SOLUTION: Probability that a person who tests positive actually has the disease. A certain disease has an incidence rate of 0.4%. If the false negative rate is 4% and the false positive r

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Question 1061835: Probability that a person who tests positive actually has the disease.
A certain disease has an incidence rate of 0.4%. If the false negative rate is 4% and the false positive rate is 4%,
Answer by jorel1380(3719) About Me  (Show Source):
You can put this solution on YOUR website!
Consider a sample population of 100,000. Then .004 x 100,000, or 400 actually have the disease. Out of these 400, 96%, or 384 will test positive. Out of the 99,600 who don't have the disease, 4%, or 3,984 will test positive. Therefore, the probability that someone who tested positive will actually have the disease is 384/384+3984, or 0.0879121
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