The extent to which something is measured.
The ratio of relevant items to all items retrieved.
Precision1 is often expressed in terms of deviation from an established benchmark. - Precision2 measures the quality of a search. It is possible to retrieve all relevant items in a database (a 100% recall ratio), but the precision of the search is likely to be low. If a database contains 100 items, and 25 are relevant to a search, a search that returns all items has 100% recall but only 25% precision.