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TABLE 7-1Research Evidence Hierarchy

LevelElement
I.Randomized controlled trial
II.Controlled trial without randomization
Cohort or case control analytic study
Multiple time series
Uncontrolled experiment with dramatic results
III.Case study
Expert opinion

SOURCE: Last, 1995, by permission of Lancet Ltd. All rights reserved.

From: 7, Evaluating and Disseminating Intervention Research

Cover of Health and Behavior
Health and Behavior: The Interplay of Biological, Behavioral, and Societal Influences.
Institute of Medicine (US) Committee on Health and Behavior: Research, Practice, and Policy.
Washington (DC): National Academies Press (US); 2001.
Copyright © 2001, National Academy of Sciences.

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