
The four numbers at the cross of the solid lines (Hit, Miss, FA=False Alarm, NE=NonEvent) are the frequencies of events predicting observed high pollution
Acc = (Hit+NE) / (Hit+NE+FA+Miss) Ideal to be 1
Bias = (Hit+FA) / (Hit+Miss) Ideal to be 1.
CSI (Critical Success Index) = Hit / (Hit+FA+Miss) Ideal to be 100%.
POD (Probability of Detection) = Hit / (Hit+Miss) Ideal to be 100%.
FAR (False Alarm Ratio) = FA / (FA+Hit) Ideal to be 0%.
Level Accuracy is the percentage of frequencies successfully predicting the 6 China AQI levels. 