Relevance Feedback and Query Expansion Local method: Relevance Feedback Relevance feedback Relevance feedback: user feedback on relevance of docs in initial set of results User issues a(short simple query The user marks some results as relevant or non -relevant The system computes a better representation of the information need based on feedback Relevance feedback can go through one or more iterations Idea: it may be difficult to formulate a good query when you dont know the collection well, so iterateRelevance Feedback and Query Expansion Relevance Feedback ▪ Relevance feedback: user feedback on relevance of docs in initial set of results ▪ User issues a (short, simple) query ▪ The user marks some results as relevant or non-relevant. ▪ The system computes a better representation of the information need based on feedback. ▪ Relevance feedback can go through one or more iterations. ▪ Idea: it may be difficult to formulate a good query when you don’t know the collection well, so iterate Local Method: Relevance Feedback 7