Harvard Business School caused controversy recently when it coached female students on how to raise their hands and speak up more in the classroom. Women had been participating less, and were earning lower grades; after Harvard intervened, women’s grades climbed.

While Harvard’s intervention was controversial, they were hardly the only ones worrying about the absence of women’s voices: commenters like Sheryl Sandberg urged women to raise their hands and be more confident. I set out to measure the extent to which women stay silent by looking at nearly 1 million comments made on the New York Times website in response to articles published between June 2013 and Jan. 2014. Only 25% of comments were made by women, even though 44% of New York Times readers are female. (I inferred the gender of the author from her first name using a list of 40,000 international names for about half the comments. I filtered out gender ambiguous names like “Pat, ” as well as initials, and obvious pseudonyms.) Women constituted the majority only on five out of the 144 forums, as this visualization shows: the Motherlode Blog (79% women), the New Old Age blog (70%), the Fashion/Weddings section (63%), the Diner’s Journal blog (53%), and the Projects pages (52%). Women were more likely to comment on articles written by women, even when I controlled for the forum in which the article appeared; it is not clear whether this is actually an effect of the author’s gender, or occurs only because women are interested in writing and reading the same articles.

Rare but valued

Even though women’s comments were rare, they actually received more recommendations from other readers than comments from men. (This isn’t just because women commented on more popular articles; I still saw the gap when I controlled for this.) And the more male-dominated a forum or article was, the more recommendations women received. (Women made only 18% of comments on the Football forum, for example, but each comment by a woman received 39% more recommendations on average.) For men, I saw the opposite effect: the more male-dominated the article, the fewer recommendations men received. Men commenting on the two most female-dominated forums—the Parenting Blog, and the New Old Age Blog—actually received more recommendations than did women. (Men commenting on “fashion/weddings,” the third-most female-dominated forum, received fewer recommendations: you can evidently trust a man with your baby, but not with your wedding.)

Why do we see these trends? It’s possible that people don’t comment on forums usually dominated by the other gender unless they have something unusually substantive to say. I see the fact that women and outsiders get more recommendations as a positive sign: it means that although gender stereotypes continue to constrain where people comment, they are not so restrictive that a woman who makes a good point about football is ignored simply because of her gender.

Leaning out

But I also saw something less encouraging: women may be rare in part because they’re less comfortable. Female commenters are significantly less likely to include their last names, in line with previous research showing that women worry more about privacy online because they are more likely to face harassment. And my program could not identify a single woman on several of the Dot Earth Blog articles on climate change (like this one or this one), even though studies show that women are, if anything, more interested than men in climate change. This may be in part because a few men tended to dominate the discussion on the blog; as one irritated commenter wrote to the blog’s author, “Have you noticed what an utter disaster your blog threads have become? Basically, you have the same five cranks authoring thousands and thousands of repetitive words.” Previous research has found that men and high-status individuals can dominate online discussions even when gender is concealed.

Vital perspective

Women’s rarity matters because men and women say very different things in response to the same article. Women were more likely to use phrases related to family, education, and healthcare. They were also more likely to use female-specific phrases (“breast,” “misogyny,” “pregnancy”) as well as phrases relating to issues which disproportionately affect women (“birth control”, “domestic violence”).

On an article about requiring employers to provide contraception, 26% of comments from men opposed the requirement, but none of the comments from women I examined did. Or consider the open letter in which Dylan Farrow accused Woody Allen of sexually assaulting her. Women were significantly less likely to include a link to a rebuttal of Farrow’s claims in their comments. When I hand-rated comments as to whether they supported or opposed Farrow, comments from men were split, with 38% expressing support and 37% expressing opposition; comments from women overwhelmingly favored Farrow, with 71% expressing support and 11% expressing opposition.

What happens when women stay silent

These differences, combined with the underrepresentation of women, have a simple implication: the views that are heard do not fairly reflect the views that are held. This would be bad enough if it were confined to the New York Times website, which has a digital readership of 1.1 million, given that online comments can change minds. But I think its broader implications are more troubling. It seems unlikely that women are rare in my data due to some misogynistic idiosyncrasy of the New York Times comment pages: indeed, the New York Times team was supportive of my research and offered to incorporate my conclusions when they redesigned the comments pages. It seems much more plausible that women are rare because of broader social forces. Studies show that women are less inclined to speak up even in childhood; studies of women’s participation on online forums find broad signs of inequality. The effects I observe are thus likely to occur elsewhere as well.

A world of all men is one in which Dylan Farrow’s story is doubted as often as it is believed; a world of all women is one in which it is accepted almost without question. We see the consequences of this not just when women comment in the New York Times, but when a woman who has been sexually assaulted remains silent rather than reporting the crime to a male-dominated police department; when a historically male Congress lags on legislation to protect sexual assault victims on college campuses; when women in the male-dominated military are more likely to be raped by fellow soldiers than killed by enemy fire.

We need women to speak up because these problems will go unsolved if they stay silent. We need them to speak up because half a million comments show they have something worth saying.

This research will be presented at the 2015 ACM conference on Computer-Supported Cooperative Work and Social Computing; you can find the academic paper here and the full dataset here.