Michael Hilton, Timothy Tunnell, Kai Huang, Darko Marinov, Danny Dig (Oregon State University / University of Illinois) · 2016
Hilton et al. analyzed 34,544 GitHub projects and found 40% use CI, surveyed 442 developers on CI usage motivations, and analyzed 1.5M Travis CI builds. The study found CI adoption grows with project popularity and that popular projects show much higher CI adoption rates.
Why read: Primary source of the 40% CI adoption claim — essential for understanding the original methodology, sample population, and stratification by project popularity that the researcher's article must cite accurately.
Mehdi Golzadeh, Alexandre Decan, Tom Mens (University of Mons, Belgium) · 2022 (SANER 2022)
Golzadeh, Decan, and Mens conducted a longitudinal study of 91,810 active npm package GitHub repositories over nine years, documenting the rise of GitHub Actions (becoming dominant in <18 months) and the fall of Travis CI.
Why read: Provides the longitudinal time-series evidence showing CI adoption growth that makes the 40% figure outdated — critical context for presenting the CI adoption claim with appropriate temporal caveats.
2026 (published in Information and Software Technology)
Empirical study reporting GitHub Actions achieved an adoption rate of 43.9% in a dataset of 68K GitHub repositories by January 2022, and examining the evolution of GHA workflows over time.
Why read: Provides the most recent peer-reviewed measurement of GitHub Actions adoption (43.9% of sampled repos) — a single CI tool matching the entire 2016 overall rate, demonstrating how much CI adoption has grown.