Augmenting bus factor analysis with visualization

Abstract

‘Bus factor’, also known as ‘truck factor’, is a measure of how vulnerable a software project is based on the minimum number of people who would have to leave the project (be ‘hit by a bus’) for it to stall. There is existing research on how to calculate bus factor for software projects but limited work on visualizing the bus factor. We believe providing visualization along with conventionally provided numerical bus factor results will help decision-makers manage the workload and knowledge distribution across the project and also help in planning and hiring decisions. This thesis proposes, implements, and evaluates a tool named BFViz to visualize bus factor and contributions for software projects from pre-processed Git history. It is a web application that provides a file-browser-like interface with an interactively navigable treemap. Additionally, it has filename-based filtering, individual contribution data for files and folders, and simulation of contributor departure. The tool is validated with a round of four user evaluations where users, ranging from project owners and engineering managers to developers, complete tasks using the tool on an open-source project that they are involved in and provide feedback with a semi-structured interview and a feature ranking activity. The overall task completion rate for the tasks was 79.55%. All case study participants preferred BFViz over text reports to understand bus factor data. The top three features, by mean ranking, were the contributors’ list, the files and folders’ visualization, and the simulation mode.