AI engineering glossary · RAG vector search
What is abstention?
Abstention: Declining to answer when the retrieved evidence is insufficient, for example by replying that the information was not found. It is a desired behaviour in RAG, since a wrong confident answer is usually worse than no answer.
Abstention: an example
When no chunk scores above the threshold, the assistant says 'I could not find this in the policy documents'.
Related terms
More RAG vector search terms
- Access control in retrieval
- Agentic RAG
- Alpha weighting
- ANN recall
- Answer correctness
- Answer relevance
- Approximate nearest neighbour search
- Asymmetric search
Where you learn it
Abstention is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.