ISR10 Search Request Formulation chapter Joseph John Rocchio Harvard University Gerard Salton Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. 7 0 5-47 modified queries is indicative of the broadness of the relevance judgments used in specifying D The use of multiple queries in general, must be justified in terms of the expected improvement in retrieval performance compared with the added cost of an additional search. Thus in respect to search cost, a two-way multiple search is equivalent to an additional iteration of a single query. Since the cost of query modification by relevance [OCRerr]eedback is likely to be a small fraction of the cost of a search operation, the typical user maximizes his return by supplying a good relevance feedback sajr[OCRerr]le (i.e. by carefully examining the initial retrieved output). [OCRerr]ulti[OCRerr]le searching may, however, be warranted in those cases where the user must obtain access to every relevant document. In such cases' one can assume that the value of obtaining the reference justifies the additional cost.