IRS13
Scientific Report No. IRS-13 Information Storage and Retrieval
Evaluation Parameters
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.
11-12
Normalized "Sliding Ratio" Statistic:
[OCRerr](n) =
f (n)
where n = rank position
f = nuii[OCRerr]ber of relevant examined in ideal result
*
f = number of relevant actually examined.
[OCRerr]xample using Cran-l Request [OCRerr]68, with Ranks of F[OCRerr]ve Relevant
l,2,[OCRerr],6,l3
*
Rank(n) f f [OCRerr]
1 1 1 1.00
2 2 2 1.00
3 3 2 0.67
[OCRerr] [OCRerr] 3 0.75
5 5 3 0.60
6 5 [OCRerr] o.8o
7 5 [OCRerr] o.8o
9 . . *
13 5 5 1.00
l[OCRerr] 5 5 1.00
. . . .
. e *
Result of Cran-l Individual Request [OCRerr]68, Thesaurus-2, Showing
E[OCRerr]valuation Using the Nomialized "Sliding Ratio" Statistic
Proposed by Giuliano and Jones [OCRerr]8].
Fig. 6.