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Table 7 The output size of the original and simplified Boolean queries in the drug collection after re-running on Ovid MEDLINE (1950 - Week 3, Nov 2008).

From: Boolean versus ranked querying for biomedical systematic reviews

    Simplified
  Original Ovid Lucene
Query all unique all unique  
1 2,153 1,986 29,074 15,027 7,654
2 1,378 1,347 120,420 111,653 1,596
3 101 101 1,857 1,799 1,568
4 994 897 12,857 11,924 81,371
5 1,526 1,343 63,494 53,319 8,093
6 276 276 159,772 153,121 36,686
7 1,200 1,117 109,584 104,743 308,329
8 309 230 106,154 81,018 64,704
9 1,464 1,464 41,544 35,618 17,686
10 64 64 2,260 2,205 243,733
11 930 540 6,420 6,172 23,896
12 140 140 3,215 3,058 1,599
13 5,578 5,378 21,332 20,588 13,491
14 1,969 1,782 39,446 36,487 24,230
15 997 997 9,859 9,568 5,189
  1. Number of unique documents returned and total number of retrieved documents are shown per query.