ISR11 Scientific Report No. ISR-11 Information Storage and Retrieval Information Analysis and Dictionary Construction chapter G. Salton M. E. Lesk Harvard University Gerard Salton Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. IV-39 Full Null Harris Two Harris Three 0.1 0.9563 0.1 0.9551 0.1 0.9735 0.2 0.861[OCRerr]8 0.2 0.8242 0.2 0.8973 0.3 0.7986 0.3 0.7389 0.3 o.8245 0.7381 o.4 0.6796 0.4 0.7551 0.5 0.6371 0.5 0.6070 0.5 0.7146 0.6 0.5589 0.6 0.5702 0.6 0.6499 0.7 0.7 0.5233 0.7 0.6012 0.8 0.4086 0.8 0.IL,821 0.8 0.5514 0.9 0.3426 0.9 0.4452 0.9 0.4973 1.0 0.2613 1.0 0.3951 1.0 0.i!118 F~CISI0N 1.0 0.9 0.8 0.7 0.6 0.5 o.4 0.3 ffl[OCRerr] __ _ [OCRerr][OCRerr]K¼[OCRerr]¾ II _ [OCRerr][OCRerr]Q¼ - - _-_ y¼½ [OCRerr]` _ _ [OCRerr]# 0.2 0.1 0 .1 .2 .3 .4 .5 .6 .7 .8 .9 1.0 RECALL Comparison Based on Thesauruses (averages over 17 search requests) 11