Private schools should focus on "student outcomes" - such as course completion rates and jobs their graduates end up in, Senior Minister of State for Education Indranee Rajah said yesterday.

Her comments came as the Council for Private Education (CPE) announced that it had launched a survey in which private school graduates will be asked if they face discrimination when seeking jobs and if they are offered the same salaries as their peers from public institutions.

Students enrolled in the schools will rate the teaching and facilities, among other things, while employers will be grilled on how private school graduates compare to those from public schools.

Some 2,000 people will be surveyed for the study, to be completed in the third quarter this year.

Ms Indranee said that without assessing student outcomes, "there is insufficient basis for us to ascertain the true quality of private education".

The CPE's chief executive officer Brandon Lee said the council, which regulates the private education industry, will use the findings to fine-tune regulations introduced in 2009 to raise standards.

Mr Lee said more private institutions are winning the quality EduTrust mark - a requirement to recruit international students.

At the end of last year, 115 of the 332 registered private schools had won the mark, compared with 94 the year before.

Of the 115, 47 of them had the four-year EduTrust award, given to those who show quality in all areas - up from 34 in 2011.

Most students are enrolled in schools with the EduTrust mark, a sign that quality matters to them, Mr Lee said.

Altogether, there were about 181,000 students enrolled in some 301 private schools, of whom 116,000 were Singaporeans. The figures exclude those studying in the 31 "foreign system schools" meant for expatriate children.

Ms Indranee said the rules introduced in 2009 were meant to provide basic protection for students and raise the quality of providers to a minimum standard.

She acknowledged that much progress has been made, adding: "The private education sector today is quite different from what it was three years ago."

Private school operators are open to the idea of carrying out the surveys but said the public must realise that their students are of a different academic calibre than those in public universities.

Mr Lee Kwok Cheong, chief executive officer of the Singapore Institute of Management's (SIM) global education arm which has more than 20,000 students, said there should be a value-added measure to study how private schools have helped their students improve beyond their academic potential.

He said: "Singaporeans are very pragmatic. They pursue degrees to get better jobs and salaries."

SIM conducted its first survey last year which showed that its graduates land jobs easily, with most receiving two or more offers. But their salaries lagged behind those of their peers from the publicly funded universities.

Parent Arthur Ong, 44, who has two sons pursuing business degrees in private schools, said graduate employment surveys should be made a requirement. "Their fees are not cheap and the public universities do it, so why not the private schools?"