When to use primary vs. secondary sources

Primary sources can be described as those sources that are closest to the origin of the information. They contain raw information and thus, must be interpreted by researchers. Secondary sources are closely related to primary sources and often interpret them.
  • Primary and secondary sources serve various purposes. 
  • You should use primary sources to back up your claims when you're presenting a theory or argument you've constructed or when you're making a clear assertion of fact. 
  • Citing primary sources enables you to provide clear, credible, and verifiable evidence to support your claims. 
  • Basically, primary sources should be your primary sources if your paper adds something new to the body of knowledge already known about the subject you are researching.
  • Most likely, you'll be required to use both primary and secondary sources for assignments. Secondary sources can support primary sources in your argument if you're writing a piece that covers the subject in greater detail.

Example 1:

You might cite statistics gathered by law enforcement authorities and organizations like the Highway Traffic Safety Administration in an article describing the elements known to reduce motor vehicle accidents (primary source). You could also rely on secondary sources like books about improvements in vehicle safety and articles about statistics on auto accidents (secondary source).

Example 2:

A paper disputing widely held biographical details about a historical figure in which you include quotes from their journals (primary source) and compare and contrast your findings.