Reply #37: The national surveillance study looks at a wide variety of sources

[HamdenRice]

There are a few dozen centers of study. So, for example, some teaching hospitals participate. When people come in for all kinds of medical issues, they may be asked to take an HIV test. In other cases, data is gathered in VD clinics, and in other studies in bars. Obviously the latter will be more skewed than the former, but statistics and probability allow the CDC to extrapolate the data to the general population.