There are now about 25 research studies available on the accuracy of the polygraph tests. In ‘real life’ cases, researchers have found it very difficult to assess the accuracy of polygraph examination because the ‘ground truth’ criteria are often lacking i.e. it is not possible to find a representative sample with which one can establish with certainty who is and is not actually telling the truth. Based on the studies now available, experts assess the accuracy of polygraph examinations administered by a competent examiner to be about 90% and with the latest training, techniques and equipment up to 98%. Studies have also shown that the level of skills and experience of the examiner plays an important part in the accuracy of the examination. Comparative studies have shown that polygraph tests yield an accuracy that equals or exceeds that of many other forms of evidence. In one study, it was shown that polygraph tests produced an accuracy that was comparable to results obtained by document examiners and fingerprint analysts, and exceeded that of eyewitnesses.
In many ways, seeking a good polygraph examiner is similar to seeking a good surgeon. It pays to get a surgeon with a good track record although you may pay more. Similarly, an examiner with a good track record and reputation increases your probability of success in arriving at the truth and avoid mistakes.