Comment Re: Directionally Right, Specifically Wrong. (Score 1) 124
The original comment was philosophically open ended.
I made the example in my response very specific because arguing about hypothetical generalities is usually not productive.
The difference is this: it's difficult to ascertain if someone is guilty or innocent without arresting them. YOu don't arrest people via a random statistical sampling; you arrest via a biased selector: You arrest people you have high odds of beleiving are likely to be guilty. And you arrest them because you cannot ascertain their guilt via non-destructive observation. Without arresting them, they are allowed to simply walk away while you are trying to ascertain their status.
An arrest rate of 10% of all humans would be ridiculous.
A false positive rate of 10% _among the population of people you arrest_ is acceptable.
So the applicable comparison isn't "your cell phone doesn't work 10% of the time", the applicable comparison is "when your cell phone wasn't working, the tech support team guessed correctly as to the root cause 90% of the time, but guessed incorrectly 10% of the time"
IOW, 90% success rate with a 10% FP rate amongst a problematic cohort.
>No I maintain it would be pathetic performance by LEO if they were willy nilly arresting people hoping to bag the perp.
Nobody is advocating for that.
The cops should only be arresting people they have a plausible reason to arrest. If it turns out that 10% of the time their guess was incorrect, that's acceptable. They are not performing random arrests and getting a lot hit rate. They are doing targeted arrests and getting an ultra high hit rate.