Probability of Double Event

[KatBradshaw]

Two throat-slitters out at, more or less, the same time and a fifteen-minute walk apart? Give me a break. The odds, in my view, say that both women were killed by the same hand.

Although murder wasn't as common as some may believe in the East End slitting throats seems to have been a popular method. Plus if you knew someone was going around slitting peoples throats and you wanted to dispatch of someone in a way that wasn't going to bring attention to you that might be the best way!

[Mitch Rowe]

As to Barnaby's original question, the laws of statistics and probability just aren't applicable in an instance like the double event.
Don.

Statistics and probability are about all we have in the JTR cases.
No matter how one picks it apart the fact is the story of JTR failing with Stride and going on to kill Eddowes is most likely. If you believe that then you can believe JTR took chances with Eddowes. He left himself vulnerable. That night was most likely the closest anyone ever got to JTR.

[Supe]

Kat,

Look at the throat wounds administered to the Canonic 5 and compare with those administed to Tabram, McKenzie and Coles. The first five have very similar wounds skillfully applied whereas the other three are quite dissimilar. That is one major reason I include Stride among the Ripper victims.

As to Barnaby's original question, the laws of statistics and probability just aren't applicable in an instance like the double event.

Don.

[The Grave Maurice]

Two throat-slitters out at, more or less, the same time and a fifteen-minute walk apart? Give me a break. The odds, in my view, say that both women were killed by the same hand.

[Monty]

I think that it is worth viewing the murder of Stride, not along with the murder of Eddowes, but in fact, in comparison to that of one of the later non canonical victims.
If Eddowes had not been killed on the same night then Stride would still probably have been linked to the Ripper as we see with the other cases we now discount.
The fact that Eddowes was killed on the same night is, in my opinion, the only reason why Stride has survived as a Ripper victim. I feel more and more that she is not. For me the differences are more important than the similarities.
I am aware that many to not ascribe to this idea and that my reasons for my belifes are in many ways 'gut' related.
On a linked but different issue I really can't see why people agree to Stride being a victim and then use the same arguements they put forward saying that she IS to say that Tabram ISN'T!

Kate,

Look at Stride then look at Coles.

Monty

[Busy Beaver]

If I am correct in recalling a 1988 Ripper Programme starring Lewis Collins, the timing of how fast the Ripper could walk from one destination to another was an issue. ie How fast could the Ripper walk from Berner Street/Dutfield Yard to Mitre Square. Was it possible for one killer to carry out the crimes in the given time frames? Do we know the Ripper routes? If he was a resident of Whitechapel, chances are he knew a lot of shortcuts.

If we start looking at the frame of mind of the killer, then just possibly he was disturbed and wanted to find another victim to do the job properly? Which he duly did.

Busy Beaver

[KatBradshaw]

For what its worth..........

I think that it is worth viewing the murder of Stride, not along with the murder of Eddowes, but in fact, in comparison to that of one of the later non canonical victims.
If Eddowes had not been killed on the same night then Stride would still probably have been linked to the Ripper as we see with the other cases we now discount.
The fact that Eddowes was killed on the same night is, in my opinion, the only reason why Stride has survived as a Ripper victim. I feel more and more that she is not. For me the differences are more important than the similarities.
I am aware that many to not ascribe to this idea and that my reasons for my belifes are in many ways 'gut' related.
On a linked but different issue I really can't see why people agree to Stride being a victim and then use the same arguements they put forward saying that she IS to say that Tabram ISN'T!

[Mitch Rowe]

Gareth and I talked this over sometime ago and he seemed to agree with me that the most significant if not the only significant factors involved in calculating the probability is the geographical difference between the two murders and the timing diffference.

Think of it this way.
A Man decides to rob Walmart in his hometown. So does another man. These men dont even know each other.(If they do know each other and have planned or even talked about killing that night or any other night then disregard these probability "guesses")

Now.. They dont know each other yet they both decide to rob the same Walmart on the same day and within the same hour. They both happen to have the same calibre handgun. In fact the same make. So that its difficult to tell them apart.

So.. One guy pulls into one side of Walmart and robs the clerk and ends up shooting the person in the neck for no reason. The clerk dies and the perp runs away.
A few mins later the other guy walks into the other side of Walmart and robs the clerk but this time he shoots the person to pieces!

What are chances of that happening today in London or anywhere else?
If Police assumed there was one killer would they be wrong in doing so?
If it happened once what are the odds it will happen again in a Policemans career?

Unless the recovered bullets are compared then its logical to assume one person killed two people in Walmart that day.

Yes its possible for something like that to happen but does anyone really think JTR was different from any other man? These crimes may be famous but JTR had no magical powers.

[Phil Carter]

Whereas the chances of the same person are higher?

If you compare the murders then there are some matches.

If you compare the weaponary, then they do not match.

Swings, roumdabouts and wishful thinking.

Monty

Hello Neil,

I have to agree, how we think of these murders... swings and roundabouts... I say tomato, you say kai tomato, they say tomato.

best wishes

Phil

[lynn cates]

evidence

Hello Barnaby. It’s difficult to pronounce on probabilities without further data. Perhaps the chap who knows most about the subject would be Gareth Williams.

It is better to look at the evidence and to be objective as possible (as if human beings ever COULD be objective). I recall that, right after the La Bianca murders, the police thought they were merely a copy of the Tate slayings. Turns out they were wrong—it was the same hand (well, nearly). On the other side, how many gangland slayings have similar features and yet are perpetrated by different hands?

One of my favourite saws regarding the “double event” is from Coroner Wynne Baxter’s inquest summary of Elizabeth Stride’s murder:

“There had been no skilful mutilation as in the cases of Nichols and Chapman, and no unskilful injuries as in the case in Mitre-square - possibly the work of an imitator. . .”

The Times, October 24, 1888

Accessed from Casebook.

Good luck sorting all this out.

The best.
LC

[Garry Wroe]

... to say nothing of a selective approach to evidential interpretation.

Garry Wroe.

[Monty]

Whereas the chances of the same person are higher?

If you compare the murders then there are some matches.

If you compare the weaponary, then they do not match.

Swings, roumdabouts and wishful thinking.

Monty

[Mitch Rowe]

The chance they were killed by different people is very very slim.

[Barnaby]

Let's put aside all evidence for and against Stride as being a victim of JTR and simply consider probability. Also keep in mind that statistical improbabilities happen every day so I'm in no way advocating a numbers analysis as proof.

From a statistical analysis, is it more probable that Stride and Eddowes were killed by the same person or that they were killed by different people? I'm not sure how to answer this question and suspect that arguments can be made in either direction. Are we even in possession of enough statistical data to be able to guestimate?