Boolean versus ranked querying for biomedical systematic reviews

Table 5 Effectiveness of query expansion using MeSH.

Target	Src	RBP99	P@1,000	R@1,000	P@10,000	R@10,000
Tier 0	1	0.162	0.124	0.157	0.043	0.449
	2	0.173	0.131	0.160	0.045	0.436
	3	0.179	0.130	0.162^†	0.045	0.440
Tier 1	1	0.066	0.043	0.320	0.010	0.673
	2	0.069	0.046	0.335	0.010	0.700
	3	0.074	0.045	0.335	0.011	0.682
Tier 2	1	0.035	0.019	0.405	0.004	0.769
	2	0.036	0.020	0.421	0.004	0.790
	3	0.038	0.020	0.416	0.004	0.758

Retrieval is from the full MEDLINE collection, to the Target level indicated. The TRC queries are expanded, using three sources (Src): 1, qualifiers (sub-headings); 2, qualifiers and concept terms; and 3, qualifiers, concept terms, abbreviations, and supplementary terms. POS tagging is applied to detect phrases in the queries. †, ‡ indicate paired t-test with 95 and 98 percent confidence levels respectively (over baseline of TRC queries).

ISSN: 1472-6947