1. From the Southern California Evidence-Based Practice Center (which includes the RAND Health Division), Santa Monica, Cedars–Sinai Medical Center and the Greater Los Angeles Veterans Administration Health Care System, Los Angeles, and Center for the Study of Health Care Provider Behavior, Sepulveda, California; the University of Nijmegen, Centre for Quality of Care Research, Nijmegen, the Netherlands; and the University of Aberdeen, Health Services Research Unit, Aberdeen, Scotland, United Kingdom.