IRS13 Thesaurus, Phrase and Hierarchy Dictionaries 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. 0 THESAURUS-I (OLD Q.S.) D THESAURUS-2 THESAURUS-3 0 0 THESAURUS-2 (NEW Q. S.) THESAURUS- 3(REVISED NEW Q.S.) o THESAURUS-I (OLD Q.S.) 0 o THESAURUS-2 (NEW Q.S.) 0 ION PRECISION PRECISION 1.0 - IC - 0.8 0.6 - 0.4 - o~~a 0.6 - 0.6 - OA - 0 0[OCRerr] [OCRerr] 0 0 0 [OCRerr] 0[OCRerr]0[OCRerr]00[OCRerr]0[OCRerr]0 0.2 - 0.2 - I j I I I 0.2 Q4 0.6 0.8 1.0 RECALL0 -3, Abstracts, 34 Requests I I I I 1[OCRerr]RECALL 0.2 0.4 0.6 0.8 1.0 0 Cran-l, Abstracts, 42 Requests I I I I [OCRerr][OCRerr]CAL 0.2 0.4 0.6 QB 1.0 Cran-l, Indexing, 42 Requests Performance Curves Comparing Different Thesaurus Dictionaries on Two Collections Fig. 18