Jokodo
Veteran Member
It's known that almost all tests have some false negatives. There's some tricks to get a rough estimate how many. For example, there could be people who got tested because they had contact with a confirmed case. If they test negative and a few days or a week later they actually developed symptoms and test positive when tested again, one plausible explanation is that they where already infected at the time of the first test. Of course in any individual case we'll never know, they might actually have gotten infected later. But if there are many such cases were can draw statistical conclusions - if people with good reason to suspect they got infected but a negative initial test get positive within the next two weeks st substantially higher rates than the general population, a high (-ish) rate of false negatives survives as the only plausible explanation.