komponisto comments on Making an Amanda Knox prediction market - Less Wrong

2 Post author: Kevin 30 June 2011 12:53AM

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Comment author: komponisto 04 July 2011 07:52:59PM 0 points [-]

Do you and Rolf want to have that debate now?

I've been ready for over a year!

Comment author: rolf_nelson 06 July 2011 03:37:04AM 0 points [-]

That'd be great! What forum should we use, should we start a Google Group? We can do it here if you like, but I'm concerned about getting distracted by other comments; the original threads got too bulky to hold a coherent conversation. It's up to you.

For my part, I'm happy to walk through the Micheli report or one of the many lists of evidence against Knox and Sollecito on the Internet, but I would pick as my top three pieces of evidence:

  1. The double-DNA knife

  2. Sollecito's DNA on Kercher's bra strap

  3. The mixed-DNA blood

If you could puncture that evidence, then from a "sampling" point of view, even though there is a large amount of additional evidence, I would agree that Knox has a large chance of being innocent.

Comment author: komponisto 06 July 2011 04:37:43PM *  0 points [-]

That'd be great! What forum should we use, should we start a Google Group? We can do it here if you like, but I'm concerned about getting distracted by other comments; the original threads got too bulky to hold a coherent conversation.

That's a problem that would presumably exist to some extent on any public forum. I'm not too bothered by it myself; my feeling is that in such a situation one is not necessarily obliged to reply to all comments individually.

Here's my suggestion: why don't we try it here first, and see how it works? I'd be interested to see if this kind of thing can work on LW. There probably won't be as many comments now as before, since it isn't a new topic.

If it does get unwieldy, we can always move somewhere else.

For my part, I'm happy to walk through the Micheli report or one of the many lists of evidence against Knox and Sollecito on the Internet, but I would pick as my top three pieces of evidence:

  1. The double-DNA knife

  2. Sollecito's DNA on Kercher's bra strap

  3. The mixed-DNA blood

Rather than the Micheli report (which was the first-level ruling in the Guede case), you'd presumably be better off with the Massei-Cristiani report, which was actually about the Knox-Sollecito case (and is even available in translation by the PMF people).

Interestingly, I agree with you that the knife and bra clasp are the strongest pieces of prosecution evidence (though I would have put them in the reverse order). However, they've been pretty severely punctured by Conti and Vecchiotti in their report. You can read the conclusions of that report here.

Anyway, I'll create a new Discussion thread upon confirmation that that's acceptable to you.

Comment author: rolf_nelson 08 July 2011 02:04:38AM 1 point [-]

That's a problem that would presumably exist to some extent on any public forum. I'm not too bothered by it myself; my feeling is that in such a situation one is not necessarily obliged to reply to all comments individually.

We could access-control the main section of a Google Group or a mini-blog, creating a separate area for comments if we like. That would also be convenient because I can easily notice if you've posted when I check Google Reader.

Here's my suggestion: why don't we try it here first, and see how it works? I'd be interested to see if this kind of thing can work on LW.

That is an excellent reason to do it here, then; go ahead and create a new thread.

Interestingly, I agree with you that the knife and bra clasp are the strongest pieces of prosecution evidence (though I would have put them in the reverse order). However, they've been pretty severely punctured by Conti and Vecchiotti in their report. You can read the conclusions of that report here.

If their main point is that the evidence doesn't meet the standard of scientific rigor, then I might not disagree with them on anything factual. Very little evidence, either way, does meet the standard of scientific rigor. Fingerprints never reach the standard of scientific rigor. DNA testing, as practiced, probably rarely if ever meets the standard of scientific rigor. Eyewitness testimony obviously can never come close to meeting the standard of scientific rigor. Heck, most science doesn't meet the standard of scientific rigor. We still need to evaluate evidence on its full merits.

So, to confirm that our initial analysis here diverges, around how much are you currently shifting based on the test results for the knife and for the bra clasp? For you, did either one shift P(guilt) by a factor of 100? 10? Not at all? It's a difficult question to answer in a calibrated way, so if you want to skip that one I'll understand.

You can guess my hypothesis for why the DNA tests came out the way they did. Do you have a specific alternative hypothesis or hypotheses you want me to consider? Is your main claim here that you believe the knife was accidentally contaminated in the laboratory, and the bra strap was accidentally contaminated in Kercher's room? Or is there a different alternative hypothesis I should consider first?

I assume we're not going to quash any evidence, since we're a court of Bayes and not a court of law? That is, I'm proposing that whenever we want to exclude or diminish evidence, we should have a Bayesian reason for why the evidence doesn't really alter P(guilt). The proposal is partly because it's the correct Bayesian thing to do, and partly because trying to divine and mimic Italian criminal procedure and admissability rules would add (IMHO unnecessary) additional complexity.

Comment author: komponisto 08 July 2011 08:26:25AM 0 points [-]

New thread here; reply to this comment here.