- Hierarchy of evidence
Evidence hierarchies reflect the relative authority of various types of
biomedical research . Although there is no single, universally-accepted hierarchy of evidence, [Two examples of evidence hierarchies can be found in the qualification of evidence section of the Wikipedia article onevidence-based medicine .] there is broad agreement on the relative strength of the principal types of research.Randomized controlled trials (RCTs) rank aboveobservational studies , while expert opinion and anecdotal experience are ranked at the bottom. Some evidence hierarchies placesystematic review andmeta analysis above RCTs, since these often combine data from multiple RCTs, and possibly from other study types as well. Evidence hierarchies are integral toevidence-based medicine .The use of evidence hierarchies has been criticized as allowing RCTs too much authority. Not all research questions can be answered through RCTs, either because of practical issues or because of ethical issues. Moreover, even when evidence is available from high-quality RCTs, evidence from other study types may still be relevant.
References
External links
School of Health and Related Research, University of Sheffield, "Hierarchy of evidence". http://www.shef.ac.uk/scharr/ir/units/systrev/hierarchy.htm. Accessed 2008-03-31.
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