President Obama signs executive actions aimed at closing a compensation gender gap that favors men, in the East Room of the White House in Washington, Tuesday, April 8, 2014, during an event marking Equal Pay Day. Lilly Ledbetter watches at left. (AP Photo/Susan Walsh)

Women working for the federal government earn less than men overall but the gap is shrinking and most of the difference is due to women being more concentrated in occupations that are lower-paying, a government report issued Friday found.

The report from the Office of Personnel Management shows an overall gender pay gap for white-collar occupations of 12.7 percent as of 2012, down from 19.8 percent in 2002 and 30 percent in 1992. However, it added that all but 3.8 percentage points of the 2012 gap can be explained by differences in occupation and certain other factors.

“The differences in the distribution of males and females across occupational categories appear to explain much of the pay gap,” the report says.

OPM’s report — which shows a closing gap but still significant work to do — caps a week of intense debate over the issue of gender pay equity. On Tuesday, President Obama issued two executive orders meant to push federal contractors on pay equity, a move that drew praise from advocates and criticism from conservatives who debated the legitimacy of a pay gap between men and women and accused the administration of pandering to female voters for the November midterm elections.

Also, the Senate this week failed to muster the needed 60 votes to pass the Paycheck Fairness Act that would have strengthened employee protections under the Equal Pay Act. Obama’s orders require government contractors to report on salaries they pay by gender and bar them from retaliating against employees who discuss salaries among themselves.

The raw pay gap number for the federal workforce falls well below the 23 percent figure that the White House and some outside groups commonly use as the overall difference between male and female salaries, a figure that some others criticize for not taking into account differences such as work experience and hours of work.

OPM said that while its study “shows that some portion of the male-female pay gap is unexplained—that is, not explained by the factors included in our analysis—that does not mean that the unexplained gap is necessarily attributable to discrimination.”

A 2009 report from the Government Accountability Office similarly found an average pay gap of 7 percent that could not be explained by occupational or other factors. GAO said its analysis “neither confirms nor refutes the presence of discriminatory practices.”

Factors other than discrimination that could contribute to the difference include differences in prior work experience, care-giving responsibilities, motivation and work performance, OPM said. However, it added: “To the extent that the explaining factors are subject to employee or employer control, some unknown portion of the explained gap may reflect the effects of discrimination (either societal or employer-specific).”

Romina Boccia, a policy analyst with the Heritage Foundation, said some of the report findings support conservative arguments that the wage gap is shrinking and that much of the remaining disparity is due to factors beyond discrimination.

“It couldn’t come at a better time with the president signing his two executive orders that suggested there was a big problem,” Boccia said. “This shows there was a gap, but it was not as big as suggested by the misleading and commonly cited figure of 77 cents on the dollar.”

Boccia said other factors besides discrimination can play a role in creating a pay disparity, including how much women are willing to aggressively negotiate for higher pay and whether they accept non-wage benefits that can help working mothers, such as longer maternity leave, assistance with child care and flexibility with work hours and locations.

Stephanie Jaros, a social scientist for the Department of Homeland Security, said she has not experienced a pay gap as she did while working in the private sector. She credits the highly structured pay system for the federal workforce and the fact that federal salary rates are public information.

“Part of the reason for the pay gap in the private sector is that salaries are not transparent,” she said. “Transparency allows communication, so people would know about disparity much quicker in the federal government.”

The report said the narrowing gap over the 20 years studied reflects the changing nature and mix of federal employment: a shift away from occupations such as clerical jobs that are lower-paying and traditionally held by women disproportionately, and growth in higher-paying professional and administrative jobs that now are increasingly held by women–68 percent of federally employed white-collar women are now in those fields, compared with 45 percent in 1992.

The portion of the white-collar federal workforce in clerical positions dropped by two-thirds to 5.3 percent in that time, while professional and administrative positions now make up 71.9 percent, up from 59.2 percent. Women make up 69 percent of clerical workers, however, compared with their 46 percent share in the overall federal workforce.

The report further found that even the raw gap is smaller at higher-paying levels. For supervisors and managers, it’s 4.4 percent and among senior executives it’s less than 1 percent. However, it added, women make up only about a third of employees at those levels. Women also are under-represented in higher-paying science, technology, engineering, and mathematics fields.

Some female federal workers believe there were fewer opportunities to advance in the past.

“Personally, I feel like I could have gone further, but I’m fortunate to be employed by a terrific agency,” said Pamela Jones, a 50-year-old Justice Department analyst from Arlington.

Jones added that she thinks pay gaps affect minorities as well as women.

The raw gap varied by age, from 5 percent for those 25 to 34 to 17 percent for those in the 55-64 age range, which the report said “may reflect the differences in occupational distribution at those ages.”

After occupation, differences in educational levels were the second-largest factor helping to explain the gap but that is growing less significant as women’s average education levels increase, it said.

OPM meanwhile found that agencies more commonly use special authorities to set higher starting salaries when hiring men than when hiring women, giving men on average a bit of a head start. However, even much of that difference is occupation-based and afterward women receive promotions and performance-based increases up the steps of their pay grade slightly more frequently, it said.

In a blog posting, OPM Director Katherine Archuleta said that while the report “shows the progress that we’ve made, we won’t be satisfied until women working in federal jobs earn the same as their male counterparts, at every level. That’s why our report also lays out a roadmap for how we can continue to address this pay disparity. For starters, we need to address the imbalance of hiring in all occupations.  We need to build stronger pipelines for women across the board. We also must improve the transparency of our pay tables, particularly when it comes to starting salaries for women, which tend to lag behind men’s.”

She meanwhile issued a memo to agencies telling them to collect data on occupations in terms of grade patterns by gender, review how they classify jobs for pay-setting, and publicly post the salary rates of agency-specific pay systems, among other steps.

OPM further said it will clarify pay-setting flexibilities and share best practices on setting starting salaries in gender-neutral ways, and will develop recruitment and outreach strategies for increasing female populations in occupations and higher levels where they are underrepresented.

Janet Kopenhaver, a spokeswoman for Federally Employed Women, said while the federal government’s efforts are appreciated, her nonprofit advocacy organization is more concerned about the inability of women to be adequately represented at the GS14, GS15 and SES levels in the government.

“This is really the ‘pay’ problem in the federal government – women face many hurdles in getting into the higher-paying jobs,” she said, adding that mentoring programs and other initiatives are necessary to help women advance in their careers.

“That is why FEW has been working so hard with OPM and the administration to get them to do something about the serious demise of the Federal Women’s Programs in federal agencies…. That is why we are a little disappointed that in the OPM report just released, no mention is included in the recommendations section of revamping these offices.”