IRS13 Scientific Report No. IRS-13 Information Storage and Retrieval 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. SPECIFIC REQUESTS GENERAL REQUESTS COLLECTION AND I I DICTIONARY Average Rank Number of Average Rank Number of of Last Relevant Requests of Last Relevant Requests ____________________ I I [OCRerr]-. I I RE-i, Abstract, Thesaurus-2 18.9 9 96.9 8 I I RE-3, Abstract, Thesaurus-3 210.0 17 293.5 17 I I RAN-i, Abstract, Thesaurus-3 1+5.2 21 85.8 21 DI, Abstract, Thesaurus-i 22.1 17 1+6.1 18 I ` omparison of Specific and General Requests using the Average Rank Position of the Last Rele- vant Document to represent High Recall Need, (Thesaurus Dictionary) Fig. 19