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. Author manuscript; available in PMC: 2009 Sep 21.
Published in final edited form as: Inf Retr Boston. 2009;12(1):69–80. doi: 10.1007/s10791-008-9074-8

Table 6.

Results of the 2006 and 2007 TREC topics with and without query expansion as measured by mean rank precision. Retrieved documents are sorted under the TF-IDF weighting scheme.

TREC Query Expansion P@5 P@10 P@20
2006 Yes 0.622 0.616 0.621
No 0.613 0.592 0.584
2007 Yes 0.538 0.525 0.503
No 0.566 0.548 0.519