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Normal Topic What If My Test is Inconclusive? (Read 21639 times)
TS Elliot
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What If My Test is Inconclusive?
Jul 2nd, 2009 at 12:58pm
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The late, great Johnny Cash said:

"How well I have learned that there is no fence to sit on between heaven and hell. There is a deep, wide gulf, a chasm, and in that chasm is no place for any man."

Some time ago I promised to discuss the inconclusive polygraph test result. Many people seem not to fully understand the inconclusive result, its probable causes or its true place in judging polygraph validity. First of all here is what the APA says about how some opponents of the polygraph deliberately or ignorantly use the inconclusive result when viewing polygraph accuracy:

"One of the problems in discussing accuracy figures and the differences between the statistics quoted by proponents and opponents of the polygraph technique is the way that the figures are calculated. At the risk of over simplification, critics, who often don't understand polygraph testing, classify inconclusive test results as errors. In the real life setting an inconclusive result simply means that the examiner is unable to render a definite diagnosis. In such cases a second examination is usually conducted at a later date.
To illustrate how the inclusion of inconclusive test results can distort accuracy figures, consider the following example: If 10 polygraph examinations are administered and the examiner is correct in 7 decisions, wrong in 1 and has 2 inconclusive test results, we calculate the accuracy rate as 87.5% (8 definitive results, 7 of which were correct.) Critics of the polygraph technique would calculate the accuracy rate in this example as 70%, (10 examinations with 7 correct decisions.) Since those who use polygraph testing do not consider inconclusive test results as negative, and do not hold them against the examinee, to consider them as errors is clearly misleading and certainly skews the figures."

So you see that an inconclusive result cannot fairly or logically be used to negatively judge polygraph accuracy. Makes a lot of sense when explained this way.

The inconclusive possibility on a polygraph test can actually be a good thing sometimes and the fact that its a possibility actually ensures greater polygraph decision accuracy than if there was no such thing as the inconclusive. You see, without the grey area of the inconclusive there would be no buffer zone for the test subject. You would either pass the test numerically or you would fail it. With no buffer zone you might more easily be judged as deceptive when you are not which is a false positive, or you might more easily be judged as truthful when you are not which is a false negative. One little mistake on one physiological channel reading and you could go from a plus to a minus--or a minus to a plus--just like that. So you see that the inconclusive area is indeed a "chasm" between passing and failing the test. In my experience the inconclusive is therefor a good thing both for judging and insuring polygraph accuracy. To fall into the false positive area, a truthful subject has to cross that chasm. Likewise a guilty subject has to somehow cross that chasm to be judged as a false negative. In my experience that just does not happen as often as opponents of the polygraph would like you to believe. In truth the false positive and the false negative are very rare, and part of that is because of the inconclusive chasm. Now for the extremely rare false positive person that is little consolation I know, but when we are dealing with human beings there is no such thing as a 100 percent accurate test process whether we are using a polygraph, CSI techniques, or medical tests. We live with the extremely rare error rate, having to accept that it's not perfect, but its pretty darn good.

Now another thing to think about when dealing with the inconclusive polygraph test is countermeasures. Studies show that countermeasures, which are attempts by a subject to skew or manipulate polygraph test results by somehow manipulating their physiology, actually tend to make a subject appear more deceptive rather than less so. Based on my experience, I have my own theory on why this happens, but suffice it to say, and the studies show, that it does. What can very often occur when an innocent subject attempts countermeasures is that it will backfire on the subject, causing him to fall into the chasm of inconclusive when, had the subject simply taken the test without messing around, he would have clearly passed the test. I think it is more rare for an innocent subject to come up inconclusive than for him to cross the chasm into the realm of a false positive, but would you want to take that chance and fall into that chasm? I would not. Although in theory the inconclusive test result does not count for or against a subject, when people are judging you on the results of a polygraph test, it's definitely preferable to be viewed as truthful than to be viewed as inconclusive. Opponents of the polygraph would have you believe that if you take a polygraph test you need to increase your odds of passing by using countermeasures, but nothing could be further from the truth. When people tell you that by using countermeasures you will help yourself pass the exam, first of all ask those people whether they have ever been a polygrapher which would give them some credibility through experience. If they have never been a polygrapher, ask them whether they've ever actually used countermeasures to pass the test and, assuming that they were an innocent subject when they took their test, how they know that they wouldn't have passed the test without messing around. Their answer, or lack of an answer, should be a real eye opener for you. As Helen Keller said:

"Many people know so little about what is beyond their short range of experience. They look within themselves - and find nothing! Therefore they conclude that there is nothing outside themselves either."

My advice is to ask a polygrapher. That way you get experienced advice. I hope this little discussion has enlightened you. Thank you for reading. May you never fall into the chasm, and may the polygraph gods shine their light on your test.
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