You are performing a new screening test for glaucoma on 100 patients. In reality, 15 of the patients have glaucoma and 85 of the patients do not. The screening test identifies 50 people with positive results and 50 people with negative (normal) results. Forty of those patients who had positive results do not have glaucoma, and five patients who truly have glaucoma have negative results on the screening test. What is the number of false positives for this test?
Answer D. 40
Explanation: 40 The number of false positives is equal to the number of patients who had positive results on the screening test but did not actually have glaucoma. The chart below further illustrates the patients’ disease status of whether or not they have glaucoma versus their results on the new screening test.
Test Results Glaucoma No Glaucoma
Positive : 10 (True positive)
40 (False positive)
Negative : 5 (False negative)
45 (True negative)