The purpose of summary statistics is to take a mass of raw data and condense it in some useful manner. With biosurveillance, the goal is to facilitate an understanding of some aspect of the biosphere. In terms of situational awareness (SA), biosurveillance systems must summarize the data in ways that facilitate an understanding of historical trends, the current state, and how the current state compares with historical trends. That is, as the chapter title says, they must effectively display the situation for the decision maker.

Whereas medical practitioners operate at the individual datum level, meaning they see the biosphere one patient at a time, the point of biosurveillance is aggregation of data in order to see events that may not be evident at the individual level. In terms of early event detection (EED), both views are necessary for effective biosurveillance because some types of events are best detected on a case-by-case basis by individual medical practitioners, and other types of events are best detected in the aggregate.