Work out alert threshold (moving average) instantly with clear inputs, formula shown and shareable results.
Builds an aberration detection threshold from a moving average plus a sigma multiple, the basis of the Early Aberration Reporting System C-charts.
Moving average threshold
Threshold = moving average + k x standard deviation of the baseline window; a signal is raised when the current count exceeds it
Seven periods is the CDC C1 default, with a guard band before the current period to avoid contaminating the baseline.
If the outbreak has already begun, including recent periods in the baseline raises the threshold and hides the signal.