The story seems to be that when Janet writes with George, her colleagues infer that George deserves the credit. That might be a reasonable inference if women were more likely to join research collaborations as the junior partner, but in fact Ms. Sarsons finds that they are less likely to do this.

Digging deeper, Ms. Sarsons assessed how credit was attributed for work done in different types of research teams. Men get about the same degree of credit for research with a co-author, whether it is written with other men, other women or both. (The exact numbers vary a little, but in a way that may just reflect statistical noise.)

It couldn’t be more different for women. When women write with men, their tenure prospects don’t improve at all. That is, women get essentially zero credit for the collaborative work with men. Papers written by women in collaboration with both a male and female co-author yield partial credit. It is only when women write with other women that they are given full credit. These differences are statistically significant.

The numbers tell a compelling story of men getting the credit, whenever there is any ambiguity about who deserves credit for work performed in teams.

And this is a very big deal: The bias that Ms. Sarsons documents is so large that it may account on its own for another statistic: Female economists are twice as likely to be denied tenure as their male colleagues.

This rather extraordinary finding resonates with my own experience. My most frequent collaborator has been a woman (Betsey Stevenson, an associate professor at the Ford School of Public Policy at the University of Michigan, who is also my romantic partner). For years, I’ve benefited from colleagues giving me the “big half” of the credit for our joint work. In some cases, they have been explicit about this. But I know what they don’t: That work was a true partnership, the result of countless late nights crunching numbers. And their misattribution occurred despite the fact that we were working in a traditionally feminized field, assessing changes in family life.