F-measure
A measure that combines precision and recall is the harmonic mean of precision and recall, the traditional F-measure or balanced F-score:
This is also known as the measure, because recall and precision are evenly weighted.
It is a special case of the general measure (for non-negative real values of ):
Two other commonly used measures are the measure, which weights recall higher than precision, and the measure, which puts more emphasis on precision than recall.
The F-measure was derived by van Rijsbergen (1979) so that "measures the effectiveness of retrieval with respect to a user who attaches times as much importance to recall as precision". It is based on van Rijsbergen's effectiveness measure . Their relationship is where .
Read more about this topic: Precision And Recall