Glossary term

F1 score

A single metric that balances precision and recall.

How it works

The F1 score is the harmonic mean of precision and recall, so it is high only when both are high. It ranges from 0 to 1.

It is useful for a single number on imbalanced problems, where accuracy can be misleading.

Precision, recall and the F1 that balances them

F1 score

f1 = 2 * precision * recall / (precision + recall)

It balances the trade-off between catching positives and avoiding false alarms.