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. o STEM ½ 0 [OCRerr] THESAURUS ½ PRECISION PRECISION I.c - 1.0 0.8 0.8 O.E - o A[OCRerr] OA - OA - [OCRerr] 0.2 - OA 0.2 - 0 I I I I i I i I I I I I j I I I I I I I 0 RECALL 0 0.2 0.4 0.6 0.8 1.0 0.2 0.4 0.6 0.8 1.0 RECAL Comparison 1 Comparison 2 o STEM A THESAURUS ½ IRE-3, Abstracts, 34 Requests IRE-3, Abstracts, 34 Requests Performance Curves Comparing Stem and Thesaurus Dictionaries on the IRE-3 Collection Fig. 8