IRS13 Word-Word Associations in Document Retrieval Systems chapter M. E. Lesk Harvard University Gerard Salton Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. IX-51 b) associative retrieval is not an effective recall device but is rather a precision device in many cases, operating by increasing the weight of significant terms rather than by introducing new significant terms; c) as a method of improving both precision and recall, a properly made thesaurus is generally preferable to as- sociative procedures. The usefulness of an associative method in operational retrieval experiments will probably be restricted to aiding dictionary constructors by pointing out unusual word relationships in a document collection, and as an alternative option for requests which do not perform well in a thesaurus. The method does not appear to be a reliable substitute for a thesaurus for the typical retrieval operation.