From the levels of evidence first published by the Canadian Task Force on the Periodic Health Examination (1979), ranked by David L. Sackett (1986) and carried into evidence-based medicine by Sackett and colleagues (1996).
Ranks kinds of evidence from pooled randomized trials at the top to expert opinion at the bottom, so competing claims are weighed by how well their support rules out confounding.
When to reach for it
When a decision rests on contested factual claims and someone has to decide whose evidence counts for more.
How it runs
- State the claim and whether it is causal or correlational.
- Find the strongest kind of evidence available for it.
- Judge each source for quality and fit to the case at hand.
- Weigh stronger evidence more without discarding the rest.
- Look for replication, and address studies that disagree.
Where it sits in SOLVE eX
Go to the source
- The Periodic Health Examination, Canadian Medical Association Journal 121 (Canadian Task Force on the Periodic Health Examination), 1979
- Rules of Evidence and Clinical Recommendations on the Use of Antithrombotic Agents, Chest, 1986
- Evidence Based Medicine: What It Is and What It Isn't, BMJ (David L. Sackett, William M. C. Rosenberg, J. A. Muir Gray, R. Brian Haynes, and W. Scott Richardson), 1996