Why do some AI answers include no sources?
Updated
Short answer
Not every engine cites on every answer. Some answer from what they already know rather than retrieving pages, and those answers carry no citation list. Perplexity cites most consistently, which is why citation rate is tracked separately from mention rate.
Answers from memory and answers from search
An engine answering from what it learned in training has nothing to cite. An engine that searches the web while answering usually lists the pages it used. The same engine can do either, depending on the question.
What it means for your data
- Answers without sources still count for visibility, share of voice and sentiment.
- Source analysis only draws on answers that cited something.
- An engine that rarely cites is shaped more by what it already knows, which changes slowly.