How One Word Can Make all the Difference - Using Subject Metadata for Automatic Query Expansion and Reformulation

Query enhancement with domain-specific metadata (thesaurus terms) is analyzed for monolingual and bilingual retrieval on the GIRT social science collection. We describe our technique of Entry Vocabulary Modules, which associates query words with thesaurus terms and suggest its use for monolingual as well as bilingual retrieval. Different weighting and merging schemes for adding keywords to queries as well as translation techniques are described. Query enhancement generally improves average precision scores for both monolingual and bilingual retrieval. We take a closer look at individual queries and discuss how the query enhancements (or substitutions in bilingual retrieval) can change retrieval results quite dramatically. A query-by-query analysis provides deeper insight into strengths and weaknesses of strategies and serves as a cautionary reminder that average precision scores don’t always tell the whole story.