The wage gap has closed between women and men with newly earned PhDs -- though the numbers are less comforting for those without a decade to spend in the halls of higher learning, according to a University of Guelph study announced Tuesday.

The study, which focuses on gender equity in the labour market, found that both male and female doctoral graduates earn about $70,000 annually during the first three years after convocation.

"This is the first time that I've seen at any level that there is no discrepancy in earnings between males and females," said Prof. David Walters.

However, the study also suggests that the lower the level of education, the bigger the gender pay gap, and that on average only PhD graduates achieved income equity.

The authors attribute the link between advanced education and equal incomes to strong collective agreements and proactive labour policies in the sectors PhD graduates gravitate toward, such as academia and government.

The pay gap is greatest among employees in the trades, where on average women earn $32,500 and men earn $40,500 -- 25 per cent more.

Lead author Anthony Jehn says men tend to go into higher-paying trades, such as pipefitting or plumbing, whereas women lean more toward hairdressing or cosmetology.

Published Monday in the journal Higher Education Policy, the study analyzed data from Statistics Canada's sweeping 2013 National Graduates Survey, which surveyed trades, college and university graduates three years after graduation -- before factors such as maternity leave start to influence results.

"You would think that if they're early in their careers, they should be on equal footing," said Jehn, noting that the wage gap tends to widen over time.

"There are different sorts of penalties that females experience, such as mat leave or taking time off work, which interfere with their ability to gain experience in the labour market. But recent graduates in the labour market are still seeing this gender bias too."

The difference in income between male master's and PhD graduates was virtually non-existent at $69,500 and $70,000, respectively. For women entering the workforce, however, investing in a doctorate meant an average pay bump to $69,000, up from $62,500 for master's graduates.

The findings show that greater pay equity exists for those who can afford to invest in education, a problem that compounds class divisions along gendered lines, Jehn said.

A "culture of gender inequality" in some male-dominated fields also discourages women from entering, said Jehn, who worked on the study with Walters and Prof. Stephanie Howells.

More than one-third of all male respondents majored in the more lucrative fields of math, engineering or computer science, versus five per cent for women, helping explain the income disparity among bachelor's and master's degree holders.

The pay gaps are smallest among those with liberal arts degrees. But the relatively few women who go into math, engineering and computer science make far less than their male colleagues, the authors found.

Men fresh out of college earned $45,500 on average, versus $38,500 for women. Men with recent undergraduate degrees earned $55,000 while their female counterparts took in $50,500, according to the study.

Those numbers show that adding a bachelor's degree to your resume prompts a 22 per cent income boost for men, and a 30 per cent jump for women. The difference points to the potential fruits of education -- particularly for female workers -- but also the financial strain faced disproportionately by women who haven't spent as much time in school.

"Some recent evidence suggests that among the highest levels of education, women are slowly moving into some fields and occupations traditionally dominated by men," the study states.

"This new post-secondary landscape, along with changing perceptions of women in the workplace and recent policy initiatives to promote employment equality, provides some optimism regarding the employment prospects and outcomes of recent post-secondary graduates, particularly for women."

The study excludes accredited professions, including teaching, nursing and law, Jehn said, where strong regulation helps narrow the income gap.