Evaluation of Stemming, Query Expansion and Manual Indexing Approaches for the Genomic Task

This paper describes our participation in TREC-2005 for the ad hoc Genomic track, in which we evaluate five different stemming approaches to performing domainspecific searches within a MEDLINE subset. We also evaluate the impact that manually assigned descriptors (MeSH headings) have on retrieval effectiveness. We design a domain-specific query expansion scheme and compare it with the more classic Rocchio approach. In our experiments on this collection subset, we discover that mean average precision does not improve when using different stemming algorithm. We then show how the presence of the MeSH headings significantly enhances mean average precision by about 9%. Finally, we illustrate how the use of various query expansion techniques can impairs retrieval performance.