A distribution-free regional cumulative sum for identifying hyperendemic periods of disease incidence

A new distribution-free cumulative sum procedure is introduced. This procedure aims to diagnose geographical-temporal clustering of events in parallel records of events over time in neighbouring geographical areas of a defined region or country. The procedure applies in the presence of possible seasonality and yearly trend provided that those patterns are maintained over all the areas of the region. The method is applied specifically to records of meningococcal disease.