IRS13 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. [OCRerr]BSTRACT(A) VERSUS TITLE(T) ABSTRACT(A) VERSUS TEXT(x) ABSTRACT(A) VERSUS IND LECTION DICTIONARY I II III I II flI I II R-2 R-5 R-8 NR NP (NR)(N?) R-2 R-5 R-8 NR NP (NR)(NP) R-2 R-5 R-8 NR NP (NR [OCRerr]RE23 Stem []A LA []A L]AL]A OA OA 3[OCRerr] Thesaurus []A LA LA DADA ([OCRerr] ([OCRerr] [OCRerr]uests -3 [OCRerr]4I)IT Stem ADADADADAOAOA xDxx XX X A 35 Thesaurus T T A LA LA OOA A X X XX XOX [OCRerr]uests -1 ___________________________ _____________________________ [OCRerr] Stem ATLALALAOOA I Li I I I [OCRerr]-l Thesa[OCRerr][OCRerr][OCRerr]s A* A* A* A* A* A* Ii+IIi+IDi 1+ I[OCRerr] I[OCRerr] [OCRerr]uests Stem(Ov'er- lap Logical) T T A A T A T Word Form [OCRerr]IELD (Co-ord. T LT [OCRerr] [OCRerr]l L[OCRerr]]Li I Cutoff) 42 Word Form [OCRerr]sts (Doc. A T A L][] I ___ ________ 7 Cutoff) I Precision at Recall O.2(-2), O.5(R-5), and O.8(R-8). II Normalized Recall(NR) and Normalized Precision(NP) LJ over D = over .05 better. [No Box] = up t bett .05 better. [No Box] = up t bett in Individual Requests based on merit assigned by Normed. Recall (NR) and Normed. Precision (NP. O = over 60% of requests better. (No Circle] = between 50% and 60% better Summary of Performance Results of Document Length Comparisons Figure 39