Barry_C wrote on Oct 29
th, 2007 at 7:39pm:
Again, more nonsense. First, "the [NDI] person" wouldn't necessarily have to prove a negative, which is difficult to impossible. Another could confess to the crime. (You could always argue the confession was false, and we'd never get anywhere.)
Think about what you said. The same is true in the courtroom when most of the evidence is circumstantial (the bulk of the cases).
Your argument implies you expect 100% accuracy with polygraph. If you hold everybody to that standard, then life isn't going to be all that pleasant.
Have you ever made an arrest on PC? How low is that standard? It's much lower than many polygraph calls. You could set alpha at .6 and still meet the PC threshold.
We're starting to go in circles, which bores me. I was hoping to have some good discussions here, but the lack of consistency is getting to be tiring.
I don’t see how you concluded that my “argument” implied that I expect 100% accuracy from the polygraph.
I was responding to the following post of yours:
Barry_C wrote on Oct 29
th, 2007 at 3:08pm:
There are thousands of polygraph tests done each year, and yes there are and will be errors (as it the case with any test), so a few anecdotal stories do not support anything.
That certainly suggests to me, as I’m sure was your meaning, that the “anecdotal” evidence of polygraph errors do not support anything.
My response, which I believe was on point rather than being circular nonsense, was to suggest that, barring confession or incontrovertible physical evidence, any polygraph result used by an examiner to demonstrate that the polygraph is accurate is also anecdotal evidence.
An oft-repeated phrase by examiners on this board and others is that only a polygraph examiner can offer a credible opinion regarding the accuracy of the polygraph, because only they have the training and the expertise to do so. Any claims (based on personal experience) by non-examiners that the polygraph is inaccurate are dismissed as merely anecdotal evidence.
I suggest that the opposite is actually true, because (again, barring a confession or physical evidence) out of the two people involved in the polygraph exam, only the examinee knows for certain if the test result is accurate. Yet the examinee’s opinion is often dismissed as mere “anecdotal” evidence, rather than (I suppose) “hard” scientific evidence.
Did you have anyone “pass” his or her polygraph with you in the past month? How do you know they weren’t being deceptive? How do you know they weren’t using countermeasures? I’m sure you can point to various indications that they were being truthful, but you cannot truly know. The person who passed, however, knows for certain if they were being truthful or deceptive. The only accurate anecdotal evidence concerning that polygraph exam would be the subject’s version of events, not the examiner’s version of events.
Did you have anyone “fail” his or her polygraph in the past month? How do you know they weren’t being truthful? Again, I am sure you can point to various indications that they were deceptive, but you cannot truly know for sure. The subject knows if he or she was being truthful or deceptive. Again, the only accurate anecdotal evidence regarding that exam would come from the subject, not the examiner.
It is wrong to dismiss anecdotal evidence from the one person in every polygraph exam who knows for a fact if the results of the exam were accurate or not.
I understand why you dismiss such evidence, and that is where I believe circular logic comes into play. There are people who claim the polygraph is not accurate, because they told the truth during their exam or exams and were falsely branded a liar. However, if you believe the polygraph is accurate, you are not going to believe such claims because if they failed a polygraph that means they were lying, and why should you listen to liars?