Are private schools better than public schools in New Zealand?

The mother wanted her daughter to attend an elite private school, viewing its small class sizes, excellent facilities and stellar academic record as a "golden ticket" to success.

The father wanted the child to go to a state school, citing the likelihood of a diverse student body that would give his daughter a well-rounded education. Not to mention the girl's sibling also attends a state school.

The decision that the daughter would attend St Cuthbert's College, an all-girls Christian school in Auckland, was ultimately decided by a High Court judge detailed in a recently released ruling from last year.

The identity of the parents and child were withheld by the court and there is a lot we don't know or can't reveal about those involved - their ethnicity, their socioeconomic background, their culture or religion, and how far the student will have to travel to St Cuthbert's.

The case does give us an inside look at two parents and a judge weighing the perceived benefits of a private versus state education. It's a debate with a growing body of research that can sometimes muddy the water rather than bring more clarity for parents. And of course, the case shows a divided family, which can have its own negative repercussions for a child.

The judge, while validating some of the father's concerns, sided with the mother due to St Cuthbert's likely being able to cater to the child's suspected learning disability and research that indicates female students perform better in single-sex schools. During the initial court case, the daughter said she was ambivalent to what school she attended but later, during the appeal, said she preferred St Cuthbert's.

The case raised a lot about what may or may not go into a good education and how much that trickles into the goal of it all: happiness and satisfaction throughout adult life. The answer to this dilemma will be unique for every student.

"You know if you can find a really good public school, then it's probably just as good as a private school, but I would say probably the public system is more variable," said Dr Michael Johnson from public policy think tank, New Zealand Initiative.

"You need at least a reasonably orderly environment for learning to take place well, and if the school is chaotic, then that's not good."

Here's what experts had to say about the issues raised in the case:

Diversity in the student body

The father expressed concern that his child would be primarily exposed to privileged families in St Cuthbert's student body, which isn't representative of New Zealand's population.

For Dr Brian Marsh, a learning and development fellow from the University of Auckland, the father's viewpoint on diversity "has my sympathy," adding that diversity was a key reason he sent his children to a state school.

"The reality of modern life is that we are all going to encounter all different sorts of people in our futures and the important part for me was that my children would be able to understand, cope and empathise with the needs of a wide variety of people, whom they would encounter in their future workplaces and social environments."

Johnston pointed to diversity of thought and opinion as an important factor. However, if the student body didn't organically bring a diverse mix of viewpoints, a good teacher should be able to bring that to a lesson.

"That's really important about education is using your knowledge to form ideas and contest them with other people's ideas," said Johnston, noting that he is not aware of hard evidence that ethnic diversity leads to better academic outcomes.

Small class sizes and school facilities

What the ideal class size is - small, medium or large - is far from settled science.

In Professor John Hattie's much respected, but much critiqued meta-analysis from 2009, reducing class size was far down the list of effective learning strategies, coming in at 106 out of 138. (He defined this as reducing size from 25 to 15 students.)

"When the class sizes get very small it probably does make a difference because students can get more individualised attention," said Johnson.

"But certainly the provision of more resources is going to help achievement if they're well used, but it's a question of how resources are used."

(More individual treatment of students, made easier with a higher teacher to student ratio can benefit those with a learning disability but more on that later.)

St Cuthbert's has a range of facilities including an indoor pool, indoor sport facilities and gym, a visual arts centre, libraries and a performing arts centre. Those are all marketing candy for parents and students, said Stuart Deerness, senior education lecturer at the Auckland University of Technology, but there is no research evidence that it impacts academic results or university entrance.

"But honestly, there's a number of studies that show that the family [socioeconomic] background is a much bigger factor in how kids do."

There are also non-economic costs to consider when sending a child to a private (or high-achieving state-school) that is far from home. A long commute can take away from family time and bring added stress to parents while plucking a child from their community and existing friendship circle, Deerness added.

A 'golden ticket' to the good life

The court cases pointed to a big disparity between the percentage of St Cuthbert's students that typically get accepted to university versus the daughter's state school option: 94.1 percent compared to about 50 percent.

University acceptance is often used as a key measure of a school's success, and there's a reason for it.

"There is substantial evidence that attending university and obtaining higher education improves life outcomes," wrote Dr Tanya Evans from the mathematics department at the University of Auckland.

Higher education is associated with better health outcomes, such as a lower risk of diabetes and a longer life expectancy. University graduates typically earn more over their life, have stronger family connections and greater job satisfaction.

However, this data-driven view overlooks people who do apprenticeships, who go on to satisfying careers without worrying about university debt or those who decide to be stay-at-home parents, said Professor Karen Nairn from the University of Otago's College of Education.

She questioned the increasing focus on university education as a must-have, especially when "there are students who are here, not because they want to be here, but because their parents expect them to come to university".

Learning disabilities

The case mentioned the possibility of a mild learning disability and that St. Cuthbert's has an educational psychologist on site, which is an advantage for students who need extra help. Resources for learning disabilities is an often-cited reason for parents taking their child's education private, said Deerness.

However, there is no evidence that students with learning disabilities do better in the private system, according to Johnson.

Nairn pointed out the amount of resources a parent could fund for support with learning disabilities in lieu of the $30,000 annual school fees at St Cuthbert's.

"You can if you want to provide a whole set of experiences and tuition for music, speech and so forth."

Same-sex schools vs single-sex schools

RNZ wrote a whole story about what is better, which you can read here. The judge said girls do better academically in single-sex schools, and he is not wrong, but it isn't the only measure to consider. Ultimately it comes down to the individual child and how their unique traits and needs will benefit from the schools you are considering.