[All posts](/blog) Nov 14, 2022 in **Data explorations** ‧ 4 min read # Bus factor of top GitHub projects ##### The Metabase Team ‧ Nov 14, 2022 in **Data explorations** ‧ 4 min read ##### Share this article Copied to clipboard The [Bus factor](https://peerj.com/preprints/1233/) is the number of people on a project that would have to be hit by a bus (or quit) before the project is in serious trouble. We were interested in the bus factors for the top 1,000 projects on GitHub (by stars). ## Observations Check out our [dashboard](https://metabase-public.metabaseapp.com/public/dashboard/552f3868-5f09-4b0b-a403-67089952d32c), or read on to learn what we’ve found. ## Dataset * We used the GitHub API and [truckfactor](https://github.com/HelgeCPH/truckfactor) to get and compute the bus factors of the top 1,000 GitHub repositories by star count. * Due to memory restrictions, we were only able to compute the bus factors for around 95% of the repos on GitHub. * To exclude codeless repos (such as learning resources, or a curated list of a topic), we removed projects where the primary programming language couldn’t be determined, or if the repo was primarily composed of one of the following file types: Makefile, TeX, Dockerfile, and Markdown. * If you want to play around with the data yourself, go ahead and [download and explore the dataset](https://metabase-public.metabaseapp.com/public/question/87cd0501-3050-4a55-99cc-59000149ca49). ## How we computed the bus factor We used a library called [truckfactor](https://github.com/HelgeCPH/truckfactor) to compute the bus/truck factor. Here’s how truck factor does its calculations. For each repo, truckfactor (and here we’re quoting directly from the repo): * Reads a git log from the repository * Computes for each file who has the *knowledge ownership* of it. + A contributor has knowledge ownership of a file when she edited the most lines in it. + That computation is inspired by [A. Tornhill *Your Code as a Crime Scene*](https://pragprog.com/titles/atcrime/your-code-as-a-crime-scene/). + Note, only for text files knowledge ownership is computed. The tool may not return a good answer for repositories containing only binary files. * Then similar to [G. Avelino et al. *A novel approach for estimating Truck Factors*](https://peerj.com/preprints/1233.pdf) low-contributing authors are removed from the analysis as long as still more than half of all files have a knowledge owner. The amount of remaining knowledge owners is the truck factor of the given repository. For some context, studies conducted in [2015](https://peerj.com/preprints/1233/) and [2016](https://arxiv.org/abs/1604.06766v1) calculated the bus/truck factor of 133 popular GitHub projects. The results show that most of the projects had a small bus factor (65% have bus factor ≤ 2) and that less than 10% of those projects had a bus factor greater than 10. ## Distribution of bus factors Almost half of the projects have a bus factor of two or less. Only 10% of projects have bus factor of 6 or higher. ## There is no correlation between repo stars and bus factor We initially thought that more popular projects should have more contributors, and therefore a higher bus factor, but that doesn’t seem to be the case. ## Average bus factor of top languages used We’re talking about languages in general here, so languages like HTML and CSS are in play. * More than half of all projects use the Shell scripting language (Bash scripts). * The most common languages were web-based tools: JavaScript, HTML, CSS, and TypeScript. The top general purpose languages included Python, C, and Java. * Projects that were written in web-based development languages (JavaScript, HTML, CSS, TypeScript and SCSS) tend to have a lower bus factor compared to projects written in general purpose programming languages (Python, C, Java and C++) ## Most popular labels Among the most-starred repositories, `JavaScript` is the most popular label, led by popular web frameworks and libraries like `React`, `Vue`, `Bootstrap`, and `Angular`. If we combine `Go` and `Golang`, projects written in Go would be the second most-labeled language (though it’s possible that some repos include both the `Go` and `Golang` labels, which would inflate the label count). `Hacktoberfest` is the second most common label, which makes sense. Hacktoberfest is a month-long celebration of open-source projects to encourage the contributions to open-source projects, and so repo maintainers are incentivized to add the label to attract contributors. ## Bus factors by software types We also broke out bus factor by software type, and machine learning had the most projects with bus factors in the double digits. ### Backend projects ### Frontend projects ### Machine learning projects ### Business intelligence projects ## Conclusions * Metabase supports public transportation. * Software is built on a house of cards. * Document your code. * Metabase’s bus factor is *decent* (4). Plus, we’re a fully distributed team, so the bus accidents would have to be globally coordinated to put the project in any kind of jeopardy. * But our bus factor could be better, so, you know, [we’re hiring](/jobs). ### You might also enjoy [All posts](/blog) Jul 15, 2025 in **Data explorations** #### The story behind our AI Dataset Generator Explore the design choices, challenges, and achievements behind our open source AI Dataset Generator. ##### Matthew Hefferon ‧ 3 min read May 12, 2023 in **Data explorations** #### The hidden costs of the data stack An incomplete list of the less obvious costs associated with maintaining a data stack, and some things you can do to keep those costs under control. ##### The Metabase Team ‧ 9 min read [All posts](/blog) ###### Subscribe to newsletter ##### Updates and news from Metabase