Biochemical markers are used by emergency room physicians to aid in diagnosing patients who have suffered acute myocardial infarction (AMI), or what’s commonly referred to as a heart attack. One type of biochemical marker used is creatine kinase (CK). Based on a review of published studies on the effectiveness of these markers (by E. M. Balk et al., Annals of Emergency Medicine, vol. 37, pp. 478–494 , 2001), CK had an estimated sensitivity of 37% and specificity of 87%. Consider a population having a prevalence rate of 25%.
a. Explain in context what is meant by the sensitivity equaling 37%.
b. Explain in context what is meant by the specificity equaling 87%.
c. Construct a tree diagram for this diagnostic test. Label the branches with the appropriate probabilities.