Imagine a test for a certain disease. Suppose the probability of a positive test result is 0.95 if someone has the disease, but the probability is only 0.08 that someone has the disease if his or her test result was positive. A patient receives a positive test, and the doctor tells him that he is very likely to have the disease. The doctor's response is
A) an example of "Confusion of the inverse."
B) an example of the "Law of small numbers."
C) an example of "The gambler's fallacy."
D) correct, because the test is 95% accurate when someone has the disease.

Question

Quizplus · Accepted Answer

The doctor's response is an example of "Confusion of the inverse" because it incorrectly assumes that the high probability of a positive test result given the disease (95%) implies a high probability of having the disease given a positive test result, ignoring the actual probability of having the disease given a positive test result (8%).

Imagine a Test for a Certain Disease