Applying cusum-based methods for the detection of outbreaks of Ross River virus disease in Western Australia

Table 4 Summary performance statistics for false alarm rates approximating 0.005^† for the negative binomial cusum with an out of control state defined as 3 standard deviations greater than the mean

Algorithm	false alarm rate	mean sensitivity	Day 1 sensitivity	Day 2 sensitivity	Days 1–7 sensitivity	CARL	median timeliness^‡
NBC 7-day	0.0049	0.80	0.2	0.07	0.33	1.6	13.0
NBC 14-day	0.0049	0.97	0.2	0.07	0.33	1.6	12.0
NBC 28-day	0.0049	1.00	0.27	0.07	0.60	3.0	6.0
NBC 56-day	0.0038	1.00	0.27	0.07	0.40	1.5	12.0

^†Test threshold that produced a false alarm rate ≤ 0.00
^‡Detection on the first outbreak day is equivalent to a timeliness of 0 days
CARL: Conditional Average Run Length – conditional on the detection of the outbreak during the first 7 days
NBC: Negative binomial cusum

ISSN: 1472-6947