A ratio that measures the success of a search. Recall is defined mathematically as the number of relevant items returned by a search divided by the total number of relevant items in the collection. Thus, a search that returned all the relevant items in a collection would have a recall of 1.0.

      Recall can be increased by the use of synonym rings and variant terms. Recall usually has an inverse relationship to precision. That is, increasing the recall of a search usually decreases the precision. For more information, see: