Question

A polygraph (lie detector) is an instrument used to determine if an individual is telling the truth. These tests are considered to be 90% reliable. In other words, if an individual lies, there is a 0.90 probability that the test will detect a lie. Let there also be a 0.045 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
a. What is the probability of a Type I error? (Round your answer to 3 decimal places.)
b. What is the probability of a Type II error? (Round your answer to 2 decimal places.

Answer 1

Answer:

A) P(Type I error) = 0.045

B) P(Type II) error = 0.1

Step-by-step explanation:

We are told that the reliability of the test is 90% reliable.

Also, we are told that the probability that the test erroneously detects a lie even when the individual is actually telling the truth is 0.045.

Thus;

A) To calculate the probability of type I error:

From statistics, in this question we can say that the probability of a type I error is the probability that the test will erroneously detect a lie even though the individual is actually telling the truth. Thus;

Probability of (type I error) = P(rejecting true null) = 0.045

B) For probability of type II error, it is defined as the error where we accept a null hypothesis that is false. We can say that it produces a false negative and the formula is;

P(Type II) error = 1 - reliability

Reliability in the question is 0.90

Thus;

P(Type II) error = 1 - 0.9

P(Type II) error = 0.1