Local peer communities and future academic success of Ph.D. candidates

Compared to senior scientists, early-career scientists have largely been neglected in the literature on academic success. This study aims to identify the effects of local peer communities of Ph.D. candidates on their future careers. We argue that local communities of Ph.D. candidates may offer both supportive and competitive environments depending on the nature of the relationships between its members. While Ph.D. candidates generally learn from and support each other in their local peer communities, they may also compete for their mentor's attention and future academic positions. We analyse such complex peer effects for 90,264 Ph.D. candidates in the field of mathematics in a genealogical way, by measuring a candidate's academic career success by the number of next-generation Ph.D. candidates supervised later on. To capture both the supportive and competitive peer effects, we distinguish between local peers who share mentors (co-mentees) and other local peers. Our result suggests that competition exists primarily among peers who share mentors, and only at the start of one's career. We also find supportive effects among peers who do not share mentors, particularly those from the same cohort. Our results highlight the importance of universities supporting informal interactions among Ph.D. candidates.