The Oxford CEBM Levels of Evidence: Introductory Document

Howick, J., Chalmers, I.,  Glasziou, P.,  Greenhalgh, T., Heneghan, C., Liberati, A., Moschetti, I., Phillips, B., & Thornton, H. (2011). The 2011 Oxford CEBM Evidence Levels of Evidence (Introductory Document). Oxford Centre for Evidence-Based Medicine.

The OCEBM Levels of Evidence outlines the hierarchy of the likely best evidence and is designed to be used as a heuristic that clinicians, researchers and patients can use to answer clinical questions quickly and without resorting to pre-appraised sources.