Re:Are courts keeping “junk science” out of the courtroom?
by AnthonyMouse on Monday February 17, 2020 @01:32PM
(#22349494)
It's the same problem as it is with most anything. They want to use huge databases, but to do that usefully you need an unrealistically low false positive rate.
Even if the rate was actually really good -- something like 99.9% accuracy -- if you apply that to a database with a ten million people in it, you get ten thousand false positives, which is crap.
If you pick one of the matches at random, they want to be able to claim that it's a 99.9% chance that it's them, but it's really a 99.99% chance that it isn't. Or worse, since it's possible the true perpetrator wasn't in the database.
Even for things like DNA that theoretically can do better than 99.9%, you can't get much better than that in practice because before you can, the error rate starts to be dominated by human error rather than coincident matches.
Even if the rate was actually really good -- something like 99.9% accuracy -- if you apply that to a database with a ten million people in it, you get ten thousand false positives, which is crap.
If you pick one of the matches at random, they want to be able to claim that it's a 99.9% chance that it's them, but it's really a 99.99% chance that it isn't. Or worse, since it's possible the true perpetrator wasn't in the database.
Even for things like DNA that theoretically can do better than 99.9%, you can't get much better than that in practice because before you can, the error rate starts to be dominated by human error rather than coincident matches.