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.
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,). 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).