Primary sources are original research. They are written by the person (or people) who are directy involved (or directly observing) with something. An example would be a published peer-reviewed journal article written by a researcher describing the results of his/her experiment. Other examples include theses and conference presentations and posters.
Secondary sources report on the results or evaluate the results from primary sources. For example, a researcher might write a review article on the results of ten primary research articles summarizing the findings in that field. Or a writer might write a book on a particular scientific topic and they use sources from a variety of places.
Tertiary sources summarize information from primary and secondary sources. The most common examples of these types of sources are textbooks, factbooks, and encyclopedias.
What is peer review?
Peer review is a process where research is evaluated by other experts in the field before being published. Well respected journals require primary research articles to go through the process of being reviewed, typically by more than one researcher. These peer reviewers may send the article back to the author(s) and ask them to conduct additional experiments before the research can be published.
When looking for research articles it is important to look for journals that require peer review. These articles are more reliable.
Do you need help reading and evaluating primary sources?
A primary source is an original document often created by someone directly involved in the endeavor being reported. For example, a scientist writing about his research in an academic journal. You might have trouble reading scientific articles at first. They take skill to read. Try the following suggestions:
The easiest way to approach reading these research articles is to focus on certain sections first and not in the order in which they are presented. Information on the different sections of a primary scientific article can be found here.
Here are some tips to help you approach your reading:
Here are some tips to help you approach evaluating:
Primary scientific research articles are structured differently than a normal research paper you might write in your other classes. Typically a primary article will have:
Tables and graphs, when available, are included in the paper. Sometimes there are also keywords provided and other small sections of the paper. Different journals may have different rules on what sections to include and how to format sections and figures.
This page, from Plant Cell, gives you an example of a published research article. Notice the format. Disclaimer: This is the format for that particular journal. Follow the format your professor requires of you. This article from Plant Cell is being used only as an example of what a scientific journal article CAN look like.