Before revision: NSF Grant Policy Manual 210f 'Definitions: Principal Investigator', available: URL NIAID (NIH) 'Glossary of Funding and Policy Terms and Acronyms' , available: URL For small projects (which might involve 1-5 people) the PI is typically the person who conceived of the investigation, but for larger projects the PI may be selected by a team to obtain the best strategic advantage for the project.
After revision: NSF Grant Policy Manual 210f 'Definitions: Principal Investigator', available: URL NIAID (NIH) 'Glossary of Funding and Policy Terms and Acronyms' , available: URL For small projects (which might involve 1–5 people) the PI is typically the person who conceived of the investigation, but for larger projects the PI may be selected by a team to obtain the best strategic advantage for the project.