The reporter who asked the question didn’t mention the name of the magazine. So it’s likely that official never heard of Nature but that can’t be deducted from the quoted text on that site.

The “chef de clinique” who at the outset persuaded Director Smits that there was something wrong with Lucia, and in fact did his “simple man’s statistics” for him, was also a woman – in fact, the sister-in-law of Ton Derksen and Metta de Noo. Apparently a very very powerful personality, who could exert a great deal of influence on everyone round her. She’s currently being treated for depression.

Actually I think the price is rather higher. Some of the new evidence which has come to light in the last year, is that the original statistics were badly biased – there are a few “missing incidents” during shifts of other nurses, a few “incidents” attributed to Lucia which aren’t incidents at all. Secondly, I think the probability model which is used in almost everyone’s calculation is very poor. The statistician for the prosecution refused to consider data from other years because “too many things could have been different”. This is an argument why it is dangerous to even combine different months. The analysis should have been stratified by time. Using the latest data and taking account of a modest amount of heterogeneity, I guestimate that about 1 in 9 nurses would experience such a large concentration of incidents in their shifts.

So do we need to build a new Gulag for approx 10% of Europe’s nurses? No, most of these coincidences won’t be noticed at all, by anyone. They were noticed in Lucia’s case because of her not quite usual clothing, way of talking, difficult youth… gossip made people keep her under scrutiny and THEN she had the bad (1 in 9) luck.

So just one small concentration camp should be quite enough.

My point was not about whether you were serious or not. It was that this figure that tms had estimated (the frequency with which criteria could convict the innocent) is what should govern the verdict, not a judgement of the probability of guilt. I know these may seem at first sight two sides of the same coin, but they are not. There are all sorts of things (like the incidence of the alleged crime, the personal profile of the defendant, or previous convictions) that may affect your judgement of the probability of guilt but that do not affect the probability that such evidence could have arisen to incriminate an innocent defendant.

When I read this I thought hard about whether it was actually seriously meant. Possibly not, but it touches what seems to me the crux of the issue. As ‘tms’ concluded in the previous post “you would expect to find [in Europe] 6 perfectly innocent nurses a year with a comparable record of happening to be there when people died.”

If such a murder trial were to be decided on the statistical evidence alone, and if the statistics were properly gathered and interpreted [which they weren't] then it is this bottom line figure that it seems to me should be the basis for a decision about whether to convict or not. We start with the presumption of innocence. Is it reasonable to believe that such a weight of evidence could amass, by chance, against an innocent person? Yes: it would be expected to happen to about 6 people in Europe every year. Then we must acquit, even if, for whatever reason, we remain highly suspicious. I have argued the logic of this strongly elsewhere [ Significance 2:9-12 (2005) : www.ucl.ac.uk/~ucgbarg/doubt.htm ]

Consider the implications of accepting “incarcerating six innocent nurses [per year, in Europe]” as a price worth paying. If one convicts on a standard of evidence that would lead to this statistic, one must also believe (as well as accepting this dire cost in human misery), that all these people one would convict are ‘probably’ (with a threshold maybe of P=0.99) guilty. The implication is that the six innocent victims are the tip of a large iceberg : there are 600 truly homicidal nurses [per year, in Europe] with no greater weight of evidence against them, who are or should be being convicted. This seems rather implausible to me, and even if it were correct (and this is the really important point) it should not justify conviction.

Whether simplified statistical scenarios, based on cases such as Lucia de B. or Sally Clark, should lead to conviction must depend on the facts of the case, and on judgement about whether such facts could plausibly and with reasonable probability or frequency have arisen so as to incriminate an innocent person. This judgement can of course be difficult, as can any legal decision, and may lead to acquittal of defendants one believes are probably guilty. But I believe it is what society and lawyers perceive as proper. It interprets “beyond reasonable doubt” as rather different from the way it is often viewed, as simply a high threshold on the probability of guilt. Utilitarianism has gone wild if one is to use statistics that would arise without guilt and with reasonable frequency as the basis for locking people up, justifying this to reduce a supposedly high level of crime or to improve patient safety. This is not where I want to live.

That said, Ben’s post does look a bit like an uncharacteristically incautious and hasty remark from someone who does vastly more than most to sustain good standards of thinking, and to keep this a place where I do want to live.

In the Netherlands, if you don’t like the verdict of the court of appeals, you can go to the high court, but, as far as I understood, they can only reconsider the case if something didn’t go according to protocol (e.g. the prosecution withheld relevant evidence, things like that).

The judges listen to prosecution, defense and their experts, and then decide whether guilt has been established ‘beyond reasonable doubt’. However, whether or not something actually IS beyond reasonable doubt is up to their discretion. If the court of appeals claims that it’s beyond reasonable doubt, but you disagree because you think that their reasoning is flawed, then there’s nothing you can do – this
is not sufficient reason to reopen the case in high court.
Now if there’s new evidence, the case CAN be reopened. If the committee who has to decide on the Lucia case decides
that there’s sufficient new evidence, then they can advise to reopen it.

Now what did the court write in this 90-page report? They first claim that for two of the 10 victims, they can actually prove murder by digoxin poisoning (in 1 case) and murder attempt by strangulation in the other case. So, according to them, these 2 cases have classical ‘beyond reasonable doubt status’. For the other 8 cases, they use something called a chain proof, a peculiar ‘tool’ in Dutch law. Basically it says that if you’ve been found guilty of a crime, and you’re a suspect in N more similar crimes, then the amount of evidence that constitutes ‘beyond reasonable doubt’ decreases with each further case. So for the second case, you need less evidence for the first. For the third, you need less than the second, etc.
In Lucia’s case, for the eight subsequent cases, they only have ‘patient died or needed reanimation rather suddenly; no immediate cause could be found; some doctors think it might be an unnatural death; the flawed statistics (‘it cannot have been a coincidence’, as they write a few times) and then there’s the weird diary. Despite the fact that for all these 8 cases, there originally was no suspicion at all (a natural death certificate was signed), all 8 cases were about VERY sick people, and in all 8 cases some doctors (often the majority of doctors asked!) still thought it was a natural death when they were asked in court (for some cases this was 5 years after the deaths happened).

So via the strange chain proof construction, everything hinges on the first two cases. In these cases, a lot of new evidence has been found: for example, the prosecution has withheld crucial evidence to medical expert witnesses.
(for example, in the digoxine case, the heart of the patient was not contracted, which is a very strong indication AGAINST digoxin poisoning, but the medical expert was not given this information, although the prosecution seems to have been aware of it)
So if the case gets reopened, and the defense manages to convice the judge that there is considerable doubt about the first two cases, then there’s nothing left.

BTW (technical aside), the chain proof construction may itself be thought of as a kind of flawed statistics. From a probabilistic point of view, you can argue that it makes sense if you find 10 bodies ‘with knifes in their chests’, so to speak: if it is clear tha t 10 MURDERS have been committed, and you know that somebody was around during all of them, then it is indeed true that, given that is has been established that that person killed already two of them, then the conditional probability that the same person has killed the other 8 as well goes up tremendously. This reasoning is justified, if, for example,you assume that only a very small part of the population is murderous.
The problem with the Lucia case is that there is hardly any evidence that these other 8 cases were murders/crimes. They may very well have been natural deaths. Under those circumstances, the chain proof construction makes no statistical/probabilistic sense at all, I think.

Peter Grunwald

In the case of new evidence, I think you always can petition for a new trial, but a court decides whether that happens or not.

In any event, I’m a mathematician, was a research scientist for 13 years, and got to be Mr. March in the Studmuffins of Skepticism calendar, and even I like tarot. It can be a lot of fun.

Is this true? Is there really no grounds for appeal? That sounds like a recipe for injustice.

I still can’t understand how these judges came to their conclusions.
“Officially, in the verdict made by the court of appeals ’statistics in the form of probability calculations plays no role’. That is what they write on the front page of the 90-page (!) report accompanying the verdict”

But they must have said somewhere what does play a role. And they can’t seriously mean the tarot and diary stuff. What’s the evidential burden in the Netherlands? Is it reasonable doubt or something else?

i just botched about with a free theme, looks alright to me in IE (6), i needed 3 columns to fit all the info in, especially with the new minilinks blog, if there are any wordpress gurus who want to help i’m always listening. if you didnt pick a forum login that was obviously a humorous sceptic you might have been misidentified as a spambot, email your login and i’ll enable it.