Exercise A.23 describes a study in which lie detector accuracy is checked by having participants read deceptive material. In addition to deceptive material, the individuals were also asked to read truthful material. The electric shock was again included to add stress. The lie detector accurately reported no deception in 21 of the 48 participants.
(a) What proportion of the time does the lie detector incorrectly report deception?
(b) If you were on a jury, would you trust results from this device?

Exercise A.23

Is lie detection software accurate? A recent study was conducted in order to test the accuracy of a commonly used method of lie detection. The researchers are specifically interested in how lie detectors perform when an individual is stressed. A sample of 48 participants were gathered and attached to the lie detection device. They were asked to read deceptive material out loud while receiving an electric shock (to add stress). The lie detector failed to report deception in 17 of the 48 participants.