National Ambulalatory Medical Care Survey (NAMCS)-national sample of visits to non federally employed office based physicians who are primarily engaged in direct patient care, and National Hospital Ambulatory Medical Care Survey (NHAMCS)- national sample of visits to emergency and outpatient departments and to ambulatory surgery facilities in noninstitutional general and short stay hospitals, exclusive of Federal, military, and Veterans Administration hospitals, located in the 50 States and the District of Columbia