negatives from screening, regardless of the techniques used. Given the limitations of the polygraph and other available employee screening techniques, any policies that decrease reliance on employee screening for achieving security objectives should be welcomed.

Although the commission recommended continued polygraph security screening for some DOE employees, it did not offer any explicit rationale for continuing the program, particularly considering the likelihood that the great majority of positive test results will be false. It did not claim that screening polygraphs accurately identify major security threats, and it left open the question of how DOE should use the results of screening polygraphs. We remain concerned about the false negative problem that can be predicted to occur if people who “pass” a screening polygraph test that gives a very low rate of positive results are presumed therefore to be “cleared” of security concerns. Given this concern, the Hamre Commission’s emphasis on improving security by means other than screening makes very good sense.

Both the Webster and Hamre Commission reports make recommendations to reduce the costs associated with false positive test results, although neither takes explicit cognizance of the extent to which such results are likely to occur in security screening. More importantly, neither report explicitly addresses the problem that can arise if negative polygraph screening results are taken too seriously. Overconfidence in the polygraph—belief in its validity that goes beyond what is justified by the evidence—presents a danger to national security objectives because it may lead to overreliance on negative polygraph test results. The limited accuracy of all available techniques of employee security screening underlines the importance of pursuing security objectives in ways that reduce reliance on employee screening to detect security threats.

Making Tradeoffs

Because of the limitations of polygraph accuracy for field screening applications, policy makers face very unpleasant tradeoffs when screening for target transgressions with very low base rates. We have summarized what is known about the likely frequencies of false positive and false negative results under a range of conditions. In making choices about employee security policies, policy makers must combine this admittedly uncertain information about the performance of the polygraph in detecting deception with consideration of a variety of other uncertain factors, including: the magnitude of the security threats being faced, the potential effect of polygraph policies on staff performance, morale, recruitment, and retention; the costs of back-up policies to address the limi-



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