Funding Longevity by Gender Among NIH-Supported Investigators

For nearly 10 years, more women than men received PhDs in the biomedical sciences, yet women are still underrepresented at every subsequent stage of academic advancement.  In 2015, for example, women earned 53% of PhDs, but they comprised only 48% of post-doctoral fellows, 44% of assistant professors, and 35% of professors.

To better understand what might be contributing to women’s underrepresentation in later stages of academia, Dr. Lisa Hechtman and her colleagues at the National Institute of General Medical Sciences (NIGMS) analyzed “funding longevity by gender” among funded NIH investigators.  Their analysis, recently published in the Proceedings of the National Academy of Sciences, yielded a number of interesting findings which I’d like to share with you.

Our NIGMS colleagues  started with 34,770 unique investigators who received their first major NIH research project grant  (RPG) between 1991 and 2010.  These supported investigators were followed over time to see how long they remained funded; if an investigator did not receive funding for 3 years in a row, they were considered to have dropped out of the funding pool.

The first key finding is that of the 34,770 unique investigators, only 10,660 of them (or 31%) were women.  Even among the 9,969 investigators who first received funding between 2006 and 2010, only 3,342 (34%) were women.

Figure 1 Panel A shows a Kaplan-Meier survival plot of funding longevity by gender.  Women had slightly less funding longevity, though at 25 years of follow-up the absolute difference was small – only 3.5%.

Figure 1

Figure 1 Panel B shows longevity for all investigators according to when they received their first RPG.  Consistent with increasing hyper-competition, longevity was worse among more recent cohorts.

Figure 2

Figure 2 shows longevity by gender and by when investigators received their first RPG.  For the first three time periods of first funding (1991-1995, 1996-2000, and 2001-2005), longevity was slightly less for women; for the last period of first funding (2006-2010) there was no difference.

Figure 3

Beyond a first grant (which typically lasts 5 years), a scientist’s funding longevity depends on securing new awards or successfully renewing existing awards.  To gain a better understanding of why longevity was less for women, we see that in Figure 3 funded women submitted fewer new applications (Panel A); however, funding rates and peer review scores for new applications were no different for men and women (Panel C).  The box plots in Figure 4 show the women sought project renewals less often (Panel A).  In contrast to new applications, funding rates were lower (Panel B) and peer review scores were worse (Panel C) for women.

Figure 4

Many other correlates may also offer insight into women’s lower funding longevity, such as age, degree type, type of initial awards, year of first funding, and institutional characteristics. Using a machine learning approach, our colleagues identified renewal submission rate, new application submission rate, and funding per year as the variables which most strongly predicted funding longevity (data not shown). Of note, gender was “the least useful variable in predicting survival time.”

In summary, the authors found “only small differences in NIH funding longevity between genders.”  The most “striking” difference was women’s initial underrepresentation. This “overwhelms all other gender differences that we report” – such as lower new application and renewal application rates and lower funding rates for renewal applications.  The authors conclude that, despite the comparable longevities of funded men and women investigators, “broad gender differences remain, and that thoughtful intervention during key transitions such as those described could help reduce the differences.