Comparative Effectiveness Research (CER) has become one of the most important and recent developments in health services and health policy research. Briefly, CER can be thought of as research that seeks to improve the effectiveness, efficacy and efficiency of health care by “comparing alternative methods of prevention, diagnosis, treatment, and monitoring of care delivery.”1,2  Although researchers and governments in several European countries have used CER extensively since the 20th century, it was only in 2009 that policymakers and researchers in the United States placed increasing emphasis on this research approach. That year, the American Recovery and Reinvestment Act and, by extension, the Health Information Technology for Economic and Clinical Health Act included more than $1.1 billion worth of funding for CER. The Affordable Care Act, passed the following year, established the Patient-Centered Outcomes Research Institute (PCORI) and, with it, set aside more than$3.5 billion of CER...