Claude Code adopters merged 24% more PRs, study finds

A team led by Emerson Murphy-Hill studied how Microsoft rolled out Claude Code and GitHub Copilot CLI to tens of thousands of engineers in early 2026. The paper hit arXiv on July 1, 2026.

First use spread mostly through social ties inside teams. Retention tracked an engineer's own coding activity more than any demographic factor. Over four months of observation, adopters merged roughly 24% more pull requests than they would have without the tool.

The authors use merged PRs as a proxy for output and are upfront that it isn't the same as value created. At organization scale, token spend can run into millions of dollars a year, so misjudging adoption makes a rollout expensive.