The joke, "Whatever women do they must do twice as well as men to be thought half as good," may not be totally off the mark in the workplace.

In a recent study, no matter how they sliced the data and controlled certain variables, American Sociological Association members Elizabeth Gorman of the University of Virginia and Julie Kmec of Washington State University, came to the same conclusion: women say they have to work harder than men.

On five different surveys given in different years, to different groups of men and women in Britain and the United States, a gender gap persisted in ratings of the statement: "My job requires that I work very hard." Women were significantly more likely to say they strongly agreed or agreed.

"Even when women and men are matched on extensive measures of job characteristics, family and household responsibilities, and individual qualifications, women report that their jobs require more effort than men do," Gorman said. “Between a man and a woman who hold the same job, shoulder the same burdens at home and have the same education and skills, the woman is likely to feel she must work harder.”

What explains the association between gender and perceived required work effort, if it’s not more difficult jobs or more demands at home?

"We argue that the association between sex and reported required work effort is best interpreted as reflecting stricter performance standards imposed on women, even when women and men hold the same jobs," said the researchers in the paper, "We (Have to) Try Harder: Gender and Required Work Effort in Britain and the United States," to be released on Nov. 21 in the December issue of the journal Gender and Society. “A lot of experimental research has shown that people rate the same performance as better when told it was done by a man. It follows that women have to do better than a man in order to get the same evaluation. Here we see how this plays out in the effort women must put in at work,” Gorman added.

"This is what women are up against. They have to prove themselves," Gorman said.

The statement in the survey about required work effort is not one in which employees are comparing themselves to the opposite sex, noted Gorman. It's also not asking for a perception of how hard the work is or how much effort they actually exerted.

"Our focus is on required work effort," the sociologists wrote in their article, "the effort that an employee is expected to exert in order to perform her or his job at a level that is satisfactory to the employer. It is important to distinguish required effort from an employee’s actual exerted effort."

The researchers compared results from the same question asked in nationally representative surveys in 1977, 1992, two in 1997, and in 2001. The four later national surveys used the same statement as in the 1977 survey to yield comparable answers. The study concentrated its analysis on the two surveys conducted in 1997, the U.S. National Study of the Changing Workforce and the Skills Survey of the Employed British Workforce, both comprising cross-sectional, representative interviews of about 3,500 and almost 2,500 workers, respectively.

Controlling for physical and mental demands of the job and whether family responsibilities drained energy, Gorman and Kmec found that neither group of factors explain the different findings about work effort. The only interpretation that held up was that women were held to higher performance standards.

The researchers analyzed the survey data to see if, in fact, women did have more difficult jobs, but that was not the case. Even when the jobs were almost identical, women still were significantly more likely to say they had to work very hard.

In looking for another potential reason, the sociologists considered whether domestic responsibilities outside of work, including child care and housework, made women feel more fatigued and that they had to work harder to keep up, but that did not emerge as the answer either.

"Marriage and parenthood had the same effect on reports of required effort for women and men. In the U.S. sample, the researchers were able to match workers on the number of hours they spent on childcare and housework. Between men and women who performed the same amount of child care and housework, women were still more likely to say their jobs required them to work very hard."

Gorman and Kmec then compared their findings to research about attitudes and beliefs held about men and women in the workplace. “We know that people give lower marks to an essay, a painting or a résumé when it has a woman’s name on it,” Gorman said. “And when a man and a woman work together on a project, people assume the man contributed more than the woman did. Even when a woman’s work is indisputably excellent, people don’t believe she’s good — they think she got lucky. In light of this previous research, it makes sense to conclude that women have to work harder to win their bosses’ approval.”

Gorman stressed that it wouldn't be fair to use this research to reinforce stereotypes. "We don't want employers to be exploiting female workers," she said, because they know women impose higher standards on themselves and will work harder.

Instead, Kmec noted, employers should take into account women's hard work when considering who to promote and reward. "We do not want to insist that female workers shirk their job responsibilities to make this gap go away. Rather, we hope employers make job performance standards more transparent and be held accountable for their evaluations of women at work," said Kmec.

The possible consequences of the effort gap in the workplace include some added difficulties: the quality of women’s work experience is likely to be lower than men’s; physical and emotional effects could, in turn, have negative repercussions for families; and the difference in required effort could also have consequences for women’s careers, making it harder for them to be recognized and promoted.