B
Evidence Grade B
Graded
accuracy verified by the review judge
Safe to Cite
Recent
26.5%
26.5% -- search engine referral decline for reference and knowledge sites (2025)
Search-engine referrals fell 26.5% for reference and knowledge sites following ChatGPT Search access expansions.
- Preprint working paper, not yet peer-reviewed
- US desktop clickstream panel data only
Attribution:
View source
Lighthouse Research Team
Last verified:
·
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Source verified
Evidence graded
Value
26.5%
Unit
Percentage
Data Vintage
2025
Entity
Sample Size
45,386
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
75
Source Trust
60
Citation Chain
20
Independence
30
Methodology
45
Freshness
95
Source
Bocconi University (Qiaoni Shi, Kai Zhu, Kai Gu)
Primary
Tier B
https://seohandbook.co.uk/seo-news-updates/chatgpt-search-access-reduces-traditional-search-study/ ↗
Source Article
AI Search Cuts Traditional Search | The SEO Handbook
Study: Wider ChatGPT Search access cuts traditional search by 9.4%
A new working paper puts a causal number on something SEOs have watched build for two years: when people gain access to ChatGPT Search, they run fewer traditional searches, and AI search rarely sends a click back to the web. The pape…
Original Research
Bocconi University (Qiaoni Shi, Kai Zhu, Kai Gu)
· Original study ↗
Methodology
Same Bocconi working paper, Comscore desktop clickstream panel
Methodology documented
Segmentation
Industrymarketing
Cite this stat
Plain Text
reference and knowledge sites: 26.5% search engine referral decline. Source: Bocconi University (Qiaoni Shi, Kai Zhu, Kai Gu) (2025). Via Lighthouse Intelligence -- https://lighthousedata.io/data/search-referral-drop-reference-sites-26-5
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<blockquote cite="https://lighthousedata.io/data/search-referral-drop-reference-sites-26-5" style="border-left:3px solid #2563eb;padding:12px 16px;margin:16px 0;font-family:system-ui,sans-serif;background:#f0f4ff;"><strong>26.5%</strong> -- search engine referral decline for reference and knowledge sites<br><small>Source: Bocconi University (Qiaoni Shi, Kai Zhu, Kai Gu) (2025) · <a href="https://lighthousedata.io/data/search-referral-drop-reference-sites-26-5" target="_blank" rel="noopener">Lighthouse Intelligence</a></small></blockquote>
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