Overall Accuracy and Predictive Values
It is possible, at each time point t, to calculate the positive and negative predictive values, defined as the probability of observing a rise or drop in the future number of cases, given that an early warning was issued or not, respectively. Finally, once the entire time series data has been observed the overall SeEVI and SpEVI can be estimated.
Sensitivity analysis
The accuracy of EVI depends on the specified case definition. Ideally, in the presence of historical data, various case definitions should be explored to identify which are suitable for the optimal monitoring of an epidemic.