Data Studies
Research on how ChatGPT, Gemini, Perplexity, Google AI Mode and Google AI Overviews answer the questions your customers ask: which brands they name, which pages they cite and link to, and where they send shoppers. Most studies are built on thousands of answers we collect from those engines, including the web searches ChatGPT runs behind the scenes. Many compare those answers with Google search and Google Maps results, Google Business Profiles, Google News, or robots.txt files from the public HTTP Archive crawl. Use them to see where AI answers pull from in your market.
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Asking Gemini for the "best plumber near me" instead of the "best plumber in Denver" changes the first business it recommends 91.5% of the time, against 68.3% when the same city question is simply asked twice. The near-me answer is built from Google Maps listings; the city answer draws on websites.
Adding "2026" to a product question changes the websites ChatGPT cites in 96.3% of answers, against 82.2% when the same question is asked twice. The year pulls in more roundup publishers and changes the top recommended product 65.4% of the time.
Adding "on a budget" to a product question changes the first product ChatGPT recommends 87.4% of the time, the biggest effect of six wording changes and 33 points above the 54.6% change from asking the same question twice.
Ask ChatGPT the same "best product" question from the UK instead of the US and it leads with a different product 69.3% of the time, against 52.5% when the US question is asked twice. UK answers swap in local brands: Aviva for Geico in car insurance, Starling for Chase in business banking.
27.2% of ChatGPT answers to questions asked from Canada cite a .gov, .edu, .mil or .us website (US government, university, military or US-registered sites), almost as many as the 29% that cite any Canadian .ca website. American health and finance agencies such as the NIH and the Consumer Financial Protection Bureau are among the sources cited in answers written for Canadians.
ChatGPT writes 99.1% of its answers to Spanish-language local questions in Spanish, yet not one of the 3,118 website citations behind those answers points to a detectable Spanish-language site. The research is done in English: Expertise.com, an English-language directory, is cited in 34% of the Spanish answers.
When a shopper in the UK asks Gemini a question and the answer includes a price, 82.9% of the time that price is in US dollars, and 69.7% of the time dollars are the only currency shown. ChatGPT quotes dollars in 18.1% of its priced UK answers and pounds in 84.8%.
A ChatGPT answer in Portuguese cites 1.94 websites on average, 29.2% fewer than the 2.74 in a US English answer, and every other language tested also gets fewer sources. ChatGPT gives no sources at all in 8% of Portuguese answers, against 1.7% in US English.
Behind each ChatGPT answer, the chatbot runs 1.48 web searches on average that the user never sees, and one question about accounting software triggered 11. Those hidden searches average 8.9 words, against 5.3 for the question the user typed: they are the queries your content really has to match.
When people asked ChatGPT for the best product without mentioning a year, 66.5% of the hidden web searches ChatGPT ran to answer added "2026" on its own. Across every kind of question without a year the rate was 31.2%, and for time-sensitive topics ChatGPT adds the full date.
45.5% of the hidden web searches ChatGPT runs to answer a question leave out at least one of the question's meaningful words. ChatGPT keeps the topic but rewrites the wording, swapping casual terms for formal ones and adding years, product names and official sources.
When someone asks ChatGPT for the best product, 52% of the time at least one of the hidden web searches it runs already names specific brands, before it has read a single result. A brand missing from that first search starts behind, and the longest search chains end on the brands' own websites.
None of the 602 hidden web searches ChatGPT ran to write its answers mention Reddit, and 7.5% ask for reviews. ChatGPT's own searches ask for "best" roundups and official sources far more often than for opinions, even on shopping questions.
Gemini answers 52.5% of legal questions without citing a single source, against 1.4% for ChatGPT. When AI answers do cite, the American Bar Association's americanbar.org leads, appearing in 14.7% of sourced answers, ahead of Wikipedia and the Bureau of Labor Statistics.
Gemini gives no source at all in 77.1% of its answers to health questions, against 2.4% for ChatGPT. When AI answers do cite, the National Institutes of Health dominates: nih.gov appears in 32.3% of sourced health answers, three times the rate of the next website, the CDC.
Gemini answers 35.4% of money questions without citing a single source, against 3.9% for ChatGPT. When AI answers do cite, the IRS website leads, appearing in 13.8% of sourced answers, ahead of the SEC's investor.gov and the Consumer Financial Protection Bureau.
ChatGPT cites the Consumer Financial Protection Bureau's consumerfinance.gov in 40.9% of its sourced answers to real estate questions, while Gemini cites it in 0.5%. Across both engines the CFPB is the top source, ahead of Experian and Bankrate, and listing portals such as Zillow rank lower.
Gemini answers 82.2% of home improvement questions without citing a single source, against 2.2% for ChatGPT. When AI answers do cite, government agencies and universities dominate: energy.gov leads, and government and university websites take 39.2% of all citations.
Companies and other commercial websites take 76.2% of the citations in AI answers to travel questions, the highest share of 12 industries, against 8.1% for government and university websites. Delta's website is the top source on both ChatGPT and Gemini.
Reddit appears in 14.7% of Gemini's sourced answers to car questions, more than any other website, against 0.3% of ChatGPT's. ChatGPT's top car source is Consumer Reports, which Gemini never cites, and no website reaches 7% of all sourced answers.
apple.com appears in 24.3% of the ChatGPT and Gemini answers to software questions that cite a source, and microsoft.com in 17.7%. On ChatGPT alone, Apple's share rises to 31%, while government and university websites take 4.7% of software citations, the lowest of 12 industries.
The most-cited website in AI answers to college questions is not a college or a rankings site but the Consumer Financial Protection Bureau's consumerfinance.gov, in 13.1% of sourced answers. Federal student aid sites and lenders fill most of the top ten, and the answers draw on 998 different websites, more than any other industry.
The National Institutes of Health's nih.gov appears in 41.5% of ChatGPT and Gemini answers to fitness questions that cite a source, the strongest lead any single website holds in 12 industries. Government and university websites take 45.5% of fitness citations; forums and social media take 0.2%.
ChatGPT cites VCA Animal Hospitals' vcahospitals.com in 23.6% of its sourced answers to pet questions, while Gemini never cites it. Across both engines VCA is the top pet source at 18.4%, just ahead of the American Kennel Club and PetMD, and Gemini answers 72.1% of pet questions with no source at all.
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