Women in life sciences research still earn less than their male counterparts, with no obvious explanation for the disparity, researchers found.
After accounting for professional characteristics and publication volume, female researchers earned an average of $13,228 less per year than men, according to Catherine DesRoches of Harvard and Massachusetts General Hospital in Boston and colleagues.
The differences ranged from $6,028 among researchers with PhDs to $14,868 for those housed in departments of medicine, they reported in the April issue of Academic Medicine.
"Even after almost a decade of looking at this issue, with universities really making some good-faith efforts to try to make sure this isn't happening, we're still seeing a significant gap in pay between equally qualified men and women," DesRoches said in an interview.
"So this is an ongoing issue. It's not something that a university can put a quick fix in place for. It's something that they need to monitor over time."
Previous studies that have identified gender disparities in compensation were based on decades-old data and were unable to adjust for research productivity and the number of hours worked, according to DesRoches.
To update the literature, she and her colleagues surveyed life sciences researchers at the 50 universities whose medical schools received the greatest amount of research funding from the NIH in 2004. Questions revolved around professional activities and salary.
About three-quarters responded, for a final sample of 2,168 researchers with an academic rank of assistant professor or higher.
The respondents were predominantly male (71.4 percent) and white (80 percent). Fewer of the women were full professors (29.3 percent versus 51 percent).
The findings indicate gender differences in the professional roles occupied throughout the respondents' careers.
Among full professors, women reported greater numbers of hours worked per week -- 60.9 versus 56.8.
The difference was largely explained by more hours spent per week on administrative tasks (13.7 for women versus 10.4 for men) and other professional activities.
Female professors were more likely to report participation in five of nine professional services activities, including serving as university administrator, member of a federal review panel, journal editor or editorial board member, chair of a university-wide committee, and officer of a professional association.
This increased time spent in nonresearch activities might help explain the decreased productivity among female faculty members of all ranks after accounting for demographic and professional characteristics.
Male professors had a median of 100 published papers, compared with a median of 84 for female professors.
The lower salaries for female researchers were consistent for all levels of faculty after adjustment for professional characteristics and productivity. The annual difference was $21,600 for assistant professors, $8,500 for associate professors, and $13,700 for full professors.
DesRoches said the analysis was not able to identify the source of the disparities.
"As elsewhere in society," she and her colleagues wrote in their paper, "these discrepancies could reflect historical practices, perhaps including sexist or otherwise disparaging attitudes about the contributions of women scientists, or they may reflect the different choices made by female researchers."
They concluded, "Compensation and advancement policies should recognize and reward the full scope of the roles that women researchers play as they advance in their careers and contribute to life sciences research."