In the last 3 months at Ahrefs, we analyzed over 1 billion data points across 11 studies*. Here’s what we learned about AI search optimization:
1. YouTube mentions are the single strongest predictor of AI visibility (correlation: 0.737) – stronger than Domain Rating, backlinks, or any traditional SEO factor. YouTube is heavily cited in AI responses, and both Google and OpenAI train on YouTube content.
2. For a given query, AI Mode and AI Overviews reach the same conclusions 86% of the time – but cite almost entirely different sources (only 13.7% citation overlap). AI Mode responses are 4x longer and mention 3x more entities.
3. Content length has essentially zero correlation with AI citations (0.04). 53% of all AI Overview citations go to pages under 1,000 words. Writing ultra-long contentisan’t necessary for AI visibility.
4. Google still sends 345x more traffic than ChatGPT, Gemini, and Perplexity combined – but ChatGPT accounts for 80%+ of all AI-driven website traffic.
5. AI Overviews have a 70% chance of changing from one observation to the next, with content lasting an average of just 2.15 days. But semantic meaning stays remarkably consistent (0.95 cosine similarity).
6. « Best X » blog lists make up 43.8% of all page types cited in ChatGPT responses. 35% of those lists come from low-authority domains.
7. 79% of blog lists cited by ChatGPT were updated in 2025, and 76% of top-cited pages were refreshed within the last 30 days. Freshness matters more than ever.
8. When asked questions without valid answers, AI systems choose fabricated content with specific numbers almost every time. ChatGPT resisted best (84% accuracy), but Grok and Copilot were fully manipulated.
9. Domain Rating correlates weakly with AI visibility (just 0.266-0.326 across platforms). Number of site pages is even weaker at 0.194.
10. 67% of ChatGPT’s top 1,000 citations are essentially off-limits to marketers – Wikipedia alone accounts for 29.7%, followed by homepages (23.8%) and educational content (at just 19.4%).
*i’ll share all the study links in a comment!