Fig. 2From: A methodological framework for the evaluation of syndromic surveillance systems: a case study of EnglandMedian time to detection per month. Median T D for influenza and Cryptosporidium spp. outbreaks stratified by month of the onset and syndromic indicator. The colour of the boxes indicate the median T D . The darkness of the box filling indicates the probability of detection (P D ) as defined in the legend. Boxes with a P D ≤0.50 were excludedBack to article page