Birds of a Feather Flock Together? A Study of Developers' Flocking and Migration Behavior in GitHub and Stack Overflow

Interactions between individuals and their participation in community activities are governed by how individuals identify themselves with their peers. We want to investigate such behavior for developers while they are learning and contributing on socially collaborative environments, specifically code hosting sites and question/answer sites. In this study, we investigate the following questions about advocates, developers who can be identified as well-rounded community contributors and active learners. Do advocates flock together in a community? How do flocks of advocates migrate within a community? Do these flocks of advocates migrate beyond a single community? To understand such behavior, we collected 12,578 common advocates across a code hosting site - GitHub and a question/answering site - Stack Overflow. These advocates were involved in 1,549 projects on GitHub and were actively asking 114,569 questions and responding 408,858 answers and 1,001,125 comments on Stack Overflow. We performed an in-depth empirical analysis using social networks to find the flocks of advocates and their migratory pattern on GitHub, Stack Overflow, and across both communities. We found that 7.5% of the advocates create flocks on GitHub and 8.7% on Stack Overflow. Further, these flocks of advocates migrate on an average of 5 times on GitHub and 2 times on Stack Overflow. In particular, advocates in flocks of two migrate more frequently than larger flocks. However, this migration behavior was only common within a single community. Our findings indicate that advocates' flocking and migration behavior differs substantially from the ones found in other social environments. This suggests a need to investigate the factors that demotivate the flocking and migration behavior of advocates and ways to enhance and integrate support for such behavior in collaborative software tools.