Number of weeks between disease emergence and cluster detection for groups of scenarios 1 to 8 for various levels of random noise added to the simulated milk losses.

Cluster detections were performed using a scan statistic for groups of scenarios 1 to 8 on simulated milk losses as well as on simulated milk losses plus 4 levels of random noise. Random noise vectors were sampled from normal distributions with means 0 and standard deviations 1, 3 and 5. Disease emergence was simulated on week 9 (01/03/2006), starting from the Western location. The None column gives the week after emergence at which the first cluster was detected using the simulated milk losses without any added random noise as input. Other columns present the delay in weeks between cluster detection in the absence of noise and for the 3 simulated levels and random noise.