Primary and secondary sources

When doing research, it is important to understand and make the distinction between primary and secondary sources. It tells you how close or removed the author of a piece is from the event being described and therefore indicates the source’s reliability.

What is a primary source?

Primary sources are the original evidence of certain events, objects, persons or work. Examples include experiment results, statistical data, eyewitness accounts, surveys, interviews and legal documents.

Primary sources enable students and researchers to get as close as possible to the actual event. The information in primary sources has not yet been analyzed, summarized or interpreted, which gives you the opportunity to do so yourself.

Example 1: Imagine a historical event that you are researching – say the moon landing. Of course, you can’t go back in time and experience the event yourself, so you decide to start looking for eyewitness reports, photographs, and videos taken that day. These are examples of primary sources, because they are the closest, most original accounts of the actual historic event.
Example 2: A professor is researching the study habits of college students. He uses a survey to gather data and conducts interviews with college students. The professor reports his findings and publishes them in a journal. This research is considered a primary source because it includes the original raw data, without any outside interpretation.

What is a secondary source?

A secondary source interprets, analyzes and/or explains primary sources. These sources are one or more steps removed from the original event and therefore sometimes lack the immediacy of the original content.

Some examples include (literature) reviews, opinion pieces, documentaries, television broadcasts and books.

Example 1: A filmmaker decides to make a documentary about the moon landing. He analyzes, interprets and explains the original primary source evidence, such as the photographs and eyewitness reports we mentioned earlier. This documentary is considered a secondary source, because it’s one step removed from the primary source.

Example 2: A student decides to write a paper on the study habits of students, just like the professor did in the earlier example. While doing research, the student finds the article published by the professor and decides to use it in his literature review, along with some other articles. The student interprets and compares the professor’s article to other publications. The student’s paper is considered a secondary source because it’s based upon and interprets the primary source (i.e. the article published by the professor).

Video explaining primary and secondary sources

Primary and Secondary Sources

Primary and secondary source examples

Academic disciplinePrimary sourceSecondary source
ArtPainting by Van GoghExhibition catalog explaining and interpreting the painting
GraphicsMovieMovie review
ScienceEmpirical studyLiterature review describing the study
JournalismNewspaper from World War IIThesis exploring the media coverage of World War II
HistoryAncient object from the Middle AgesMuseum catalog describing the ancient object
MusicSongSong review
EconomyAutobiography by Warren BuffettThird-party book about Warren Buffet
BiologyOriginal research about how the brain functionsBlog post about the findings of this research
MathematicsResearch on new mathematical models to calculate a rocket launchBook explaining and teaching these mathematical models
EngineeringPatentArticle about this patent and its applications
LawDeclaration of IndependenceDocumentary about the creation of the Declaration of Independence

Questions to ask yourself

To help you determine whether a source is primary or secondary, there are some simple questions you can ask yourself:

  • Was the source created at the time and/or location of the event or time period? (e.g. a photograph of the moon landing)
  • Was the person who created the source somehow directly involved in the event or time period
  • Does the source provide an outlet for persons who were directly involved in the event or time period to share their story?
  • Is the source a piece of art, a work of literature, a film created by or starring your subject of study, or a photograph?
  • Is the source a legal document, an original collection of data or statistics, or a personal communication?

If the answer to any of these questions is yes, then it’s most likely a primary source.

Context can influence which sources are primary sources

It’s important to be aware that your research focus and your research question have an impact on what is considered to be a primary source for your specific research.

Let’s say you write a paper about the September 11 attacks. You could consult primary sources such as news articles written at the time, photographs, TV news clips, interviews with people who were onsite, and radio clips from that time. Secondary sources could include documentaries or newspaper articles.

Now let’s assume your paper is not about the September 11 attacks itself, but about the media coverage of the September 11 attacks. In this scenario, the documentaries and newspaper articles become the primary sources.

Primary vs. secondary sources: which is better?

In general, primary sources are considered more credible and authoritative. They report actual evidence, and evidence cannot be wrong.

However, there are secondary sources (e.g. literature reviews) that combine a great deal of prior research and analyze the collection of research from a unique perspective. Using and citing such a literature review could add great value to your own research.

Your research will involve the use of both primary and secondary sources. Even if you are conducting a scientific experiment, you will draw upon previous methods used by others, existing theories, and complete a review of the extant literature.

Remember to cite the primary and secondary sources you decide to use to avoid plagiarism.

Locating primary sources

If you are not conducting an experiment or gathering the primary data yourself, the best way to find primary sources is through secondary sources.

Most often, finding the primary source upon which a secondary source is based is fairly easy, as the information should be readily shared.

You’ll find this information in three key places in the secondary source:

  • Works cited
  • Reference list
  • Internet links, in the case of online resources

For example, let’s say you find an interesting quote from Barack Obama cited in a news article: “As Obama said in a 1995 interview with the Washington Post…” It’s clear that you need to locate the original Washington Post interview, as the interview is the primary source.

For this reason, it is crucial that you complete a thorough literature review, paying attention to the primary sources upon which your secondary sources are based.

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Raimo has a bachelor's and master's degree and has written several papers and theses. He likes to share his knowledge by writing helpful articles.

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