一句话：提出fork熵指标，基于Rao二次熵从文件修改度量开源项目fork群体多样性，并在GitHub数据上验证其与外部贡献等指标相关。
在GitHub等平台上，fork与接受pull request是项目获取外部贡献的重要方式，但除fork数量外，尚缺乏简单且有信息量的指标刻画fork群体多样性。受生物多样性与团队多样性研究启发，本文提出基于Rao二次熵的fork熵指标，依据各fork对项目文件的修改度量多样性，并证明其具有对称性、连续性与单调性。作者在GitHub 50个项目数据上实证，发现fork熵与外部生产力（外部贡献者提交数）、外部贡献者pull request接受率及报告缺陷数等显著相关，并与fork数量等因素存在显著交互。结果表明，fork熵能丰富对开源项目fork的理解，并支持后续研究与应用。
On open source software (OSS) platforms such as GitHub, forking and accepting pull-requests is an important approach for OSS projects to receive contributions, especially from external contributors who cannot directly commit into the source repositories. Having a large number of forks is often considered as an indicator of a project being popular. While extensive studies have been conducted to understand the reasons of forking, communications between forks, features and impacts of forks, there are few quantitative measures that can provide a simple yet informative way to gain insights about an OSS project's forks besides their count. Inspired by studies on biodiversity and OSS team diversity, in this paper, we propose an approach to measure the diversity of an OSS project's forks (i.e., its fork population). We devise a novel fork entropy metric based on Rao's quadratic entropy to measure such diversity according to the forks' modifications to project files. With properties including symmetry, continuity, and monotonicity, the proposed fork entropy metric is effective in quantifying the diversity of a project's fork population. To further examine the usefulness of the proposed metric, we conduct empirical studies with data retrieved from fifty projects on GitHub. We observe significant correlations between a project's fork entropy and different outcome variables including the project's external productivity measured by the number of external contributors' commits, acceptance rate of external contributors' pull-requests, and the number of reported bugs. We also observe significant interactions between fork entropy and other factors such as the number of forks. The results suggest that fork entropy effectively enriches our understanding of OSS projects' forks beyond the simple number of forks, and can potentially support further research and applications.
DOI 原文 · arXiv · PDF（开放获取） · DBLP
@inproceedings{WangZWSZT23,
title = {Fork Entropy: Assessing the Diversity of Open Source Software Projects' Forks},
author = {Liang Wang and Zhiwen Zheng and Xiangchen Wu and Baihui Sang and Jierui Zhang and Xianping Tao},
booktitle = {ASE},
year = {2023},
doi = {10.1109/ase56229.2023.00168}
}