Assessing Polygraph Accuracy: The importance of choosing an evaluation technique which is compatible with the way the examinations were conducted

Sterzer and Elaad in their study found that using a zero cutoff point with no inclusive zone results in false positive error rates of 23.33% for the minor crime sample and 43.14% for the severe crime sample. The difference between these two error rates, which was found to be significant, was attributed to the different levels of threat presented by the relevant questions in the two levels of crime severity. During the year 1979, the Israel National Police Polygraph Laboratory went through a substantial change regarding the conduct and evaluation of polygraph examinations. In contrast, the MC sample was taken on the whole from examinations conducted in the 1980’s, and the percentage of negative scores for these 27 records was 18.5%. Examinations whose conduct was geared to the global evaluation and behavioral symptoms approach might be unsuitable for analysis by the objective numerical scoring technique, or even by a blind global evaluation which is not accompanied by behavioral symptoms analysis.