ChristianKl comments on [LINK] Amanda Knox exonerated - Less Wrong
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Comments (58)
That's still base-rate neglect as you are picking and choosing what you want to look at and not conditioning on one of the more relevant variables.
What fraction of the pretty girls who lived with the victims turned out to be murderers? By looking at the genderless conditional probability ('somebody'), you're implying that women like Knox might have male-like murder levels, which is obviously wrong. And to the extent that pretty girls do not have differing patterns of murdering roommates from other women, you're making the exact same mistake, even (it doesn't matter whether you update on pretty girl then roommate or roommate then pretty girl).
Update on both living with the victim and being female and the small probability is bigger but... still small, since the still relatively low probability of a roommate murdering is penalized substantially by being female (female murder rates are like 1/10th male and that's the raw rates, not adjusted for age or SES or race etc). As the top comment says, "Once we take into account that AK and MK aren't in a relationship, AK is female, and there is very strong evidence that someone else committed the murder then I'd agree that the probability drops".
That's an interesting claim. Do you have a source for "pretty girls are less likely to murder than girls who aren't pretty?"
Working Paper Ugly Criminals "Using data from three waves of Add Health we find that being very attractive reduces a young adult's (ages 18-26) propensity for criminal activity and being unattractive increases it for a number of crimes, ranging from burglary to selling drugs. A variety of tests demonstrate that this result is not because beauty is acting as a proxy for socio-economic status. Being very attractive is also positively associated adult vocabulary test scores, which suggests the possibility that beauty may have an impact on human capital formation. We demonstrate that, especially for females, holding constant current beauty, high school beauty (pre-labor market beauty) has a separate impact on crime, and that high school beauty is correlated with variables that gauge various aspects of high school experience, such as GPA, suspension or having being expelled from school, and problems with teachers."
More generally: Good human traits are almost always positively correlated with most other good human traits.
Kalos kagathos or halo effect?
Kalos kagathos. I don't this is merely a perception bias.
Both a true correlation and a perception bias may be present, but it would be difficult to distinguish them without using standardized tests.
Correlations between attractiveness and academic performance or criminal record could be confounded by the perception bias, we would need something like IQ or SAT to have a fair estimate.
Also the correlation itself may be caused by perception biases directly, e.g teachers unaware of the halo effect rank the intelligence and agreeableness of the beautiful students greater than they should and such are more unlikely to expel the students or report behavioral problems.
But does beauty influence our judgement in accordance with the correlation, or disproportionally so? It may be for example that ugly people are 10% more likely to commit crimes, 200% more likely to be villains in the movies, and 100% more likely to get flagged as suspects by the prosecutor, or get other massive penalty before you even think consciously about it.
Without looking at evidence I would guess disproportionately so.
Same here. The reason I think so low of the self proclaimed Bayesianism is the sort of thinking where someone sees someone ugly accused and they're like, ha, I am going to be more rational than everyone else today, by ticking my estimate of the guilt up because they're ugly. Completely ignorant that it even makes a difference to the way you should apply Bayes rule that the police and the witnesses and the like had already picked the suspect with this sort of prejudice.
Yes, knowing just a little about Bayesianism can make you less rational.
It seems to me that knowing only a little (and/or being bad at applied math) is kind of a pre-requisite for the level of enthusiasm involved in the use of it as a movement name. It's exciting to see all those bits of evidence and see yourself one-upping all those classy educated people that are dead set against use of those bits of evidence, or who even seen to use them in the completely wrong way. It's even more fun to do that with friends.
You know about little math, and it makes a huge difference to everything, that's exciting.
Or you spent years studying and/or working and all that math almost never matters - almost any evidence that's not overwhelmingly strong is extremely confounded with what's already been considered and/or with the chain of events bringing something to your attention.