Table 2.

The number of signals, sensitivity, time to detection, and false alarm rates for the C1, C2, and C3 algorithms by epidemic and non-epidemic season, based on the optimal thresholds identified separately for the epidemic and non-epidemic seasons

Period	Algorithm	Optimal threshold	No. signals	Sensitivity (%)	Time to detection (days)	False alarm rate (%)
Epidemic season*	C1	0.2	6614	95.88	1.0	1.83
	C2	0.6	5850	95.88	1.0	1.61
	C3	0.6	6000	95.88	1.0	1.65
Non-epidemic season*	C1	2.2	278	100	4.0	0.07
	C2	2.2	295	100	4.0	0.07
	C3	2.2	328	100	4.0	0.08

^*The period from March 20, 2009 to September 2, 2009 was defined as the epidemic season, a total of 167 days. The rest of the year was defined as the non-epidemic season, a total of 198 days.