Study: OpenAI API and Google Search Results Return Only About Half of What ChatGPT Cites
A preliminary study found that the OpenAI API and Google Search results together return only about half of the websites cited by ChatGPT, with the overlap reaching 50.3% for GPT-5.3.
A preliminary study conducted by researchers at the National University of Singapore and Xi'an Jiaotong University found that the OpenAI API and Google Search results together return only about half of the websites cited by ChatGPT.
The researchers tested 80 queries, finding that the combined overlap of both intermediaries reached 50.3% of the websites cited by the GPT-5.3 model, and about 48.7% with the GPT-5.5 model.
The overlap at the individual page level was lower, and none of the visible searches used the exact phrasing of the query, indicating a difference in how sources are selected.
The researchers recommend tracking both pages and domains together, and re-running the same queries multiple times, as results change from one run to another, making it difficult to measure brand visibility in answer engines.
What Do These Terms Mean?
Preprint: A research study published before review by other scientists, so its findings are considered preliminary.
Citation: A reference placed by the system to a website or page it relied on in its response.
API: A channel through which developers connect to a service like ChatGPT to request automated results from it.
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