Current Events > Covid Positivity Rates misleading and meaningless

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Sample size? Any epidemiologists or statisticians here? Reliability not only depends on the taking of the specimen and the test. Reliability depends on the fulfilment of the underlying assumption.

The sample of people taking the test is representative or at least the sample of people taking the test is of a consistent distribution.

Representative: A 5% positivity rate means 5% of those taking the test have covid and this is representative if exactly 5% of the population have covid.

Why would it not be representative? Metropolitan Chicago has extremely low positivity rate for Illinois. People in Chicago take a weekly test for their jobs. Compare this to Northern Illinois District where people get tested when they are sick.

What does it mean for the distribution to be consistent? Even if healthy people are more likely to get tested than sick people as long as this likelihood is the same throughout the state, the positively rate will be informative even though it will be too low. Point is healthy people in Chicago are way, way more likely to take the test than in other areas.

The positivity rates need to be normalized. Anyone fool enough to believe there is less covid in Chicago than in Northern Illinois? * tempted to send mentions to some of these fools *

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