Abstract
Group decision-making (GDM) processes shape the evolution of open source software (OSS) products, thus playing an important role in the governance of open source software communities. While these GDM processes have attracted the attention of researchers, the rationale behind decisions, that is, how decisions are made that enhance the OSS, have not received much attention. This work bridges this gap by extracting these rationales from a large open source repository comprising 1.55 million emails available in Python development archives. This work makes a methodological contribution by presenting a heuristics-based rationale extraction system called Rationale Miner that employs information retrieval, natural language processing, and heuristics-based techniques. Using these techniques, it extracts the rationale behind specific decisions (for example, whether a new module was added based on core developer consensus or a benevolent dictator's pronouncement). This work unearths 11 such rationales behind decisions in the Python community and thus makes a knowledge contribution. It also analyzes the prevalence of these rationales across all PEPs and three sub-types of PEPs: Process, Informational, and Standard Track PEPs. The effectiveness of our contributions has been positively evaluated using quantitative and qualitative approaches (e.g., comparison against baselines for rationale identification showed up to 47% improvement in the most conservative case, and feedback from the Python steering committee showed the accurate identification of rationales respectively). The approach proposed in this work can be used and extended to discover the rationale behind decisions that remain hidden in communication repositories of other OSS projects, which will make the decision-making (DM) process transparent to stakeholders and encourage decision-makers to be more accountable.