I've always wondered-- is the error between tests correlated? Why does it not suffice to gather all the positive outcomes and test them again, then again and again until you have sufficient power depending on the rarity of the disease in the population? I know that for covid tests for example the test outcome errors aren't independent, which is why even taking several tests you can't be confident you're negative even if you tested negative. But I figured that was a special case and it was because their error comes from variance in viral load or something. But would that apply to these genetic marker tests?
Unlike a false negative where there isnt enough to trigger the test, false positive implies that something triggered a positive.
You have something, just not what the test thinks you have. For example, men with testicular cancer, apparently, show up as pregnant in pregnancy tests. Clearly thats a false positive for pregnancy.
