IRS13 Search Matching Functions 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. 111-20 Request QA2 ADI Collection, full text, thesaurus dictionary. 2 relevant documents. Cosine Correlation (Logical Vectors) Relevant Rank Documents Correlation Length(Thesaurus Concepts) 25 12 0.2l[OCRerr]l 159 29 71 0.2108 162 Normalized Recall = 0.6813 Normalized Precision = 0.2732 Overlap Correlation (Logical Vectors) Relevant Rank Documents Correlation Length(Thesaurus Concepts) 12 o.8888 159 71 o.8888 162 Normalized Recall = 0.8438 Normalized Precision = 0.[OCRerr]3[OCRerr]5 Example of individual request where overlap is superior to cosine. Figure 10.