The potential and actual effectiveness of interactive query expansion

In query expansion, terms from a source such as relevance feedback are added to the query. This often improves retrieval effectiveness but results are variable across queries. In interactive query expansion (IQE) the automatically-derived terms are instead offered as suggestions to the searcher, who decides which to add. There is little evidence of whether IQE is likely to be effective over multiple iterations in a large scale retrieval context, or whether inexperienced users can achieve this effectiveness in practice. These experiments address these two questions. A small but significant improvement in potential retrieval effectiveness is found. This is consistent across a range of topics. Inexperienced users’ term selections consistently fail to improve on automatic query expansion, however. It is concluded that interactive query expansion has good potential, particular y for term sources that are porer than relevance feedback. But it may be difficult for searchers to realise this potential without experience or training in term selection and free-text search strategies.