Even if you count only the men who have mustaches, you'll find a group that holds more leadership positions in medicine than women, a new study finds.

Women hold 13 percent of department leader positions at U.S. medical schools, whereas men with mustaches hold 19 percent of these positions, according to the study, published today (Dec. 16) in the annual Christmas issue of the BMJ, which is a tongue-in-cheek edition of the medical journal that normally publishes serious research.

The researchers hoped their study would draw attention to the lack of women in leadership positions in medicine, said Dr. Mackenzie Wehner, a resident physician at the University of Pennsylvania and the lead author of the study.  [5 Reasons Women Trail Men in Science]

The researchers wanted to broach the topic of equality from a different angle, one that would really pique people's interest, Wehner told Live Science.

For the study, the researchers looked at photos of department heads in 19 specialties at the top 50 NIH-funded medical schools in the U.S. They chose to compare the number of women heading departments to the number of men with mustaches heading departments because mustaches are rare, according to the study.

The researchers did consider some other rare attributes of department leaders as well, such as sporting a bow tie, said Dr. Eleni Linos, a dermatologist at the University of California San Francisco and the senior author on the study.

But ultimately, mustaches were the most humorous, Linos told Live Science.  

They defined a mustache as hair on the upper lip, Wehner said. The goal was to be objective and scientific about what qualified as a mustache, but it did get a little hairy at times, she added.

The mustache index

Next, the researchers calculated what they called the "mustache index" for each school: the ratio of the number of women in leadership positions to the number of all mustachioed individuals. Wehner noted that women were included in the search for 'stached individuals, but the researchers didn't come across any in the search.

Some medical schools did have a higher mustache indexes than others, but none were as high as the researchers would have liked, Wehner said. The researchers deemed a mustache index of 1 or higher —meaning women outnumbered men with mustaches — as "good."

The University of California, San Francisco, for example, had a mustache index of 4, with four women in leadership positions and one mustachioed individual in a leadership position, according to the study. Johns Hopkins University, on the other hand, had a mustache index of 0.17, with one woman in a leadership position and six mustachioed individuals in a leadership position, according to the study.

In addition, when the researchers looked across all the schools in the study, some medical specialties fared better than others, Linos said. Obstetrics and gynecology had a high mustache index, as well as pediatrics and dermatology, according to the study.

Of course, a high mustache index could also be the result of a smaller number of mustaches rather than a greater number of women.

Specialties such as general surgery and plastic surgery had very few mustaches, for example. Psychiatry had the thickest mustache density, according to the study.

Linos noted that the study had some limitations. For example, it's possible that some of the photos were outdated, or that mustaches were mischaracterized, she said.

But the message remains the same.

"We believe that every department and institution should strive for a mustache index greater than or equal to 1," the researchers wrote.

Wehner suggested two ways to increase the mustache index — everyone could shave their mustaches, or institutions could simply hire more women.

"Asking people to shave their mustaches would be discriminatory and might affect workplace satisfaction," Wehner said. Hiring more women stands out as the obvious choice, she said. 

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