Female grant applicants are equally successful when peer reviewers assess the science, but not when they assess the scientist

Background Funding agencies around the world show gender gaps in grant success, with women often receiving less funding than men. However, these studies have been observational and some have not accounted for potential confounding variables, making it difficult to draw robust conclusions about whether gaps were due to bias or to other factors. In 2014, the Canadian Institutes of Health Research (CIHR) phased out traditional investigator-initiated programs and created a natural experiment by dividing all investigator-initiated funding into two new grant programs: one with and one without an explicit review focus on the caliber of the principal investigator. In this study, we aimed to determine whether these differently-structured grant programs had different success rates among male and female applicants.

Methods We analyzed results of 23,918 grant applications from 7,093 unique applicants in a 5-year natural experiment across all open, investigator-initiated CIHR grant programs in 2011-2016. Our primary outcome was grant application success. We used Generalized Estimating Equations to account for multiple applications by the same applicant and an interaction term between each principal investigator’s self-reported sex and grant program group to compare any gaps in success rates among male and female applicants in the two new programs to the baseline gap in traditional programs. Because younger cohorts of investigators and fields such as health services research and population health have higher proportions of women, our analysis controlled for principal investigators’ ages and applications’ research domains.

Results The overall grant success rate across all competitions was 15.8%. After adjusting for age and research domain, the predicted probability of funding success among male principal investigators’ applications in traditional programs was 0.9 percentage points higher than it was among female principal investigators’ applications (OR 0.934, 95% CI 0.854-1.022). In the new program in which review focused on the quality of the proposed science, the gap was 0.9% in favour of male principal investigators and not significantly different from traditional programs (OR 0.998, 95% CI 0.794-1.229). In the new program with an explicit review focus on the caliber of the principal investigator, the gap was 4.0% in favour of male principal investigators, significantly larger than in traditional programs (OR 0.705, 95% CI 0.519-0.960).

Conclusions Avoiding bias in grant review is necessary to ensure the best research is funded, regardless of who proposes it. In this study, gender gaps in grant success rates were significantly larger when there was an explicit review focus on the principal investigator. Because of the quasi-experimental study design, these findings offer more conclusive evidence than was previously available about the causes of gender gaps in grant funding. Specifically, this study suggests that such gaps are attributable to differences in how women are assessed as principal investigators, not differences in the quality of science led by women.