Hierarchy of clinical evidence Hierarchy of clinical evidence. Adapted, with permission, from SUNY Downstate Medical Center, Medical Library of Brooklyn. Evidence Based Medicine Course. A Guide to Research Methods: The Evidence Pyramid. 2004. http://library.downstate.edu/EBM2/2100.htm. Accessed May 4, 2012. Source: Chapter 10. Observational Research, Understanding Clinical Research Citation: Lopes RD, Harrington RA. Understanding Clinical Research; 2013 Available at: http://accessmedicine.mhmedical.com/DownloadImage.aspx?image=/data/Books/harr1/harr1_c010f001.png&sec=45408121&BookID=674&ChapterSecID=45407255&imagename= Accessed: December 26, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved