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This logic is not necessarily true. The tests are inherently probabilistic. Medical professionals must use the impact of a False positive or negative and the ba
by nsgoetz 11y ago
This logic is not necessarily true. The tests are inherently probabilistic. Medical professionals must use the impact of a False positive or negative and the baysean probability of a disease given their test results to determine the best thresholds for patients. False positives can still be very harmful to patients (surgery, medication, lifestyle changes, etc) so they must be taken into account as well.
One classic example is a pregnancy test. You're going to find out eventually, and the impact of a false positive is huge, so the test errs toward false negatives instead of false positives.
This video does a good job explaining it (and is where I learned most of what I know): https://www.youtube.com/watch?v=UF1T7KzRnrs https://www.youtube.com/watch?v=UF1T7KzRnrs
- mc808 11y ago> False positives can still be very harmful to patients (surgery, medication, lifestyle changes, etc) so they must be taken into account as well. Well yes, I wasn't suggesting jumping into treatment before verifying with the expensive, higher specificity test. Even with pregnancy, the impact of a false positive isn't huge when the next step is just to take another test - the same test that would've been done anyway if the first one wasn't available. Though the potential savings probably aren't great with pregnancy tests because they're already cheap, and I'd imagine the overall incidence for people taking the test is pretty high.