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. 111-19 Request QA9 ADI Collection, full text, thesaurus dictionarv. 2 relevant documents Cosine Correlation (Logical Vectors) Relevant Documents Correlation 82 0.1867 50 0.1624 Recall = 0.8250 Precision = 0.4535 Rank 7 24 Normalized Normalized Overlap Correlation (Logical Vectors) Relevant Rank Documents Correlation 36 50 o.6666 59 82 0.5000 Normalized Recall = 0.4250 Normalized Precision = 0.1406 Length (Thesaurus Concepts) 43 102 Length (Thesauru8 Concepts) 102 43 Example of individual request where cosine is superior to overlap Figure 9.