Skill

From AMS Glossary
(Redirected from False alarm rate)
Jump to: navigation, search


skill

A statistical evaluation of the accuracy of forecasts or the effectiveness of detection techniques.

Several simple formulations are commonly used in meteorology. The skill score (SS) is useful for evaluating predictions of temperatures, pressures, or the numerical values of other parameters. It compares a forecaster's root-mean-squared or mean-absolute prediction errors, Ef, over a period of time, with those of a reference technique, Erefr, such as forecasts based entirely on climatology or persistence, which involve no analysis of synoptic weather conditions:
ams2001glos-Se28
If SS > 0, the forecaster or technique is deemed to possess some skill compared to the reference technique. For binary, yes/no kinds of forecasts or detection techniques, the probability of detection (POD), false alarm rate (FAR), and critical success index (CSI) may be useful evaluators. For example, if A is the number of forecasts that rain would occur when it subsequently did occur (forecast = yes, observation = yes), B is the number of forecasts of no rain when rain occurred (no, yes), and C is the number of forecasts of rain when rain did not occur (yes, no), then
ams2001glos-Se29
ams2001glos-Se30
ams2001glos-Se31
For perfect forecasting or detection, POD = CSI =1.0 and FAR = 0.0. POD and FAR scores should be presented as a pair.

Personal tools
Namespaces
Variants