There is often uncertainty about how best to diagnose or manage various medical conditions. One accepted approach to guide clinicians through circumstances of uncertainty is to elicit opinions from experts in the field. This approach, first developed and validated by the RAND Corporation, is now widely employed to identify areas of variation and consensus in medical fields lacking sufficient high-level evidence to guide decision-making. This technique is especially suited for defining "appropriateness" of care when standards of appropriateness are otherwise lacking. Member of the Center have experience in convening and conducting expert panels across a range of medical conditions, including gastrointestinal bleeding, irritable bowel syndrome, and chronic viral hepatitis, among others. In addition, members of the Center have served as experts on similar panels, and are therefore in the unique position of having participating in and planned expert panels.