Mentoring is traditionally viewed as a dyadic, top-down apprenticeship. This perspective, however, overlooks other forms of informal mentoring taking place in everyday activities in which developers invest time and effort. Here, we investigate informal mentoring taking place in Open Source Software (OSS). We define a specific type of informal mentoring—\textit{implicit mentoring}—situations where contributors guide others through instructions and suggestions embedded in everyday (OSS) activities. We defined implicit mentoring by first performing a review of related work on mentoring, and then through formative interviews with OSS contributors and member-checking.
Next, through an empirical investigation of Pull Requests (PRs) in 37 Apache Projects, we built a classifier to extract implicit mentoring. Our analysis of 107,895 PRs shows that implicit mentoring does occur through code reviews (27.41% of all PRs included implicit mentoring) and is beneficial for both mentors and mentees. We analyzed the impact of implicit mentoring on OSS contributors by investigating their contributions and learning trajectories in their projects.
Through an online survey (N=231), we then triangulated these results and identified the potential benefits of implicit mentoring from OSS contributors' perspectives.