F-beta score ("f-score")

Recall that the -score is defined as

This score is the harmonic mean of precision and recall and so puts equal weight on both. We can add a tunable parameter to assign an importance (weight) to either precision or recall. is conventionally associated with precision to produce :

Typically is used to emphasize recall and is used to emphasize precision. (Whatever your intuition may say, this is NOT the other way around!)