Question

Testing a Lie Detector The table below includes results from polygraph (lie detector) experiments conducted by researchers Charles R. Honts (Boise State University) and Gordon H. Barland (Department of Defense Polygraph Institute). In each case, it was known if the subject lied or did not lie, so the table indicates when the polygraph test was correct. Use a 0.05 significance level to test the claim that whether a subject lies is independent of the polygraph test indication. Do the results suggest that polygraphs are effective in distinguishing between truths and lies?
Did the Subject Actually Lie?
Did the Subject Actually Lie?

No (Did Not Lie)
Yes (Lied)
Polygraph test indicated that the subject lied.
15
42
Polygraph test indicated that the subject did not lie.

Answer 1

If we divide 15 by 42:
15 / 42 = 0.3571 or 35.71%

Since the level of significance is 0.05, an accuracy of 35.71%, based on the data, the results of the polygraph suggest that the polygraphs are not effective in distinguishing between truths and lies.