CSI and cadaver dogs - some facts and statistics.

[G-Unit]

The fact that she may have left the apartment alive shows that the alerts may be totally wrong.

The fact that she may have left the apartment dead shows that the alerts may be totally correct.

[OxfordBloo]

The fact that she may be dead shows that the alerts may be totally right,

And the fact that she may be alive shows that the alerts may be totally wrong.

[OxfordBloo]

No comment about the NPIA and  ACPO report calling VRD dogs' alerts into question?

[Brietta]

No comment about the NPIA and  ACPO report calling VRD dogs' alerts into question?

Why bother with the facts of the matter when there is perfectly usable fiction to hand?

[Carana]

The only interesting probability is that of them both being wrong, not them both being right.

I don't understand that at the moment (and I can't find your post with the chart at the moment).

From memory, I believe you were pointing out that if dog A was 80% accurate and dog B is 90& accurate, then the probability of both of them alerting correctly would be 72%. And turning that on its head, the probability of both being wrong would be 2%.

But then there is the issue of when one of them alerts accurately and the other doesn't (in a given instance). If you can't determine which one alerted correctly and which one didn't, because there's no evidence to verify it, that's a bit of a headache.

[OxfordBloo]

Why bother with the facts of the matter when there is perfectly usable fiction to hand?

I agree. There is a great cloud of unknowing- people glaring in ignorance and false assumptions at the same time.

It is a FACT that all scent dogs are open to substantial error
It is a FACT that a twin Eddie Keela alert has its accuracy reduced by the product of their uncertainties
It is a FACT that Eddie reacting alone adds no knowledge to the question of cadaver odour
It is a FACT that Shannon Matthews was found after being 'declared dead' by VRDs
It is a FACT that the NPIA and ACPO have severely questioned the use of VRDs including Eddie
It is a FACT that no evidence of material of cadaver origin was found in PdL
It is a FACT that cadaver origin was only indicated separately twice in PdL

[Carana]

I was thinking about Oxfordbloo's point and it reminded me of this (not dog-related as such):

Pseudoscience in the Witness Box

The FBI faked an entire field of forensic science.
By Dahlia Lithwick
(2 pages)

http://www.slate.com/articles/news_and_politics/jurisprudence/2015/04/fbi_s_flawed_forensics_expert_testimony_hair_analysis_bite_marks_fingerprints.1.html

I'm now wondering whether a solution which I had thought would have increased the likelihood of a correct identification actually does...

"In some recent cases, courts have explicitly stated that microscopic hair analysis is a technique generally accepted in the scientific community. But courts also have recognized that testimony linking microscopic hair analysis with particular defendants is highly unreliable. In cases where there seems to be a morphological match (based on microscopic examination), it must be confirmed using mtDNA analysis; microscopic studies alone are of limited probative value. The committee found no scientific support for the use of hair comparisons for individualization in the absence of nuclear DNA. Microscopy and mtDNA analysis can be used in tandem and may add to one another’s value for classifying a common source, but no studies have been performed specifically to quantify the reliability of their joint use."

https://www.ncjrs.gov/pdffiles1/nij/grants/228091.pdf

(Found with thanks to Heri.)

[OxfordBloo]

I was thinking about Oxfordbloo's point and it reminded me of this (not dog-related as such):

Pseudoscience in the Witness Box

The FBI faked an entire field of forensic science.
By Dahlia Lithwick
(2 pages)

http://www.slate.com/articles/news_and_politics/jurisprudence/2015/04/fbi_s_flawed_forensics_expert_testimony_hair_analysis_bite_marks_fingerprints.1.html

I'm now wondering whether a solution which I had thought would have increased the likelihood of a correct identification actually does...

"In some recent cases, courts have explicitly stated that microscopic hair analysis is a technique generally accepted in the scientific community. But courts also have recognized that testimony linking microscopic hair analysis with particular defendants is highly unreliable. In cases where there seems to be a morphological match (based on microscopic examination), it must be confirmed using mtDNA analysis; microscopic studies alone are of limited probative value. The committee found no scientific support for the use of hair comparisons for individualization in the absence of nuclear DNA. Microscopy and mtDNA analysis can be used in tandem and may add to one another’s value for classifying a common source, but no studies have been performed specifically to quantify the reliability of their joint use."

https://www.ncjrs.gov/pdffiles1/nij/grants/228091.pdf

(Found with thanks to Heri.)

Scent Dogs and other practical forensic skills are on the edge of science and pseudo science. It is in the interest of people who employ such tools to claim validity above reality. That is why all such claims must be tested in court and in the laboratory using the principle of falsification- it is up to the proponent to prove that their contentions are not false; not up to the sceptics to prove that their scepticism is false.

It is better to start from a position of ignorance, rather than from a position of belief which maybbe a false assumption.

[John]

First, an alert by Eddie does not indicate a cadaver has been there. He also alerts to dead pigs and any human or pig blood. They also alert to transferred scent on objects that have previously been in the presence of or in contact with a cadaver.

If a blood dog fails to alert to the same place where he did, that suggests the possibility of the presence of a cadaver, but only a finite possibility.

That is not anyway an exclusive test.

There are however many cases where Eddie has alerted and no proof of death has been produced and there may be many cases where he has failed to react while the target odour was present. Research suggests that all scent dogs have false positives and false negatives.

And in answer to your question, the cadaver dog (I can't remember if it was Eddie) reacted in the case of the missing girl that later turned up alive hidden in the box under a bed. This was blamed on second hand furniture that had been bought from a house where someone had died.

So there is your example.

Eddie correctly alerted to cadaver scent, it was the humans who wrongly assumed where it originated.

[G-Unit]

I agree. There is a great cloud of unknowing- people glaring in ignorance and false assumptions at the same time.

It is a FACT that all scent dogs are open to substantial error
It is a FACT that a twin Eddie Keela alert has its accuracy reduced by the product of their uncertainties
It is a FACT that Eddie reacting alone adds no knowledge to the question of cadaver odour
It is a FACT that Shannon Matthews was found after being 'declared dead' by VRDs
It is a FACT that the NPIA and ACPO have severely questioned the use of VRDs including Eddie
It is a FACT that no evidence of material of cadaver origin was found in PdL
It is a FACT that cadaver origin was only indicated separately twice in PdL

All denied by people determined to reach their own predetermined version of the 'truth' in order to protect their beliefs from reality.

It is a fact that no matter how much people try, they cannot PROVE that the alerts by these two dogs in this particular case were false.

Alerts behind the sofa in G5A were correct. (both dogs)
Alerts to the hire car were corrrect. (both dogs)

[John]

And no one can prove that dogs are 100% accurate, both theoretically or practically.

Even if a dog alerts regularly correctly, the next possible test could be a failure.

Every justifiable investigation has shown all scent dogs tested to be fallible.

Grime never claims they are 100% accurate.

CSI and cadaver dogs can never possibly achieve 100% accuracy but their accomplishments are all the same remarkable.

[OxfordBloo]

Eddie correctly alerted to cadaver scent, it was the humans who wrongly assumed where it originated.

You do not know that. It is a belief that you have. You have no proof that either Eddie alerted to a scent or that that scent was cadaver scent.

Please specify exactly which of his many alerts you claiming to be definitely an alert to cadaver odour, then we can discuss it in detail.

[OxfordBloo]

It is a fact that no matter how much people try, they cannot PROVE that the alerts by these two dogs in this particular case were false.

Alerts behind the sofa in G5A were correct. (both dogs)
Alerts to the hire car were corrrect. (both dogs)

It is not up to people to prove they were false.

Being false can never be excluded as a possibility.

It is up to proponents to prove that they are correct in their assumptions

Both Forensics and Science start from an assumption of ignorance and require proof of any contention.

[Carana]

Scent Dogs and other practical forensic skills are on the edge of science and pseudo science. It is in the interest of people who employ such tools to claim validity above reality. That is why all such claims must be tested in court and in the laboratory using the principle of falsification- it is up to the proponent to prove that their contentions are not false; not up to the sceptics to prove that their scepticism is false.

It is better to start from a position of ignorance, rather than from a position of belief which maybbe a false assumption.

But that's not always the reality in courtrooms... particularly if you can't afford defence counsel prepared to do their homework or independent experts. A bit scary.

[OxfordBloo]

CSI and cadaver dogs can never possibly achieve 100% accuracy but their accomplishments are all the same remarkable.

Agreed. But we cannot tell whether alerts are valid or not in any particular case.