The productivity story for ai coding has a perception gap too wide to ignore. metr's randomized…
the productivity story for ai coding has a perception gap too wide to ignore. metr's randomized trial had experienced devs finishing tasks 19% slower with ai tools while believing they were 20% faster, and stack overflow's 2026 survey found only 3% highly trust ai output even as 84% use it.
we are standardizing on tools the data keeps failing to justify.
Context
METR's July 2025 study of 16 experienced open-source developers across 246 issues, using early-2025 tools, found tasks took 19% longer with AI, while the developers expected a 24% speedup beforehand and believed afterward they had been sped up by 20%. METR's page now says it believes these historical results no longer reflect the current impact of AI models. METR's February 2026 update estimates a speedup of about 18% less time for returning developers in a later experiment, with wide intervals, and says selection effects make that data an unreliable signal. Stack Overflow's 2025 Developer Survey reports 84% using or planning to use AI tools, more distrusting accuracy at 46% than trusting at 33%, and only a fraction, 3%, highly trusting.
This is the author's take. The 3% and 84% figures are from the 2025 survey, not 2026, and the 84% is use or plan to use, not use only. Stack Overflow's 30 September 2026 post says 2026 results were still to come, and none were read. The trial used early-2025 tools with 16 developers, and METR's later, different result and its own caveat are left out of the author's the data keeps failing to justify. METR measured time on developers' own repositories and Stack Overflow measured self-reported trust, which are different things. Standardizing on unjustified tools is the author's opinion.
Watch next
- METR's redesigned study and the Stack Overflow 2026 results when published.
Sources
- Early 2025 AI experienced open-source developer study (METR, 10 Jul 2025)metr.org
- Uplift update (METR, 24 Feb 2026)metr.org
- AI (Stack Overflow Developer Survey 2025)survey.stackoverflow.co
- Getting ready for 2026 results (Stack Overflow, 30 Sep 2026)stackoverflow.blog
Provenance
The note above is reproduced unedited from the original post, first published on Threads on 20 September 2026 at 00:39 IST. Sources are the papers and datasets the note draws on.
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