This is my first time posting in this forum (or in any forum if truth is to be told, but anyways..) so please be patient...
First and foremost this site and the ebook "The Lie Behind the Lie Detector" have been really helpful and I congratulate Mr George Maschke for the extensive work he has provided on the polygraph test.
Having said that, I still remain with a little dilemma on the accuracy of a polygraph test. Those who are in favour of the polygraph test mark the accuracy at 90-98% however those who are against the polygraph state that the accuracy is better than chance but lower than perfection.
Quote: Quote #1:
These studies, almost exclusively carried out in criminal investigation settings using one particular test, the Comparison Question Test (CQT), indicate that the CQT is able to discriminate between truth tellers and liars above the level of chance, but the accuracy levels are far from perfect.
Vrij, A. (2008). Detecting lies and deceit, 2nd Edition
Pgs. 295-29
Quote: Quote #2: [You should know this
]
...specific-incident polygraph tests for event-specific investigations can discriminate lying from truth telling at rates well above chance, though well below perfection.
Maschke, G. W. and Scalabrini, G. J. (2005). The lie behind the lie detector, 4th Digital Edition
Pg. 27
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However whilst reading a paper by Lykken D. T. (1988)
The case against polygraph testing I encountered the following statement:
Quote:"We can conclude, therefore, that the CQT, while reasonably accurate (about 84 percent on guilty suspects) in detecting lying in persons not specifically trained in countermeasures, is exceedingly inaccurate in detecting truthfulness (about 53 percent accuracy, versus a chance of accuracy of 50 percent)."
Pg. 117
How come CQT has a high percentage in detecting lying but a lower one in detecting truthfulness? ..Aren't these percentages related with each other?
Having said that I also have an interesting quote :
Quote: Why do critics figures vary?
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. How important are inconclusive tests? As far as I have understood inconclusive tests which a polygrapher cannot give a definite verdict upon [if the person is either lying or not], so technically they shouldn't be included in accuracy rates because they are neither correct or incorrect... or am I absolutely wrong on this?
PS. I know, it's a bit foggy and some of you may find it stupid so please excuse my ignorance.
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The issue of Accuracy (Read 2223 times)
