On Tuesday the Royal Swedish Academy of Sciences will announce the winners of the 2013 Nobel Prize in Physics. Since 1901, when Wilhelm Conrad Röntgen was named the first recipient, a total of 193 people have been honored as Physics Laureates.
In 1903, one of the very first Prizes in went to Marie Curie, and in the 110 years since, the only other woman to win the distinction was Maria Goeppert Mayer, whose prize was announced in 1963, prior to the Kennedy assassination. In the 50 years since, 114 men have won. All the men have deserved it, of course. The prize recognizes the very best scientists and most important discoveries of the day. But with only 2 out of 193 winners, women have won only about 1 percent of the time. So why are so few prizes going to women?
Science relies on data, and we wanted to ask if the lack of women among award recipients can be explained by our own data. For decades at the Statistical Research Center at the American Institute of Physics (AIP), we have collected a wealth of trend data on physicists from the United States and abroad who earned degrees in this country, and more recently we collected data from physicists around the globe.
We used this data to test five possible explanations for the low number of women who have received a Nobel Prize in Physics:
- There are not enough women earning PhDs in physics.
- Not enough of women are doing the type of "cutting edge" research that earns these prestigious awards.
- Women do not have equal access to career-building opportunities and resources to enable them to be in position to win a Nobel Prize.
- The pool of nominees includes too few women.
- The likelihood of winning the award depends on the sex of the researcher.
First, while the Nobel Prize is an international award, over one-third of the Physics Laureates are U.S. citizens. The representation of women among recipients of PhDs in physics from U.S. institutions has ranged from 7 percent in 1980 to about 20 percent in 2011. Let's take the 7 percent women in 1980 and look at Nobel Prizes awarded since 1990. While this is, admittedly, a simplistic approach, it does give us a data-based lens through which we can examine the situation. Going forward ten years gives the graduates time to establish their careers; using the 7 percent women based on doctorates in physics in the United States gives us a baseline. Fifty-seven men have been named Nobel Laureates in Physics since 1990. If the pool of nominees for the Nobel Prize in Physics has included 7 percent women, the chances that all 57 of the recipients would be men is less than 2 percent. Using standard statistical guidelines, this difference from what we would expect to find is significant. This suggests that the number of women earning PhDs in physics does not account for the absence of women among Nobel Prize recipients.
Second, a recent AIP study of PhD recipients who earned their degrees at U.S. institutions ten to fifteen years ago shows that these men and women are equally likely to be employed in research labs and academic settings. Furthermore, both men and women are equally likely to be doing basic research -- the type of work that leads to a Nobel Prize. It is very possible that women are doing cutting-edge research that earns Nobels, and thus the second explanation does not account for the low number of women winning them.
The third question may account for at least some of the disparity. Even if they follow similar career paths, perhaps something happens along the way that makes men more likely to do the type of research that leads to a Nobel Prize. Results from our survey of nearly 15,000 physicists from around the world suggest that women do not have the same access to opportunities and resources to advance their careers as do men.
Fourth, since the Nobel Prize nominees in the last fifty years are kept secret, we cannot know the representation of women among nominees. It is possible that women never make it into the select group of final nominees. However, suppose that the pool of nominees has included a representative number of women. It is still possible that the fifth explanation is correct: the likelihood of winning the award depends on the sex of the researcher, and that women, although nominated, are less likely to win because of overt or unconscious bias.
There is a body of social science literature to support the existence of unconscious bias, in which people act on preconceived schemas that include the assumption that women cannot do science as well as men. Whether this unconscious bias means women have too few opportunities and resources, fewer opportunities to promote their work, are less likely to be nominated, or are less likely to be selected as winners, the effect is the same: fewer prizes awarded, including the Nobel.
Could it be that, even as policy makers have been supporting efforts to increase the representation of women in physics and other science, technology, engineering and mathematics (STEM) fields, those judging the merits of scientific work have been guilty of unconscious bias? The dearth of women winning the top prize in physics suggests this may be the case.
To combat unconscious bias, could we insist on blind reviews? This would be difficult in the case of the Nobel Prize since, in most cases, the researchers are well known and closely tied to the research. However, we could start with blind reviews at lower levels to begin to address inequities in the allocation of resources and opportunities to do cutting-edge research.
To date, most efforts have focused on increasing the representation of women in physics; have those efforts distorted -- or even blinded us to -- the more fundamental problem of equal access for the women already in the field? Achieving an increase in the number of women winning Nobel prizes may not be a question of getting women into the field if only to abandon them to the wilderness once they're there. Rather than focusing solely on increasing the representation of women in the field, we may need to address any inequities in the opportunities and resources available to women physicists.
When the new prizes are announced this coming week, it will be a cause to celebrate. But it is also an occasion to reflect. In judging the merits of scientific work, we should be blind to the sex of the researcher.
That should be our blind ambition.
Rachel Ivie and Susan White, Statistical Research Center, American Institute of Physics