Surveillance methods monitor changes in the occurrence of some event, such as the temporal or spatial pattern of a disease. Surveillance methods can signal when current conditions differ from a historical baseline (O'Brien and Christie 1997).
For surveillance, the important steps are determining the baseline rate and the threshold for alarm, how much change from the baseline is "enough" for concern. Thus, statistical surveillance methods trade-off sensitivity to changes with the likelihood of producing a false alarm. Surveillance methods have the highest accuracy for larger datasets and the highest sensitivity for lower baseline disease rates (Barbujani and Calzolari 1984).
ClusterSeer contains one surveillance method:
Rogerson's Spatial Pattern Surveillance Technique for spatial surveillance. This method explores changes in the spatial pattern of an event.