CORRIGENDUM: False Alarm Rate or False Alarm Ratio?

Two items need to be clarified from an earlier work of the authors. The first is that the layout of the 2 3 2 contingency table was reversed from standard practice, with the titles of ‘‘observed event’’ and ‘‘forecast’’ transposed. The second is that FAR should have represented ‘‘false alarm ratio,’’ not ‘‘false alarm rate.’’ Unfortunately, the terminology used in the atmospheric sciences is confusing, with authors as early as 1965 having used the terminology differently from currently accepted practice. More recent studies are not much better. A survey of peer-reviewed articles published in American Meteorological Society journals between 2001 and 2007 found that, of 26 articles using those terms, 10 (38%) used them inconsistently with the currently accepted definitions. This article recommends that authors make explicit how their verification statistics are calculated in their manuscripts and consider using the terms probability of false detection and probability of false alarm instead of false alarm rate and false alarm ratio.