{
    "statement": "longer: experienced open-source developers took 19% more time on tasks when allowed AI tools (early-2025 test; METR now calls it out of date)",
    "value_display": "19%",
    "value_numeric": 19,
    "unit": "%",
    "data_label": "Feb to Jun 2025",
    "data_period_end": "2025-06-30",
    "region": "Global",
    "size": "all",
    "source": {
        "name": "METR research notes",
        "publisher": "METR (Model Evaluation and Threat Research)",
        "type": "study",
        "url": "https://metr.org/"
    },
    "source_url": "https://metr.org/blog/2025-07-10-early-2025-ai-experienced-os-dev-study/",
    "source_quote": "Surprisingly, we find that when developers use AI tools, they take 19% longer than without—AI makes them slower.",
    "verification_note": "Read on metr.org. 16 developers, 246 issues. METR's page now says these results are out of date; Feb 2026 update estimates -18% (CI -38% to +9%) for returning developers and -4% for new ones, with strong selection effects.",
    "verified_at": "2026-10-23T00:00:00+00:00",
    "margin_of_error": null,
    "dont_know": null,
    "data_table": null,
    "revisions": [
        {
            "happened_on": "2026-02-24",
            "kind": "method_change",
            "value_display": "-18%",
            "note": "METR update: for returning developers METR now estimates -18% (CI -38% to +9%), which it reads as some evidence of speed-up, but it says the new data is unreliable because many developers refused to work without AI."
        }
    ],
    "page_url": "https://digitaltreed.com/statistics/web-development/experienced-developers-slower-with-ai-2025",
    "csv_url": "https://digitaltreed.com/statistics/web-development/experienced-developers-slower-with-ai-2025.csv"
}