"Medicine is a science of uncertainty and an art of probability."–Sir William OslerWhat is the likelihood of a patient having a PE? Or UTI? Or breast cancer? Bayesian reasoning can tell us, and Rx-Bayes is your portal to using Bayesian reasoning at the bedside.Let’s face it, very few clinicians have a good grasp of Bayesian probability. That is why expensive tests are ordered when they won’t really make a difference and false-positive tests are acted upon – jeopardizing patients while increasing costs.Till now, even physicians who understand it could not apply Bayesian theory at the bedside because it required complex calculation and previous knowledge of tests’ sensitivity and specificity.Rx-Bayes does away with these obstacles with its:-GRAPHICAL INTERFACE, making Bayesian reasoning INTUITIVE AND EASY to understand.-EXPANDING DATABASE of sensitivities and specificities.-included REFERENCES to the high-quality studies used to create the database.-our COMMENTARY on those studies.-ability to ADD YOUR OWN SENSITIVITY/SPECIFICITY DATA.For teachers, this app is perfect for communicating the concepts of false-negative and false-positive test results, and for demonstrating the importance of Bayesian reasoning to medical students and residents.-pre-test, sensitivity and specificity sliders show instantly how playing around changes the post-test probability.-demonstrate why certain tests are only useful if the pre-test likelihood is already high.-at your fingertips for teaching at the bedside.See the app in action at http://www.youtube.com/watch?v=4v9soEQqjaoWe hope Rx-Bayes will help all clinicians to make better decisions, for safer, more cost-effective care.Created by:Zain Hakeem, DOAtif Shahnawaz, MDCoded by Chris Auyeung