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## Definition

- The of and , often used in studies as a measure of the effectiveness of a search or review effort, which accounts for the tradeoff between Recall and Precision. In order to achieve a high F1 score, a search or review effort must achieve
*both*high Recall and high Precision.^{1} - One form of van Rijsbergen’s F formula for combining precision and recall into a single number to make it easier to compare the information retrieval accuracy of different systems. F1 is the weighted harmonic mean of precision and recall =
*2 * precision * recall / (precision + recall)*.^{2}

## See also

## Notes

- Maura R. Grossman and Gordon V. Cormack, EDRM page &
*The Grossman-Cormack Glossary of Technology-Assisted Review, with Foreword by John M. Facciola, U.S. Magistrate Judge*, 2013 Fed. Cts. L. Rev. 7 (January 2013). ↩ - Herb Roitblat,
*Predictive Coding Glossary*. ↩

*a*and

*b*, their Harmonic Mean is 2 / ( ( 1 / a ) + ( 1 / b ) ). In information Retrieval, F1 is the Harmonic Mean of Recall and Precision. The Harmonic Mean, unlike the more common arithmetic mean (i.e., average), falls closer to the lower of the two quantities. As a summary measure, a Harmonic Mean may be preferable to an arithmetic mean because a high Harmonic Mean depends on both high Recall and high Precision, whereas a high arithmetic mean can be achieved with high Recall at the expense of low Precision, or high Precision at the expense of low Recall.

Maura R. Grossman and Gordon V. Cormack, EDRM page & *The Grossman-Cormack Glossary of Technology-Assisted Review, with Foreword by John M. Facciola, U.S. Magistrate Judge*, 2013 Fed. Cts. L. Rev. 7 (January 2013).

Maura R. Grossman and Gordon V. Cormack, EDRM page & *The Grossman-Cormack Glossary of Technology-Assisted Review, with Foreword by John M. Facciola, U.S. Magistrate Judge*, 2013 Fed. Cts. L. Rev. 7 (January 2013).

Maura R. Grossman and Gordon V. Cormack, EDRM page &

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