In her blog entry, How Do Multi-PI Applications Fare?, Dr. Sally Rockey, Deputy Director for Extramural Research at the NIH, explains that:
Only in 2013 is there a significant difference in award rate between single PI and multi-PI award rates, and this is in favor of multi-PI awards. But for most years, and overall, there doesn’t seem to be a trend indicating that multi-PI applications are more (or less) likely to be awarded than single PI applications.
So, when you’re applying to NIH for research funding, while there are many other considerations to take into account in deciding whether to submit a multiple-PI application, preference for funding is not one of them. As always, the key questions to ask is: what would best address the science being proposed? Would a single- or multiple-PI model best ensure optimal leadership of this research project? Additionally, when considering the multi-PI option, be sure to consider how you will structure the roles of the investigators to meet the goals of your proposed research.
While it is great to hear this answer for the NIH, I would suggest that researchers be careful not to extrapolate this answer to other funders for which team science with multiple PIs might more closely align with the mission. The prudent grant writer should research what types of projects are getting funded by the agency or foundation with which they think their proposed research might closely align. This should be done early in the process of developing a team and a proposal. This process includes analyzing what type of teams are able to complete the type of work being done–as Dr. Rockey phrases it, “what would best address the science being proposed?” What applies for the NIH does not necessarily apply for your team’s proposed project or another funder–know what will, and then build your team accordingly!