RETRIEVAL FEEDBACK IN MEDLINE

Objective: To investigate a new approach for query expansion based on retrieval feedback. The first objective in this study was to examine a lternative query-expansion methods within the same retrieval-feedback framework. The three alternatives proposed are: expansion on the MeSH query field alone, expansion on the free-text field alone, and expansi on on both the MeSH and the free-text fields. The second objective was to gain further understanding of retrieval feedback by examining poss ible dependencies on relevant documents during the feedback cycle. Des ign: Comparative study of retrieval effectiveness using the original u nexpanded and the alternative expanded user queries on a MEDLINE test collection of 75 queries and 2,334 MEDLINE citations. Measurements: Re trieval effectivenesses of the original unexpanded and the alternative expanded queries were compared using 11-point-average precision score s (11-AvgP). These are averages of precision scores obtained at 11 sta ndard recall points. Results: All three expansion strategies significa ntly improved the original queries in terms of retrieval effectiveness . Expansion on MeSH alone was equivalent to expansion on both MeSH and the free-text fields. Expansion on the free-text field alone improved the queries significantly less than did the other two strategies. The second part of the study indicated that retrieval-feedback-based expa nsion yields significant performance improvements independent of the a vailability of relevant documents for feedback information. Conclusion s: Retrieval feedback offers a robust procedure for query expansion th at is most effective for MEDLINE when applied to the MeSH field.