Most tertiary courses deliver a big pay off over the course of a working life but some leave graduates worse off than if they had never studied at all, new figures show.
The Universities New Zealand analysis of the earnings, employment status and qualifications of 2.5 million people showed some qualifications provided hundreds of thousands of dollars more over a working life than others.
Scroll down for a selection of key figures from the study.
Those who studied medicine, law and some types of engineering would on average earn more than $1 million more over a lifetime than those with no tertiary qualifications, after accounting for the cost of student loans and time spent studying rather than earning.
But people with degrees in complementary therapies and certificates in 'other education' were worse off than people who went straight into the workforce from school.
The figures were based on the average earnings, tax and student loan costs over the working life of students in 72 different fields, compared to the working-life earnings of people with no tertiary qualifications.
A PhD in medical studies gave the biggest margin over someone with no tertiary education: $1.7m over a working life.
The worst return was for certificates in 'other education', a category that included teacher aide qualifications, which left students $78,218 worse off over their lifetime than someone with no tertiary qualifications.
Degrees in complementary therapies resulted in a lifetime return $75,071 lower than that of a person with only secondary school qualifications.
The return on a science degree ranged from $391,017 to $622,926, depending on the field of study. A BA in human welfare studies returned $178,184, while a degree in political science, or justice and law enforcement, provided more than $500,000 return over a working life.
First analysis of its kind
Universities New Zealand director Chris Whelan said the study used census information and other government data sets to conduct the analysis.
"This is the first time people have actually reached into these kinds of national data sets and pulled out a complete set of earnings information and employment information for every type of study you can do at every level, and it's the most comprehensive that's been done to date.
"We looked at all 2.5 million people in the workforce in 2013 using the census data, for example, all of course observing privacy requirements. But our goal was to look at real people, and real data, and try and identify what the real outcomes look like."
The results also looked at median earnings and total earnings over a lifetime and should help dispel many of the myths about higher education, Mr Whelan said.
"A typical doctorate, who people often regard as unemployable, will actually earn on average $2m more over their working life, an average honours or master's graduate will earn $1.6m more than a school leaver over their working life [and] an average bachelor's graduate $1.3 million."
The analysis found arts graduates were more likely to be employed than most other people and they typically earned more than the national median for salary and wage earners within a few years of graduation, Mr Whelan said.
The analysis was part of an international trend to get better information for prospective students, he said.
By the numbers
Biggest return* overall:
Qualifications providing lifetime returns* of more than $1 million:
Biggest return* from a bachelor's degree:
Biggest returns* for certificate-level study:
Level 4 = Certificate
Level 5-6 = Diploma
Level 7 = Bachelor's degree
Level 8 = Postgraduate diplomas and certificates, honours degree
Level 9 = Master's degree
Level 10 = Doctoral degree
*The financial return over a working lifetime based on average income, student loan repayments and income foregone while studying, compared to the average working-life income of people with no tertiary qualifications.