How Accurate is it?
The American Polygraph Association, the body responsible for a majority of research in this area lists a single issue test at up to 98% percent accurate, based on the test being conducted by a qualified examiner who uses the latest computerised equipment and who uses validated techniques. In other words, it is very accurate.
It is also important that the person taking the test follows the instructions given by the examiner as these instructions are designed to help the truthful person through the process. If you are not being truthful you will not pass the test.
A polygraph test does not ‘detect the truth’. It monitors your reactions, both voluntary and involuntary and records them so a qualified examiner can determine if you reacted in a way consistent with someone telling the truth. A polygraph is only as accurate as the test and the examiner. That is why there is so much importance put on the person doing the test, the type of test, the environment, and the examiner’s ability to observe and detect counter measures.
In summary, only the latest professional equipment, operated by an experienced and trained specialist, with APA certification and ongoing continuing education, can properly administer a test. Even then it is considered 95-98% accurate…not absolute. It is a guide, like asking a question, looking into someone’s eyes, or observing how they react to certain things, but it is based on thousands of tests and studies, not personal opinion or conjecture and is a diagnostic tool, like many others. In this case, a highly reliable one.