F1 Score

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In statistics, the F1 Score (also F-score or F-measure) is a measure of a test's accuracy. It is defined as (2×p×r)/(p+r), where p is the precision and r is the recall of the test. This is the harmonic mean of p and r. The F1 score can be computed by finding p as the number of correct results divided by the number of all returned results and r as the number of correct results divided by the number of results that should have been returned. The F1 score can be interpreted as a weighted average of the precision and recall, where an F1 score reaches its best value at 1 and worst score at 0.