Answer:
Sensitivity, Predictive value positive, representativeness and timeliness.
Explanation:
In order to detect outbreaks and thus group people based on greatest risks, it is mandatory for a surveillance system to be sensitive and thus detect a reasonable amount of cases in the community alongside changes in severity of cases over a period of time. It is also expected that there is high predictability and be representative of cases in the community capable of describing the occurrence of disease by person, time ad place. It should also be timely in its execution, without any delays, as this will allow investigation and control measures to commence quickly.