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RE: POLYGRAPH TESTS
Refer Letter elsewhere on this site by:

John Furedy, Emeritus Professor of Psychology
University of Toronto
Sydney, Australia 

"The Polygraph “Test” Is Not A Test"

"What one would think if one heard that IQ tests “varied among agencies”. Wouldn’t one conclude that these so-called tests were not tests at all, but rather unstandardized interviews where IQ “testers” arrived at their scores by having a conversation with the examinee to determine the examinee’s IQ?  Why is it that even North American scientists commonly accept the polygraph as a “test”, and then go on to argue about validity, whereas the argument about validity cannot even begin if one is not dealing with a test.
It would be bad enough if faith in these polygraph “tests” were confined to talk show hosts like Dr. Phil, who deal with personal problems.  What is worse is that national security depends on this peculiarly North American superstitious flight of technological fancy."

Barry_C wrote on Nov 20^th, 2007 at 2:32pm:


9x6 = 54.
Oops. That's plagiarism. My teacher said it first.

I have many original thoughts. Sadly all of which would pass over your head like Swissair - you're too shallow and undeveloped. 

When the polyshop biz grinds to a halt you can always write out parking tickets and tell the public about all the research behind parking meters. 

Barry_C wrote on Nov 20^th, 2007 at 2:32pm:


Good Boy Noddy. You fetched the bone. Good Boy Noddy.

Here's some more - you're on the clock..... go  for it:

Refer: www.mentalfloss.com
"A stupid or silly person named NoodleNush a dolt. A person named CarryB whose mental acumen is well below par. A person of moderate to severe mental retardation having a mental age of from three to seven years and generally being capable of some degree of communication and performance of simple tasks under supervision. Namely CarryB. The term belongs to a classification system no longer in use and is now considered offensive, except if used correctly."

Go Boy.

1904,

Good catch.  Two typos - that everybody else figured out.  If you do the math and follow the logic, then you'll see those should be 500 - not 50, but my point is the same.

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More plagiarism.  Have you any ability to think on your own?

http://en.wikipedia.org/wiki/Statistics

Barry_C wrote on Nov 1^st, 2007 at 7:26pm:


I think he punched you in the head. Your arithmetic (sorry Noodle, I mean your 'math') contains some elementary errors. I certainly hope that someone brighter than you checks out your research before you
publish it.

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No. it comes from the same place where they teach you that 80% of 50 = 400 


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Since when does 80% of 50 = 400 ???

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Since when does 20% of 50 = 100 ???
And so the BS continues......

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Refer: Wikipedia: Staitics:
"The idea that statistics branched off from mathematics is a widely held misconception. Some place an undue emphasis on the relationship, but the two disciplines are very different.

The purpose of descriptive statistics is to communicate information, while inferential statistics is used to reach conclusions and deductions that possibly explain the data. Both of these together make up applied statistics. There is also a discipline called mathematical statistics, which is concerned with the theoretical basis of the subject."

The bone has been thrown. Go fetch Noddy !!!

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Statistics is a branch of applied mathematics.  You should have learned that in college.  Regardless, you haven't shown where I err in my math or reasoning.   

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That is true of a CQT.  Other testing techniques can result in in INC too.  In some situations it means you made a post-test admission to a question so further testing is necessary to clear the issue.  (Some would report it as deceptive; others, as I've explained.)

cielo wrote on Nov 17^th, 2007 at 7:59pm:


An "inconclusive" result means that reactions to relevant and so-called "control" or comparison questions were about the same. To pass, reactions to the "control" questions must be larger than those to the relevant questions. You'll find polygraph procedure explained in detail in Chapter 3 of The Lie Behind the Lie Detector:

https://antipolygraph.org/lie-behind-the-lie-detector.pdf

The results of my polygraph were inclonclusive and I have to take it again. Can you define inconclusive when it comes to a poly result?

Thanks

Barry_C wrote on Nov 3^rd, 2007 at 6:34pm:


Cough cough coughBS cough
Quite fanciful to call your simple arithmetic 'math'
It's in the same vein as examiners titling themselves Forensic Psychophysiologists.......shortly before the phony PhD is added.

Translation:

"I don't understand the math.  I don't understand statistics or research methodology.  I haven't read the research literature I've implied I have, and I haven't an intelligent and sound response, so I'll resort to name-calling."

I think most have figured that our already, but I am curious as to why you continue to post when you have nothing of substance to add to the discussion.

Do you have a problem with my math?  Have I presented it wrong?  What's the issue?  I suspect you don't really have one, but I'm willing to listen if you're up to the task.

Cough, cough, coughbullshit, cough cough.
Nostradamus predicted a great flood in the year 2007.
I didnt know it was gonna be a river of bs.

Okay Ray,

You beat me to the punch.  I've been typing a line here and there (in Word) all day.  Here's my much similar response:

Sarge,

Is your glass always half empty?

Let’s look at the numbers and see what’s really what.

Assume you have 1000 candidates for 500 jobs.  Assume further that half of them have failed to disclose information at what would be the polygraph stage had the hiring agency had a polygraph program. Therefore, the base rate of “liars” is 50%.  (That’s not a figure I pulled out of thin air as you’ll recall that I have that data, which has yet to be published.)  Since this agency has no polygraph requirement, then chance will dictate which 50 get the job offers (as we’re at the end of the road as far as the hiring process goes.)

1000 candidates
50% base rate of liars
500 jobs
50% chance of catching liars (chance / coin flipping)

So, we’re going to end up hiring 250 liars (50%) and 250 truthful candidates (50%):

Truthful hired      = 250 (50% of 50 job applicants)
Liars hired      = 250 (50% of 50 job applicants)

If, however, we introduce polygraph, what will happen?  Assume a polygraph is 80% accurate.  (That number doesn’t come from thin air either.  There are a few studies on screening exams: the TES and the R/I.  Both exceed 80% accuracy, so this figure is conservative.  For those of you who aren’t data-driven, I can’t help you understand this.)

1000 candidates
50% base rate of liars
500 jobs
80% chance of catching liars with polygraph

Let’s do the math now:

Truthful hired      = 400 (80% of 50 polygraph NDI decision candidates – that are really truthful)

Liars hired      = 100 (20% of 50 polygraph NDI decision candidates – that are really liars)

400 truthful hired with polygraph – 250 hired without polygraph = 150 additional truthful hires.

150/250 = 60% more truthful people get jobs with polygraph that is 80% accurate if base rate of liars is 50%.

Let’s look at your figure, 60%, which the research shows to be a very conservative figure:

1000 candidates
50% base rate of liars
500 jobs
60% chance of catching liars with polygraph

Truthful hired      = 300 (60% of 500 polygraph NDI decision candidates – that are really truthful)

Liars hired      = 200 (40% of 500 polygraph NDI decision candidates – that are really liars)

50/250= 20% more truthful people get jobs with polygraph that is 60% accurate if base rate of liars is 50%.

So even with your 60% figure, the process is fairer to the truthful (on average) when all is said and done.  (Of course, the percentages are the same whether it’s 10 candidates and 5 jobs or 10,000 candidates and 5,000 jobs.)

Sergeant1107: Quote:


Except, good sergeant, your math is far from complete.

If you are going to use math examples to prove a point, then please do so correctly. To do an incomplete, and therefore incorrect, job is to provide inaccurate, false, and misleading information to others (that's bad).

You didn't state this, but assuming you have your hypothetical N=100 (lets say they are police applicants, hoping for a long and rewarding, and safe career of service to their communities), lets complete your example.

For the purpose of completely this example we can accept your hypothetical suggestion that 40 will lie about something (perhaps underreporting the frequency or currency of their use of illegal drugs, involvement in thefts or other crimes, or history of sexual contact with animals or sexual assaults against persons). 

You have suggested an “accuracy” of 60%. Keep in mind that accuracy is a complex, and therefore vague, term unless you specify what type of accuracy you are discussing. Your example is a Bayesian type, of which so many people seem to gain an incomplete understanding from the NAS report. You make the completely unjustified assumption that (accuracy/sensitivity is uniform with Fps). It reality its not that simple, and most Bayesian models are not uniform. Polygraph is an example of a non-uniform model, because it is in effect a test of two different signal issues of concern. But we'll accept your overly simplified premise for this example, and set a hypothetical suggestion of a sensitivity level of .6 (though there is a lot of evidence to suggest greater sensitivity).  We will, for this example only, accept your ridiculous suggestion that accuracy/sensitivity is uniform and inverse with errors, and assume a hypothetical error rate of .4.

Accepting that your simple addition/subtraction math is correct, we have to take the concern to two (or three) practical levels.

• One practical concern is  whom, if you are a law enforcement administrator, do you hire and how do you decide who are the decent law abiding citizens who would make responsible law enforcement officers, and who are the people who lack integrity and would bring corruption and problems to a department. How to hire "good guys" and not hire "bad guys."
• Another concern is can you get hired if you are a decent, law abiding citizen who desires to work in law enforcement. How to get hired if you are a "good guy."
• Perhaps a third concern is how to get hired into law enforcement if you know your past behavior, and perhaps future intentions, wrought with integrity flaws, poor judgment and behavior that violates laws, social mores, and the rights of others. What happens to the hiring prospects of "bad guys."

Now, for the purpose of completing your hypothetical example, lets assume the impossible and pretend that we could control for all extraneous variables that might affect the hiring process and focus all of our attention on the role that polygraph outcomes would have on those practical concerns.

In your hypothetical example involving 100 police applicants of which 40 are lying, and therefore presumably unsuitable for police work, 52 people would pass the polygraph and 36 of those results would be accurate. Additionally 48 people would not pass, of which ½ or 24 would be accurate. 

That may look unimpressive at simple-minded first glance, but data are sometimes not obvious or intuitive (they are sometimes counterintuitive). 

So, lets loot at the mathematical and practical aspects of those hypothetical results.

A simple test of proportions of 36/52 and 24/24 provides a z value of 1.961161, which gives a value of p=0.02493. There are, or course, better statistical models with greater power to determine the presence of a significant difference. We could build a simulation sample and use monte-carlo techniques to build say distribution of 1000, or 10,000, or 30,000 resampled distributions, and then calculate standard error rates and confidence intervals around our estimates. But why take the time and expense for a monte-carlo simulation when quick and dirty test reveals the point so well. A statistical test with more power would only reveal a greater, not lesser, degree of significance. So why take the time and expense for a monte-carlo simulation when quick and dirty test reveals the point so well.

By common standards p=0.02493 is a statistically significant result. 

I know, that's just math.

Lets look at the practical application, using your over-simplified Bayesian example to interpret our statically significant hypothetical of p=0.025, using an “accuracy” level of only 60% and a base rate of 40%.

Remember now that we have hypothetically controlled for all other variables. Human judgment, being what it is, can be assumed to be no better than chance (at least for those of us who don't possess some magical mind-reading capabilities). 

• To a police hiring administrator, using the polygraph, even if in this hypothetical example with as low as 60%, appears to provide a statistically significant improvement, over chance (alternative method/human judgment/not using the polygraph) in the likelihood of hiring a “good guy” vs hiring a “bad guy.”
• OK, you say, what if you are a “good guy” and want a job. Chance alone (all other variables being controlled for) would reveal the obvious – you have a 50/50 chance of being hired, compared with the chance of a “bad-guy” getting the job instead. With the polygraph, your chances are 36/52 = .69 which seems to be an improvement. Though some might point out the obvious fact that this is still “well below perfection,” it is a statistically significant improvement.
• Now, if you are a bad guy, without the polygraph (all else being hypothetically equal) you seem to have a 50/50 of being hired. Now with the polygraph, your chances seem to be reduced to about 40%.

In summary, good sergeant, using your own (over-simplified) hypothetical example - using the polygraph can be expected to produce three results: 

• Improve the probabilities of police hiring administrators to hire "good guys," 
• Improve the probabilities of "good guys" to get hired, and 
• Decrease the the probabilities of "bad guys" getting hired.

Sounds OK to me.

Sure its not perfect, and if you experienced a inaccurate result, that is truly unfortunate. But but claims that it is unsound are not accurate and not scientific.



r

Barry_C wrote on Oct 31^st, 2007 at 1:50pm:

Are you suggesting that applicants fail the polygraph on drug-related questions, and the PD continues them through the application process to the medical test, where the presence of drugs are detected in their urine?  I think that scenario is unlikely, as applicants who fail their polygraph are immediately removed from the application process.

Possibly you are suggesting that people who pass their polygraph are then confirmed as drug users by urinalysis during medical screening?  I suppose that happens, but if and when it does it serves more to justify a lack of confidence in the accuracy of the polygraph than anything else.

Barry_C wrote on Oct 31^st, 2007 at 1:50pm:


I don’t follow you on this.  Tell what, exactly, to the hundreds labeled as child molesters?  That there are safeguards in place and a Constitutional guarantee of due process?  If they have already been “saved” by those safeguards, why would I need to tell them about those safeguards?


Barry_C wrote on Oct 31^st, 2007 at 1:50pm:

That is precisely my point.  I don’t know they are telling the truth any more than you know they are lying.  You could also simply disqualify a random 50% of all applicants using the same logic;  "We don't know they are telling the truth, so let's get rid of them."  If nobody knows, why disqualify them?  

After my own personal experiences with the polygraph, and having three different examiners look me straight in the eye and tell me they “knew” I was lying when I actually did know I was telling the truth, I have no reason to believe that an unproven accusation of deception by a polygraph examiner is any more credible than the corresponding protestation of innocence by a police applicant.  Again, if there's no proof either way, why disqualify them?

Barry_C wrote on Oct 31^st, 2007 at 1:50pm:


First of all, I am not compiling any anecdotal (or any other) data.  I have made reference to anecdotal data because you were so dismissive of it, and I believe that the majority of data used by polygraph examiners to justify their belief in the polygraph’s accuracy is simply anecdotal data.  If you dismiss the data offered by false positives because it is “merely” anecdotal data you should also dismiss the data offered by examiners, but you do not.

I don’t believe there is any problem with my logic.  If a police candidate fails his polygraph and there is no indication on the background investigation that he was lying about anything, I think it is far more logical and justifiable to believe him than it is to believe a pseudoscientific process that, in my own personal experience, was inaccurate three out of four times.  During the background investigation, detectives speak with people who have known the applicant for years, sometimes for his whole life.  If there is no indication from any of those people that the applicant is an unsuitable candidate, do you really feel it is logical to take the word of someone who met the applicant for the first time ever, interviewed him for an hour or two, and then concluded he was lying about drug use, or theft, or whatever?

Barry_C wrote on Oct 31^st, 2007 at 1:50pm:

I guess that depends on how you look at it.  I think the test would have to nearly perfect in order to be worthwhile.

If you have a test that is 60% accurate (which would be better than average chance) it will be inaccurate, on average, 40% of the time.  If you have one hundred applicants, how many do you believe will lie about something on their application?  Twenty?  Thirty?  Half?  Let’s say that 40 of them will lie about something, just for the sake of simplifying the math.

If the 60% accurate test functions normally, at the end of the test you will have 36 truthful people pass, and 24 truthful people fail.  You will also have 24 deceptive people fail, and 16 deceptive people pass.  

You will have a total of 52 people pass, and 48 people fail.  But of the people who passed, 16 of them lied and got away with it.  And out of the people who failed, 24 of them were telling the truth.

So now you are left with 52 applicants, nearly a third of which are liars who were able to defeat the test.  And out of the 48 people you booted from the application process, half of them were telling the truth and were disqualified for absolutely no reason whatsoever.

I don’t think that sort of process is fair or logical.  It allows too many liars to proceed and disqualifies too many truthful applicants.  It also provides a false sense of security because the 16 liars who just got sworn in as police officers are viewed as having already “passed” a test designed to detect deception.

Quoted by Barry_C:
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The inference is that they were 'caught' in their polygraph examination. The examiner says guilty or DI whatever. The subject says "No - you're wrong". 
What makes your way any better ? Just because you say so ???
You seem to think that you're some kind of polygraph demigod. 
Its quite sad.

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Okay.

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Some PDs do drug testing, and that can offer some confirmation of polygraph.  I don't know how much of that has been published.  It's a good area to look at more closely.

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Tell that to the hundreds labeled as child molesters early in the process but were "saved" by those "safeguards."  My point is that there are errors in any system.  Failing a polygraph has, in most instances, limited costs.  The criminal system is heavily weighted in favor of the accused, yes, because the cost is so high.  However, the civil system is not, because the costs are lower: money verses liberty.  Look at OJ for example.

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This is where we disagree.  The process is not arbitrary.  How do you know the person is telling the truth?

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You do what you accuse polygraph examiners of doing as you can't know that is true.  That is why there is a desire for polygraph and truthfulness testing of all sorts.

That is the problem with your logic.  Consider this: Candidate A comes in for a job and "fails" his polygraph, being called a liar.  You say there's no way to know if that's true (and investigation may help), but we should accept the person's claim of innocence so you can compile your anecdotal data.  You accept his story based on your personal disbelief in polygraph screening, but to believe him requires you accept (blindly) that he's truthful.  Why is your way better?

Any test that discriminates truth from lies at better than chance rates, no matter how poor, is going to get your more accurate results than blindly accepting people's claims.

I did a study that I've yet to publish in which I found that about 50% of LE candidates disclose more drug involvement to the polygraph examiner than they do during the background / application process.  Not a single spy has been reported to have been caught based on an interview alone.  Those are factors that must be considered when determining the costs verses benefits of polygraph screening. 

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It could be that I don't know the numbers.

I was referring to pre-employment polygraph screening, as that is the only aspect of the polygraph with which I have any experience.

I don't believe any results of pre-employment polygraph screening exams are ever verified one way or the other, unless as I mentioned, there is some sort of confession or damning physical evidence produced after the fact.  All pre-employment screening exams result in anecdotal evidence, and of the two versions of each exam, only the anecdotal evidence offered by the subject is accurate.  The anecdotal evidence offered by the examiner is as much of a guess (influenced by his or her training and experience, but still a guess) as the original results.

I think that comparing the polygraph process to an arrest made with probable cause or a jury trial is intentionally misleading.  There are, of course, errors made by police when arresting people on probable cause, and there are errors made by juries.  But there are also safeguards in place and a Constitutional guarantee of due process, and the entire system is heavily weighted in favor of the accused.  The same cannot be said of the polygraph.

A police applicant can tell the truth on his polygraph, be arbitrarily and incorrectly labeled a liar by the examiner, and will then be summarily removed from the hiring process and sometimes blackballed with other agencies as well.  The examiner will not have to prove anything, and the applicant will not be permitted to defend himself, though even if he was I don't know if it is possible for one to prove he has never used or sold drugs (or whatever the imagined transgression was.)

I think anecdotal evidence is going to comprise the bulk of evidence regarding the polygraph, because there is virtually no way to prove truth or deception.  A person can fail a polygraph and later (credibly) confess, or there could be some incontrovertible physical evidence found that shows the person was actually lying on their polygraph.  If there is no confession or physical evidence the results of the polygraph will never be confirmed and will simply be anecdotal evidence, and only the anecdotal evidence from the examinee's point of view will be accurate.

A person can pass his or her polygraph, and unless they later confess or there is physical evidence produced, the results of that polygraph will never be confirmed either.  Once again, only the anecdotal evidence from the subject of that polygraph will be accurate.

You admitted in your post that only "some" results are confirmed independently.  I wonder what percentage is ever confirmed.  It cannot be a high percentage or you would have quoted the numbers.

There is a built-in bias against accurate feedback in the polygraph process.  If a person passes the polygraph (and there is no later confession or forthcoming physical evidence to show they were lying) their story will be touted as proof the polygraph is accurate.  Just tell the truth and you'll be fine, as the party line goes.  If the person who passed was actually lying they are not going to tell anyone about it, and same holds true if they passed by using countermeasures.  So how much of that feedback is accurate?  The truth is that neither you nor I have any idea.

If a person fails the polygraph, they may confess to something.  If that happens, that exam will be used to show the polygraph is accurate.  The person who fails may also maintain they were telling the truth, but in that case the feedback is discarded because they just failed a polygraph for lying, so why should anyone believe them?  Instead of using that feedback as proof the polygraph is inaccurate, it is instead added to the "accurate" pile of evidence, since there is virtually no way for the person who failed to ever prove that they were not lying.  So how much of that feedback is accurate?  Again, there is no way to know.

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That's not science.

You act as if there is no way to confirm our findings.  When we run tests in the field, we do confirm some of them independently.  If we take a random sample of 100 cases confirmed, by say, DNA, and we compute accuracy rates, why would there be any reason to believe those figures would different from those not independently verified?  That makes no sense.  For example, I ran tests in one case that we treated like a murder (the most "impossible" of cases according to the anti crowd).  (I asked if the subjects killed a person.)  We later learned - with video - no murder took place, and nobody was responsible for the person's death.  That's confirmed data.  We in the polygraph community also have confirmed errors.  We can use all that data to determine accuracy.  It's not anecdotal.  It's empirical, which is what counts, but we're going round and round again.

We come up with the error and accuracy rates of juries in the same manner.  We prove cases historically.  Witnesses come in and say what they saw, heard, smelled, etc.  Do we convict the innocent with "good" witnesses?  Of course we do.  Elizabeth Loftus documented a case in her book on eyewitness memory in which a person was convicted of a crime based on positive IDs of 17 eyewitnesses!  DNA, it turns out, said they were wrong.  So, we don't "really" know if a person is guilty just because a jury says so.  We all know that though, and we are willing to take that risk.  We weigh the benefits against the costs, and we have what we have.  Our system is designed to avoid false positives, which is why we end up with more false negatives.  We could change the "cut-offs" though, which would change the direction of those errors.

How many people are arrested or charged (on PC) but not convicted?  Why?  Again, the cost of a false arrest is not as problematic as a false conviction.  Whether you like that or not, that's the way it is.  How did we get to that point?  Data.  We've gotten better at analyzing it, and I'm sure there are more changes to come.  (Look at line-ups, for example.)

To day we should look at anecdotal "evidence" is a step back time as there is no way to verify it (which is why it's anecdotal).

To Barry C,

I'm pre-empting your next question and answering it in anticipation:

Yes. Sarge not only is a real police officer. He also went to college.

Barry_C wrote on Oct 29^th, 2007 at 7:39pm:


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:


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? 

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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.

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It depends.  What is the cost of those errors?  It's a philosophical question, and I've addressed that already elsewhere.

I have not found Barry C to be disrespectful.  Of course, I may not be hearing effectively, the words of Supreme Court Justice C. Thomas keeps ringing in my ears:

"Although the degree of reliability of polygraph evidence may depend upon a variety of identifiable factors, there is simply no way to know in a particular case whether a polygraph examiner's Conclusion is accurate, because certain doubts and uncertainties plague even the best polygraph exams."  United States v. Scheffer, 523 U.S. 303, 118 S.Ct. 1261, 140 L.Ed.2d 413 (U.S. 03/31/1998)

Barry_C wrote on Oct 29^th, 2007 at 3:08pm:

When you score an exam DI the only way you would know you are right is if the person confesses or if some sort of incontrovertible physical evidence is discovered.  If neither of those are present your conclusion that said exam's result was accurate is simply anectdotal evidence.

When you score an exam NDI the only way you would know if you are right is if the person somehow produces proof of a negative, that they have not done whatever they were being asked about.  Lacking that any conclusion in the accuracy of that particular exam is simply anectdotal evidence.

In the vast majority of pre-employment screening exams where no damaging admission occurs, there is only one person who truly knows if the subject was being truthful or deceptive, and it is NOT the polygraph examiner.  The examiner can guess, and they can claim that the person did or did not show signs that they (the examiner) has been trained to discern as signs of truth or deception, but they cannot know.  The subject knows.

Why should the anectdotal evidence of people who have taken the polygraph be any less credible than the anectdotal evidence of the polygraph examiners?

Logically, since only the people who have taken the polygraph truly know if the test result was accurate or not, they should have far greater credibility than the examiner.