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BIOL 5503: Research Methods

Primary v. Secondary Sources

Graduate and professional researchers need to recognize when they're looking at an original research article or a review article. When citing a particular finding, you should cite the first article that shared this finding. Original research articles are typically where new findings are shared with the research community. 

As a researcher, you need to know how to tell the difference between an original research article (primary source) and a review article (secondary source).


Primary Sources / Original Research

In the sciences, a primary source is also called “original research” or an “original research article.” This means that the authors of the article are reporting the findings of an original experiment or study that they performed themselves. An “original research article” is the first time that these findings have been shared.

In the sciences, most original research articles have the following outline:

  1. Introduction
  2. Materials & Methods
  3. Results
  4. Discussion
  5. Conclusion
  6. References

Sometimes the Methods section is at the end of the article instead of near the beginning, but the Methods section is a required piece of an original research article. When sharing the findings of an original experiment or study, authors must describe exactly how they designed and performed the study.


Secondary Sources / Review Articles

In the sciences, a secondary source is usually called a review article. It is called a “secondary source” because the author(s) are describing and summarizing previous research. 

The purpose of a review article is to gather all of the previous research on a particular topic. After reviewing the previous research, the author(s) of a review article will summarize all of this research to inform the audience of things like:

  • Which studies had similar findings.
  • Which studies had different findings or disagreed with each other.
  • Which questions are still unanswered and need to be researched.

Review articles identify where we've been and where we need to go in researching a particular topic.


How to Tell the Difference?

The best way to tell the difference between an original research article (primary) and a review article (secondary) is to look at the Methods section.

  • Original research articles must have a Methods section. This section describes the study design, including who/what was the subject of the study, what was done to the subjects and how, how long the study lasted, and how the study data was analyzed afterwards.
  • Review articles aren’t required to have a Methods section, because no original experiment or study was performed. If you find an article that is peer-reviewed (has a References list) but it doesn’t have a Methods section, it’s probably a review article. IF a review article has a Methods section, it only describes how the authors searched for the articles they used in the review: which databases were searched, which search words were used, and other criteria for including or excluding an article from the review.

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