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Experts warn Letby inquiry of misreading stats to explain 'suspicious' deaths

thejusticegap.com

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Re: Experts warn Letby inquiry of misreading stats to explain 'suspicious' deaths

#71
post #40

Earlier quoted context omitted.

I went down the rabbit hole on this a couple of months ago. Some of the details are a bit hazy in my memory now as it was about 2 months ago, but in the interest of playing devil's advocate... > the suspicious deaths all lined up perfectly with Lucy Letby's shifts Once a nurse has been around the ward for long enough to have seen several deaths, you can produce a table showing a set of baby deaths correlating to any…

Considering point #4: I am aware of a case locally where a nurse was accused of murdering a baby. Digging deeper we find: The nurses had been complaining of the low quality supplies that were being provided. Specifically mentioned were IV lines that were prone to breakage. The baby died from a failure of an IV line at just the wrong spot. The hospital's expert witness supposedly said the line had been cut. Dig deeper…

I worked for an ambulance company that has had one of our local hospitals try to throw us or our employees under the bus on at least two occasions in five years:

1) understand that there are two types of ambulance (generally) - basic life support and advanced life support - the latter carries invasive care options, and narcotics, the former does not. They called us for an interfaculty transport approximately 200 miles. Patient was given pain meds before transport. Late in transport, EMTs on a BLS ambulance (no narcotics physically on board the ambulance) noted the patient was in profound respiratory depression and treated that - arriving at the hospital, it was discovered that the patient had been given vastly too much narcotics. Originating hospital insisted that it must have been given in transport. Kept insisting all the way to a DOH hearing. The EMT and the ambulance company were cleared and the hospital and nurse faced repercussions for documentation, administration, cover-up issues, but they still had to have their day in "court" to get to that point.

2) A deputy cracked his neck, and unbeknownst to him, partially severed a blood vessel. He contacted EMS complaining of nausea and vomiting. Among other things, a stroke test was done (negative) and he was taken to the hospital. CTs were done, and the physician at the hospital was insistent that all was clear, and was about to discharge him with vertigo, while other deputies insisted something was seriously wrong, and getting worse with him. Another provider sent scans to a major trauma center who noted that he had indeed had a stroke. He was also now failing a stroke test. He was transferred and treated but irreversible damage had occurred needing 24/7 nursing care, and lawsuits were launched. He died a month or so later. The hospital tried to throw EMTs under the bus, saying that they failed to diagnose or tell the hospital that the patient was having a stroke. Even though at the hospital another initial stroke test was performed by a physician with a negative result. The hospital then said there were subtle signs that in hindsight the EMTs "should have recognized" (but apparently a physician should not have been expected to...). That case is still ongoing, but the ambulance company managed to extricate itself after settling for policy limits (which was farcical in itself).

Re: Experts warn Letby inquiry of misreading stats to explain 'suspicious' deaths

#72
post #40

Earlier quoted context omitted.

Those arguments included that the suspicious deaths all lined up perfectly with Lucy Letby's shifts, that she was often caught interacting with those babies when she had been instructed not to, and that when she was taken off the ward the deaths instantly stopped. That is a level of causality checking far stronger than most Bayesian analyses.

I went down the rabbit hole on this a couple of months ago. Some of the details are a bit hazy in my memory now as it was about 2 months ago, but in the interest of playing devil's advocate... > the suspicious deaths all lined up perfectly with Lucy Letby's shifts Once a nurse has been around the ward for long enough to have seen several deaths, you can produce a table showing a set of baby deaths correlating to any…

Criminal trials are very tough. I've spent thousands of hours in criminal courts. One thing I would say first is that most lawyers are generally not experts in anything outside of law, so things like medicine and statistics are tough for them. That's why they bring in their own experts.

Before trial the experts will go through all the discovery and try to come up with theories that refute the prosecutions idea. You essentially have infinite time to go through the discovery. But, you do not know in advance what the witnesses and opposing experts are going to testify to on the stand.

During trial things move very, very quickly and you don't have any time to really take into account everything the witnesses are saying, and if there are things that say needed some time to run a statistical analysis to see if they were true, well you'd be screwed because you don't have that time. So, essentially witnesses can say things that seem really bad to a lay jurist, but if you had time to run the math they would easily be explained as common and not statistically significant.

In a complex trial like this I think it would be fairly easy for it to go the wrong way.

The justice system is definitely designed to produce convictions. Acquittals are a rare bird.

Re: Experts warn Letby inquiry of misreading stats to explain 'suspicious' deaths

#73

In two cases, the victim died by insulin overdose, Letby herself admitted that the only possible explanation was foul play. That means there is a killer on the ward. The police interviewed the other nurse on the shift, and she was cleared. Even if Letby gets acquitted from the other cases, her sentencing likely will not change. One challenge for the defence was that there are few studies on injecting air in small bab…

Those babies didn't die. Those were not murder accusations but attempted murder. To clarify. Lucy Letby was accused of deliberately administering a high dose of insulin to two babies, in an attempt to murder them. Those two babies were "Child F", and "Child L" for both of which she was charged , and convicted of attempted murder. My source for this information is this article in "Nursing Times": https://www.nursingti…

Thanks for correcting this mistake.

My point is that the judge awarded her a life sentence on each of the cases:

"on each of the seven offences of murder, and the seven offences of attempted murder, I sentence you to imprisonment for life."

Even if the other cases turn out to be unsafe, she would still be imprisoned for life.

Re: Experts warn Letby inquiry of misreading stats to explain 'suspicious' deaths

#74
post #57

Earlier quoted context omitted.

Those notes had little effect in her conviction apparently, according to a criminal psychiatrist on BBC radio. It is behaviour typical of someone suffering depression, for which she was having treatment at the time.

Writing "I killed them on purpose" is not typical behaviour of depressed people.

I'm going by the testimony of a psychiatrist who had been following the trial. Depression can apparently push people into a mental world where everything is at rock bottom and what gets written is just an expression of that.

Re: Experts warn Letby inquiry of misreading stats to explain 'suspicious' deaths

#75
post #57

Earlier quoted context omitted.

Those notes had little effect in her conviction apparently, according to a criminal psychiatrist on BBC radio. It is behaviour typical of someone suffering depression, for which she was having treatment at the time.

Writing "I killed them on purpose" is not typical behaviour of depressed people.

Most depressed people don't have strings of deaths following them wherever they go.

It is not unexpected of depressed people to blame themselves for bad things that happen around them, I think. …For multiple reasons, (1.) because you really do hate yourself that much, and might view those tragic events as also personal failures, and (2.) because for the suicidally depressed, it can be a way to manufacture a reason to believe why you deserve to be hated or physically injured.

IIRC the insulin levels or something were rather suspicious, but in general I sorta can't and shouldn't comment on the validity of rest of the case as a bystander. But when I read about that note in particular, my read on it was that somebody who actually did kill them versus somebody who just feels really bad about the situation and wants to vent in their own private space would write down the exact same thing in the exact same way with equivalent plausibility. She was a nurse, and babies died in her care; it is entirely plausible that, especially if she was already depressed, she would view that as being her fault and find some way to internalize the tragedy even if she didn't actually do anything to cause it.

And, IIRC, Letby did basically say that that was what she meant by the note— So, in sum, an innocent person who had been blaming themselves and a murderer trying to lie their way out of justice IMO would have written down the exact same thing with equal plausibility, and then tried to explain it the exact same way, which means that IMO that datapoint is basically useless for determining her guilt.

There was other evidence presented too, of course. I'm glad to hear that the conviction didn't rest on just that note, because given the situation, we don't actually know in isolation why she wrote that or what she meant by it— Most murderers try to avoid leaving confessions lying around to be used as evidence too.

Re: Experts warn Letby inquiry of misreading stats to explain 'suspicious' deaths

#76
post #11

While the statisticians are right to be cautious about clusters of deaths => serial killer, we also have to remember that a 9 month trial presented lots of evidence to a jury, they deliberated for over a week, and returned seven guilty verdicts. Unless you were also sitting at that trial or have read every line of court transcript, it would be very unwise to start claiming there's a miscarriage of justice.

According to the judge of the trial, most of the evidence was circumstantial [1]. I don't know which part of the evidence the judge considered circumstantial, and which not.

The police have said that the duty roster spreadsheet shown to the jurors was an important piece of evidence used to convince the jurors [2].

The spreadsheet in question has been circulated in the media (I'm assuming, by the police) and it can be found in various places [3].

Looking at that spreadsheet there is something that immediately jumps out to me and that makes me think that at least that piece of "statistical" evidence was downright dodgy.

I am curious to know if anyone else on HN sees the same thing. Here's a direct link to the image on the Mail website:

https://i.dailymail.co.uk/1s/2023/08/18/22/74487747-12286051...

To be clear: I'm not trying to trap anyone, I'm just really curious to see what everyone else thinks _about this particular piece of evidence_.

____________

[1] https://www.bbc.co.uk/news/uk-england-merseyside-66823777

Summing up at the end of her trial, judge Mr Justice Goss told the jury it was a case in which the prosecution "substantially, but not wholly" relied on circumstantial evidence.

[2] https://theweek.com/law/lucy-letby-and-the-importance-of-und...

Chief among these was the duty roster spreadsheet showing staff shifts, through which the Crown Prosecution Service (CPS) was "able to show the jury that Letby was the one common denominator in the series of deaths and sudden collapses on the neonatal unit".

[3] https://www.dailymail.co.uk/news/article-12286051/Lucy-Letby...

See first image on top, titled: "Staff chart that shows Letby was present at every chilling incident".

Re: Experts warn Letby inquiry of misreading stats to explain 'suspicious' deaths

#77
post #57
post #25

Earlier quoted context omitted.

And the little old thing that she wrote "I killed them on purpose" on a post-it-note at her house.

Those notes had little effect in her conviction apparently, according to a criminal psychiatrist on BBC radio. It is behaviour typical of someone suffering depression, for which she was having treatment at the time.

It's important to keep in mind that the post-it note [1] with the "confession" was not meant as a confession, for example it wasn't a signed confession and it wasn't accepted by Lucy Letby as a confession. The prosecution pointed out to the note as a confession.

I have no idea how much that affected the jury but it's just as important to remember that false confessions are a thing, and a common thing at that [2], and they have led to many false convictions. The wikipedia article I cite has a _very_ long list from many places in the world.

At the end of the day, innocent people can confess and guilty people can maintain their innocence. A confession is no more reason to accept guilt than protestations of innocence are reason to assume innocence.

Again, I don't know how much the jury were influenced by the note, but, anecdotally, the press has certainly held it up as some sort of evidence, and I've seen people on the internet take it as such, also. See for example a parent comment.

_____________

[1] For example, here:

https://www.liverpoolecho.co.uk/news/liverpool-news/lucy-let...

[2] https://en.wikipedia.org/wiki/False_confession

Re: Experts warn Letby inquiry of misreading stats to explain 'suspicious' deaths

#78
post #11

While the statisticians are right to be cautious about clusters of deaths => serial killer, we also have to remember that a 9 month trial presented lots of evidence to a jury, they deliberated for over a week, and returned seven guilty verdicts. Unless you were also sitting at that trial or have read every line of court transcript, it would be very unwise to start claiming there's a miscarriage of justice.

Those arguments included that the suspicious deaths all lined up perfectly with Lucy Letby's shifts, that she was often caught interacting with those babies when she had been instructed not to, and that when she was taken off the ward the deaths instantly stopped. That is a level of causality checking far stronger than most Bayesian analyses.

I’ve watched enough cop procedurals to know that this means it was the ward manager. It’s too neat, obviously a set up. /s

Re: Experts warn Letby inquiry of misreading stats to explain 'suspicious' deaths

#79
post #29

Earlier quoted context omitted.

I suppose, but it wouldn't be the first time a judge or jury was swayed by dubious statistics. At least that is exactly what happened to Lucia de B [1] (which they mention in the article), which at first glance looks eerily similar. [1]: https://en.m.wikipedia.org/wiki/Lucia_de_Berk

The difference is that statistics were used in de Berk's prosecution, but were not used in Letby's prosecution.

Woa, careful. That's not true. The staff duty roster was used by the prosecution to argue that Lucy Letby "the common denominator" in all the suspicious deaths:

Chief among these was the duty roster spreadsheet showing staff shifts, through which the Crown Prosecution Service (CPS) was "able to show the jury that Letby was the one common denominator in the series of deaths and sudden collapses on the neonatal unit".

https://theweek.com/law/lucy-letby-and-the-importance-of-und...

That is totally statistical information - even though it's, shall we say, lay statistics and not what you'd expect to see from a statistician.

Re: Experts warn Letby inquiry of misreading stats to explain 'suspicious' deaths

#80
post #6
post #3

Quite right. I remember Ben Goldacre's book Bad Science documenting a few examples. I hope these are the same examples raised in the letter, because otherwise a lot of miscarriage of justice has happened in the UK. What I remember from the book is entirely innocent people jailed because the wrong statistical question was asked. IIRC along the lines of two deaths, and the question asked was what is the chance of this…

Just for clarity: statistics were not used in the Letby prosecution. The problem with Letby is that a serial killer was able to hide because finding a rare event (a member of staff murdering multiple babies) is hard to do in the noise (the mish mash of data available). Currently the English NHS is moving away from SIRI (Serious Incident Requiring Investigation) to PSIRF (Patient Safety Incident Response Framework) wh…

>> Just for clarity: statistics were not used in the Letby prosecution.

I was going to say that this is the second time I see someone in this thread claim this, but I noticed the other comment is also from your account:

https://news.ycombinator.com/item?id=37814660

As I say in that other comment, statistics were used in Lucy Letby's trial, in the form of the staff duty roster spreadsheet that the prosecution showed to the jurors to convince them that Lucy Letby was a "common denominator" in all the suspicious incidents.

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