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Nursing Science and Research: Understanding Evidence

Levels of Evidence

Filtered Information versus Unfiltered Information

Systematic Reviews - Highest level of evidence, sometimes called a Meta-Analysis, which attempts to summarize quantitative data.

Randomized Controlled Trials - Includes both a control and test group of subjects that fit certain criteria and are divided randomly to avoid bias.

Practice Guidelines – Developed based on available evidence to recommend a course of treatment


Filtered Information – Condensed so that the conclusions are easy to read and can be quickly applied

Unfiltered Information – Used to create filtered information and can be used as a basis for clinical decisions when other evidence is lacking

Evidence Based Practice Tutorials

Evidence Based Practice, Step by Step

The series received the Nursing Media Award for Print from Sigma Theta Tau International Awards for Nursing Excellence.