At the second debate between President Obama and his Republican challenger Mitt Romney on Oct. 16, 24-year-old teacher Katherine Fenton asked the candidates for their positions on equal pay for women.

She was unprepared for the shower of online criticism that began even as the debate aired live.

“Katherine Fenton, questioner, brings up the feminazi leftist lie that women don’t get paid equally,” tweeted conservative author Matthew Vadum.

Despite ongoing criticism that the gender pay gap does not exist, a report released Wednesday cites new research indicating that the gap is stubbornly persistent.

The research, by the American Association of University Women (AAUW), narrowly focused on recent college graduates with few of the differences that can eventually explain some pay gaps – such as children, marriage, and different work experience. It showed that female graduates make 18 percent less than their male counterparts one year out of college.

Even adjusting for differences such as career choices, the study, “Graduating to a Pay Gap,” finds what it calls “an unexplained seven percent pay gap.”

“This report goes behind the pay gap to fully understand its causes,” said Catherine Hill, the AAUW director of research and a study author, in a statement. “We hope the new figures will help employers understand the problem and implement measures to pay their workers fair and honest wages.”

What makes the study particularly important is that it focused in narrowly on men and women one year out of higher education, says Francine Blau, a professor of industrial and labor relations at Cornell University in Ithaca, N.Y.

Most studies focus on the overall labor force, which contains many factors that influence differences in pay, such as career choices, college majors, children, and marriage. But, Professor Blau noted in a conference call with reporters, “this study focuses on a relatively homogeneous group: all recent graduates and all young.”

Other factors that influence pay, such as previous experience, also are less important here, she says.

“This pay gap is not merely the result of women’s choices,” say Ms. Hill and co-author Christianne Corbett in the study.

Lower earnings have an immediate effect after college, setting into motion a chain of disparities that will follow women throughout their careers, the authors say, adding that “women experience the consequences of the pay gap from their very first paycheck to their very last Social Security check.”

A study that has such extensive controls for the type of school, the majors they took, even their grades, and what occupation they work in now, notes Blau, “is quite significant.”

The unexplained seven percent pay gap is important, she notes, adding it seems to fit in with a broader pattern of research results to suggest that discrimination is still a factor. While this doesn’t mean it is conscious or overt, “it still is a problem,” she adds.

The report targeted 2008 college graduates, looking at what each group was paid a year into their work after college.

On average, women made $35,296, compared with $42,918 for men. The figures were culled from a US Department of Education survey of some 15,000 graduates, conducted via phone and the Internet.

There were differences within the various fields. While worker pay scales were relatively equal in health care and education, the fields of business, science, engineering, and technology had pay gaps of from 12 to 23 percent between the genders.

Business schools have been tracking this for over 10 years, says Patricia Werhane, a professor of business ethics at DePaul University in Chicago. Their discovery, she notes, is that after earning their MBAs, women and men earn starting salaries that are pretty much even, but within 5 years men are receiving at least 20 percent more than women as well as better promotions.

“This is true even of women who do not have families,” she says, adding via e-mail, “the glass ceiling is alive and well.” This is unfair, she says, “particularly in the 21st century.”

The study authors have assembled a list of recommendations to deal with the pay gap.

Individuals are encouraged to learn to value their work, familiarize themselves with pay scales in their field, and learn to negotiate. Businesses are urged to offer transparent pay information to employees as well as hire and pay without bias. And legislators are enjoined to pass the Paycheck Fairness Act, which is widely seen as a necessary update to the nearly 50-year-old Equal Pay Act.

The study results have also been sent to both the Romney and Obama campaigns.