IRS13 Scientific Report No. IRS-13 Information Storage and Retrieval Document Length 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. V-19 TOTAL TOTAL DOCUMENTS AVERAGE* COLLECTION INPUT AND DICTIONARY RELEVANT WITH ZERO RECALL (ALL REQUESTS) CORRELATION CEILING WITH REQUEST Abstract Stem 592 23 .96 IRE-3 Title Stem 592 129 .78 3[OCRerr] Abstract Thesaurus-3 592 i4 .98 Requests Title Thesaurus-3 592 92 [OCRerr] Abstract Stem 198 17 .91 CRAN-l Title Stem 198 59 .70 1+2 Abstract Thesaurus-3 198 10 .95 Requests Title Thesaurus-3 198 1+4 .78 Abstract Stem 170 15 .91 ADI Title Stem 170 58 .66 35 Abstract Thesaurus-l 170 i1+ .92 Requests Title Thesaurus-l 170 1+9 .71 *Computed using the aggregate recall (11micro11 evaluation). Average recall ceiling figures comparing abstract and titles searches on three collections each with two dictionaries. Fig. 8.