[HN Gopher] Experts warn Letby inquiry of misreading stats to ex...
___________________________________________________________________
Experts warn Letby inquiry of misreading stats to explain
'suspicious' deaths
Author : YeGoblynQueenne
Score : 78 points
Date : 2023-10-08 10:22 UTC (12 hours ago)
(HTM) web link (www.thejusticegap.com)
(TXT) w3m dump (www.thejusticegap.com)
| JackeJR wrote:
| The expert statistical analysis alluded to is simply the
| framework for causal inference. Had Letby not been on duty for a
| similar group of patients, would the number of patients who had
| died been the same?
|
| If the answer is no, then a follow on question regarding whether
| or not factors associated with Letby could have resulted in the
| deaths rather than Letby herself. This could be a fellow worker
| who always worked in tandem with her etc.
|
| Finding the appropriate set of data and applying statistical
| techniques for this is not trivial hence the expert mention.
| oxfordmale wrote:
| 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 babies for obvious reasons. Air embolisms
| are very painful, and such a study wouldn't pass ethics approval,
| let alone parental consent.
| YeGoblynQueenne wrote:
| 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.nursingtimes.net/news/children/breaking-lucy-let...
| oxfordmale wrote:
| 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.
| rwmj wrote:
| 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.
| contravariant wrote:
| 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
| DanBC wrote:
| The difference is that statistics were used in de Berk's
| prosecution, but were not used in Letby's prosecution.
| contravariant wrote:
| Just implicitly assuming that something couldn't have been
| chance is just trying to do statistics on pure intuition,
| which is notoriously difficult.
|
| Though unlike the Lucia de B case it doesn't seem likely
| these deaths could all have been natural. The evidence
| pointing towards Letby seems mostly probalistic in nature
| though, which should be treated carefully.
| YeGoblynQueenne wrote:
| 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.
| Freak_NL wrote:
| Please; write 'Lucia de Berk', not 'Lucia de B'. She was
| exonerated in full, and has since indicated quite clearly
| that she wishes to be known under her full name, not the
| initialized suspect name.
| contravariant wrote:
| Oh, seems I got that exactly the wrong way around. I was a
| bit on the fence about it, and figured not using her real
| name was the safest option.
|
| However if Lucia de Berk herself wishes people to use her
| full name then that is a very noble decision. The edit
| window has passed unfortunately, but I will use her full
| name in future.
| iudqnolq wrote:
| edit: wrong, can't delete
| [deleted]
| quietbritishjim wrote:
| 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.
| automatic6131 wrote:
| And she took home documents from several of those patients,
| which she'd have no ordinary reason to have fished out of the
| trash.
| frou_dh wrote:
| And the little old thing that she wrote "I killed them on
| purpose" on a post-it-note at her house.
| kitd wrote:
| 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.
| YeGoblynQueenne wrote:
| 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
| atlantic wrote:
| Yes, typically, when people are depressed, they write
| things like "I ate my neighbours for breakfast" or "I
| massacred everyone in the mall". I get that too. My desk
| is covered with those notes.
| adammarples wrote:
| Writing "I killed them on purpose" is not typical
| behaviour of depressed people.
| Intralexical wrote:
| 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.
| kitd wrote:
| 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.
| ad404b8a372f2b9 wrote:
| Ah jinx!
| ad404b8a372f2b9 wrote:
| And she had post-it notes at home where she had written "I
| killed them on purpose."...
| littlestymaar wrote:
| Like with the unauthorized interaction with the babies[1],
| this is only relevant to the case if (1) it's not a common
| behavior among nurses in her unit and (2) she did that
| specifically to the victims, and not with many of her
| patients.
|
| [1] https://news.ycombinator.com/item?id=37810382
| ssl232 wrote:
| 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 nurse's shifts [1]. The ward
| was for seriously ill newborn babies, so baby deaths were
| unfortunately common, and each nurse would regularly be on
| shifts where one would die.
|
| As you say, these deaths were considered "suspicious", but
| some (e.g. [2]) claim otherwise, saying key tests that would
| rule the accused method of murder in or out were not done at
| the time of death.
|
| > she was often caught interacting with those babies when she
| had been instructed not to
|
| (Again, playing devil's advocate) the job selects for nurses
| who (apart from Letby, it seems) deeply care for young
| babies. Not a smoking gun.
|
| > when she was taken off the ward the deaths instantly
| stopped
|
| This has been contested. As far I can tell the hospital's
| death rate statistics disagree with the Office for National
| Statistics. The latter's data appears to show the deaths
| peaked after Letby was taken off the ward [3] (note, I
| haven't checked the underlying source mentioned in the
| tweet).
|
| Replies to some comments below yours:
|
| > And she took home documents from several of those patients,
| which she'd have no ordinary reason to have fished out of the
| trash.
|
| Apparently this is quite common for nurses working on this
| and other intensive care wards. Nurses just off duty are
| often phoned by the nurses who took over the shift, asking
| for details on particular babies' treatment or behaviours
| that day. Having files on the babies to hand would let Letby
| give exact details without having to remember or misremember
| them.
|
| > And the little old thing that she wrote "I killed them on
| purpose" on a post-it-note at her house.
|
| This looks bad, yes, but again not a smoking gun. I think I
| read this happened after she was already taken off the ward
| or had somehow found out she was under investigation for
| causing baby deaths. I could believe a note like that could
| be written by someone on the verge of a breakdown or under
| extreme stress. The "I killed them" bit I could believe
| someone could write if they regret not having spotted
| something earlier that someone more experienced might have,
| especially if they have imposter syndrome.
|
| As the blog makes clear, it's not really about whether Letby
| is innocent or guilty, it's about whether she got a fair
| trial. It seems many statistics were misused in her case,
| circumstantial evidence was used as smoking guns, and some
| evidence was not fully addressed [4]; basically enough to
| question the verdict.
|
| [1]
| https://twitter.com/profnfenton/status/1692837686166368660
|
| [2] https://gill1109.com/2023/05/24/the-lucy-letby-case/
|
| [3]
| https://twitter.com/LawHealthTech/status/1692917506078376019
|
| [4] Apparently during the trial it was mentioned that sewage
| pipes crossed the ceiling and backflow sometimes came into
| the sinks. Definitely not a good mix to have in a ward with
| very ill babies. Hopefully infection spread from bad plumbing
| was fully ruled out as causes of death during the trial. Some
| critics don't seem to think it was.
| weinzierl wrote:
| I'd like to add another point that struck me as odd when
| going down the same rabbit hole:
|
| The C-peptide level in Child F's discharge letter have been
| called _" the golden thread"_ of the case by the leading
| Detective Sergeant of the investigation Paul Hughes.
|
| The deputy senior investigating officer DCI Nicola Evans
| called it a _" real milestone"_ in the investigation.
|
| The Guardian called it _" a smoking gun in this medically
| complex case"_.
|
| Dr Stephen Breary, the hospital's neonatal unit head
| consultant, said about its discovery: _" If there was a
| iota of doubt, it was removed then."_
|
| I think it is fair to say that if this letter would not
| have been found, after already a year of rather fruitless
| investigation, there would quite likely not have been a
| case.
|
| Yet, the very same Dr Breary, who was also under pressure
| because of the apparent rise of deaths in his department,
| came up with this document more than two and a half years
| after the child was released and just a couple of days
| before Letby was about to return to his department against
| his will.
|
| I'm not saying Dr Breary is under suspicion or Letby is
| innocent, but think the discharge letter should have seen
| more scrutiny.
|
| My point is that I don't think there is anything in this
| case that really holds water if you seriously probe it and
| if you pile up flawed arguments - no matter how many - it
| will not bring you any closer to the truth. If I can wagger
| a prediction, and I already said this when Letby was
| convicted: I see a successful appeal and this verdict be
| shredded. Not because I think Letby is innocent, but
| because a working legal system should not put anyone behind
| bars for life with such a weak case.
| notahacker wrote:
| Apart from the general ridiculousness of insinuating that
| of all records someone might adulterate or invent, he
| would pick a digital copy of a _discharge letter sent to
| an third party whose other baby had died_ , your
| timelines are all wrong. Breary got the police involved
| in April 2017. Nobody thinks it's a coincidence that it
| was a few days before Letby was due to return to the
| ward; stopping her from returning to the ward was his
| stated reason for going to the police.
|
| The "smoking gun" turned up inconveniently _late_ , in
| February of the following year, when he'd been asked to
| go through the records of the kids who survived.
| weinzierl wrote:
| _" Apart from the general ridiculousness of insinuating
| that of all records someone might adulterate or invent,
| he would pick a digital copy of a discharge letter sent
| to an third party whose other baby had died, [..]"_
|
| That's what you say. I neither said nor insinuated any of
| that.
|
| The case is supported by two main pillars. One is the
| idea that the stats support suspicions clusters of
| deaths. I expected that to be challenged back in August
| and we see it happen now.
|
| The second pillar is the _" smoking gun"_ of Child F's
| raised peptide levels. In my opinion this pillar is far
| from being strong enough to support this case alone. If
| we don't see any additional props appear, I expect it to
| crumble in the appeal.
|
| _" your timelines are all wrong."_
|
| - August 2015: Child F blood sample [2]
|
| - February 2017: Police investigation launched
|
| _" On the night before Valentine's Day in February 2018,
| nearly a year after police launched their investigation"_
| [1]
|
| - July 2016: Letby removed from frontline care [1]
|
| - February 2018: Smoking gun found [1]
|
| - May 2017: Letby scheduled to return [1]
|
| [1] https://www.theguardian.com/uk-
| news/2023/aug/19/trust-me-im-...
|
| [2] https://www.theguardian.com/uk-news/ng-
| interactive/2023/aug/...
| notahacker wrote:
| Thank you for posting the timeline
|
| So unless you're going to insist on a special calendar in
| which February 2018 occured two days before March 2017,
| you're basically confirming that I was correct to point
| out that your original statement that "Dr Breary, who was
| also under pressure because of the apparent rise of
| deaths in his department, came up with this document more
| than two and a half years after the child was released
| and just a couple of days before Letby was about to
| return to his department against his will." got the
| timeline all wrong.
| weinzierl wrote:
| Oh, this is so embarrassing and I only see it now.
|
| What I initially misread was _" Letby had been just six
| days from returning to work on the neonatal unit at this
| point."_ from [1]. This sentence refers to the 27 April
| 2017 two paragraphs before and not to the smoking gun
| discovery in the following paragraph. When I compiled the
| timeline I totally focussed on the months. 27 April plus
| six days would be May. But 2017, not 2018.
|
| I stand corrected and thank you for pointing it out.
| gus_massa wrote:
| Why was Child F in the hospital? Is it posible to be a
| false positive?
|
| From
| https://www.google.com/search?q=c-peptide+false+positive
|
| https://labs.selfdecode.com/blog/c-peptide/
|
| > _However, while healthy kidneys are efficient at
| breaking down C-peptide, in people with impaired kidney
| function and kidney disease, blood C-peptide levels will
| falsely increase and urine levels will falsely decrease._
| LorenPechtel wrote:
| 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: No, the witness was asked if the
| damage to the line was consistent with being cut. Yes, it
| was, but that doesn't mean it wasn't also consistent with
| simply breaking.
|
| In the end it's pretty clear the hospital tried to throw
| the nurse under the bus to cover up the fact that it was
| their shoddy supplies that killed the baby. No idea on what
| sort of settlement the parents got, no details on what the
| nurse got but it was substantial.
| FireBeyond wrote:
| 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).
| qingcharles wrote:
| 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.
| littlestymaar wrote:
| > that she was often caught interacting with those babies
| when she had been instructed not to
|
| This is only a piece of evidence if:
|
| - it's not a common behavior among nurses in her unit.
|
| - she did that specifically to the victims.
|
| Otherwise it could be that this rule isn't applied in
| practice, or that she is just the kind of people who don't
| really listen to instructions if they think they should not,
| which albeit a questionable attitude in an hospital isn't the
| same thing as "she killed them".
| [deleted]
| mrangle wrote:
| Your second attempted point is nonsense in a working hospital
| setting in general, or in a courtroom as far as evidence is
| concerned. Your bookend points are the definition of
| particularly weak circumstantial evidence. Also known as
| statistical illusion.
|
| She should be in prison if guilty of these horrific crimes.
| However, sending an innocent person to prison for them is
| substantially worse than no one going to prison for them.
| tbalsam wrote:
| Every "innocent until proven guilty" still has a p value.
| taneq wrote:
| 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
| YeGoblynQueenne wrote:
| 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".
| Marazan wrote:
| Yeah, this is not a case of someone being convicted based on
| dodgy statistical data. Indeed she was found not guilty on a
| large number of other deaths.
|
| There was corroborating evidence which lead to her conviction.
| notahacker wrote:
| Not to mention the fact the background was the complete
| opposite of a statistical witch hunt. The overlap between
| Letby and abnormal baby collapses and deaths and her strange
| behaviour around them had been noted by several colleagues,
| but hospital management stuck doggedly to the null hypothesis
| that it was just bad luck and resisted attempts to
| investigate even after moving her to other duties (at which
| point the unexpected baby collapses stopped)
| rgrieselhuber wrote:
| Also "experts warn" is argumentum ad verecundiam.
| munch117 wrote:
| What's the latin name for "argument by using fancy latin
| names for things that could just as easily have been said in
| English"?
| lolinder wrote:
| No, the headline is just documenting what the experts are
| saying, it can't contain a fallacy because it doesn't contain
| an argument. It's the experts themselves who are making the
| argument, and they're not simply saying "trust us, we're
| statisticians".
| avianlyric wrote:
| The other half of the equation is bias in the investigation.
| Often a poor understanding of statistics is used to start
| investigations, unfortunately those investigations are started
| with the premise that a particular person "is probably guilty".
| Turns out that when medical investigations are performed
| looking for wrongdoing, they're much more likely to find
| wrongdoing that if the investigation was performed simply to
| understand if correct policy and procedure are followed. As a
| consequence it's very normal for deaths previously ruled
| "normal" to suddenly become "suspicious".
|
| When people have studied these types of investigations, and has
| the evidence re-evaluated by unbiased investigators, the
| results are usually that nothing untoward occurred, or that
| deaths are better explained by systemic failures rather than
| the actions of specific individuals.
|
| There's a good reason why we don't let police go on fishing
| expeditions. Medical investigations, frequently initiated by
| untrained administrators, and performed by individuals within a
| hospital with no formal training in performing unbiased
| investigations, nor given enough to perform proper
| investigations, simply don't hold up to the standards we would
| expect from a criminal investigation.
|
| None of this is to say that the Letby verdict is unsafe, but it
| wouldn't be the first time a medical investigation with lots of
| evidence resulted in an awful miscarriage of justice.
| crote wrote:
| To a large extent they didn't _have_ to involve statistics.
| There was plenty of better evidence in the Letby case.
|
| However, the public perception around the time of the trial was
| substantially different. Especially early on, the media focused
| strongly on the fact that it "could not possibly be a
| coincidence". Reading the trial coverage I got a very strong
| feeling of deja vu, seeing the coverage pretty much mirroring
| the Lucia de Berk case.
|
| Considering the mountain of other evidence in the Letby case, I
| highly doubt it was a miscarriage of justice. But I definitely
| agree with the Statistical Society that just because something
| _looks_ like a duck, it doesn 't _have_ to be a duck.
| mrangle wrote:
| Better evidence is irrelevant to her jury trial if false
| evidence was included in the form of misrepresented stats.
| Because that's how trial by jury works. She would get a
| retrial, at minimum, if a judiciary body were to be convinced
| that the prosecution introduced false evidence.
| mrangle wrote:
| No one forgets. 'We have to remember the jury" isn't a
| persuasive argument. Juries are no match for statistical
| misrepresentation. Even beyond stats, juries get it wrong
| constantly. Courts don't have staff math experts, including the
| judge. Were expert witness mathemeticians trial participants at
| any point? It may be premature to claim that there was a
| miscarriage of justice, but it may be similarly unwise to imply
| that there likely wasn't.
| wolverine876 wrote:
| Did the statisticians question Letby's verdict? They are
| talking about inquiries into other clusters of deaths.
| rossant wrote:
| Not directly related to this case, but the book Math on trial by
| Leila Schneps and Coralie Colmez covers several examples of
| misapplied statistics in court:
| https://en.m.wikipedia.org/wiki/Math_on_Trial
| mberning wrote:
| I think this is a great example of a justice system working as
| intended. The statistical evidence alone likely would not have
| convicted her, but it could have exonerated or cast doubt on her
| being the perpetrator. It did not, for reasons which were obvious
| to the jury.
| mellosouls wrote:
| There seems to be some (understandable) confusion in some of the
| comments about what the article here is reporting which isn't
| helped by a lack of clarity in it or the underlying Guardian
| piece, possibly in each case intended to push their own agendas.
|
| There appears to be an interpretation here by some of a
| potentially unsafe verdict due to misreading of statistics in her
| conviction - which has certainly happened in the past in other
| cases including those mentioned.
|
| The expert input here though is intended as advice for the
| inquiry into _what went wrong at the places Letby worked_ to
| lessen the risk of it happening again.
|
| That necessarily includes qualified and responsible analyses of
| statistics, which will also have the benefit of increasing
| protection and support of staff as well as improving safety
| generally.
| fiftyacorn wrote:
| One thing the Letby trial left me wondering was how do doctors
| and nurses working in areas with higher levels of mortality
| protect themselves from this sort of accusation? And whether this
| would put doctors off doing riskier procedures?
| jdietrich wrote:
| The suspicious deaths in this case were systematically ignored
| by hospital management. Doctors who raised concerns about Letby
| were disciplined for doing so. The hospital is now under police
| investigation on suspicion of corporate manslaughter, because
| it is highly likely that deaths could have been prevented if
| they had investigated rather than silenced those concerns.
|
| https://www.bbc.co.uk/news/uk-66120934
|
| https://www.bbc.co.uk/news/uk-england-merseyside-67006930
| Xenoamorphous wrote:
| Kathleen Folbig case might me related to what it's being
| discussed. She had four children die shortly after being born and
| she was sent to jail.
| zee2345 wrote:
| [flagged]
| piker wrote:
| Anybody who closely followed this case who could identify for the
| readers here any direct evidence of these crimes, or should we
| read this article to imply Lucy herself might be innocent?
| randomcarbloke wrote:
| She kept notes, apparently there was an abundance of evidence
| in her home, doctors had raised concerns.
|
| This isn't a case of relying solely on data, rather the data
| bear out what everything else suggests.
| pbhjpbhj wrote:
| IIRC, doctors/administrators dismissed statistical evidence
| as "it couldn't be lovely Lucy". Whether it was possible to
| make statistical inferences probably speaks more to whether
| the family's have a case against the hospitals/health
| authorities for neglect, eg neglecting to follow up on
| suspicions.
| crote wrote:
| I recommend reading the Wikipedia page, the "2023 Trial"
| section has a pretty good overview.
| krisoft wrote:
| There were various postmortem findings described as anomalous.
|
| Child F had a bloodwork which indicated that someone gave them
| a large amount of insulin.
|
| Child D's post mortem X-ray is said to show air injected into
| their blood vessels.
|
| Child L also had insulin in their blood.
|
| I'm not an expert so I can't say for certain how strong these
| evidence are. Also my understanding that while these are
| evidence that a crime happened, they do not tie Lucy directly
| to the crime. The evidence for that is circumstatial, mainly
| that she was the only one on duty for all the collapses said to
| be suspicious.
| YeGoblynQueenne wrote:
| >> Child F had a bloodwork which indicated that someone gave
| them a large amount of insulin.
|
| >> Child L also had insulin in their blood.
|
| Those were not post-mortems because these two children didn't
| die. Lucy Letby was accused of attempting to murder them, by
| injecting them with insulin.
|
| See here, towards the end of the article, a summary of
| accusations and convictions:
|
| https://www.nursingtimes.net/news/children/breaking-lucy-
| let...
| anewhnaccount2 wrote:
| The evidence suggests that many of the deaths had symptoms
| consistent with being injected with air. We would need to have
| a model of P(symptoms_i|not injected with air) to try and get
| to the possibility of there having been a miscarriage of
| justice.
| DanBC wrote:
| > or should we read this article to imply Lucy herself might be
| innocent?
|
| No, the point being made is that a murderer was able to evade
| detection because her employing organisation did not understand
| the data they had, because they did not understand statistics.
| d1sxeyes wrote:
| I don't think that's the point either. I think the point is
| "be very careful jumping to conclusions, and just because you
| may find patterns similar to those in this case elsewhere,
| that does not mean that we are necessarily dealing with
| another serial killer".
| orra wrote:
| 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 happening? As opposed to, assuming the first
| death, what is the chance of the second? As opposed to, assuming
| two deaths, what is the chance of bad luck versus malice.
|
| (I am not commenting on the Letby case per se. AIUI there is an
| appeal pending and UK law can be rather strict. Simply, we should
| not respond to possible horrible events by convicting other
| people who are innocent of statistical flukes, or misrepresented
| statistics.)
| InCityDreams wrote:
| >otherwise a lot of miscarriage of justice has happened in the
| UK.
|
| Depends on 'a lot', but I rather suspect there will be/ will
| have been fewer, now cops have to use cameras, but yes - a lot
| of miscarriages of justice has happened in the UK. And every
| other country.
| DanBC wrote:
| 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) which focuses a lot more on "no
| blame" and "open culture", so it's important that NHS Trusts
| get the stats right to be able to detect and understand these
| very rare events.
| YeGoblynQueenne wrote:
| >> 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.
| hmottestad wrote:
| I like to remember that the odds of winning the lottery are
| easily in the 1 in 50 million, yet people still seem to win it.
|
| It's statistically improbably to get 7 sons, but I'm certain that
| throughout history that's happened at least once.
| sgt101 wrote:
| it's only statistically improbable to get 7 sons (in a row) if
| you have all couples that create 7 children have a 50/50 chance
| of son/daughter. If you have a reason why a couple will only
| produce sons (genetics) then it becomes much less surprising.
| brvsft wrote:
| > There are obvious parallels with the Lethby case. Statements in
| de Berk's diary about 'a very great secret' and a 'compulsion' on
| a day that a patient had died were given a sinister
| interpretation.
|
| They didn't include any examples of the parallel. This goes over
| some of the notes:
|
| https://www.theguardian.com/uk-news/2022/oct/13/lucy-letby-p...
|
| > On another, she wrote "I am a horrible evil person" and on
| another in capital letters: "I AM EVIL I DID THIS," the jury was
| told.
|
| > She also wrote on the note: "There are no words", "I can't
| breathe", "kill myself", "I haven't done anything wrong", "how
| can I get through it?" and "I am an awful person". She had also
| written "No Hope" and "Panic Fear" and then circled in capital
| letters "HATE".
|
| Personally, I don't think any of this is strong evidence, since
| she contradicts herself a bit. But the notes more directly
| address the murders because she wrote them in response to the
| accusations. It isn't as vague as a diary entry mentioning a
| secret.
|
| And as far as I know, they had more evidence in the form of
| testimony from experts suggesting the babies were killed by
| injecting them with air, but I'm sure there are reasons to be
| skeptical of that.
|
| Mainly, I don't know how strongly any statistical "evidence" was
| presented in court, how much the jury depended on it in their
| guilty verdict, and how the UK court system works, so I don't
| have a strong opinion. But I also don't believe a not-guilty
| person would think to write anything like what she wrote in those
| notes.
|
| One last thing I'm curious about and have never heard definitive
| information on is whether babies stopped dying when they took
| Letby out of the NICU or whatever they call it. I suppose that
| might still be accounted for in this statistical coincidence
| element the RSS and other statisticians are discussing.
| specialist wrote:
| [deletia, cuz I misread the article.]
| kitd wrote:
| No it wasn't. See my sibling comment in this thread. At
| worst, it alerted authorities to there potentially being foul
| play. Her actual conviction was based on other factors.
| specialist wrote:
| Thanks for clarification. That's very reassuring.
| [deleted]
| kitd wrote:
| On the afternoon of the conviction, there was an expert
| criminal psychiatrist on BBC radio who had been following the
| trial closely. Apparently those notes, though they made all the
| headlines, played little part in her conviction, and are
| typical for someone suffering stress &| depression.
|
| The thing that did for her apparently were messages she had
| sent some of the parents, the times of which contradicted her
| testimony she had given the police and put her clearly in the
| frame when she had given them an alibi.
|
| So I'm not sure the clusters of "unlikely" cases played much
| role either, other than alerting authorities to there
| _potentially_ being foul play.
| crote wrote:
| That's a very good reason to warn the public about it, is it
| not?
|
| People generally do not read court transcripts, they read
| media headlines. It's basically a guarantee that some people
| are already convinced their statistically unlucky coworkers
| are _also_ serial killers. It can easily lead to witch hunts.
| kitd wrote:
| You're right, but I think the article is about the RSS
| warning the official inquiry rather than the public. One
| would expect them to have a higher threshold of quality of
| evidence than the typical tabloids or Twitter feeds.
| [deleted]
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