(go to Outline)
Surveillance, even if done very well, is NOT very good at doing some things:
- Providing the data necessary to calculate the population prevalence of some health condition
Remember, prevalence is the number of people with the disease divided by the total number of people. Surveillance often gives you only information about cases of disease because the data reporters are those who take care of sick people. As a result, you do not have the population denominator with which to calculate a incidence or prevalence rate.
- Providing health information where few people have access to or seek health care services
If data reporters are health care providers and most people don't come for health care, you will never hear about most cases of disease.
- Gathering detailed data on many health conditions
The health care workers who act as data reporters are often very busy and cannot write down a lot of data on each patient. As a result, you should only ask them to collect only the most essential data for you.