PI is Principal Investigator (think professor in charge of a research group) and R1 is the rating (top tier) research university. See a list here, https://www.

PI is Principal Investigator (think professor in charge of a research group) and R1 is the rating (top tier) research university. See a list here, https://www.brandeis.edu/diversity/dei-recruitment-hiring/outreach-institutions/r1-research.html https://www.brandeis.edu/diversity/dei-recruitment-hiring/ou...