A forensic researcher wanted to test the validity of the polygraph or "lie detector" machine. She recruited ten test subjects. All test
subjects were male high school graduates between the ages of 20
and 25. She wrote a list of ten questions and asked the subjects to
tell the truth on questions 1, 2, 5, 8, and 10, and lie on questions 3,
4,6,7, and 9. She recorded the blood pressure of all test subjects
during all ten questions.