Consider a disease whose prevalence is one in a thousand. A test to detect the disease has a false positive rate of 5 percent. Let D = person has the disease, ND = person does not have the disease, POS = person tests positive, and NEG = person tests negative.
What is the chance that a person found to have a positive test result actually has the disease?
(Hint: Track 1,000 individuals who take the test.)