Continuation Part 2 - Discussion of the Amanda Knox case

[komponisto]

So the question to Bayesians: if a priori is 0.97, and the probability of Knox being guilty solely based on case details is judged to be 0.05, what is the resulting probability?

Excellent question, actually. There's a very important probability-theoretic point here.

Kevin gave you the following response:

If 95% of fuzzballs are blue, and it's 95% likely the fuzzball I hold in my hand is red, what is the resulting probability that the fuzzball I hold in my hand is red?

Now, maybe you thought this didn't address your question, but actually, it did. It's almost precisely analogous to the question you asked.

You see, because verdicts are based on case details, the rate of accurate conviction is not an independent piece of information from the case details. In fact, once we know the case details, the rate of accurate conviction is almost entirely irrelevant: if we're using someone else's opinion (e.g. a jury's) to judge whether we think someone is guilty, it's only because we don't think we have the relevant information ourselves. The diagram for the situation would look like this:

case details -> jury's opinion -> our opinion

In such a situation, we're listening to the jury's opinion because we expect that it results from the case details.

However, if we know the case details ourselves, then knowing the jury's opinion won't tell us anything more about the defendant's guilt:

case details -> our opinion

We no longer need the jury as a proxy.

This phenomenon is called screening off. (Note that the entry linked to uses another example of the phenomenon from a different aspect of the Kercher case.) See the excellent Less Wrong post on the topic, Argument Screens Off Authority.

 

[RoseMontague]

Originally Posted by RoseMontague View Post
I think the rate that the first court is overturned at one of the appeal levels is probably a better estimate of an error rate in Italy. Perhaps after this case has gone through all three steps could you use a rate similar to the one you are using.

Well no, that is a different thing. That is the rate of convictions, not the rate of wrongful convictions.

Also I think you would also need to filter on murder cases that hinge on DNA evidence.

It would seem to me if you accept the first court's decision as a conviction, then you should accept the higher courts overturning of that conviction as meaning the first one was a wrongful one.

 

[komponisto]

I've had a similar experience. I've been asking:

• What lethal acts do we know for certain that Amanda Knox performed?
• What lethal acts do we know for certain that Raffaele Sollecito performed?
• What lethal acts do we know for certain that Rudy Guede performed?

and have yet to get an answer. How can we possibly say we know enough to convict people of murder when we can't even answer that basic question?

Firstly, CDHost, welcome; I've appreciated your blog entries on this topic.

I also appreciate your attempt to solicit a theory of the crime from the pro-guilt faction.

However, it must be emphasized at every opportunity that there is no analogy to be made between the evidence regarding Knox and Sollecito and the evidence regarding Guede. The situations are completely different -- and this very fact is at the core of the pro-innocence case. I cringe whenever anyone, in the context of explaining the weakness of the case against Knox and Sollecito, suggests that there may also be doubts about the culpability of Guede.

The strict answers to your questions are is that we know Guede slashed Meredith's throat with a knife, and we don't know of any lethal acts performed by Knox or Sollecito against anyone, at any time.

 

[Chris C]

Firstly, CDHost, welcome; I've appreciated your blog entries on this topic.

I also appreciate your attempt to solicit a theory of the crime from the pro-guilt faction.

However, it must be emphasized at every opportunity that there is no analogy to be made between the evidence regarding Knox and Sollecito and the evidence regarding Guede. The situations are completely different -- and this very fact is at the core of the pro-innocence case. I cringe whenever anyone, in the context of explaining the weakness of the case against Knox and Sollecito, suggests that there may also be doubts about the culpability of Guede.

The strict answers to your questions are is that we know Guede slashed Meredith's throat with a knife, and we don't know of any lethal acts performed by Knox or Sollecito against anyone, at any time.

I honestly believe there is little doubt that Guede killed Meredith. However, he could still go free thanks to all the mistakes the prosecution seems to have made. I honestly think that if Knox/Sollecito get set free, Rudy will get a retrial at the bare min. The evidence presented against him was part of a group murder involving Knox/Sollecito. If they walk free, Guede's conviction is flawed. Plus to top it off, all the mistakes with evidence gathering and the police working with blinders on could set Guede free. If Rudy gets put on the stand at Knox/Sollecito's appeal, i bet you he will say Knox/Sollecito had nothing to do with the murder. Since his conviction was affirmed at his appeals, his fate is now directly tied to Knox/Sollecito's fate.

 

[LondonJohn]

I honestly believe there is little doubt that Guede killed Meredith. However, he could still go free thanks to all the mistakes the prosecution seems to have made. I honestly think that if Knox/Sollecito get set free, Rudy will get a retrial at the bare min. The evidence presented against him was part of a group murder involving Knox/Sollecito. If they walk free, Guede's conviction is false. Plus to top it off, all the mistakes with evidence gathering and the police working with blinders on could set Guede free.

I've wondered what would happen to Guede's situation if (when) the case against Knox and Sollecito gets thrown out. As you say, he's been convicted based on a group dynamic, but I can't see him getting anything more than a retrial. And his hand print in Meredith's blood in her room, coupled with his behaviour after the murder (especially when set against his ludicrous "explanation" that he was an innocent bystander who was trying to help Meredith), should be enough to keep him where he belongs.

But it would be a horrible irony if the suspected incompetence and malpractice of the police/prosecutors, which looks increasingly likely to lead to the reversal of Knox's/Sollecito's convictions, also had an unintended effect upon the conviction of the actual murderer.

 

[RoseMontague]

So now he's only among Amanda's phone book contacts, not her sexual contacts. And what happened to that calls before and after the murder?

One of them could have been in one of her classes for all we know. This is a smear, and a stupid one at that. Still no names just the lawyers? Interesting.

 

[LondonJohn]

An idle thought about the "unanimous" convictions of Knox and Sollecito: I wonder how many verdicts in Italian corte d'assise trials have any of the lay judges disagreeing with the opinions of the two professional judges? For example, I wonder how many verdicts are 6-2, with the two professional judges amongst the six, and two dissenting lay judges? And I wonder if there's EVER been a case of 2-6, where the two professional judges are outvoted by the six lay judges.....

It would be interesting to know what proportion of judicial panels vote 8-0 for conviction (or 8-0 for acquittal). I'm purely guessing, but I'd suggest well over 90% go this way.

 

[LondonJohn]

These were probably typical college kids. I don't know that I would have included the anal sex thing. I don't consider it proven nor is it necessary to make the point. Just my opinion.

True I guess. I'll substitute smoking dope for the anal sex element (even though IIRC her charming new boyfriend confirmed it). As you say, Meredith's and Amanda's behaviours were no more than typical of college students away from home. In fact, I'd find it a little strange if people DIDN'T experiment to this sort of degree at that age - it's natural curiosity, coupled with liberation and the first feeling of true adulthood.

And that last point is important: it's very interesting that some people choose to think that I'm vilifying Meredith by listing her recreational behaviour. Nothing could be further from the truth. In fact, I'm trying to point out how hypocritical and biased some people are when they attempt to portray Knox's behaviour as despicable.

But you know what they say in that there France: plus ca change, plus c'est la meme chose.............

 

[Dan O.]

One of them could have been in one of her classes for all we know. This is a smear, and a stupid one at that. Still no names just the lawyers? Interesting.

I think that is a Google translation artifact. The names appear to be the defendants.

ETA: ...or maybe not. Does Italy have some law protecting the identities of the defendants (and even convicts) in minor crimes?

Latest update: Most definitely attorneys. They are all in the book.

 

[Malkmus]

Edited by Gaspode: 

Removed breach of rule 0

BTW, i think it's more insulting to Meredith that you find the mere mention of her sexual experimentation and association with drug cultivators as painting her in a bad light. I find nothing wrong with what Meredith chose to do and I don't think LJ does either, but your post makes it look like what she did was somehow bad. If you're trying to make a point that somehow these things are private and shouldn't be spoken of you need to go to the source of the information and complain, either that or not mention Amanda's personal life either. You know she's got two more trials before Italy considers her officially guilty.

 

[Chris_Halkides]

typical college kids

These were probably typical college kids. I don't know that I would have included the anal sex thing. I don't consider it proven nor is it necessary to make the point. Just my opinion.

RoseMontague,

I agree with you that they were typical college kids, and they were not all that different from Laura and Filomena, who had boyfriends and who smoked pot (or are we calling it a street drug or narcotic this week--whatever). One of the most perceptive of the commenters I have met when discussing a different case said words to the effect that when we send our children to college, we expect them to experiment with alcohol and intimate behaviors.

Danceme,

Each person on this thread speaks for himself or herself. My silence is not a sign of agreement or disagreement.

 

[LondonJohn]

BTW, i think it's more insulting to Meredith that you find the mere mention of her sexual experimentation and association with drug cultivators as painting her in a bad light. I find nothing wrong with what Meredith chose to do and I don't think LJ does either, but your post makes it look like what she did was somehow bad. If you're trying to make a point that somehow these things are private and shouldn't be spoken of you need to go to the source of the information and complain, either that or not mention Amanda's personal life either. You know she's got two more trials before Italy considers her officially guilty.

You're right: I don't see anything wrong with what either Meredith or Knox chose to do (although I wouldn't exactly endorse cannabis use...). I never said anything that in any way implied that I did, but Danceme chose to "interpret" my comments in that way - for reasons that only he or she knows.

 

[Chris C]

BTW, i think it's more insulting to Meredith that you find the mere mention of her sexual experimentation and association with drug cultivators as painting her in a bad light. I find nothing wrong with what Meredith chose to do and I don't think LJ does either, but your post makes it look like what she did was somehow bad. If you're trying to make a point that somehow these things are private and shouldn't be spoken of you need to go to the source of the information and complain, either that or not mention Amanda's personal life either. You know she's got two more trials before Italy considers her officially guilty.

Yeah, I agree. Everytime someone tries to point out that Meredith was an average college girl having the time of her life, the PMF croud gets upset. I'm sorry Meredith wasn't the Virgin Mary, she was just the typical college girl and she was tragicly murdered before her time.

 

[RoseMontague]

True I guess. I'll substitute smoking dope for the anal sex element (even though IIRC her charming new boyfriend confirmed it). As you say, Meredith's and Amanda's behaviours were no more than typical of college students away from home. In fact, I'd find it a little strange if people DIDN'T experiment to this sort of degree at that age - it's natural curiosity, coupled with liberation and the first feeling of true adulthood.

And that last point is important: it's very interesting that some people choose to think that I'm vilifying Meredith by listing her recreational behaviour. Nothing could be further from the truth. In fact, I'm trying to point out how hypocritical and biased some people are when they attempt to portray Knox's behaviour as despicable.

But you know what they say in that there France: plus ca change, plus c'est la meme chose.............

It is a selective indignation LJ. Not Meredith, we should not speak poorly of the dead. Not Filomena, we should not speak poorly of those that work for lawyers. Now Amanda, she is a murderer and we believe this partly because she did the same sort of things Meredith and Filomena did, but Amanda is evil and they are not, so we can justify our outrage over typical college kid normal behavior because it is an evil person that does such things.

 

[Katody Matrass]

It is a selective indignation LJ. Not Meredith, we should not speak poorly of the dead. Not Filomena, we should not speak poorly of those that work for lawyers. Now Amanda, she is a murderer and we believe this partly because she did the same sort of things Meredith and Filomena did, but Amanda is evil and they are not, so we can justify our outrage over typical college kid normal behavior because it is an evil person that does such things.

You're right on the mark, sadly.

 

[RoseMontague]

I think that is a Google translation artifact. The names appear to be the defendants.

I think they all come up on this lawyer list:

http://translate.google.com/transla...lla:en-US:official&tbs=lr:lang_1it&prmd=ivnso

 

[LondonJohn]

I think they all come up on this lawyer list:

http://translate.google.com/transla...lla:en-US:official&tbs=lr:lang_1it&prmd=ivnso

Yes, they're the three lawyers for the three accused. The context within the article makes this fairly clear, although there is admittedly some ambiguity in the language (both in the Italian and in the translation).

 

[LondonJohn]

Interesting reading from today's Sindie:

http://www.independent.co.uk/opinio...nox-is-a-victim-of-italian-pride-2185628.html

 

[komponisto]

An idle thought about the "unanimous" convictions of Knox and Sollecito: I wonder how many verdicts in Italian corte d'assise trials have any of the lay judges disagreeing with the opinions of the two professional judges? For example, I wonder how many verdicts are 6-2, with the two professional judges amongst the six, and two dissenting lay judges? And I wonder if there's EVER been a case of 2-6, where the two professional judges are outvoted by the six lay judges.....

And imagine the judges having to write a motivation in such a case!

Among the millions of cases that have passed through the Italian court system, it's probably happened, but I'm guessing it's extremely rare.

(I may take a look at the Italian criminal code to see if things really work this way or if there's some kind of escape clause for judges who think their lay jurors are nuts.)

With regard to this business about the "unanimous" verdict, two (related) points:

(1) In the US, verdicts are typically required to be unanimous. Yet plenty of them are still wrong.

(2) Asch's conformity experiment. Enough said.

 

[LondonJohn]

And imagine the judges having to write a motivation in such a case!

Among the millions of cases that have passed through the Italian court system, it's probably happened, but I'm guessing it's extremely rare.

(I may take a look at the Italian criminal code to see if things really work this way or if there's some kind of escape clause for judges who think their lay jurors are nuts.)

With regard to this business about the "unanimous" verdict, two (related) points:

(1) In the US, verdicts are typically required to be unanimous. Yet plenty of them are still wrong.

(2) Asch's conformity experiment. Enough said.

Yes, it's a long-known phenomenon that experiments like Asch's can have demonstrable real-world effects in jury rooms, where all it can sometimes take is a couple of strong characters amongst the twelve with the same opinion to set in motion a mass spread of conformity amongst the remaining ten.

And this is when all twelve jurors have equal status. When you add in the overt and subliminal authority displayed by the two professional judges in the Italian system against the six lay jurors, there's a clear inbuilt deference to authority built in right there.

(BTW, In the UK, most criminal convictions require a unanimous (12-0) verdict either way, but if the jury gets deadlocked, judges will often accept an 11-1 verdict, or sometimes even 10-2.)