Precision and recall in the text information retrieval, are the two evaluation index of search results
Precision ( Precision ): Back to the results and the real information needs related documentation percentage of
recall ( Recall ): the percentage of all documents and information related to the real needs of the returned retrieval system
that is precision = return results the number of relevant documents / number of results returned = P | (retrieved relevant), recall rate = number of results returned in relevant documents / number of all relevant documents = P (retrieved | relevant)
Referring next to FIG: