Cadaver Dog question

[Carana]

Given the involvement of two national police forces and the array of private investigators employed by the McCanns I would say it inconcievable that those sorts of enquiries have not been made

The PT police were responsible for taking the lead. The UK police were assisting.

I haven't found anything in the files to indicate anything beyond informal questioning as to whether anyone was aware of any death (mega injury) in that apartment.

If you have found something beyond that, please share.

[Gildas]

Debunker posted ;
Why would that matter? All scent dogs have a maximum average reliability of 70-90%.

Debunker, could you explain what what this means?

Any measuring instrument has a reliability associated with it. For instance, speedometers in cars are often 5-10% out as a consequence of inbuilt inaccuracy or the tires wearing down changing the speed shown.

Any measurement has a possibility of being in error, even yes/no decisions.

Errors may be of two kinds- false positives and false negatives. A false positive result is where something indicates something is there when it is not; a false negative is where something indicates that something is not there when it is.

Scent dogs in carefully controlled (artificial) circumstances are up to 90% accurate. Usual estimates of reliability in  the real world is between 70 and 90%. Because identifying cadaver requires two measurements (Eddie + Keela -) the reliability is reduced because each measurement has a reliability of 70-90%. This gives a reliability for the dyad at 49-81%- expecting between 2 and 5 false alerts in every 10.

Drug detection jobs in real life react with no evidence of drugs being found 2 times out of 3!

So the beat you can say about the dogs is that they give you hints about where you should look for real evidence.

Thank you for your explanation, Debunker. A reliability of only 49% seems quite low, considering that the dogs are reasonably reliable.

[icabodcrane]

If Shannon had remained successfully hidden there would no doubt be forums dedicated to getting justice for a dead Shannon all over the internet by now.

Why would there be when the explanation for the accurate cadaver dog alerts had been found ?

Because if Shannon remained unfound I doubt such an explanation would have fully satisfied the 'trial by social media' crew, just as any possible explanation for the alerts in the McCann case always fails to satisfy Kate and Gerry's own set of detractors.

I don't think you can reasonably compare the two cases

In the Mathews case definite evidence was found for the  (accurate )  dog alerts

In the McCann case no such evidence has been found  ...  'possible'  explanations are not the same thing at all 

[icabodcrane]

Shannon Matthews.

There were dead bodies involved in the Mathews case  (  known deaths in the properties searched resulted in cadavarine  being transfered )  and the dogs were accurate in identifying it

Where did you read that?

In a sky news article on this board  (  I can't remember which thread,  sorry  )

It may have been that it was the furniture in the properties that had been in contact with the corpses  ...  in any event,  the dogs alerts were proven to be accurate

In which case, has it been excluded that Eddie could have been reacting to the residual smell of (perhaps second-hand) furniture which may have been brought into that apartment when it became a holiday rental?

This was once a private residence (cf T.S's statement), which was subsequently rented out as a holiday apartment.


Were the various owners ever questioned on this aspect?

Given the involvement of two national police forces and the array of private investigators employed by the McCanns I would say it inconcievable that those sorts of enquiries have not been made

Why are there no details in the files about any investigation of Apt 5A furniture or of all the residents who stayed in the apartment for months after the McCanns vacated it?

It seems there is quite a bit that does not appear in the translated files  ( that we have access to, at least  )  ...  like Lee Rainbow's report for instance ...  that came as a complete shock when it was produced in court 

[Carana]

Shannon Matthews.

There were dead bodies involved in the Mathews case  (  known deaths in the properties searched resulted in cadavarine  being transfered )  and the dogs were accurate in identifying it

Where did you read that?

In a sky news article on this board  (  I can't remember which thread,  sorry  )

It may have been that it was the furniture in the properties that had been in contact with the corpses  ...  in any event,  the dogs alerts were proven to be accurate

In which case, has it been excluded that Eddie could have been reacting to the residual smell of (perhaps second-hand) furniture which may have been brought into that apartment when it became a holiday rental?

This was once a private residence (cf T.S's statement), which was subsequently rented out as a holiday apartment.


Were the various owners ever questioned on this aspect?

Given the involvement of two national police forces and the array of private investigators employed by the McCanns I would say it inconcievable that those sorts of enquiries have not been made

Why are there no details in the files about any investigation of Apt 5A furniture or of all the residents who stayed in the apartment for months after the McCanns vacated it?

It seems there is quite a bit that does not appear in the translated files  ( that we have access to, at least  )  ...  like Lee Rainbow's report for instance ...  that came as a complete shock when it was produced in court

Possibly. But what would be so secret about eliminating potentially second-hand furniture?

[debunker]

Debunker posted ;
Why would that matter? All scent dogs have a maximum average reliability of 70-90%.

Debunker, could you explain what what this means?

Any measuring instrument has a reliability associated with it. For instance, speedometers in cars are often 5-10% out as a consequence of inbuilt inaccuracy or the tires wearing down changing the speed shown.

Any measurement has a possibility of being in error, even yes/no decisions.

Errors may be of two kinds- false positives and false negatives. A false positive result is where something indicates something is there when it is not; a false negative is where something indicates that something is not there when it is.

Scent dogs in carefully controlled (artificial) circumstances are up to 90% accurate. Usual estimates of reliability in  the real world is between 70 and 90%. Because identifying cadaver requires two measurements (Eddie + Keela -) the reliability is reduced because each measurement has a reliability of 70-90%. This gives a reliability for the dyad at 49-81%- expecting between 2 and 5 false alerts in every 10.

Drug detection jobs in real life react with no evidence of drugs being found 2 times out of 3!

So the beat you can say about the dogs is that they give you hints about where you should look for real evidence.

Thank you for your explanation, Debunker. A reliability of only 49% seems quite low, considering that the dogs are reasonably reliable.

You're welcome. Glad to be able to help.

[icabodcrane]

Debunker posted ;
Why would that matter? All scent dogs have a maximum average reliability of 70-90%.

Debunker, could you explain what what this means?

Any measuring instrument has a reliability associated with it. For instance, speedometers in cars are often 5-10% out as a consequence of inbuilt inaccuracy or the tires wearing down changing the speed shown.

Any measurement has a possibility of being in error, even yes/no decisions.

Errors may be of two kinds- false positives and false negatives. A false positive result is where something indicates something is there when it is not; a false negative is where something indicates that something is not there when it is.

Scent dogs in carefully controlled (artificial) circumstances are up to 90% accurate. Usual estimates of reliability in  the real world is between 70 and 90%. Because identifying cadaver requires two measurements (Eddie + Keela -) the reliability is reduced because each measurement has a reliability of 70-90%. This gives a reliability for the dyad at 49-81%- expecting between 2 and 5 false alerts in every 10.

Drug detection jobs in real life react with no evidence of drugs being found 2 times out of 3!

So the beat you can say about the dogs is that they give you hints about where you should look for real evidence.

How do these statistics transfer to the McCann case ?

Are you suggesting that alerts in the McCann apartment were only correct on a 2 to 5 out of 10  basis   ? 

What explanation do you give for the other nine apartments the dogs visited  ...  where no alerts were made  ?   ...  how does  their  'only right  5 out of 10 times'  ratio fit in with that  ?  (  bearing in mind your reference to  false negatives  ) 

[debunker]

I am afraid that is what the academic research into scent dogs shows. In ideal condition they can be 90% reliable. In the field their reliability decreases. Research into handler cuing shows that knowledge held by handlers affects the dog's alerts- if handlers are led to expect an alert, a dog is more likely to alert.

Dual alerts as needed in Cadaver odor detection are doubly unreliable, relying on two alerts, each with an error potentiality.

[icabodcrane]

I am afraid that is what the academic research into scent dogs shows. In ideal condition they can be 90% reliable. In the field their reliability decreases. Research into handler cuing shows that knowledge held by handlers affects the dog's alerts- if handlers are led to expect an alert, a dog is more likely to alert.

Dual alerts as needed in Cadaver odor detection are doubly unreliable, relying on two alerts, each with an error potentiality.

So you have no explanation as to how the  error ratio described can be used in relation to the nine apartments the dogs did not  alert in

Rather a pointless excersise in bringing these stats up at all then 

[icabodcrane]

Perhaps Debunker could use his statistics to explain the spectacular failure rate of Zampo the cadaver dog instead?

"Zampo marked for human remains 45 times at those 24 locations. Not a single trace of blood or body parts was ever found..."

I'm more interested in how the  statistics  cannot be applied logically in the McCann case   ...  aren't you  ?

[debunker]

Perhaps Debunker could use his statistics to explain the spectacular failure rate of Zampo the cadaver dog instead?

"Zampo marked for human remains 45 times at those 24 locations. Not a single trace of blood or body parts was ever found..."

I'm more interested in how the  statistics  cannot be applied logically in the McCann case   ...  aren't you  ?

What do you mean?

[icabodcrane]

Perhaps Debunker could use his statistics to explain the spectacular failure rate of Zampo the cadaver dog instead?

"Zampo marked for human remains 45 times at those 24 locations. Not a single trace of blood or body parts was ever found..."

I'm more interested in how the  statistics  cannot be applied logically in the McCann case   ...  aren't you  ?

What do you mean?

I asked you how the error ratio described could be applied to the nine apartments where the dogs did not alert 

You had no explanation   ... how could you  ?  other than to suggest the  non-alerts in the nine other apartments were also  wrong  5 times out of 10 

[debunker]

Perhaps Debunker could use his statistics to explain the spectacular failure rate of Zampo the cadaver dog instead?

"Zampo marked for human remains 45 times at those 24 locations. Not a single trace of blood or body parts was ever found..."

I'm more interested in how the  statistics  cannot be applied logically in the McCann case   ...  aren't you  ?

What do you mean?

I asked you how the error ratio described could be applied to the nine apartments where the dogs did not alert 

You had no explanation   ... how could you  ?  other than to suggest the  non-alerts in the nine other apartments were also  wrong  5 times out of 10

I don't understand your question. Even if we credit the dogs with 90% reliability, there will still be one error in every ten tests.

Do you not understand statistics and reliabilities?

[icabodcrane]

Perhaps Debunker could use his statistics to explain the spectacular failure rate of Zampo the cadaver dog instead?

"Zampo marked for human remains 45 times at those 24 locations. Not a single trace of blood or body parts was ever found..."

I'm more interested in how the  statistics  cannot be applied logically in the McCann case   ...  aren't you  ?

What do you mean?

I asked you how the error ratio described could be applied to the nine apartments where the dogs did not alert 

You had no explanation   ... how could you  ?  other than to suggest the  non-alerts in the nine other apartments were also  wrong  5 times out of 10

I don't understand your question. Even if we credit the dogs with 90% reliability, there will still be one error in every ten tests.

Do you not understand statistics and reliabilities?

What I understand is that you are avoiding the question

Where were the inevitable errors in the tests done in the other nine apartments  ?  ...  based on the statistice you have quoted, how many of those non alerts would you ascribe to  being inevitably  'false negatives'  ? 

[debunker]

Perhaps Debunker could use his statistics to explain the spectacular failure rate of Zampo the cadaver dog instead?

"Zampo marked for human remains 45 times at those 24 locations. Not a single trace of blood or body parts was ever found..."

I'm more interested in how the  statistics  cannot be applied logically in the McCann case   ...  aren't you  ?

What do you mean?

I asked you how the error ratio described could be applied to the nine apartments where the dogs did not alert 

You had no explanation   ... how could you  ?  other than to suggest the  non-alerts in the nine other apartments were also  wrong  5 times out of 10

I don't understand your question. Even if we credit the dogs with 90% reliability, there will still be one error in every ten tests.

Do you not understand statistics and reliabilities?

What I understand is that you are avoiding the question

Where were the inevitable errors in the tests done in the other nine apartments  ?  ...  based on the statistice you have quoted, how many of those non alerts would you ascribe to  being inevitably  'false negatives'  ?

I don't understand what you are asking. The very nature of statistics is that the specific is lost in the general. It is not possible to say which alerts were in error, but scent dogs are only correct 9 times out of ten in very favorable conditions; in the real world they are less reliable.