PRESUMPTIVE LOGIC (APPLIED EPISTEMOLOGY)

[Mick Harper]

The Letby case came up on Medium here https://alexeisorokinstories.medium.com/the-most-staggering-observation-about-lucy-letby-the-serial-baby-killer-3de93f2b8942 to which I posted a response suggesting Medium readers have a look at this thread. Reading through it a week or two later it seems to stand up quite well.

Obviously we're not equipped to mount a full-scale defence -- and we should concede that the chances of her guilt are quite high -- but I thought I would prepare a Letby story for Medium, incorporating -- even by direct but anonymous quotation -- some of your thoughts. Does anyone have any objection to this?

[Mick Harper]

I'll put up a first draft of the story here to gather some feedback. Talons out, I can take it. I can't really but I'd rather you than the world.

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Lucy Letby: Baby-Killer or Patsy?

I am as ignorant about statistics as most people but, as an Applied Epistemologist, I am aware that people being ignorant about statistics can have devastating effects in wrongful conviction cases. For example, if profiling is used to seek out a serial killer living among a population of a million non-serial killers, it is perfectly possible for a single person to be identified who meets all the criteria. Does this mean that person is the serial killer? Of course not, and no court would convict him (serial killers are overwhelmingly male) on such evidence.

However, police have an understandable conviction they have ‘found their man’ and begin piecing together the evidence that will convict him in court. This can be a dangerous procedure because evidence can be twisted (quite properly, we are not dealing here with so-called ‘noble-cause corruption') to read one way when in reality it should be read another. When the police have gathered sufficient evidence to satisfy the Crown Prosecution Service there is a greater than 50/50 chance of a conviction, the matter goes to trial. When someone utters the fateful words (and someone always does) “It’s a million to one, the accused did the crime,” fifty-fifty goes up to nearer ninety-nine to one.

In the Letby case there was a further twist. Were any crimes committed in the first place? So let us begin there.

[Mick Harper]

Lucy Letby (2)

Letby worked in the neonatal unit of The Countess of Chester hospital from 2009 until 2016. A neonatal unit is where babies that are premature or otherwise not routine births are cared for. It can be expected to have a higher mortality rate than an ordinary maternity ward. Though still not high

[Wile E. Coyote]

There is a discussion about Letby here. A key point is there is no evidence against her based on post mortems as these were all considered natural deaths at the time, they happened. The Criminal barrister being interviewed points out that there are worrying similarities between Letby and some other cases of nurses he believes were also wrongly convicted. Worth a look.

https://www.youtube.com/watch?v=qwunlsP6nbA

[Mick Harper]

That's made my mind up.

[Mick Harper]

One trouble I'm having is that I've taken (I think this is literally true) nil interest in this case. I'm coming at it new but everything the barrister bloke (and he was extremely bloke-ish) said was incredibly familiar. I didn't quite get the references to him having worked in casualty though it reminded me that I too have straddled hospitals and lawcourts in my patchwork career.

I was surprised at the degree of hostility on the part of the TV interviewer, his talking-head sidekick and the text-messengers. Definitely a general air of outraged citizenry with which we are so familiar. I will look on Medium to see what is being said there.

[Mick Harper]

I thing we've got the field to ourselves

Lucy Letby’s White Privilege Is The Reason She Could Kill So Many Babies
Was White Female Privilege, The reason Why Lucy Letby Got Away With Murdering Babies For The Longest Time?
The most staggering observation about Lucy Letby (the “serial baby killer”). [criticism of hospital administration]
Lucy Letby, Innocence, and Deception: The Paradox of Female Psychopaths
Lucy Letby — monster in human form, or product of cultural values that empower rather than reject cruelty?
The Dark Tale of Lucy Letby: Exploring the Motives Behind the Unthinkable Actions of a Serial Killer
Lucy Letby, The Angel of Death
And as for monster Letby she is far from the first and will hardly be the last.
etc etc

[Mick Harper]

Lucy Letby (3)

Bayesian statistics are the least understood branch of the subject and the most relevant when it comes to hospital deaths. People are dying all the time, mortality spikes are happening all the time, serial killers are responsible almost none of the time. When non-statisticians such as doctors, hospital administrators and the police are faced with spikes they do not say (and nor initially should they say) “Oh, it’s our turn to have a spike.” The real mischief comes when they say, “Let’s assume it is a serial killer, who’s in the frame?” Because in hospitals that is a very difficult question to answer.

Even when it is the relatively close confines of a neonatal unit and the victims are present for a relatively short time, the number of people that have access is very large. But that number comes down very, very quickly when you start going through one maternity nurse’s attendance records, look for any suspicious deaths that occurred during those periods and discover that a hundred per cent of them occurred on her watch. That is in essence what put Lucy Letby in the frame.

Now it was just a question of gathering the evidence.

[Mick Harper]

Lucy Letby (4)

The problem battering the case from every side was there was no evidence. Every baby had been signed off as dying from natural causes -- if that is the right phrase in the circumstances -- and the causes of death, established after a rigorous examination at the time, were the ordinary ones -- if that is the right phrase for such a rare event -- that affect babies in neonatal units. The prosecution turned this to their advantage by listing the ways Letby could have murdered the seven babies without leaving a trace, creating the unfortunate impression that that's how she did it. Stands to reason.

It's not a cart before the horse situation, it's a cart looking for a horse situation. In fact it's a looking for a cart, then looking for a horse situation, times seven. But Bayesian statistics really start kicking in when we come to the real evidence, the evidence that convicted a serial killer. The material found in Letby's home. Because she was that strange kind of serial killer, the one who keeps all the evidence of her crimes in loving detail...

[Wile E. Coyote]

The death rates across English neonatal hospitals vary according to area. In the South West the survival rates are better. The West Midlands is worst. Hospitals are currently under governmnet targets (a worthy ambition) to reduce neonatal deaths by a half.

As of last year within England

West Midlands has the worst at 5.6 deaths per 1,000 live births.

South West had the lowest 2.5 deaths per 1,000 live birth.

That's quite a difference, the presumptive explanation is not the number of serial nurse killers in the West Midlands. It is more likely something to do with ethnicity, deprivation, maternal age or the nature of hospital care within those areas....Least, that is what I would have thought.

[Mick Harper]

[Wile E. Coyote]

Note Wiley tends to go to the excellent House of Commons Library for data. (I know you like Wiki)

[Mick Harper]

This is great ammunition. By the by, as an AE-ist I oppose targets such as

[Mick Harper]

Lucy Letby (5)

Take care, we are all just a smartphone examination away from a life sentence for murder. If you are on holiday confine yourself to sending ‘wish you were here’ postcard to work colleagues. Do not send a text: “I’ll be back with a bang” because you might be accused of ‘being out of control’. If someone is poorly do not on any account enquire how they are doing because if that person dies you could easily be accused of ‘playing God’. Adding all those texts together may not cast you in the best of all possible lights

[Mick Harper]

Lucy Letby (6)

Do not take your emotions home either. If you do make sure not to record them indelibly, they can be used against you at any time