Finding Sociopaths on Facebook
11–20 of 73 posts
Re: Finding Sociopaths on Facebook
#12An excellent post by Schneier. > The problem isn't just that such a system is wrong, it's that the mathematics of testing makes this sort of thing pretty ineffective in practice. It's called the "base rate fallacy." Suppose you have a test that's 90% accurate in identifying both sociopaths and non-sociopaths. If you assume that 4% of people are sociopaths, then the chance of someone who tests positive actually being…
Re: Finding Sociopaths on Facebook
#13Even wildly inaccurate tests can be useful. Imagine that driving drunk will result in a accident 10% of the time. 90% of the time, however, a driver will make it home safely. This is a wildly inaccurate predictor, but it still critical to know someone's blood alcohol level before giving them their keys.
One must simply be aware of the uncertainty involved in any test, and treat test results as probabilistic signal, not as proof.
Re: Finding Sociopaths on Facebook
#14Earlier quoted context omitted.
This is a pretty bad example to illustrate the fallacy because a 25% confidence is actually extremely good. I don't know what good a test for sociopathy is, but if we had a test this good at identifying terrorists, it would be incredibly useful. If signals intelligence could produce a list of people and guarantee that a quarter of the people on that list are terrorists, it would absolutely revolutionize law enforceme…
> and guarantee that a quarter of the people on that list are terrorists, Honest question, what would happen to the other three quarters?
Re: Finding Sociopaths on Facebook
#15The "fallacy" described here is a non-issue. Medical tests have the same characteristics but are still incredibly useful. HIV testing is roughly 99% accurate, but given the large number of tests performed, a very large percentage of people will end up with the wrong result. And yet this test is vital. Even wildly inaccurate tests can be useful. Imagine that driving drunk will result in a accident 10% of the time. 90%…
Re: Finding Sociopaths on Facebook
#16The "fallacy" described here is a non-issue. Medical tests have the same characteristics but are still incredibly useful. HIV testing is roughly 99% accurate, but given the large number of tests performed, a very large percentage of people will end up with the wrong result. And yet this test is vital. Even wildly inaccurate tests can be useful. Imagine that driving drunk will result in a accident 10% of the time. 90%…
Look at the numbers of people getting very serious medical treatment because they, and their clinicians, have not understood the numbers.
If doctor (well educated intelligent person) cannot get this right I'm scared that labelling someone as "POTENTIAL TERRORIST" on the basis of a 1 in X possibility is going to have disastrous consequences.
Re: Finding Sociopaths on Facebook
#17I really doubt sociopaths would use facebook at all anyway
Re: Finding Sociopaths on Facebook
#18Earlier quoted context omitted.
This is a pretty bad example to illustrate the fallacy because a 25% confidence is actually extremely good. I don't know what good a test for sociopathy is, but if we had a test this good at identifying terrorists, it would be incredibly useful. If signals intelligence could produce a list of people and guarantee that a quarter of the people on that list are terrorists, it would absolutely revolutionize law enforceme…
> and guarantee that a quarter of the people on that list are terrorists, Honest question, what would happen to the other three quarters?
What Schneier is missing is that while you can't ID people that well from a single test, you can apply a bunch of them. In his example, one test improves the probability of correctly ID a sociopath from 4% to 24%. Apply another, different test of similar efficacy to that result set and you'll have a population of 21 true positives, and 8 or 9 false positives, increasing the probabiliy of a successful ID from 25% to ~70%. Sure, there's no single test that will give you reliable answers, but so what? It's OK to use a multi-pronged solution.
Re: Finding Sociopaths on Facebook
#19I really doubt sociopaths would use facebook at all anyway
Perhaps you’re thinking of people who are antisocial? I wouldn’t be surprised if some of the Facebook members who are most active and have the most ‘friends’ are sociopaths.
If that'd be the case, would facebook just be some sort of crime catching tool ?
I wonder though, is sociopathy a crime, or some trait that will turn people into criminal ?
> I wouldn’t be surprised if some of the Facebook members who are most active and have the most ‘friends’ are sociopaths.
I doubt the people you are talking about can be criminal.
Crime and psychology, sigh
Re: Finding Sociopaths on Facebook
#20An excellent post by Schneier. > The problem isn't just that such a system is wrong, it's that the mathematics of testing makes this sort of thing pretty ineffective in practice. It's called the "base rate fallacy." Suppose you have a test that's 90% accurate in identifying both sociopaths and non-sociopaths. If you assume that 4% of people are sociopaths, then the chance of someone who tests positive actually being…
This is a pretty bad example to illustrate the fallacy because a 25% confidence is actually extremely good. I don't know what good a test for sociopathy is, but if we had a test this good at identifying terrorists, it would be incredibly useful. If signals intelligence could produce a list of people and guarantee that a quarter of the people on that list are terrorists, it would absolutely revolutionize law enforceme…