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Undergraduate Nursing Resources


PICO is a framework for asking focused clinical questions.

PICO stands for:

Patient and Problem
Intervention or exposure
Comparison or Control

Grey Literature

You may hear your professor say that you need to look in the grey literature for information.  In its most simple definition, grey literature is anything outside of the usual academic (book and journal) publishing world.  Grey literature can be government documents, agency reports, white papers, and other non-published items.  For example Evidence Based Clinical Guidelines could often be considered grey literature.

Evidence Based Practice Hierarchy

Evidence Based Practice PyramidHierarchy of Evidence Summary

Level I:
a. Evidence of a systematic review or meta analysis of all relevant randomized controlled trials (RCT), or evidence-based clinical practice guidelines based on the above.
​b. Evidence of a systematic review of RCTs
​c. Evidence of a systematic review of nonrandomized trials

Level II:
a. Evidence from at least 1 RCT.
​b. Single nonrandomized trial

Level III: Evidence from a systematic review of correlational/observational studies

Level IV: Evidence from a single correlational/observational study

Level V: Evidence from systematic reviews of descriptive,  qualitative or physiologic studies.

Level VI: Evidence from a single descriptive, qualitative, or physiologic study.

Level VII: Evidence of authority opinion or reports of expert committees.

Pyramid modified from: Navigating the Maze, University of Virginia, Health Sciences Library, by University of Washington. Health Sciences Library and Information Center

Find the Evidence

Systematic Reviews:
Cochrane Database of Systematic Reviews:

Other Systematic Reviews and Meta-Analyses:

Evidence Guidelines:

Journal Articles and Original Studies:

Clinical Research Critiques:

Case Reports, Case Series, Other Articles, Practice Guidelines:

Clinical pathways, textbook summaries, practice guidelines:

Meta-Search Tools:

  • ACCESSSS - McMaster University resource, with pre-appraised evidence to support clinical decisions
  • TRIP+ Database (Turning Research Into Practice) - this database arranges results using the hierarchy of evidence levels.
  • SUMSearch- University of Kansas, returns research broken down into original research, systematic reviews, and guidelines
  • Epistemonikos - Metasearch in mutilple languages

More information about EBP

Basic Information and Tutorials about EBP:

Writing your topic a PIO, PICO, PICOT question: