A test with high sensitivity is not necessarily a useful test. The sign “10 fingers” would be extremely sensitive for almost any disease because most patients with the disease will have ten fingers. Very few patients with the disease will have a different number of fingers. Thus, the ratio of true positives (number of patients with the disease who have ten fingers) to the sum of true positives plus false negatives (where false negatives are people who have the disease and do not have ten fingers)
