Reports original research or experimentation
- Empirical: uses data collected by the article's authors themselves or by others (for example, US Census data) (Example)
Critically surveys and analyzes the current state of published research on a particular topic; doesn't include original research
- Includes narrative literature reviews, systematic review, meta-analysis, and meta-synthesis (Example)
Describes one or more theories, frameworks, models, etc. and tends not to include empirical data
- May describe development of a theoretical approach, compare theories, or discuss issues surrounding a theory (Example)
Comments on or offers a perspective or opinion on a topic; doesn't require original research
- May appear as an article in a column, editorial, letter to the editor, etc. (Example)