B
Evidence Grade B
Graded
accuracy verified by the review judge
Safe to Cite
Current
32%
32% -- grammar performance difference for AI-generated content vs human-written content (2026)
AI scores 32% better than humans on grammar according to Grammarly research.
Attribution:
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Lighthouse Research Team
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Source verified
Evidence graded
Value
32%
Unit
Percentage
Data Vintage
2026
Entity
Evidence Quality
B
Strong, reliable evidence
Sourced from a well-regarded research firm or industry leader with transparent methodology and a reasonably large sample.
Single source - not yet corroborated
Score breakdown
Extraction
50
Source Trust
60
Citation Chain
20
Independence
30
Methodology
45
Freshness
95
Source
Grammarly
Primary
Tier C
https://www.studiothink.com/blog/we-use-ai-to-write-copy-heres-where-it-fails-and-how-you-can-use-ou… ↗
Source Article
We use AI to write copy. Here's where it fails, and how to fix it. | Studiothink
Key points
*This summary is created by generative AI, we cannot guarantee the accuracy and encourage you to read the full article… you’ll enjoy it we promise.
I’ll be honest with you. I would rather poke a fork in my eye than let AI write my copy.
I am a writer. I have spent my career honing the rig…
Original Research
Grammarly
· Original study ↗
Methodology
Grammarly research, as cited by Studiothink
Methodology documented
Segmentation
Industrymarketing
Cite this stat
Plain Text
AI-generated content vs human-written content: 32% grammar performance difference. Source: Grammarly (2026). Via Lighthouse Intelligence -- https://lighthousedata.io/data/ai-grammar-32pct-better
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<blockquote cite="https://lighthousedata.io/data/ai-grammar-32pct-better" style="border-left:3px solid #2563eb;padding:12px 16px;margin:16px 0;font-family:system-ui,sans-serif;background:#f0f4ff;"><strong>32%</strong> -- grammar performance difference for AI-generated content vs human-written content<br><small>Source: Grammarly (2026) · <a href="https://lighthousedata.io/data/ai-grammar-32pct-better" target="_blank" rel="noopener">Lighthouse Intelligence</a></small></blockquote>
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