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Acquiring Evidence

Subject Librarian

Lisa Tjosvold
​2K4.14 WC Mackenzie Health Sciences Centre
University of Alberta
Edmonton, AB Canada
T6G 2R7
(780) 248-2025

Purpose of this guide

To assist the user's understanding of different levels of evidence, including both pre-appraised or 'filtered' evidence and non preapparased evidence. Lists of key databases/resources for each level of research are provided.

Levels of Evidence-based Resources

Start by searching resources found at the top of the Pyramid and work your way to the bottom. 

The 6S Model of Evidence Adapted by L. Tjosvold from: Agoritsas T, Vandvik P, Neumann I, Rochwerg B, Jaeschke R, Hayward R, Guyatt G, McKibbon K. Finding Current Best Evidence. In: Guyatt G, Meade MO, Rennie D, Cook DJ. eds. JAMA evidence Using Evidence to Improve Care. New York, NY: McGraw-Hill; 2014.

Summaries & Guidelines

"Summaries integrate the best available evidence from the lower provide a full range of evidence concerning management options for a given health problem" (DiCenso 2009). 

Point of Care Tools

Evidence-based Clinical Practice Guidelines

Clinical practice guidelines often provide recommendations for clinical decision making.

Preappraised Research


These are narrative descriptions of systematic reviews, and often include a critical appraisal of the methodology used to conduct the review.


Syntheses include systematic reviews, health technology assessments and comprehensive meta-analyses.  The methodology of the review is not appraised but the methodology of individual studies within the review are assessed for quality or risk of bias.



These are narrative descriptions of high quality single studies and may include an appraisal of the study methodology.

Non Preappraised Research


The quality and validity of primary studies has not yet been critically appraised or evaluated.


Filtered Studies

Some databases include only primary studies with specific study designs such as clinical trials or diagnostic studies.

To retrieve primary research studies with the best study design appropriate to your research question, consider applying a study design filter or clinical query.

Unfiltered Studies

The majority of studies are located in unfiltered databases, which contain other references and publication types in addition to primary research, such as comments, letters, and general journal articles.  

Your Research Question

Determine the type of question you are asking  and select the most appropriate resources to use:

 Question Type



eBook Collections


Resources found in Levels of Evidence Pyramid


More information on which resources to use for your question type:

Glover J, Wang L. Find It Fast Series: #2 The clinical question. [Video]: Yale University School of Medicine; 2010 [updated January 13, 2012]; Available from:

eBook Collections

Use the Library website to search print and electronic books.  Below are selected eBook packages.  

Related Library Guide