[sliken]

50% accurate I'd agree is useless.

But the parent said 50% false positive, presumably with close to a 0% false negative would be VERY useful and save potentially millions of lives. We need enough tests yesterday or so to avoid a repeat of Italy and a 50% false positive rate (with a very low false negative rate) could help do that.

[makomk]

Even the properly-conducted version of this test has a fairly substantial false negative rate, somewhere around the 30% mark, and if it's done by students using samples that might not be taken correctly on a rigged-together testing setup that's going to get worse. Seriously, you might as well flip a coin.

[leereeves]

A test with a 50% false positive rate, administered to 100 million people who aren't infected, would say 50 million people were infected.

False positive rate is a confusing term; it means the % of tests that should be negative that report a false positive.

I think the term for what you're probably thinking of (% of positive results that are false positives) is the false discovery rate.

[awrence]

That’s fair, if the assumption is that false negatives are very low or 0 (in which case it’s a super high accuracy test at low contamination rates and super useful).

And yeah obviously we desperately need a decent test like three months ago.