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The Truck Factor designates the minimal number of developers that have to be hit by a truck (or quit) before a project is incapacitated. It can be seen as a measurement of the concentration of information in individual team members. We calculate the Truck Factor for 133 popular GitHub applications, in six languages. To infer the authors of a file we use the Degree-of-Authorship (DOA) metric, which is computed using version history data, and to estimate the Truck Factor, we use a greedy heuristic. Results show that most systems have a small truck factor (46% have Truck Factor=1 and 28% have Truck Factor=2).
An extended and detailed version of this preprint was accepted at ICPC 2016. Please refer to: Guilherme Avelino, Leonardo Passos, Andre Hora, Marco Tulio Valente. A Novel Approach for Estimating Truck Factors. In 24th International Conference on Program Comprehension (ICPC), pages 1-10, 2016. https://arxiv.org/abs/1604.06766