In screening, it is a method to maximize accuracy when base rates are unbalanced or very low. For example, an agency may have a vital interest in uncovering past activities of applicants before hiring them, behaviors that are very difficult to investigate effectively with any method except the polygraph. The agency may choose to conduct a single-issue polygraph for each of the subject areas. If there only two or three areas, this approach may be effective, however, if the number is greater, it would tax the agency’s resources in terms of polygraph examiners and processing time. Alternatively, in the successive hurdles approach, each applicant would begin with a multiple-issue examination. Though multiple-issue examinations have a higher false positive rate (incorrect decision of deception) than do single-issue examinations, they have a very small rate of false negatives. If no significant responses were noted during the multiple-issue examination, the polygraph session would be over. However, if there were significant responses during the multiple-issue examination, the polygraph session would continue. Next, a single- issue examination would be administered in the area the examiner observed significant responses during the multiple-issue examination. The single-issue examination has much better discrimination power and would help to elucidate physiological arousal more specifically. In this way, the more resource-intensive single-issue examinations would be reserved for the smaller subset of applicants who did not pass the multiple-issue examination. The net effect of the two-stage screening process is a better accuracy without increased resources. See: Krapohl & Stern (2003); Meehl & Rosen (1955).
