What will it take for IBM's Watson technology to stop being a dud in health care?

Paul Tang was with his wife in the hospital just after her knee replacement surgery, a procedure performed on about 700,000 people in the U.S. every year. The surgeon came by, and Tang, who is himself a primary-care physician, asked when he expected her to be back at her normal routines, given his experience with patients like her. The surgeon kept giving vague non-answers. "Finally it hit me," says Tang. "He didn't know." Tang would soon learn that most physicians don't know how their patients do in the ordinary measures of life back at home and at work--the measures that most matter to patients.