Definition
Precision measures the accuracy of an information retrieval (IR) system. More precisely, precision is the fraction of retrieved documents that are relevant. Consider a test document collection and an information need Q. Let R be the set of documents in the collection that are relevant to Q. Assume an IR system processes the information need Q and retrieves a document set A. Let |R a | denote the number of documents that are in both R and A. Further let |R| and |A| be the numbers of documents in R and A, respectively. The precision of the IR system for Q is defined as P = |R a |∕|A|.
Key Points
Precision and recall are the most frequently used and basic retrieval performance measures. Many other standard performance metrics are based on the two concepts.
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© 2009 Springer Science+Business Media, LLC
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Zhang, E., Zhang, Y. (2009). Precision. In: LIU, L., ÖZSU, M.T. (eds) Encyclopedia of Database Systems. Springer, Boston, MA. https://doi.org/10.1007/978-0-387-39940-9_480
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DOI: https://doi.org/10.1007/978-0-387-39940-9_480
Publisher Name: Springer, Boston, MA
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