This 2x2 contingency table summarizes the joint distribution of K 5 short-term warnings during years 1999-2006. The "Correct Null" value in the table represents the number of 3-hour geomagnetic intervals in the four year period for which no warning was issued and no K 5 activity occurred. The summary statistics derived from the contingency table include the Bias (values less than 1 indicate fewer warnings issued than events observed), Heidke skill score (a corrected skill score that accounts for hits due to chance), Critical Success Index (also called the Threat Score), Probability of Detection (POD), and the False Alarm Ratio (FAR). Detailed definitions of these metrics are in the Verification Glossary.

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