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-32 TOTAL DOCUMENTS AVERAGE* TOTAL WITH ZERO RECALL COLLECTION INPUT AND DICTIONARY [OCRerr]LEVANT CORRELATION CEILING ALL REQUESTS WITH REQUEST Abstract Stem 170 15 e91 ADI Text Stem 170 0 1.00 35 Abstract Thesaurus-i 170 l[OCRerr] .92 Requests Text Thesaurus-i 170 1[OCRerr] .99[OCRerr] * Computed using the aggr[OCRerr]gate recall ("micro'1 evaluation). The one document having zero correlation with the thesaurus does c[OCRerr]rrelate with r[OCRerr]quest concepts "terhniquet1 and "[OCRerr]ystem" in the stem dictionary, but these terms are in the conmion words list for the thesaurus [OCRerr]ictionar[OCRerr]. Average r[OCRerr].call ceiling figures comparing abstract and' full text searches on two dictionaries. Figure 20.