Mpany gives everyone a polygraph test, asking "Have you ever stolen anything from your place of work?" Naturally, all the applicants answer "No," but the polygraph identifies some of those answers as lies, making the person ineligible for a job. What's the probability that a job applicant rejected under suspicion of dishonesty was actually trustworthy?

These values suggest that among + polygraphs, all of which are rejected for employment, 81% will have been rejected incorrectly!  

Explanation:

We want to calculate Probability (Trustworthy | + polygraph) •Probability (Trustworthy) = .95

Probability (not Trustworthy) = .05

•Probability (+ polygraph | trustworthy) = .15 •Probability

(+ polygraph | not trustworthy) = .65 Pr( trustworthy | + polygraph ) = Pr(trustworthy and + polygraph)Pr (+ polygraph)=Pr(+ polygraph | trustworthy) Pr(trustworthy)Pr(+ polygraph)=Pr(+ polygraph | trustworthy) Pr(trustworthy)Pr(+ polygraph | trustworthy) Pr(trustworthy) + Pr(+ polygraph | not trustworhty) Pr(not trustworthy)=(.15) (.95)(.15) (.95) + (.65) (.05)= .8143 5b. (5 points)In 1-2 sentences, in your opinion, what do these values suggest about using lie detector tests to identify dishonest applicants?