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-[OCRerr]3 AVERAGE TOTAL TOTAL DOCUMENT RELEVM[OCRerr] DOCUME[OCRerr][OCRerr][OCRerr][OCRerr] AVERAGE[OCRerr] COLLECTION INPUT AND DICTIONARY LENGTH, (ALL RE WITH ZERO [OCRerr]CALL re CONCEPTS CORRELATION CEILING PER DOCT. QUESTS) WITH REQUEST CRAN-l Abstract, Stem 61 198 17 .91 142 Indexing, Stem 32 198 11 .91+ Requests Abstract, Thesaurus-2 14o 198 1+ .98 Indexing, Thesaurus-2 30 198 0 1.00 *Computed usLng aggregate recall ("micro" evaluation). Average recall ceiling figures comparing abstracts and indexing on two dictionaries, Cran-l Collection. Figure 29.