Why can’t LLM’s like ChatGPT calculate a confidence score when providing an answer to your question and simply reply “I don’t know” instead of hallucinating an answer?

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It seems like they all happily make up a completely incorrect answer and never simply say “I don’t know”. It seems like hallucinated answers come when there’s not a lot of information to train them on a topic. Why can’t the model recognize the low amount of training data and generate with a confidence score to determine if they’re making stuff up?

EDIT: Many people point out rightly that the LLMs themselves can’t “understand” their own response and therefore cannot determine if their answers are made up. But I guess the question includes the fact that chat services like ChatGPT already have support services like the Moderation API that evaluate the content of your query and it’s own responses for content moderation purposes, and intervene when the content violates their terms of use. So couldn’t you have another service that evaluates the LLM response for a confidence score to make this work? Perhaps I should have said “LLM chat services” instead of just LLM, but alas, I did not.

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Anonymous 0 Comments

It doesn’t *never* say “I don’t know.”, but it is rare.

The model doesn’t inherently know how much training data it has. It’s “knowledge” is a series of numbers in an abstract web of correlations between ‘tokens’ (i.e groupings of letters).

My understanding is that internally, the base GPT structure does have an internal confidence score that seems moderately well calibrated. However, in the fine-tuning to ChatGPT, that confidence score seems to go to extremes. I recall reading something iek that from the relevant people working on GPT3.

My opinion is that responses that don’t answer questions or are unconfident get downvoted in the human reinforncement training stage. This has the benefit of it answering questions more often (which is the goal of the product), but has the side effect of overconfidence when its answer is poor.

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