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Brian Mowrey's avatar

Right, but the point still stands. The weeks before November are a partial negative control of the weeks after, and likewise for the weeks before July. If the current positives are all false there should have been just as high a positivity rate before then. In fact the percentage of false positives will be highest when the rate of all positives is lowest.

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Tam Hunt's avatar

False positives increase as testing increases (for whatever reason), and there's likely also some strong cross-reactivity with seasonal common cold coronaviruses, if we are to take the survey data about omicron symptoms being basically identical to common cold symptoms seriously.

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Brian Mowrey's avatar

Right, but I was referring to the "percentage" of false positives (as in how many positives are false / all positives), which goes up when the rate of positives is lower (how many tests are positives / all tests), so you are correct that you can drive up the former by doing more tests, but you would have to also see the latter go down at the same time.

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