Extracting new metrics from Version Control System for the comparison of software developers

Previous studies have evaluated the work done by software developers using data extracted from version control systems (VCS). However, they have focused mostly on counting the amount of written lines of code and the number of commits, which are general information that can be obtained from these software repositories. In the present article, we innovate by considering fine-grain operations at line and file levels stored in the VCS, like additions, deletions and modifications, which allow to derive a much more detailed and rich information about the work done by developers. We also define a new set of metrics to measure such fine-grain information and present two simple approaches for comparing developers based on the proposed metrics. This helps to improve our understanding of how important and alike the developers were. A case study using data from a real software development project is described. The study showed that the metrics and the comparative approaches resulted in information that is consistent with the perception of the project manager. Furthermore, our investigation points to a great potential for future work by expanding the set of metrics and exploring new comparative approaches.