The cut in the throat

[Colin Roberts]

I have contended that at the onset of 1888, the likelihood of the so-called 'Double Event' occurring as it did, and involving two independent murders, should have been perceived as being similar to that of 30.15212 sequential tosses of a coin, landing entirely on 'Heads', or that of 11.66443 sequential tosses of a single die, landing entirely on '1'.

The perceptual odds of such an occurrence, i.e. the odds of such an occurrence, which should have been perceived, at the onset of 1888, are indeed, astronomical!

- They are slightly greater than the odds of thirty (30) sequential tosses of a coin, landing entirely on 'Heads'.

- They are significantly greater than the odds of ten (10) sequential tosses of a single die, landing entirely on '1'.

They are, in fact equivalent to the odds of 30.15212 sequential tosses of a coin, landing entirely on 'Heads'.

They are, in fact equivalent to the odds of 11.66443 sequential tosses of a single die, landing entirely on '1'.

Again; ...

Assuming a mathematically derived 'expectation', at the onset of 1888, that 4.40¹ murders of female adults, by way of 'Cut Throat', would occur throughout England, during the coming year, ...

¹ The mean number of registered deaths of female adults (ages 20 - xx) throughout England, classified as 'Murder', by way of 'Cut Throat': 1883-1887, i.e. during the five-year period, preceding 1888.

~~~

But, what if someone had taken it upon themselves, to derive an 'expectation', at the onset of 1888, that nine murders of female adults, by way of 'Cut Throat', would occur throughout England, during the coming year; purely on the basis that nine such murders had occurred during the previous year, i.e. 1887?

Well, their 'expectation', in this instance, would certainly have been more accurate than the one, which should have - in my opinion - prevailed. But, ...

Assuming an 'expectation', at the onset of 1888, that nine murders of female adults, by way of 'Cut Throat', would occur throughout England, during the coming year, ...

...

That Two Independent Murders, of Female Adults, by way of 'Cut Throat', would Occur; within the depicted Color-Shaded Circular Region, and during a particular One-Hour Period:

- Perceptual Probability: 0.000001467124%

- Perceptual Chance: 1 -in- 68,160,556.97

- Perceptual Odds: 68,160,555.97 -to- 1

- Odds, which are, in fact, equivalent to the odds of 26.02243 sequential tosses of a coin, landing entirely on 'Heads'.

- Odds, which are, in fact, equivalent to the odds of 10.06685 sequential tosses of a single die, landing entirely on '1'.

So, I should be contending that at the onset of 1888, the likelihood of the so-called 'Double Event' occurring as it did, and involving two independent murders, should have been perceived as being similar to that of 26.02243 -to- 30.15212 sequential tosses of a coin, landing entirely on 'Heads', or that of 10.06685 -to- 11.66443 sequential tosses of a single die, landing entirely on '1'.

~~~

And, what if someone had taken it upon themselves, to look into a crystal ball, so to speak, and in so doing, derive an 'expectation', at the onset of 1888, that as many as thirteen independent murders² of female adults, by way of 'Cut Throat', would occur throughout England, during the coming year?

² Registered Deaths of Female Adults (Ages 20 - xx) throughout England, Classified as 'Murder', by way of 'Cut Throat'; 1888: 15

The 'expectation' that as many as thirteen independent murders of female adults, by way of 'Cut Throat', would occur throughout England, during the coming year, in this particular instance, would be based on the assumption that each of the fifteen murders of female adults, by way of 'Cut Throat', that actually would occur (excepting those of Mary Ann Nichols, Annie Chapman, and Catherine Eddowes), would be independent.

In other words; the nearly universal agreement that Mary Ann Nichols, Annie Chapman, and Catherine Eddowes, were murdered by the same perpetrator, would effectively dictate that their murders be counted, in this regard, as one independent murder of a female adult, by way of 'Cut Throat'; thereby reducing the 1888 total, of fifteen murders of female adults, by way of 'Cut Throat', to thirteen independent murders of female adults, by way of the same.

Well, their 'expectation', in this instance, would certainly have been more realistic than the one, which should have - in my opinion - prevailed; but, perhaps a bit too surrealistic, as well ...

Assuming an 'expectation', at the onset of 1888, that thirteen independent murders of female adults, by way of 'Cut Throat', would occur throughout England, during the coming year, ...

...

That Two Independent Murders, of Female Adults, by way of 'Cut Throat', would Occur; within the depicted Color-Shaded Circular Region, and during a particular One-Hour Period:

- Perceptual Probability: 0.000006386608%

- Perceptual Chance: 1 -in- 15,657,764.58

- Perceptual Odds: 15,657,763.58 -to- 1

- Odds, which are, in fact, equivalent to the odds of 23.90037 sequential tosses of a coin, landing entirely on 'Heads'.

- Odds, which are, in fact, equivalent to the odds of 9.24593 sequential tosses of a single die, landing entirely on '1'.

And, therefore, I should be contending that today, the likelihood of the so-called 'Double Event' having occurred as it did, and having involved two independent murders, should be perceived as being similar to that of 23.90037 -to- 30.15212 sequential tosses of a coin, landing entirely on 'Heads', or that of 9.24593 -to- 11.66443 sequential tosses of a single die, landing entirely on '1'.

~~~

In any case, the likelihood that the so-called 'Double Event' occurred as it did, involving two independent murders, should be perceived as being minuscule, when considered purely on the basis of the degrees of time & space that were involved.

~~~

A Point of Reiteration:

I am not here to discuss whether Elizabeth Stride and Catherine Eddowes were felled by the same hand.

I am here to insist that the extraordinary nature of the so-called 'Double Event' not be marginalized, as a means of 'lobbying' for the likelihood of two independent perpetrators.

[Colin Roberts]

Well, in EVERY case, probability is merely a way of calculating our human ignorance. Need convincing? Try this.

We say that the probability of a fair coin (whatever that means--I suppose 2 sided; evenly weighted metal throughout, etc) coming down heads after being tossed is 1/2 (better: as the number of occurrences approaches infinity, the probability of tossing heads nears 1/2). BUT, if we knew ALL the variables--attitude of the flipper, strength of flip, why the flip had strength value X rather than Y, what the flipper had for breakfast, how the coin was initially placed in the hand, etc--we would KNOW precisely whether a given flip would result in heads, or not. Hence my claim that probability is merely a calculation of our unknowing (ie, human ignorance), and, as such. properly within epistemology (theory of knowledge) not ontology (study of being as such).

OK, Lynn!

So, given complete control of every conceivable variable, we should be able to accurately predict the outcome of any event.

Hence, when predicting the outcome of the single toss of a coin, - generally speaking - we posses 50% of the knowledge, i.e. 'predictability', that is potentially available.

I haven't been taking my Lexapro lately, and the last thing I need is something else to obsessively ponder for the next six months.



But, what bearing, if any, at all, does this have on my contention that at the onset of 1888, the likelihood of the so-called 'Double Event' occurring as it did, and involving two independent murders, should have been perceived as being similar to that of 30.15212 sequential tosses of a coin, landing entirely on 'Heads', or that of 11.66443 sequential tosses of a single die, landing entirely on '1'?

[lynn cates]

probability again

Hello Claire.

"Coin flips aren't a particularly good analogy in the Stride case (or in most cases in the real world), since the Stride case has significantly more variables than does a simple binary. There is no unified form for murder that means that one is qualitatively the same as any other, so there's little point in treating every murder that occurred in London as an empirically coterminous group, irrespective of their characteristics."

I completely agree. Hence, my looking at probability and statistics through a jaundiced eye.

My remarks were aimed at probability in general and, yes, I took the simplest case possible to illustrate my point.

Cheers.
LC

[sleekviper]

The distance was 950 yards? Sweet, I had a maximum distance of 1097 yards, now things are getting interesting!

[claire]

That's not quite correct. Probability may be a reasoned solution to our inability to know, but it's not a calculation of our ignorance. The variables pertain to what we know; there's no way of knowing, or calculating, the extent or nature of what we don't know.

Coin flips aren't a particularly good analogy in the Stride case (or in most cases in the real world), since the Stride case has significantly more variables than does a simple binary. There is no unified form for murder that means that one is qualitatively the same as any other, so there's little point in treating every murder that occurred in London as an empirically coterminous group, irrespective of their characteristics.

[lynn cates]

probability

Hello Colin.

"resultant probabilities, in this instance, is merely perceptual, as opposed to being actual?"

Well, in EVERY case, probability is merely a way of calculating our human ignorance. Need convincing? Try this.

We say that the probability of a fair coin (whatever that means--I suppose 2 sided; evenly weighted metal throughout, etc) coming down heads after being tossed is 1/2 (better: as the number of occurrences approaches infinity, the probability of tossing heads nears 1/2). BUT, if we knew ALL the variables--attitude of the flipper, strength of flip, why the flip had strength value X rather than Y, what the flipper had for breakfast, how the coin was initially placed in the hand, etc--we would KNOW precisely whether a given flip would result in heads, or not. Hence my claim that probability is merely a calculation of our unknowing (ie, human ignorance), and, as such. properly within epistemology (theory of knowledge) not ontology (study of being as such).

Cheers.
LC

[Colin Roberts]

Hello Colin. You seem to be saying that, your view of probability, as more fittingly ascribed to epistemology, rather than to ontology, is correct. I heartily agree!

You're going to have to toss me a line, Lynn. I can no longer touch the bottom, and I am not wearing my floaties.

Our knowledge enables the conception and application of probability theory; but, the existence of any resultant probabilities, in this instance, is merely perceptual, as opposed to being actual?

I am somewhat puzzled by your (seeming) disagreement with my endorsement of Christer's dictum. If I understand your thinking on Liz Stride, it is that this gains credence as a "Ripper murder" PRECISELY because it happened fairly close to the others in space and time. (And this is the main stream view.) But I understood Christer's remark as saying that same thing also. Put in other words, "If Liz were killed in the same location, but, say, a couple of years before or after her actual TOD, she would not be considered a "Ripper victim." Is that not your view?

And of course, if Stride had not fallen prey to her slayer in the midst of the Ripper scare, ...

I do not condone the hypothetical extrication of determinant factors.

If Rob Clack had a single hair on his head, he might be the obvious choice for the leading role, in that series of shampoo commercials that is being filmed, in Croydon, next week.

But, Rob Clack does not have a single hair on his head!

And, Elizabeth Stride did "fall prey to her slayer in the midst of the Ripper scare"! Period!

And again, ...

And of course, if Stride had not fallen prey to her slayer in the midst of the Ripper scare, ...

"in the midst of the Ripper scare" ???

Let's try ... 'within one hour, and within 950 yards, of the murder of Catherine Eddowes'.

And finally, ...

And of course, if Stride had not fallen prey to her slayer in the midst of the Ripper scare, none of us would have known her name today.

Funny, isn't it?

That we should know, today, the name of the woman that was murdered in Swallow('s) Gardens, some two-and-a-half years after the "Ripper scare" had begun to subside.

[lynn cates]

epistemology

Hello Colin. You seem to be saying that, your view of probability, as more fittingly ascribed to epistemology, rather than to ontology, is correct. I heartily agree!

I am somewhat puzzled by your (seeming) disagreement with my endorsement of Christer's dictum. If I understand your thinking on Liz Stride, it is that this gains credence as a "Ripper murder" PRECISELY because it happened fairly close to the others in space and time. (And this is the main stream view.) But I understood Christer's remark as saying that same thing also. Put in other words, "If Liz were killed in the same location, but, say, a couple of years before or after her actual TOD, she would not be considered a "Ripper victim." Is that not your view?

Cheers.
LC

[Colin Roberts]

"I won't 'beat around the bush', Lynn."

Nor even the Cutbush? (Couldn't resist.)

"I will return, later this weekend, with some estimations of the perceptual probability, chance, and odds, - i.e. the probability, chance, and odds that I believe should have been perceived, at the onset of 1888 - of two independent murders of female adults, by way of 'Cut Throat', occurring within the same hour, within the observed 'killing field' of 'Jack the Ripper'.¹"

Very well. But please to observe the ontological status of probability.

I believe that I have, Lynn!

The perceptual probability, chance, and odds¹, of two independent murders of female adults, by way of 'Cut Throat', occurring within the same hour, within the observed 'killing field' of 'Jack the Ripper'

¹ i.e. the probability, chance, and odds that I believe should have been perceived, at the onset of 1888

---

Please Note:

I am presenting calculated estimations of the perceptual odds, chances, and probabilities, that I believe should prevail, in any effort to gauge the extraordinary nature of the so-called 'Double Event'; as opposed to calculations of the actual odds, chances, and probabilities, that do prevail, in any analysis of ... let's say ... the toss of a coin.

In other words: I am effectively presenting 'theory', as opposed to 'reality'.

When a human being resolves to commit murder, ... all bets are off. Probability will not stand in his way, or affect his resolution.

But, probability theory is certainly a viable means of gauging any sort of extraordinary nature that his resolution might posses, with regard to timing and/or placement.

---

Thanks again!

You are most welcome, Lynn!

[Colin Roberts]

Colin Roberts:

"I have returned to Casebook, and entered this discussion, specifically, because I believe that you and 'Fisherman' are attempting - either wittingly, or unwittingly - to apply a certain degree of 'spin' to the argument that the so-called 'Double Event' was not, in fact, extraordinary."

Let´s skip the wittingly or unwittingly business and be very straightforward with no "spin" at all, Colin

Very well, Christer!

And of course, if Stride had not fallen prey to her slayer in the midst of the Ripper scare, none of us would have known her name today.

'Spin'!

That is 'spin', and you know that that is 'spin'.

As is ...

Hello Christer.

"if Stride had not fallen prey to her slayer in the midst of the Ripper scare, none of us would have known her name today."

A hearty "amen" to that my friend!

... Lynn's endorsement.

That is the 'spin' of a lobbyist, Christer!

It is the sort of thing that is shoved in your face, on a very regular basis, by the clique of Hutchinson lobbyists, before whom, you so admirably stand your ground.

Please don't descend to such depths.

---

I am not here to discuss whether Elizabeth Stride and Catherine Eddowes were felled by the same hand.

I am here to insist that the extraordinary nature of the so-called 'Double Event' not be marginalized, as a means of 'lobbying' for the likelihood of two independent perpetrators.

[Colin Roberts]

The perceptual probability¹, chance, and odds, of two independent murders of female adults, by way of 'Cut Throat', occurring within the same hour, within the observed 'killing field' of 'Jack the Ripper'

¹ i.e. the probability, chance, and odds that I believe should have been perceived, at the onset of 1888

---

Please Note:

I am presenting calculated estimations of the perceptual odds, chances, and probabilities, that I believe should prevail, in any effort to gauge the extraordinary nature of the so-called 'Double Event'; as opposed to calculations of the actual odds, chances, and probabilities, that do prevail, in any analysis of ... let's say ... the toss of a coin.

In other words: I am effectively presenting 'theory', as opposed to 'reality'.

When a human being resolves to commit murder, ... all bets are off. Probability will not stand in his way, or affect his resolution.

But, probability theory is certainly a viable means of gauging any sort of extraordinary nature that his resolution might posses, with regard to timing and/or placement.

---

In the five calendar-years prior to 1888, there were a total of twenty two (22) registered deaths of female adults, throughout the whole of England, classified as 'Murder', by way of 'Cut Throat': i.e. an average of 4.40 such registered deaths, per annum.

So, a reasonable expectation, at the onset of 1888, would have been that four (4) deaths of female adults, classified as 'Murder', by way of 'Cut Throat', would be registered, throughout England, during the coming year.

However, for the sake of more accurate estimation, of the perceptual odds that two female adults would be murdered independently, by way of 'Cut Throat', within the aforementioned color-shaded region, ... and, within the same hour, during the coming year; the calculated average of 4.40 will be utilized.

---


Cumulative Probability Distribution (Murder-Site Mean-Center (Green Dot) -to- Greatest Observed Deviation (Mary Ann Nichols Murder-Site)) (Circular) (Click Image, to Enlarge in flickr)
Underlying Aerial Imagery: Copyright Google Earth, 2007
Overlying Plots, Labels and Color-Shadings: Copyright Colin C. Roberts, 2010

The Perceptual Probability that One Murder, of a Female Adult, by way of 'Cut Throat', would Occur, within the depicted Color-Shaded Circular Region

- Assume a Population of 27,482,104, for the Whole of England, in Accordance with the Census of England & Wales, 1891

- Assume a Population of 120,000*, for the depicted Color-Shaded Circular Region, in Accordance with the Census of England & Wales, 1891; and Charles Booth's "Labour & Life of the People: London", Appendix to Volume II, Williams & Norgate, 1891

- Calculate the Number of Regions that Must be Drawn, in order to Divide England's Total Population, of 27,482,104; into Sub-Sets that Consist of 120,000 Persons: 27,482,104 ÷ 120,000 = 229.02

- Calculate the Perceptual Probability that One Murder, of a Female Adult, by way of 'Cut Throat', would Occur, within the depicted Color-Shaded Circular Region: 4.40 ÷ 229.02 = 0.01921250 (i.e. 1.921250%)

* I have estimated the population, of the depicted color-shaded circular region, to have been between 90,000 and 120,000, in 1888

- Perceptual Probability: 1.921250%

---

The Perceptual Chance that One Murder, ...

- Calculate the Perceptual Chance: 1 ÷ (1 ÷ 0.01921250) = 1 / 52.05 (i.e. 1 -in- 52.05)

- Perceptual Chance: 1 -in- 52.05

---

The Perceptual Odds that One Murder, ...

- Calculate the Perceptual Odds: (52.05 - 1) -to- 1 (i.e. 51.05 -to- 1)

- Perceptual Odds: 51.05 -to- 1

---

Again; ...

That One Murder, of a Female Adult, by way of 'Cut Throat', would Occur, within the depicted Color-Shaded Circular Region:

- Perceptual Probability: 1.921250%

- Perceptual Chance: 1 -in- 52.05

- Perceptual Odds: 51.05 -to- 1

---------

The Perceptual Probability that One Murder, of a Female Adult, by way of 'Cut Throat', would Occur, during a particular One-Hour Period

- Assume Three Hundred and Sixty Five (365)* Twenty-Four-Hour Periods, per Year

- Assume Eight (8) 'Prime Throat-Cutting Hours' (i.e. 10:00PM - 6:00AM), per Twenty-Four-Hour Period

- Calculate the Number of 'Prime Throat-Cutting Hours' (i.e. 10:00PM - 6:00AM), per Year: 365 x 8 = 2,920

- Calculate the Perceptual Probability that One Murder, of a Female Adult, by way of 'Cut Throat', would Occur, during a particular One-Hour Period; i.e. during a particular 'Prime Throat-Cutting Hour': 4.40 ÷ 2,920 = 0.00150685 (i.e. 0.150685%)

* Calendar-Year 1888 was, in fact, a 'Leap-Year'; and consisted, therefore, of three hundred and sixty six (366) twenty-four-hour periods

- Perceptual Probability: 0.150685%

---

The Perceptual Chance that One Murder, ...

- Calculate the Perceptual Chance: 1 ÷ (1 ÷ 0.00150685) = 1 / 663.64 (i.e. 1 -in- 663.64)

- Perceptual Chance: 1 -in- 663.64

---

The Perceptual Odds that One Murder, ...

- Calculate the Perceptual Odds: (663.64 - 1) -to- 1 (i.e. 662.64 -to- 1)

- Perceptual Odds: 662.64 -to- 1

---

Again; ...

That One Murder, of a Female Adult, by way of 'Cut Throat', would Occur, during a particular One-Hour Period:

- Perceptual Probability: 0.150685%

- Perceptual Chance: 1 -in- 663.64

- Perceptual Odds: 662.64 -to- 1

---------

The Perceptual Probability that One Murder, of a Female Adult, by way of 'Cut Throat', would Occur, within the depicted Color-Shaded Circular Region; and during a particular One-Hour Period

This involves a 'Joint Probability', with respect to the first, of four possible outcomes:

1.) Region 'Yes', Hour 'Yes'
2.) Region 'Yes', Hour 'No'
3.) Region 'No', Hour 'No'
4.) Region 'No', Hour 'Yes'

- Calculate The Perceptual Probability that One Murder, of a Female Adult, by way of 'Cut Throat', would Occur, within the depicted Color-Shaded Circular Region; and during a particular One-Hour Period: 1.921250% x 0.150685% = 0.002895%

- Perceptual Probability: 0.002895%

---

The Perceptual Chance that One Murder, ...

- Calculate the Perceptual Chance: 1 ÷ (1 ÷ 0.00002895) = 1 / 34,541.90 (i.e. 1 -in- 34,541.90)

- Perceptual Chance: 1 -in- 34,541.90

---

The Perceptual Odds that One Murder, ...

- Calculate the Perceptual Odds: (34,541.90 - 1) -to- 1 (i.e. 34,540.90 -to- 1)

- Perceptual Odds: 34,540.90 -to- 1

---

Again; ...

That One Murder, of a Female Adult, by way of 'Cut Throat', would Occur, within the depicted Color-Shaded Circular Region; and during a particular One-Hour Period:

- Perceptual Probability: 0.002895%

- Perceptual Chance: 1 -in- 34,541.90

- Perceptual Odds: 34,540.90 -to- 1

---------

The Perceptual Probability that Two Independent Murders, of Female Adults, by way of 'Cut Throat', would Occur, within the depicted Color-Shaded Circular Region; and during a particular One-Hour Period

This involves a 'Joint Probability', with respect to the first, of four possible outcomes:

1.) First Murder 'Yes', Second Murder 'Yes'
2.) First Murder 'Yes', Second Murder 'No'
3.) First Murder 'No', Second Murder 'No'
4.) First Murder 'No', Second Murder 'Yes'

- Calculate The Perceptual Probability that Two Independent Murders, of Female Adults, by way of 'Cut Throat', would Occur, within the depicted Color-Shaded Circular Region; and during a particular One-Hour Period: 0.002895% x 0.002895% = 0.000000083812%

- Perceptual Probability: 0.000000083812%

---

The Perceptual Chance that Two Independent Murders, ...

- Calculate the Perceptual Chance: 1 ÷ (1 ÷ 0.00000000083812) = 1 / 1,193,142,903.19 (i.e. 1 -in- 1,193,142,903.19)

- Perceptual Chance: 1 -in- 1,193,142,903.19

---

The Perceptual Odds that Two Independent Murders, ...

- Calculate the Perceptual Odds: (1,193,142,903.19 - 1) -to- 1 (i.e. 1,193,142,902.19 -to- 1)

- Perceptual Odds: 1,193,142,902.19 -to- 1

---

Again; ...

That Two Independent Murders, of Female Adults, by way of 'Cut Throat', would Occur, within the depicted Color-Shaded Circular Region; and during a particular One-Hour Period:

- Perceptual Probability: 0.000000083812%

- Perceptual Chance: 1 -in- 1,193,142,903.19

- Perceptual Odds: 1,193,142,902.19 -to- 1

~~~

The perceptual odds, i.e. the odds of such an occurrence that should have been perceived, at the onset of 1888, are indeed, astronomical!

- They are slightly greater than the odds of thirty (30) sequential tosses of a coin, landing entirely on 'Heads'.

- They are significantly greater than the odds of ten (10) sequential tosses of a single die, landing entirely on '1'.

~~~

Again:

I have presented calculated estimations of the perceptual odds, chances, and probabilities, that I believe should prevail, in any effort to gauge the extraordinary nature of the so-called 'Double Event'; as opposed to calculations of the actual odds, chances, and probabilities, that do prevail, in any analysis of ... let's say ... the toss of a coin.

In other words: I have effectively presented 'theory', as opposed to 'reality'.

[lynn cates]

reply

Hello Colin. Thanks for the kind words.

"I won't 'beat around the bush', Lynn."

Nor even the Cutbush? (Couldn't resist.)

"I have returned to Casebook, and entered this discussion, specifically, because I believe that you and 'Fisherman' are attempting - either wittingly, or unwittingly - to apply a certain degree of 'spin' to the argument that the so-called 'Double Event' was not, in fact, extraordinary."

Actually, I consider ALL murder extraordinary in one sense. As for the "Double Event," 1. No, I do not consider both murders by the same hand, but possibly similar in conception. (By the way, Christer and I have SIGNIFICANT differences in conception vis-a-vis the Stride killing. That is good--well informed, thinking adults sometimes differ.) 2. I do not consider it linked to Polly and Annie before nor MJ after.

"Instances of domestic homicide, here, and infanticide, there, are plainly and simply irrelevant; and, quite frankly, ... need not apply."

Right. There is no need to apply ANYTHING (although I am always struck by the violence in 1888 whist trawling the newspapers). But, from my point of view, a knifing (as the other one on the night of the "Double Event") need not apply either.

"What is relevant, when attempting to gauge the extraordinary nature, of the so-called 'Double Event', is instances of uninhibited slaughter, to which there were no known witnesses, for which there was no apparent 'rational' motive, in which there was no attempt to conceal corpus delicti, and, which occurred within some reasonable degree of deviation - let's say, ... eight-to-ten standard deviations - from the murder-site mean center that is applicable to those murders, which are most widely attributable to 'Jack the Ripper' (Tabram, Nichols, Chapman, Stride, Eddowes, and Kelly)."

Relevance may be where one finds it. The reasoning in the last paragraph is cogent and, I daresay, rather standard. I have no particular problem with it. I do think, however, that whilst most are researching the possibility of one killer, a lone researcher (possibly 2) might conceivably look elsewhere. Case in point: look at the claim that Barnett killed MJ. Very well, I suppose a minimal case could be concocted. But now, look what happens when we extend that to ALL the WCM. Barnett?

"In light of the fact that only fifteen registered deaths of female adults, throughout England, were classified as 'Murder', by way of 'Cut Throat', in 1888: The occurrence of two such deaths, i.e. the murders of two vagrant dolly-mops, - whose last known addresses, incidentally, were separated by just 120 yards - by way of having their throats cut, within a span of just one hour, and within a distance of just 950 yards, of each other, was truly extraordinary."

Yes, truly extraordinary. (I find it interesting that your criterion is cut throat--above you mentioned Tabram.) And certainly, it likely changes the inductive probability here. But an induction is STILL an induction and NEVER entails its conclusion.

"And, regardless of whether these two dolly-mops were felled by the same hand; the remarkable proximities of their murders, with regard to both time, and placement, should not - under any circumstances, whatsoever - be trivialized."

Agreed. And since I have spent--and continue to spend--beaucoups of good money and time on this, I certainly do not consider it trivial.

"I will return, later this weekend, with some estimations of the perceptual probability, chance, and odds, - i.e. the probability, chance, and odds that I believe should have been perceived, at the onset of 1888 - of two independent murders of female adults, by way of 'Cut Throat', occurring within the same hour, within the observed 'killing field' of 'Jack the Ripper'.¹"

Very well. But please to observe the ontological status of probability.

Thanks again!

Cheers.
LC

[Fisherman]

Colin Roberts:

"I have returned to Casebook, and entered this discussion, specifically, because I believe that you and 'Fisherman' are attempting - either wittingly, or unwittingly - to apply a certain degree of 'spin' to the argument that the so-called 'Double Event' was not, in fact, extraordinary."

Let´s skip the wittingly or unwittingly business and be very straightforward with no "spin" at all, Colin: if it WAS a true double event, it was extraordinary. If it was not, is was extraordinary anyway, in the respect that two murders within such a short space in time and so close to each other geographically, are ALWAYS extraordinary.
But Strides murder being extraordinary in this context does not in any fashion tell us anything at all about the identity of her killer. It only tells us that there either was an element of coincidence involved - or there was not.

Whenever a killing takes place within a short span of time and close in geography to another killing, it is reasonable to suggest that the perpetrator was one and the same. That must be a main line of inquiry. It applies in this case too.

But the moment we satisfy ourselves that it MUST have been so, we are doing ourselves a disservice. The door must be left open for another killer at any time, until the case is proven and closed.

Proving the case involves looking at the case-specifics. And here, they differ very much inbetween Stride and the other four canonicals. And that does NOT strengthen the one-killer scenario; it DETRACTS from it. I think most people would agree about that.

I have no trouble acknowledging that Strides killer may have been interrupted. Nor do I have any problems with a scenario where he never INTENDED to eviscerate in the first place. I think both suggestions are viable, though I much favour suggestion 1 over suggestion 2 in viability, since my take on the Ripper is that the eviscerations were his main driving force.

When looking at the evidence and the timetable attached to it, my own personal feeling is that there is no source of interruption recorded that tallies with my scenario. That does not mean that there could NOT have been such a thing; someone could have, for example, rattled the handle of the kitchen door in the yard. Or the killer may simply have spooked. But he normally did NOT spook, judging by the other crimes, and my guess remains that he was not interrupted, so that means TO ME that I don´t think it was Jack.
The most telling little bit in this puzzle, though, is that the cut in the throat differed from the ones we have on the other victims. It IS shallower, and to argue that the killer may have been interrupted at the very moment he cut is an even MORE coincidental suggestion than the overall interruption theory, and so I am inclined to rule Stride out as a Ripper victim.

After this, there is the all-important discussion of the locality and the surrounding circumstances, but I will leave that aside here for now, BS man and all. I have argumented my stance so many times about that already.

My conclusion remains that Stride may well have been the victim of somebody else than the Ripper. I am not saying that I can weigh it in percentages, but I am saying that I favour her as not being Jack´s. Others have come to the same conclusion too, some of them researchers I hold high in regard, people with knowledge and backgrounds that offer good insights into topics like this one.

I very much appreciate your work, by the way - statistics are always helpful. But they are only statistics, no matter how long we stare at them and interpret away. They provide us with a rough overall background, though, and that is a good thing.

The best,
Fisherman

[Colin Roberts]

Hello Colin. Welcome back.

Thank you, Lynn!

Thank you so much for posting these. They seem to confirm my posts #15, #32, #35, #50, and #75. There were INDEED many murders in London in 1888.

Relatively speaking, ...

In accordance with the Reports of the Commissioner of Police of the Metropolis, 1883-1893:


Cases of 'Murder': Metropolitan Police District, 1883-1893 (Click Image, to Enlarge in flickr)

... there were, as you say, "many murders in London in 1888". Especially, when one considers the fact that the twenty eight cases of 'Murder' that did occur within the Metropolitan Police District, during that year, did not include the murder of Catherine Eddowes.

But, we must take into account, the fact that the overall crime rate, throughout the Metropolitan & City of London Police Districts, i.e. 'Greater London', was abnormally high, in 1888.

"Crime during the year has shown a decided tendency to increase. This fact may be accounted for, to a certain extent, by circumstances which affected the administration of the Force in a peculiar manner at different periods of the year. The agitation which centered in Trafalgar Square, and the murders in Whitechapel, necessitated the concentration in particular localities of large bodies of police, and such an increase of force in one quarter of the Metropolis, it must be remembered, is only procurable by diminishing the number of men ordinarily employed in other divisions. In the present state of the force increase of protection in the East End means diminished numbers of police in other quarters, and so long as the available force is hardly sufficient, as it is just now, for the performance of the ordinary and every day duties of the Police, any additional drain on its resources leads to diminished protection against, and consequent increase of, crime. There has been no relaxation of effort on the part of the Police to cope with crime; the fact is that the Force is overworked, and under such circumstances crime cannot be met or coped with in a satisfactory and efficient manner. The statistics of crime will be found in the tables attached. I need not do more than merely allude to the extraordinary series of murders which occurred in Whitechapel, which gave rise to the greatest excitement in London. I regret to say that in spite of most strenuous efforts on the part of the Police, the criminal has up till now remained undiscovered." [sic]

James Monro,

The Commissioner of Police of the Metropolis

Is it possible that this increased rate of crime 'set the stage', so to speak, for the murder of Elizabeth Stride? Of course, it is!

But, I am inclined to believe -and, very much so - that the murder of Elizabeth Stride ...

"I need not do more than merely allude to the extraordinary series of murders which occurred in Whitechapel, which gave rise to the greatest excitement in London." (My Emphasis)

... was part of an "extraordinary series of murders" (My Emphasis), - as well as having been part of a hyper-extraordinary sub-set of that series, i.e. the so-called 'Double Event' - that may have helped to 'set the stage', for the observed increase, in the overall crime rate.

---

I won't 'beat around the bush', Lynn.

I have returned to Casebook, and entered this discussion, specifically, because I believe that you and 'Fisherman' are attempting - either wittingly, or unwittingly - to apply a certain degree of 'spin' to the argument that the so-called 'Double Event' was not, in fact, extraordinary.

Instances of domestic homicide, here, and infanticide, there, are plainly and simply irrelevant; and, quite frankly, ... need not apply.

What is relevant, when attempting to gauge the extraordinary nature, of the so-called 'Double Event', is instances of uninhibited slaughter, to which there were no known witnesses, for which there was no apparent 'rational' motive, in which there was no attempt to conceal corpus delicti, and, which occurred within some reasonable degree of deviation - let's say, ... eight-to-ten standard deviations - from the murder-site mean center that is applicable to those murders, which are most widely attributable to 'Jack the Ripper' (Tabram, Nichols, Chapman, Stride, Eddowes, and Kelly).

In light of the fact that only fifteen registered deaths of female adults, throughout England, were classified as 'Murder', by way of 'Cut Throat', in 1888: The occurrence of two such deaths, i.e. the murders of two vagrant dolly-mops, - whose last known addresses, incidentally, were separated by just 120 yards - by way of having their throats cut, within a span of just one hour, and within a distance of just 950 yards, of each other, was truly extraordinary.

And, regardless of whether these two dolly-mops were felled by the same hand; the remarkable proximities of their murders, with regard to both time, and placement, should not - under any circumstances, whatsoever - be trivialized.

---

Incidentally, in light of the fact that only fifteen registered deaths of female adults, throughout England, were classified as 'Murder', by way of 'Cut Throat', in 1888: The murder of Sarah Brown does not serve to marginalize the extraordinary nature of the so-called 'Double Event'. It serves to make it even more extraordinary!

---

I will return, later this weekend, with some estimations of the perceptual probability, chance, and odds, - i.e. the probability, chance, and odds that I believe should have been perceived, at the onset of 1888 - of two independent murders of female adults, by way of 'Cut Throat', occurring within the same hour, within the observed 'killing field' of 'Jack the Ripper'.¹

¹ i.e. the observed 'killing field' of 'Jack the Ripper', regardless of whoever/whatever 'it' - he, she, or they - happened to be.

Again, thanks!

You are most welcome, Lynn!

Somewhere here there is a wall. I'm going to find it and...oof! Yup, that's it. And again. And again.

And you gotta love Colin with those charts...

Thanks, Tom!

Colin!! It's so nice to have you back, SB.

Thanks, Ken!

[The Grave Maurice]

Colin!! It's so nice to have you back, SB. I've already learned new stuff thanks to you. Keep at it.