On a cursory reading of Wikipedia the obvious interpretation is that Knox and Sollecito are innocent and Guede is guilty. I didn't go through all the sites so I don't know if this would qualify as a litmus test, and assigning probabilities in this state of knowledge would be extra work.

EDIT: Read comments and am surprised at how many estimates of "Knox and Sollecito probably didn't do it" have probabilities in the range of 40% attached that they did. If it were a binary judgment or a confidence interval, then yes we should avoid extreme probabilities and widen intervals to compensate for known overconfidence biases. But in this case the hypothesis space of equally plausible possibilities is large, and some low-probability symbols were used to write the message (multi-person rape-murder vs. single-person rape-murder, female rape-murder vs. male rape-murder). It may not always be easy to unravel crime scenes (though this one sounds pretty straightforward) but to focus on Knox or Sollecito seems like privileging the hypothesis.

Unless there's major prosecutorial evidence not in Wikipedia, then this seems like a case of paying too much attention to other people's opinions (the jury, in a case where we have further information that the verdict gained media attention as possibly inaccurate), and I would suggest that anyone who gave a probability higher than .15 be more arrogant in the future.

If, of course, I just haven't done enough reading, then ignore the above.

What is completely sad (besides this horrible murder case), is the inability of either website linked to present a coherent, rational argument. In fact, I haven't been able to find one website that reveals all facts and then explains them with their point of view in a rational (or even semi-rational) way.

I find this situation almost as depressing as the murder. I couldn't come to any conclusion based on the poor quality of reasoning used on most websites. Wikipedia, as usual, presents a decent collection of facts.

From the Wikipedia article I could only ascertain that Rudy Guede is very likely guilty. My probabilities for the other two being guilty are low (but have a lot of uncertainty), certainly not enough for me to feel that the verdict is correct.

I began with zero familiarity with the case.

1. Knox: 8%
2. Sollecito: 10%
3. Guede: 95%
4. Agree with komponisto: 80%

Rationale for considering Sollecito more likely than Knox: They're linked quite closely here, but there's enough confusion surrounding the case that I can't take that completely for granted. That being the case, it's unlikely-but-possible that one of Knox or Sollecito was directly involved while the other wasn't, and my prior for a male committing a violent rape/murder is a lot higher than for a female.

Guede is clearly guilty. He fled town immediately after the murder. His DNA was found in the victim's body, by far the most difficult-to-contaminate piece of DNA evidence in the case, making it extremely likely he's the rapist. Very low prior on a rape/murder being committed by separate parties.

The inconsistencies in Knox and Sollecito's stories are definitely worth paying attention to. But there are several factors diluting their importance:

• I already had a reasonably high prior on the prevalence of brutality and corruption in Italian police forces. This doesn't leave me with much faith in their competence, especially when it comes to interrogations.
• It's known that Knox and Sollecito were intoxicated with alcohol and marijuana at the time. I don't know how many of you have ever been thoroughly trashed on this duo (I'm guessing the number is disproportionately low here), but memories formed under such circumstances are very fragile. I've personally experienced disagreements provoked by divergent recollections of events that had transpired an hour previously. Given that sort of influence, I know I would have a damn hard time reconstructing a coherent narrative of the night's events after the brutal murder of my roommate and several days of interrogation by Italian police.

The DNA evidence against Knox and Sollecito is also worth paying attention to, and is in fact the primary reason my estimate on their guilt is as high as it is. However, this is partially mitigated by a glaring problem with the case: Most of the evidence was collected before Guede was a suspect. If Guede had been identified from the start, the Knox-Sollecito hypothesis may not have been quite so "privileged". IIRC, the DNA of four unidentified individuals was also found on the knife. Plus the doubt wrt the knife matching the wounds. Plus the odds that Sollecito would take a murder weapon back to his apartment and put it away. My generally unfavorable prior wrt Italy's justice system also adds a fair amount of room for uncertainty here.

The fact that Guede wasn't initially identified also provides the police with a mild motive for contaminating the evidence. It's unlikely that such an action would be detected. That said, my prior for this sort of action is pretty low.

Finally, we come to the elephant in the case: The hypothesis that the murder was committed by three people working together, as the result of a sex game gone bad. This reads like a parody of a flailing prosecutor. Contrast prior with that for a "normal" rape/murder... ouch. And it just so happens that the one party implicated by actual, solid evidence is the one party who fled after the crime.

The rationale for my 80% chance of agreement with komponisto is mostly based on "metagaming" his position. He admits to having a "rather strong" opinion on the case, and it seems much, much harder to form a strong opinion in favor of guilt as opposed to innocence in this case. My estimate would be higher, but given how asymmetrical this case appears to me, I can't rule out "initial counterintuitiveness" and/or extra evidence as a possible motivation for posting this in the first place.

I'll read the other comments and post my update later today.

Perhaps this is after all a litmus test for rationality, in a different sense than (I suspect) komponisto intended.

I mean, here I am looking at a 100+ comments thread, discussing a highly charged issue, and everyone is thoughtful, respectful, and willing to take others' points into account.

That is... extremely unusual.

5% for the couple, 99% for the first convict. 90% that my probability estimate is close to yours in the sense that you think the two are innocent and the one is guilty.

I'd read a bit about this in the news, and I checked out those sites and wikipedia.

Given the fact that there is no evidence of prior acquaintance of the couple and the man, combined with the fact that the man did not attempt to implicate the couple despite the overwhelming evidence against him, make it very unlikely that they were involved. That, and one person being crazy/desperate/disturbed enough to commit a brutal rape-homicide is much, much more likely than one person and a completely unrelated couple he's never met before being disturbed enough to commit a rape homicide. The defense's response to forensic evidence appeared pretty strong, and the pro-guilt group did not seem like they tried to seriously rebut this (they mentioned that one defendan't DNA was on the bra strap, but failed to mention three other unidentified people's DNA on it as well).

The fact that the prosecutor is under investigation for previously using crazy psychotic hypersexual homicidal maniac theories without basis does a lot to explain how the prosecutors ended up with such a crazy theory.

My estimate of your position was (as I perceived it) largely independent of my own analysis. You mention a number of confounding factors as to why people are likely to be wrong about these things, with no mention of why they might be right, and you posted this in response to their conviction. It would be very surprising to choose a decision you agree with as an example of problems with human rationality.

Having lived for 14 years in Italy, my impression is that several commenters severely overestimate the rationality and fairness of the italian police force.

priors

Amanda Knox is guilty: 75%, Raffaele Sollecito: 75%, Rudy Guede: 25%. I shall abbreviate future percentage triples as 75/75/25.

No knowledge of the case before reading this post. My prior is due to my assumption that trial people know what they are doing, and on the fact that I imagined that the trial was trying to show that the guilty were K+S instead of G.

acquiring information

Reading about G's DNA, which should be rather good evidence: switching to 50/50/75. I contemplated switching all the way to 25/25/75, but I figured there had to be some reason for the new trial.

Reading about the police's claim that the murder was linked to a group sex game; thinking that this would be a ridiculous motive. This made me think that maybe the trial people didn't knew what they were doing after all. Switching to 25/25/80.

Finally realized that the trial was in fact trying to show that the guilty were K+S+G instead of just G, not K+S instead of G. Stopped keeping track of percentages for some reason.

Reading about the police switching from K+S+L to K+S+G, which lowered my esteem of the police even more.

Reading about the DNA of K+S, figured it was natural for a woman and her boyfriend to have DNA all over the woman's own house.

Still trying to understand who was G relative to the others. I think he's a robber now. Definitely not part of the group sex thing. Even worse feelings toward the police.

Over all, the truejustice website seems more emotional than the friends of K website, which surprises me. I would have expected the family of the victim to have calmed down after the original G trial, yet truejustice still seemed angry; and doesn't even seem to be ran by the victim's family at all. They should be a lot less emotional about this than K's friend, which seem to be a lot more clearheaded than truejustice is.

I'm now quite convinced of the innocence of K+S, although I'm too shy to give an actual percentage. 5/5/95, if not more extreme.

I was unfamiliar with the case. I came up with: 1 - 20% 2 - 20% 3 - 96% 4 - probably in the same direction, but no idea how confident you were.

From reading other comments, it seems like I put a different interpretation on the numbers than most people. Mine were based on times in the past that I've formed an opinion from secondhand sources (blogs etc.) on a controversial issue like this, and then later reversed that opinion after learning many more facts.

Thus, about 1 time in 5 when I'm convinced by a similar story of how some innocent person was falsely convicted, then later get more facts, I change my mind about their innocence. Hence the 20%.

I don't think it's correct to put any evidential weight on the jury's ruling. Conditioning on the simple fact that thier ruling is controversial screens off most of its value.

Familiarity pretty good - I've read the Wiki page, revisited several articles from when the murder was first discovered and I watched Sky news the day of the verdict and saw/heard Prof of Criminology, feminist journalist, UK barrister and two Italian barristers. I frequently search the web, hence I found this site.

(I don't understand the up/down system.)

I find the logic of the murder disturbing - if the murder was a game gone wrong, then it was not premeditated, so unlikely gloves were worn. If bleach was used to clean, then why was Guede's DNA all over the body and room? The only DNA evidence for Raffaelle is highly suspect and a physical impossibility to leave DNA only in that one place I would think. That really is the beginning and the end of it.

The Prof of Criminology's view I have to take seriously. But, in saying that Amanda's diary reads like a gap-year Rosemary West he failed to draw contrasts as well as comparisons. Rosemary West was severely abused from early chidlhood, she did not study languages or develop an interest in creative writing.

I have an alternative scenario - a young woman from a comfortable secure All-American upbringing, who has no idea of the level of corruption and politicking in the world, visits Italy and discovers the magic of old Europe and the unexpected appeal of herself to Italian men - the intoxicating culture of Italy, the constant calls of 'Ciao Bella' from men lounging in doorways - and, being naive and unwordly, behaves carelessly and without circumspection not realising that beneath the relaxed veneer of Italian culture lies a strict code of conduct, especially for women. Amanda has behaved exactly as you would expect of an innocent girl with that background - she simply could not comprehend that she could be convicted for a crime that she did not commit and didn't take her interview with the police seriously.

Given the above scenario, when asked to imagine what might have happened that night, Amanda may well have enjoyed being able to apply her obvious interest in macarbre story telling. I myself wonder at the violence depicted in much fiction but being able to express the human condition in fiction is important and we should not rush to criminalise the use of the macarbre in fiction.

I don't want to cast aspersions but I found it very strange that Meredith's parents did not talk at the press conference and I started to find their silence spooky rather than dignified. I also think that Meredith had made it clear to her family that she did not at all like her flatmate's arrogant American 'no one can touch me' attitude. Supposing the Italian barrister dangled the potential for millions in compensation in front of them? How would they feel?

And why does Meredith's mother now say that querying the verdict is making her unhappy? Would she not care if an innocent went to jail? And surely the pain of her daughter's death is not going to disappear from her mind even when the story disappears from the media? It starts to sound more like a desire for revenge than for justice.

Finally, I've worked with about a dozen Italian professionals and was astounded by their anti-American feeling. There have been US bases in Italy since WWII and Italy led the anti-Iraq war movement with their colourful Pace flags.

I don't know what Amanda and Raffaelle were up to that night. I think they were in the first bloom of attraction to each other, on drugs (perhaps more than just cannabis), and not being particularly sensible. But the case is not beyond reasonable doubt, neither is accusing the other, and they have served 2 years in jail already.

PS. this site is a very welcome find - it seems that many, many people these days prefer 'opinion' to logic or standards - I call it the Strictly Syndrome - a cult of personality combined with sectarian affiliations - it's really quite scary to hear how little people care about evidence, universal standards or intelligent debate nowadays. Bring back the Enlightenment, I've had enough of postmodernism!

I averaged up the answers given so far in this thread for Knox and got 35% mean, 20% median.

I arrived at the site from the HP fanfiction after reading the author's notes concerning the case.

Probability estimate that Amanda Knox is guilty -- 99%

Knox and Sollecito's alibis are contingent on the other. However, I recognize that there is a probability that one may lie to cover the other, so it is not implausible that one may be guilty without the other being so. While they certainly had the opportunity to murder, there appears to be neither motive nor weapon. The only credible evidence against Sollecito is his DNA being on the bra hook material, and there's a great deal of controversy regarding that specimen. The knife thing is just stupid. I have had roommates, and I can guarantee you there are DNA traces of both me and my roommate on pretty much every knife we've ever had. Frankly, the only reason I'm judging Knox's probability of being a murderer being so high is that they're two girls who shared a bathroom, so she automatically has motive.

I recognize that having read the author's notes, I am biased to believe that Amanda Knox is innocent. That being said, I am completely unfamiliar with the case. I went to the pro-guilty site first, where I had a great deal of difficulty discerning relevant information. I spent approximately 20 minutes navigating the site, growing more and more convinced that Amanda Knox and Rafaele Solecito were not guilty because of the near-impossibility of finding relevant facts that pointed out to their guilt. I then went to the pro-innocent site, and spent about 5 minutes there, which confirmed what I suspected; that the evidence against said defendants was completely circumstantial. I then proceeded to read approximately 1/2 of the Massei report, which struck me as rather biased, which made me very sad when I realized he was the presiding judge in the case. Regardless, by that point I was convinced the prosecution had no case, and was largely built on inconsistencies in Amanda Knox's testimony. I was then annoyed to realize that much of the case had to do with Pretty White Girl Syndrome, because however little evidence there was against Amanda Knox, there was even less against her boyfriend Sollecito. I the proceeded to the Wikipedia article, because let's face it, there's really no better place for an overview of the whole shebang . At this point, I'm pretty much offended at this travesty of justice. The evidence against these two defendants seems to be, "they did not have completely time-consistent alibis" and some bum says he saw them together near the murder scene.

edit: I am basing my probabilities on two primary factors: 1) I saw no evidence that Knox or Sollecito were at the crime scene and their alibi seems eminently plausible to me and 2) The pro-guilty site seems batshit crazy.

Page one of the site arguing defendants are guilty has nothing that would count as evidence for guilt. When I got to the bottom of the page and saw that there were 24 more pages, I lost patience for the exercise because the low quality of the argumentation on page one (most saliently, the picture of the vicitim when she was five, which if course is not evidence at all, but which will tend to evoke biased thinking in the reader) was a sign that the other 24 pages would be very sparse in actual evidence.

Aren't there enough opportunities for us to practice rationality such that we can check our answers to make it mostly a waste of time to assign probabilities to an event for which it will probably forever be impossible to know "the answer"?

Your job will be to browse around these sites to learn info about the case, as much as you need to in order to arrive at a judgment. The order, manner, and quantity of browsing will be left up to you

If you are going to leave it up to the reader, you should at least tell us where on the 25 pages the strongest evidence is on the site arguing defendants are guilty.

Never heard of the case before, after reading the wikipedia page on the crime and its associated discussion page I think it's very unlikely that knox and sollecito are guilty. Certainly the evidence does not seem at all sufficient to convict them, and interrogating someone for 14 to 30 hours without recording the interrogation is downright idiotic.

I expect you agree.

I'd like to see more posts of this nature. This site has too much theory and not enough practice.

I guess we were all guilty, in a way. We all shot him, we all skinned him, and we all got a complimentary bumper sticker that said "I helped skin Bob".

Would anyone actually be up for discussing the specifics of the case? (I don't know why but I find myself oddly interested in this case.)

As far as I can tell, the biggest pro-defendant evidence is that there is no major DNA evidence of Sollecito and Knox in the room where murder took place. We are told that there is a bra clasp with Sollecito's DNA and a knife that has both Amanda's and Kercher's DNA - both of these DNA traces are 'weak' in the sense that they are not that obvious, require a hefty search and are hard to see in lab. On the other hand, there are 'strong' traces of Guede's DNA in the victim's blood and in the room.

So, the first thing that worries me is that if it were a crime committed by three people, why would you have one person's DNA everywhere in the room and yet two others' only faintly there?

Again, this is the strongest pro-innocent (for Knox and Sollecito) argument that I have - and the one that convinces me most likely that Sollecito and Knox haven't done it.

I don't know - can anyone else site cases in which there was a group murder and yet only a single person left behind 'strong' traces of DNA? Maybe this isn't so unusual after all.

On the pro-guilty side, I must admit that I find Knox's and Sollecito's behavior the morning after the murder and during the investigation a bit strange. If 'Meredith was [her] friend', as Amanda Knox says in her trial, why were she doing cart-wheels during the investigation the morning after the murder? Shouldn't she be distraught and upset like all of other Meredith Kercher's friends? Accuse me of the mind projection fallacy but I feel like I would be distraught (and in a bad mood) even if the victim wasn't someone I knew.

But again, strange behavior isn't really an evidence. It's just something that makes one suspicious and raises uncertainty.

I can't find that many pro-guilty arguments. There are some tidbits that have a lot of uncertainty in them: i.e. Sollecito (allegedly) bought cleaning supplies the night of the murder allegedly again to clean up the murder mess, Sollecito claimed to be using the Internet at the time of the murder but his ISP records indicate otherwise, a woman claims to have heard three people running down that street that night.. etc. None of them as strong to make a case.

Besides these, a few other thoughts:

I really don't know how Sollecito and Knox got linked to this murder. How did they get dragged into this in the first place? Is there really evidence for the fact that it was a satanic sex-orgy gone wrong as the prosecutor claims it is? I mean, this satanic sex-orgy idea seems to be the prosecutor's imagination - there is no evidence for it.

Also, supposing Guede did it alone, would there be additional penalty or a reduction in penalty for him if he were to simply confess?

This whole thing seems to be like a backlash of conservative Italians' against whom they deem the immoral, selfish and arrogant youth. I have a hunch that the Italian prosecutor wants to punish Sollecito and Knox for a lifestyle he considers wrong.

I don't know what anyone else feels but the uncertainty of the case is somewhat disturbing. I wish there was a knockdown evidence and I could know the truth and be done with it instead of this restless search. Any else feeling that way?

1. Knox guilt: 80%
2. Sollecito guilt: 80%
3. Guede guilt: 99%

4. prob of agreement: 0.8

5. I was unfamiliar with the case before hearing about the verdicts on the news. I spent about 10 minutes on the Wikipedia article, then20 minutes on each of the sites you linked, and made these judgments before reading others' comments.

Guede's guilt seems almost beyond doubt, given the DNA evidence, his implausible story, and his flight without calling police. Regarding Knox & Sollecito, I'm convinced of the prosecution's version of events mainly by the cell-phone record evidence and the many conflicting statements given by Knox and Sollecito over time, with variation that goes beyond my (only moderately informed) expectations for bad memory or coercive interrogation.

Meta-evidence judgments: in the pro-guilt site you linked, it took a while to find concrete info, but when I found the Prosecution's case->Facts Presented section, I found a lot of very specific detail regarding the exact times cell phones were turned on and off and the times and durations of calls made, as well as detail regarding the forensic evidence and the credentials of the experts who testified about it. The pro-innocent site lacked such specifics and didn't seem to account for all the damning details. Both sites seemed very distorted by affection for Kercher (pro-guilt) and Knox (pro-innocence) and their nationalities.

I read the pro-guilt site before the pro-innocent site, and I noticed this causing bias: as I read the pro-innocence site, I felt myself internally "rooting" against them, expecting that they couldn't answer all the evidence and (maybe not surprising) finding that this was so. I tried to adjust for this in my judgments.

I have a low prior for this mix of murderers committing the crime together, and a high prior for a guilty verdict given by a jury, and feel like these two facts approximately cancel out.

After reading others' comments, I was surprised that most others leaned toward Knox's and Sollecito's innocence. I would update my judgments only marginally because of this, because I read the linked sites more closely than others' claimed to. I do however revise my estimate of agreement with komponisto down a bit to 0.6.

p.s. This is a very interesting exercise, which led me to register and comment for the first time after lurking for several months. I am very curious about your (komponisto's) judgment and reasoning.

my somewhat admittedly sketchy reasoning:

I go to the University of Washington where there is considerable interest in the case. Of the people who have only been marginally involved in the case, most believe that Amanda Knox is innocent. Of the people who are interested in the case, many believe she is guilty. There's an obvious hometown effect here which biases towards innocence so I'm assuming those who look into the case are taking that into account when and still reach a guilty verdict.

Therefore, I assign a 70% probability to Amanda Knox being guilty (+ or - 30%).

No prior familiarity; thus I started with no information and no particular beliefs about their guilt or innocence either way.

The first thing I saw was that Ann Coulter is convinced that Amanda and Raffaele are guilty. I immediately moved my belief in their guilt way down. When Ann Coulter takes a strong position on a controversial issue, she is almost always wrong.

From there it was mostly downhill for the prosecution, as far as I could tell.

"Later, when a airtight alibi forced the authorities to release Lumumba, they substituted Guede as the third participant in the alleged sex game, even though he had no known connection to either Amanda or Raffaele." That's just stupid. I don't trust the Italian police, or any police, when it comes to high-profile cases. The political pressure to get a guilty verdict is strong. Then, clear evidence that their original theory of the case was wrong came in, and they didn't significantly revise the theory. Not good.

The pro-guilt side keeps promising links to the "evidence," but I'm not finding it. Very irritating.

I don't care at all that their statements were confused. "She was kept up all night, claims to have been hit, and was denied a lawyer and professional translator" -- or so says the pro-innocence site. Sounds like standard operating procedure when you want to get someone convicted, regardless of the truth.

The physical evidence is confusing. I would need to know a lot more about DNA and luminol and so on to evaluate the claims and counter-claims here.

Total time spent, 45 minutes. My conclusion is maybe 10% guilty for these two, but it's a very tentative conclusion and I know that much of it is based on my belief in Ann Coulter's wrongness ... which is the sort of appeal that shouldn't be reliable -- although based on experience it appears to be.