# gwern comments on The Amanda Knox Test: How an Hour on the Internet Beats a Year in the Courtroom - Less Wrong

42 13 December 2009 04:16AM

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Comment author: 03 April 2013 06:00:51PM 0 points [-]

Reference class tennis. Being an attractive female with a (formerly) well-off family is far more important a reference class than being named Amanda; and the corresponding reference class for Rudy would be being an unattractive man who is a poor African immigrant.

Comment author: 03 April 2013 11:44:24PM 1 point [-]

Reread your comment. What is the point of your your first bullet point that pretty girls are rare? That tells you nothing, just as the fact that Amandas are rare tells you nothing. Points 2-4 about the relative propensity to murder are relevant. But I'm explicitly talking about point 1 in isolation.

Comment author: 03 April 2013 11:53:42PM 0 points [-]

What is the point of your your first bullet point that pretty girls are rare? That tells you nothing, just as the fact that Amandas are rare tells you nothing.

Yes, it does. If there is any sort of inverse quasi-linear relationship between prettiness and propensity to murder, as one would expect, we would expect the reduction in murder rates compared to the average to be the largest at the extremes - that is, for rarely pretty girls we will expect rarely large effects.

Comment author: 04 April 2013 12:18:20AM 0 points [-]

That's not how you used it in your post. Seriously, just read your post. What do these numbers mean?

Comment author: 04 April 2013 01:37:40AM 0 points [-]

I rather think I did, since I wrote it.

What do these numbers mean?

It means that we're talking about an extreme part of the population.

Comment author: 04 April 2013 03:12:22AM 1 point [-]

My own reading of the bullet points in the post is something like this:

1) Group X is a small fraction of the population.

2) Reason A why group X is disproportionately unlikely to commit murder.

3) Reason B why group X is disproportionately unlikely to commit murder.

4) Reason C why group X is disproportionately unlikely to commit murder.

In the great-grandparent comment above you list an additional reason why pretty girls would be disproportionately unlikely to commit murder, but that wasn't clear at least to me from the original post. So, I agree with Douglas_Knight that bullet point 1 seems to serve a different purpose from points 2 through 4.