title: How can I evaluate out-of-domain question in a domain-specific Q&A bot when I only have in-domain data?
body: <p>I learned that some popular bots like RASA or LUIS will have "confidence scores" to evaluate the out-of-domain questions, but none of them provide documentation of how they calculate these scores. Also, information retrieval has some approaches to compute similarity, but I don't know what approaches it will use for out-of-domain classification. Could someone give me some ideas about which papers, directions, or codes I can work on?</p>