The NSAS is the only national study of ambulatory surgical care in hospital and independent surgery centers. Conducted from 1994 to 1996, the survey was discontinued because of lack of resources. The questionnaire used in the 1994-1996 survey collects information about the patient's admission status to the surgical facility, patient payment data, time in surgery, type of anesthesia administered, narratives of procedure and final diagnosis. The study resumed again in 2006 and results from that survey were published in 2010.