A primary research article reports on a study conducted by the authors. This type of article:

• Asks a research question or states a hypothesis
• Identifies a research population
• Describes a specific research method
• Tests or measures something
• Includes a section called "method" or "methodology." 
• Includes a section called "results."

Words to look for as clues include: analysis, study, investigation, examination, experiment, numbers of people or objects analyzed, control group, or survey.

To contrast, the following are NOT primary research articles (they are secondary sources):

• Literature reviews*
• Meta-Analyses/Review articles* (arrive at conclusions based on research from many other studies)
• Editorials
• Letters
• Chapters in books
• Encyclopedia articles
• Speeches and interviews

* Literature reviews and meta-analyses also describe the authors' research method/methodology, focusing on their database search strategy and development of criteria for including or excluding individual study results. These articles are still secondary sources because they synthesize the findings of multiple research studies; the authors are not the primary researchers.

As you read and evaluate articles, look at the methods or methodology to determine the type of research conducted:

• Randomized controlled trials (RCTs)
• Cohort studies
• Case-control studies
• Cross-sectional studies
• Qualitative studies
• Other types and definitions of study designs 

Research study types are not always obvious. Researchers may use elements of more than one design to achieve their purpose. Read carefully and use your best judgement to identify the overall category or type of a particular study's methodology.