Software population pyramids: the current and the future of OSS development communities

Context: Since human power is an essential resource, the number of contributors in a software development community is one of the health indicators of an open source software (OSS) project. For maintaining and increasing the populations in software development communities, both attracting new contributors and retaining existing contributors are important. Goal: Our goal is understanding the current status of projects' population, especially the different experienced contributors' composition of the projects. Method: We propose software population pyramids, a graphical illustration of the distribution of various experience groups in a software development community. Results: From the study with OSS projects in GitHub, we found that the shapes of software population pyramids varies depending on the current status of OSS development communities. Conclusions: This paper present a software population pyramid of the distribution of various experience groups in a software community population. Our results can be considered as predictors of the near future of a project.