The engagement of contributors in open source projects is crucial for them to be alive. External contributors are usually encouraged by means of rewards to foster their participation and involvement.
In GitHub, project members and project owners have the permissions to turn external contributors into collaborators (according to the project policy), which can be seen as a kind of reward for their involvement in the project. Therefore, the study of how long it takes to become a collaborator may help to better assess the openness level in GitHub projects. Note that this metric cannot be calculated for those projects where nobody is promoted to collaborator. Below, we present the results of the community composition analysis for the 91 GitHub original projects of our dataset.