probability

[GUT]

But even if you take all this at its highest it doesn't prove that one hand didn't kill both, does it?

[The Good Michael]

And I never cease to be amazed at how the non-Jack crowd comes across with an air of superiority which is especially amusing seeing how they are posting on a site dedicated to Jack the Ripper.

The arrogance comes from the fact that invisible things can't be disproved. They have the same faith as fundamentalists.

Mike

[SirJohnFalstaff]

Hello CD. Thanks.

"I see you are still heavily into being condescending in your posts. Is that really necessary?"

Oh, I beg pardon. I was going to write out a nice post, but, unfortunately, I was interrupted.

"You are still leaving out a salient fact in your argument. There is no evidence whatsoever that Mrs. Brown was a prostitute or ever engaged in soliciting."

Ah, but perhaps her husband saw her out at night and THOUGHT she was soliciting. That's all it would take, right?

You'll forgive me, but the rest of your argument is so weak that I will be nice and not comment.

Cheers.
LC

The husband was insane. Thought she drugged his beer so he'd fall asleep and she would invite men to her home. He's been threatening her for months.
The only point in common is the throat slashing.
In a city with millions of inhabitants, it's no surprise that there are several silmutaneous murders.

But two murders, 1 hour apart, walking distance, two prostitutes, both throat slashed? You can't rule anything out, imo.

[Barnaby]

Lynn is correct that just because something is a low probability event doesn't allow one to assert that it couldn't happen. Given two (or more) explanations of the Double Event, we can though give more weight to the account that is more probable. And for those discounting probability, this is a fact of investigations; for example more likely persons are eliminated as suspects before the investigation expands.

Another factor to consider is parsimony. Which is the simpler explanation? But again, this doesn't rule out the more complex one. These are tools to guide investigations that more often than not expedite things. Maybe this case is an exception but probably not.

[Rob Clack]

Hello Rob. Thanks.

Different area? Indeed. Rather like Aldgate and St. George in the East, what?

Cheers.
LC

True, but one was ten minutes apart and the other about an hour (walking). My point is that each should be investigated/treated separately. And draw conclusions.

Rob

[Debra A]

You are right it can never be conclusively proven but when you look at Strides murder there are so many significant factors, which when put together clearly suggest she wasn't killed by the same hand as Eddowes.

But of course its like other contentious issues surrounding this mystery there are those who want to believe she was, simply because the police suggested she was back in 1888 and the killer killed 5 and 5 only. That is another accepted theory that doesn't stand up to close scrutiny in the 21st century.

Yes, but I find most people are able to study the cases and make up their own minds. Many people do question whether Stride was a victim of the same killer as Eddowes and I doubt you'll find many people who believe in '5 and 5 only'. That's what always annoys me about this type of discussion, even those who believe there was a serial killer at large have differing views on the number of victims.
I hated probability theory. I would never use it to try and determine the number of victims...I'm obviously not smart enough to, for a start.

[The Good Michael]

Yes, but I find most people are able to study the cases and make up their own minds. Many people do question whether Stride was a victim of the same killer as Eddowes and I doubt you'll find many people who believe in '5 and 5 only'. That's what always annoys me about this type of discussion, even those who believe there was a serial killer at large have differing views on the number of victims.
I hated probability theory. I would never use it to try and determine the number of victims...I'm obviously not smart enough to, for a start.

Said Debs Einstein.

Mike

[lynn cates]

"Laugh, and the world laughs with you . . ."

Hello Phil. Thanks.

Perhaps some day we shall know what happened and have a good laugh.

Cheers.
LC

[lynn cates]

irrelevant

Hello GUT. Thanks.

"But even if you take all this at its highest it doesn't prove that one hand didn't kill both, does it?"

Not at all. In fact, probability is irrelevant to the number of hands involved.

Cheers.
LC

[lynn cates]

disproofs

Hello Michael.

"invisible things can't be disproved."

Not quite correct. Your dictum applies ONLY to empirical objects. Permit an example. The proposition:

(P) 2 + 2 = 5

is invisible (obviously, its REPRESENTATION by means of symbols is not--I am sure you are far too intelligent to be thrown off by that).

But it is easily disproved by adverting to Peano's axioms, definitions and the successor function.

Cheers.
LC

[lynn cates]

substitute for a prostitute

Hello Sir John. Thanks.

Prostitutes? And the evidence for that?

Cheers.
LC

[lynn cates]

Double Events R Us

Hello Barnaby. Thanks.

I think we have given due regard for a "Double Event."

Not much going on?

Cheers.
LC

[lynn cates]

dictum

Hello Rob. Thanks.

"My point is that each should be investigated/treated separately. And draw conclusions."

Could not possibly agree more. In fact, your dictum should be emblazoned above all ripper research sites.

If only investigators would adhere to what you say.

Cheers.
LC

[lynn cates]

On boredom.

Hello Debs.

"I hated probability theory."

Indeed. "Probability and Statistics" was the most boring class I had in 13 years at university.

"I would never use it to try and determine the number of victims."

Right again.

Cheers.
LC

[Abby Normal]

Indeed they do, Lynn. But I must respectfully assert that it is you!

I would never consider buying a lottery ticket because I cannot justify a willingness to risk money on a near impossibility.

But let's say that my wife decided to tease my obsessive compulsive type 'A' personality by surprising me on my birthday with … a lottery ticket; one for a particular lottery in which the chance of winning was stated as being 1-in-25,000,000, i.e. odds of 24,999,999-to-1 against. And let's say that she happened to purchase the winning ticket, and I was consequently $10,000,000 the richer.

Now, even though a "near impossibility" had just occurred, I would still never go on to buy a lottery ticket myself, and I would scold my wife in the event that she were to do so again.

Why? Because any subsequent lottery would be independent of the one that I had just had the miraculous fortune of winning, and the chances of winning again would be totally unaffected by my remarkable luck in the first instance.

You once cited an incident in which a symphonic musician was killed by a bale of hay whist driving his car, in order to make the point that extraordinary things do occur. Have you since added 'flying hay bale' coverage to your automobile insurance policy? I doubt you have, because even though the aforementioned tragedy did occur, you have the good sense to realize that a reoccurrence would be a near impossibility.

Sarah Brown's murder was independent of those of Elizabeth Stride and Catherine Eddowes. That much we know! It does not therefore have any bearing on dependence or independence of the latter two. Period!

What the Brown murder does tend to do, each time that it is championed as a reason to believe in an independent (i.e. multi-perpetrator) 'Double Event' by the likes of Messrs. Richards, Carter, Wood and Marriott (and of course, yourself), is make the whole idea seemingly more extraordinary than even probability theory would dictate.

Two extraordinary occurrences would be more extraordinary than just one; and three extraordinary occurrences would be more extraordinary than just two; and four extraordinary occurrences …

"Wonder if we can learn a lesson from this? Nah?

Thought so."

---

For the record:

My position on this issue notwithstanding, I perceive a chance of as much as 1-in-3, i.e. a probability of as much as 33.33% that Elizabeth Stride and Catherine Eddowes were felled by different hands. I think I would be foolish not to do so.

I'd go with this guy : )

Thanks for posting Colin!