This the knowledge based on facts and learned through experiments and observations. Commonly done through theory or hypothesis testing. Objectively conducted experiments usually performed in a controlled enviornemnt. An idea or set of ideas that is intended to explain facts or events - (merriam-webster) Based principle behind ebm: we should treat where there is evidence of benefit and not treat where there is evidence of no benefit (no harm) The systematic use of an approach to critically evaluate all medical knowledge used in medical education and clinical practice dates from the 1980"s. Clinical decision making is based on data from research. Health care providers, health care policy makers, and hospital administrators make decisions based on the latest information from clinical trials and other medical research. His knowledge was based on experience and through understanding of patient care. Common sources included: personal experiences, reasoning and intuition, colleagues.