The proportion of Australian private school students - about 35 per cent and climbing - is the highest since Federation and far greater than most developed nations.

A survey of more than 1000 Australians commissioned by the Per Capita research group found the perceived quality of education was the main reason parents chose private schools, followed by discipline, facilities, class size and status.

Discussions with parents also revealed a belief in the importance of attending the ''right'' school for making professional connections, the ''old school tie'' theory.

Public education's main benefit was financial, or doubts that private education was worth the investment, while concerns often focused on the perceived poor quality of teachers.

''There is this kind of anxiety about the public system, this sense you're at the whim of fate in a way that you aren't in the private system,'' researcher and co-author Rebecca Huntley said.

''Sometimes the fear can be about the quality of education and sometimes it can be cultural issues and this idea there is less bullying and more discipline in the private system.''

Despite system loyalties, most respondents did not think the type of school had an impact on a student's career success. Only three out of 10 believed public school children were less successful.

Former NSW education minister Verity Firth, who is chief executive of the Public Education Foundation and co-wrote the report, said parents needed to be given greater confidence in the public system to stem the move to private schools.

''The best performing education systems are always the ones that are also the most equitable,'' Ms Firth said. ''Now we are not an equitable education system and we are getting less equitable.

''We're not going to succeed in global economic terms if we're just leaving a whole lot of our people behind based on their socioeconomic class.''

If anxious parents left the local school, its performance would fall, forcing more to flee.

''Having proper, robust parental engagement that is taught in teacher training at university is something the public sector has to seize and own,'' Ms Firth said.

Parental perspectives

Alan Gardiner, from Killara

David (year 12) at North Sydney Boys High, Peter (year 7) at Killara High School and Michael (year 4) at Killara Public School

''My wife and I both came from a public school background and I certainly remember my school days fondly. It set me up well for my life, and I was hoping for the same kind of education for my own children.

''It's perhaps an easier decision where we live because all the public schools are very highly regarded. I really don't know what I would have done had I lived in another part of Sydney because it's just too hard to put myself in that hypothetical situation.

''We'd be paying a lot more money in the private system and we might have had better facilities and less crowding. But, while we could have afforded it, I don't think that would have had any bearing on the quality of education they receive.

We've had a lot of very good teachers and principals at our public schools, not universally but in general, and the schools have provided excellent opportunities for our children.''

Liz Hurley, from Erskineville

Son Hamish Waddell is in year 11 at St Andrew's Cathedral School

''The pastoral care and access to teachers in the independent system has been really top-notch.

''I think because there is a sense of being a customer because you are paying that there is a level of security and accountability on both sides. I guess there's that sense of control or access that you have if you think things are going wrong. It's also the school's values and the type of all-round student it was producing.

The opportunities the school provided really appealed to us. It's not every day you get to see your child sing a mass at St Peter's in the Vatican.

''Our children are the most precious things in our life. It's not been an easy thing, financially, for us to do - it's not like we're rolling in money - but they're my kids and I want them to have the best.''