> even if the scanner is 99.99% accurate, because an even higher percentage of photos are innocent, most matches the scanner will find will be false positives.
If the scanner is 99.99% accurate, then most classifications will be correct.
> even if the scanner is 99.99% accurate, because an even higher percentage of photos are innocent, most matches the scanner will find will be false positives.
If the scanner is 99.99% accurate, then most classifications will be correct.
If you scan 1,000,000 pictures (with let's say 10 CSAM), you'll have 100 false positives and 10 true positives, giving you like only 10% correct results
Ah, sorry, I misread what the OP meant by "matches" - thought they were referring to all classifier outputs, while they specifically meant the positives. I changed my original comment to better reflect what I meant, even though that makes it a bit of a non-sequitur now.
https://en.wikipedia.org/wiki/Base_rate_fallacy
How many child abusers do you think there are out there?
Even if 10% of population were actively criminal pedos (which is waaaay too high), its pretty safe to assume that the majority of even their online footprint would be ordinary images/messages.
So a quota of 0.1% or even less material being detectably criminal sounds realistic (probably not much less, though).