IRS13 Test Environment chapter E. M. Keen Harvard University Gerard Salton Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. FIRST RELEVANT SECOND RELEVANT LAST RELE ECTION AND Number of I I I CT IONARY Average % of Average % of Average Documents Requests Rank Collection Rank Collection Rank Co I I tracts, Thesaurus-3 780 34 5.2 0.7% 11.2 I 1.4% 251.8 I I I tracts, Thesaurus-3 200 I 42 4.5 i 2.3% 9.7 I 4.9% 65.5 I I I tracts, Thesaurus-l 82 35 4.3 i 5.2% 12.2 14.9% 34.5 I I I I I I _________ Comparison of the Three Collections using Average Rank Positions of the First, Second and Last Relevant Documents, Thesaurus Dictionary Fig. 24