make no difference at all when students have similar social and economic backgrounds.

A new review of research studies shows strong evidence of a positive causal relationship between school funding and student achievement and that certain school resources that cost money have a positive influence on student results. As well, more equitable allocation of funds between schools increases equity in student outcomes.

Spending growth for private schools has outstripped spending growth for public schools over the past decade, according to the Productivity Commission. Annual funding for government schools rose about 23% to A$42 billion, while funding for private schools jumped 42% to A$13 billion.

Read more: FactCheck: does Victoria have Australia's lowest rate of public school funding?

When all other things are held equal, it seems the only factors that could be making the difference to the VCE results are the teachers and students in public schools who are defying expectations and labels. The best-performing education systems worldwide are those that combine equity with quality. They give all children opportunities for a quality education.

The table in this article previously contained errors. These have now been fixed. The table was also updated to reflect recent changes on the MySchool website.