1. (4 pts) Suppose that two different diagnostic imaging tests - A and B - designed to detect lung cancer in its early stages produce the following data in individuals aged 64-73, where the rating scale ranges from 1 (definitely normal) to 5 (definitely abnormal): Rating Lung cancer? 2 3 A 5 Total Test A No 30 6 6 4 4 50 Yes 4 4 6 6 30 50 Total 34 10 12 10 34 100 Test B No 40 4 4 50 Yes 4 4 40 50 Total 41 5 8 5 41 100 Table 1. Ratings of 100 images from tests A and B a. (1 pt) Calculate sensitivity and specificity for each test if the following cutoff values are used to determine whether someone likely has lung cancer: (0.5, 1.5, 2.5, 3.5, 4.5, 5.5). b. (1 pt) Sketch the ROC curve for each test. C. (1 pt) Which test is better? Justify your answer. d. (1 pt) If the prevalence of lung cancer in 64-73 year olds is 5%, what are the positive and negative predictive values of test B using a cutoff of 2.5