• The Harmonic Mean of Recall and Precision, often used in Information Retrieval 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


  1. 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 Judge2013 Fed. Cts. L. Rev. 7 (January 2013).
  2. Herb Roitblat, Predictive Coding Glossary.
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