Doctors from Beaumont Hospital in Troy, Michigan, looked at more than 2,000 patient-satisfaction surveys from the first part of 2007 and found that patients whose stays in the ER lasted up to three and a half hours had satisfaction scores in the 83rd percentile as compared with patients at comparable ERs around the country. But for those who spent between three and a half and four hours, satisfaction plunged to the 49th percentile. And those who spent more than four hours had an average satisfaction score in the 24th percentile.