In this video I will calculate a numeric answer to the “tree diagram” method of finding the PROBILITY that someone WILL HAVE THE DISEASE IF THEY TEST POSITIVE. If 1000 subjects are tested, 4% have the disease. The test is 98% sensitive and 95% specific; or 2% FALSE NEGATIVE and 5% FALSE POSITIVE. Find the PROBILITY that someone WILL HAVE THE DISEASE IF THEY TEST POSITIVE.