A 2016 study said that women do, in fact, ask for raises as often as men, but are 25 percent less likely to get them — which would mean that the only problem was the fact that we don't reward women for assertiveness (rather than that issue, coupled with the fact that women are often hesitant to be assertive in the first place).
However, many felt that the survey's findings didn't hold up to close scrutiny. Kim Elsesser at Forbes pointed out that there's a long-held and much-replicated body of evidence to suggest women don't ask for raises as often as male peers, which predates this study — and also suggested that the study framed the question in a way that actually showed that women were less likely to even think of asking for a raise.
While the study found that men and women both asked for raises when it was made clear that pay was negotiable, 48 percent of the men surveyed thought their salary was negotiable, while only 32 percent of women did. In other words, if women weren't explicitly told that they could ask for more money, they tended to assume it wasn't possible — meaning that many did not attempt to ask for raises in situations where their male peers asked for more cash.
This backs up a finding from 2012, in which scientists discovered that while women are often eager to negotiate for more pay, they're much less likely to do so if there isn't "an explicit statement in the job description that payment is negotiable." Men, according to this formulation, are more likely to simply take the risk when there is no clear indication that they are expected to negotiate their salary.
Elsesser also pointed out that the study revealed that, in response to the question "I have attempted to attain a better wage/salary for myself in my role, but was unsuccessful," a whopping 74 percent of men had tried, while only 66 percent of women had. The picture this reveals is that men are willing to ask for a wage increase even if their job description doesn't say they can (and they're likely to get turned down).
It's a problem that's exacerbated by the gender of the people being asked, too. A 2005 study found that while women negotiating a pay raise with male bosses experienced more "pushback" than male colleagues, female bosses tended to treat requests gender-equally.
Luisa Zhou, who runs the program From Employee To Entrepreneur, points out that there's gender inequality in the way in which women highlight their accomplishments to employers. “A common mistake," she told Bustle, "is to quietly do good work throughout the year and assume that it’s being noticed and accounted for when you ask for a raise. Like many women, I didn’t know how to talk about my accomplishments without sounding like I was bragging, so I didn’t talk about them at all. The result was that when it came time for promotions or raises and I pointed out all the things I’d done, my managers would say, ‘Oh, you did all of that? Next time, tell me about it in advance'."