CowPunk wrote:
Let's assume that the labs and their tests are 99% accurate.

The UCI did around 12000 tests last year, and about 380 came back
positive. These are just rough numbers off the top of my head.
It worked out to around 3.8% of all tests came back positive.

So, if you take that 99% accuracy number and apply it,
you end up with roughly 1 out of 3 positives due to bad testing.

I'm not a medical technician, and I don't play one on TV, but I have
heard from reliable sources that the false-positive and false-negative
rates in medical testing can be substantially different. For all I
know, this might be the rule rather than the exception.

An illustration with made-up numbers: Some test might have a false
positive rate of 10% (10% of those who are really "negative" are deemed
"positive" by the test) while only returning a 3% false negative rate
(only 3% of thoses truly "positive" are "missed" by the test). Again,
these numbers are entirely made up, only to illustrate the phenomenon.

Mark