Research
What we learned measuring which sources AI assistants quote, and why. Written for an earlier version of this business, kept because it is true and because it is why the offer check exists.
Income Lab used to measure how often AI assistants named and cited a brand, and sold that measurement. It no longer does. The pages below are from that work and are dated to it, so read them as research rather than as a service on offer.
They stay up because they are true and because they are the knowledge behind what we do now. The free offer check we give brands exists because of this: knowing which crawlers decide whether you can be quoted, that a training crawler is a different thing entirely, and that a snippet control removes a page from AI Overviews even when Google is welcome.
How citation actually works
The mechanics, from vendor documentation and our own measurements.
- How pages become sources, and why they stopWhat gets a page quoted in an AI answer, and what quietly removes it again.
- The research we build onThe published studies, each with its source, sample size and date. Three figures here were corrected on 19 August 2026 after a fact-check.
- GlossaryThe words used across this research, defined once.
What we measured
Our own runs against ChatGPT, Claude and Perplexity, with the answers kept as evidence.