Precision and recall

Precision and recall

http://en.wikipedia.org/wiki/Precision_and_recall

Definition (classification context)

For (binary) classification tasks, the terms

true positives, 

true negatives, 

false positives, 

and false negatives 

(see alsoType I and type II errors) 

compare the results of the classifier under test with trusted external judgments. 

Precision and recall are then defined as:^[5]

A measure that combines precision and recall is the harmonic mean of precision and recall, the traditional F-measure or balanced F-score:

"Precisionrecall" by Walber - Own work. Licensed under CC BY-SA 4.0 via Wikimedia Commons.