A polygraph lie detector is an instrument used to determine

A polygraph (lie detector) is an instrument used to determine if the individual is telling the truth. These tests are considered to be 96% reliable. In other words, if an individual lies, there is a 0.96 probability that the test will detect a lie. Let there also be a 0.065 probability that the test erroneously detects a lie even when the individual is actually telling the truth. Consider the null hypothesis, \"the individual is telling the truth,\" to answer the following questions.

Solution

a. The probability of Type I error is given as

P(Rejecting a true null hypothesis) = 0.065

b. The probability of Type II error is given as

P(Failing to reject a false null hypothesis) = 1 - 0.96 = 0.04