High Quality Content by WIKIPEDIA articles! In pattern recognition and information retrieval, precision is the fraction of retrieved instances that are relevant, while recall is the fraction of relevant instances that are retrieved. Both precision and recall are therefore based on an understanding and measure of relevance. When a program for recognizing the dogs in a scene correctly identifies four of the nine dogs but mistakes three cats for dogs, its precision is 4/7 while its recall is 4/9. When a search engine returns 30 pages only 20 of which were relevant while failing to return 40 relevant pages, its precision is 20/30 = 2/3 while its recall is 20/60 = 1/3.