As a University of Chicago-trained economist and Harvard medical school professor and doctor, Anupam Jena is uniquely equipped to answer these questions. And as a critical care doctor at Massachusetts General who researches health care policy, Christopher Worsham confronts their impact on the hospital's sickest patients. Jena and Worsham show us how medicine really works, and its effect on all of us. Relying on ingeniously devised natural experiments-random events that unknowingly turn us into experimental subjects-Jena and Worsham do more than offer readers colorful stories. They help us see the way our health is shaped by forces invisible to the untrained eye. Is there ever a good time to have a heart attack? Do you choose the veteran doctor or the rookie? Do you really need the surgery your doctor recommends?