Treatment and Selection Effects of Formal Workplace Mentorship Programs

While formal mentorship programs are ubiquitous, less is known about who gains from receiving mentorship. In this paper, we report the outcome of a Randomized Controlled Trial (RCT) carried out in a US-based inbound sales call center where one branch of the experiment assigned a random subset of new hires to mentors (Broad-Mentoring), whereas a second branch (Selective-Mentoring) gave new hires the opportunity to opt into a mentoring relationship before assigning a random subset to mentors. In the Broad-Mentoring branch, mentored sales agents outperformed non-mentored agents by over 18% in the first six months on the job. Among agents who opt into the program in the Selective-Mentoring branch, those who received mentorship had negligible performance gains. The differences between the two branches indicates that formal mentorship program treatment effects are largest for workers who would otherwise opt out of these programs. Demographic and personality characteristics are relatively weak predictors of selection into the program, suggesting broad-based programs are likely more effective than alternative targeting rules.