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Nursing Research Guide

Guidance for Nurses and Allied Health Researchers

What is a primary source?

In healthcare literature, a  primary source is a document or record (usually a peer reviewed journal article) which reports a study, experiment, event or other phenomenon firsthand. Primary sources detail original research and are usually written by the person(s) who did the research or conducted the study. 

Primary Sources include:

  • pilot/prospective studies
  • cohort studies
  • survey research
  • case studies, case series
  • qualitative studies
  • clinical trials and  randomized clinical trials/RCTs
  1. Read the Method section of an article to determine what kind of research was conducted. If you cannot find a section that details the method- you are probably not looking at a primary source.
  2. Protocol articles talk about studies that have not yet occurred. They are not reporting evidence, they are describing a plan to generate evidence. Note if the method section is past tense or future tense.
  3. Pre-prints of peer-reviewed articles may be available but they have not undergone the peer-review process, etc. They are not generally acceptable sources for assignments.

Searching for Primary Sources (original research, unfiltered sources)

Randomized Controlled Trials, Case Studies, Cohort Studies, Clinical Studies, etc.

Check for filters to limit your search by study type. Look for clues in title or abstract. Read the "Method" section; if the author's methods only involve search for literature and analyzing publications that detail the clinical work of others, it is not a primary source.

What is a secondary source?

Secondary sources evaluate or synthesize multiple primary studies so as to draw conclusions on or present our current state of knowledge in a discipline or subject. These are typically peer-reviewed before being published. Secondary sources often include a bibliography which may direct you back to the primary research reported in the article.

Topic Reviews, literature reviews, and narrative reviews are overviews of a topic (these can make great background sources).

Systematic Reviews and Meta-analyses are the most comprehensive investigations into the healthcare literature, which is why they are at the top of the evidence pyramid. 


 key characteristics of a systematic review are:

  • a clearly stated set of objectives with pre-defined eligibility criteria for studies;
  • an explicit, reproducible methodology;
  • a systematic search that attempts to identify all studies that would meet the eligibility criteria;
  • an assessment of the validity of the findings of the included studies, for example through the assessment of risk of bias; and
  • a systematic presentation, and synthesis, of the characteristics and findings of the included studies.

Meta-analysis is the use of statistical methods to summarise the results of independent studies. By combining information from all relevant studies, meta-analyses can provide more precise estimates of the effects of health care than those derived from the individual studies included within a review. Meta-analyses also facilitate investigations of the consistency of evidence across studies, and the exploration of differences across studies.

Cochrane Handbook 1.2.2

Searching for Secondary Sources, Filtered Sources

Systematic Reviews and Meta-analyses- the top of the EBP pyramid.

Use filters to limit your search by study type. Look for clues in the title or abstract. Read the "Method" section; if the authors conducted any clinical work it is not a systematic review or meta-analyisis.