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Health & Behavioral Sciences

The Medical Research Process

Levels of Evidence 

Levels of evidence from broadest to most rigorous

In vitro research - "test tube" research performed with cells, biological molecules or microorganisms outside of their biological context.

Animal research - research performed on non-human animals to control variables that affect behavioral or biological systems being studied.

Ideas, editorials, opinions - analysis and opinions of individuals often experts in the field being discussed.  These ideas do not necessarily reflect the opinions or recommendations of the medical community as a whole.

Case series - research that tracks subjects with a known exposure like a treatment.  Tracking is generally done through medical records.

Case control studies - observational research which compares two groups with differing outcomes to determine causes and natural history.

Randomized controlled trials - research that attempts to reduce bias by randomly assigning subject to two or more groups with differing interventions and comparing them to a measured response.

Randomized controlled double blind studies - these are considered the gold standard for medical evidence.  Like a randomized controlled trial, subjects are assigned to two or more groups for comparison of a response, but neither the participant nor the researcher knows to which group the participant has been assigned.  This research, when correctly performed, produces results that are unbiased.



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