{
  "id": "F-09",
  "url": "https://evy.so/facts/ai-writing-speed-and-quality/",
  "chapter": "What AI Saves",
  "question": "How much faster do people finish writing tasks with AI, and is the work better?",
  "answer": "In controlled experiments, professionals using ChatGPT or GPT-4 finished defined writing and consulting tasks 25 to 40 percent faster, and graders rated the work 18 to 34 percent better. In a six-month field trial of everyday work, time spent writing documents did not change measurably.",
  "range": {
    "low": 25,
    "high": 40,
    "unit": "% less time on a defined writing or consulting task",
    "display": "25–40% less time on a defined writing or consulting task, with quality up 18 to 34%"
  },
  "confidence": "medium",
  "confidence_reason": "Two independent teams with different designs agree on direction and roughly on size. Both time one-off tasks chosen to suit the AI, and the one long-run field trial finds no measurable change in document time.",
  "last_checked": "2026-10-14",
  "how_to_read": "Both experiments time one well-defined task, chosen to suit the AI, in a single session. Noy and Zhang's task took people without AI about 27 minutes; the BCG tasks were longer, multi-part consulting exercises. Quality was graded on different scales (1 to 7 and 1 to 10). The six-month field trial found no change in time in Word, though its authors say too few people used Word regularly to detect small effects.",
  "sources": [
    {
      "creator": "Shakked Noy and Whitney Zhang (MIT)",
      "title": "Experimental evidence on the productivity effects of generative artificial intelligence (Science)",
      "year": 2023,
      "sample": "453 college-educated professionals: marketers, grant writers, consultants, data analysts, HR professionals and managers",
      "method": "Preregistered online randomized experiment on a 20 to 30 minute writing task, graded blind by people in the same occupation. Minute figures from the authors' MIT working paper.",
      "figure": "40% less time and 18% higher quality; in the working paper, 27 minutes without ChatGPT and 17 with it",
      "url": "https://www.science.org/doi/10.1126/science.adh2586",
      "quote": "The average time taken decreased by 40% and output quality rose by 18%."
    },
    {
      "creator": "Fabrizio Dell'Acqua, Ethan Mollick, Karim R. Lakhani and colleagues (Harvard Business School, Wharton, MIT, Warwick, Boston Consulting Group)",
      "title": "Navigating the Jagged Technological Frontier (Organization Science)",
      "year": 2026,
      "sample": "758 BCG consultants, about 7% of its individual-contributor consultants",
      "method": "Preregistered randomized experiment on 18 realistic consulting tasks, graded by humans",
      "figure": "25.1% faster on average (22.5% and 27.6% in the two AI groups), 12.2% more tasks done, quality up 29.9% to 33.9%",
      "url": "https://doi.org/10.1287/orsc.2025.21838",
      "quote": "completing 12.2% more tasks and completing them 25.1% more quickly on average"
    },
    {
      "creator": "Dillon, Jaffe and Immorlica (Microsoft Research) and Stanton (Harvard Business School)",
      "title": "Shifting Work Patterns with Generative AI (NBER Working Paper 33795)",
      "year": 2025,
      "sample": "7,137 knowledge workers at 66 large firms",
      "method": "Randomized field experiment over six months, timed with Microsoft 365 usage data",
      "figure": "No significant change in time spent writing in Word, and the same number of documents completed",
      "url": "https://www.nber.org/papers/w33795",
      "quote": "no significant average changes in total time spent in video meetings or writing documents"
    }
  ],
  "related_findings": [
    {
      "question": "Is writing done with AI better?",
      "answer": "Graders rated it higher in both experiments: 18% higher in Noy and Zhang's study, graded blind by professionals in the same occupation, and 29.9% to 33.9% higher in the BCG study, graded by humans (about half that when GPT-4 did the grading). In Noy and Zhang's study, 68% of people with ChatGPT handed in its first draft without editing it.",
      "sources": []
    },
    {
      "question": "What happens on tasks the AI handles badly?",
      "answer": "The gain can turn into a loss. On a business problem chosen so that GPT-4 would give a plausible wrong answer, BCG consultants without AI were right 84.5% of the time, against 60% and 70.6% in the two AI groups, even though the AI groups spent less time on it. F-13 covers this in more detail.",
      "sources": []
    }
  ],
  "numbers_you_may_have_seen": [
    {
      "claim": "ChatGPT makes workers 40% more productive (Noy and Zhang).",
      "what_the_source_says": "The study found 40% less time and 18% higher quality, on one 20 to 30 minute writing task. A 40% cut in time is a different number from a 40% rise in output."
    },
    {
      "claim": "AI raised BCG consultants' quality by more than 40%.",
      "what_the_source_says": "That comes from the 2023 working paper. The peer-reviewed 2026 version reports human-graded gains of 29.9% to 33.9%."
    },
    {
      "claim": "Consultants using AI were 19% less likely to be correct.",
      "what_the_source_says": "The paper's tables give 84.5% correct without AI and 60% and 70.6% with it: a drop of 14 to 25 percentage points, 19 on average, on one task chosen to sit outside the AI's abilities."
    }
  ],
  "citation": "EVY (2026). How much faster do people finish writing tasks with AI, and is the work better? The AI at Work Fact Book, F-09. https://evy.so/facts/ai-writing-speed-and-quality/ (last checked October 14, 2026). CC BY 4.0.",
  "license": "CC BY 4.0"
}