Fig. 3.
Choropleth maps of observed (a) and true (b) West Nile virus dead bird mortality in southern Ontario 2005 with disease clusters identified by the circular spatial scan statistic. In (a) the large circle indicates the location of a single cluster in the observed mortalities and is based on a maximum cluster population size of 50%. The two smaller circles correspond to clusters identified with a maximum cluster population 30% or 40%. In (b) the two circles indicate cluster location in the true mortalities as with a maximum cluster population size of 50%, 40% or 30%.