Concept

Hierarchy of evidence

Overview

A hierarchy of evidence, comprising levels of evidence (LOEs), that is, evidence levels (ELs), is a heuristic used to rank the relative strength of results obtained from experimental research, especially medical research. There is broad agreement on the relative strength of large-scale, epidemiological studies. More than 80 different hierarchies have been proposed for assessing medical evidence. The design of the study (such as a case report for an individual patient or a blinded randomized controlled trial) and the endpoints measured (such as survival or quality of life) affect the strength of the evidence. In clinical research, the best evidence for treatment efficacy is mainly from meta-analyses of randomized controlled trials (RCTs) and the least relevant evidence is expert opinion, including consensus of such. Systematic reviews of completed, high-quality randomized controlled trials – such as those published by the Cochrane Collaboration – rank the same as systematic review of completed high-quality observational studies in regard to the study of side effects. Evidence hierarchies are often applied in evidence-based practices and are integral to evidence-based medicine (EBM).

Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).

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Simplicity and objectivity do not have to be secured through elaborate and labored metaphysical construction. The data are simple and the hypothesis objective in so far as they accomplish the work where unto they are called--the removal of conflict, ambiguity, and inhibition in conduct and affection. In the experimental conception of inference it is clear that the principles of formal logic must play their role…
John Dewey, Creative Intelligence
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The most universal of the forms in which this difference of method is accustomed to present itself, is the ancient feud between what is called theory, and what is called practice or experience. There are, on social and political questions, two kinds of reasoners: there is one portion who term themselves practical men, and call the others theorists; a title which the latter do not reject, though they by no…
John Stuart Mill, Essays on some unsettled Questions of Political Economy
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An abstractive hierarchy is called ‘finite’ if it stops at a finite grade of complexity. It is called ‘infinite’ if it includes members belonging respectively to all degrees of complexity. It is to be noted that the base of an abstractive hierarchy may contain any number of members, finite or infinite. Further, the infinity of the number of the members of the base has nothing to do with the question as to whether…
Alfred North Whitehead, Science and the modern world
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Related ideas

Place in the tradition

Part of Philosophy of medicine.

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