We appreciate Drs Maldonado and West’s interest in our article in CHEST (September 2010).1 They are correct to point out that our article did not address Bayesian analysis of research studies, but we did not intend it to. Although Bayesian approaches are often used in analyzing diagnostic test characteristics, as the authors note, Bayesian applications in analyzing research studies are not as straightforward. To begin with, the a priori (ie, pretest) probabilities required for Bayesian statistics are usually more easily available for diagnostic tests than they are for research studies. In the simplest instance, the a priori probability for a diagnostic test can be estimated by the rate of occurrence of the disease of interest in the population. In addition, the results of any previous tests (eg, a chest radiograph) will further refine the a priori probability for subsequent tests (eg, a chest CT scan). Such a priori probabilities are usually not available for research studies,2,3 although 50% can be chosen to reflect the uncertainty of the ultimate outcome. Of note, Rosenthal4 illustrates how both Bayesian and frequentist analyses can produce similar results when an a priori probability of 50% is chosen for the Bayesian analysis.