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Most blood tests or tests for any major disease have a high rate of false positive, that's why you take the tests ALONG with a doctor analysing your symptoms (a
by ucaetano 10y ago
Most blood tests or tests for any major disease have a high rate of false positive, that's why you take the tests ALONG with a doctor analysing your symptoms (and that's there Bayes' theorem plays a big role).
So applying a single test to a huge general population makes little sense. But applying that to a population that already carries some traits is highly relevant.
- jacquesm 10y agoBlood tests for diseases tend to have a much higher true positive rate as well because of substantial higher incidence rate of diseases for which simple blood tests exist than terrorism, besides that the cost of a false positive isn't that high (you just order another test to improve the odds, roughly at the same cost level as the first one).
- ucaetano 10y agoI wasn't comparing the rates, but the process. Bayes' theorem can make predictions far more precise.
- jacquesm 10y agoEven Bayes can't make sense of garbage input, there has to be some relevance to the input numbers. It's not magic, it's applied statistics. If your probabilities are on the order of 'nonexistent' and your test has a false positive rate on the order of a few 10'ths of a % then you are wasting your time no matter what the method you use to analyze your data.