Scientific articles are peer-reviewed articles dealing with the results from research and published in an academic journals. Most scientific articles contain original and previously unpublished research which makes them primary sources, the exception being review articles.
Other shared features of scientific articles are peer-reviewing and references. Peer-reviewing is a very important part of the scientific publishing process. It means that the article has been examined and evaluated by experts prior to publishing, to ensure that the research is relevant and of good quality. Scientific articles will also include references to other scientific sources in the form of in-text citations and a list of cited reference at the end.
The two main types of scientific articles are the Experimental research article and the Review article, which are both presented in more detail below. There is also a number of atypical publications, i.e. recently accepted papers, preprint papers and retracted articles, that you might encounter and which may or may not be appropriate to use as references. You can read more about these and how to recognize them in the section Atypical publications below.
You should always evaluate the article yourself to make sure that it really is scientific, even if you find it thru a trusted channel. This becomes even more important when the article is found thru an informal channel, for example on website or a search engine such as Google Scholar. Advice on how to determine whether or not a source is scientific can be found in the section Evaluating scientific sources.
The results from experimental studies are usually reported in the form of an experimental research article. The format includes specific elements that show how the research study was designed, how the data was gathered, how it was analyzed, and what the results and conclusions are. This format usually follows a specific structure which is commonly referred to as IMRaD, i.e. Introduction-Methods-Results-and-Discussion. Sometimes these sections may be labeled a bit differently, but these basic elements are consistent. You can learn more about the content of each of the elements of IMRaD in the box below.
Introduction: Introduces the problem and why it is important, and outlines the background, purpose, and hypotheses the authors are trying to test.
Methods: Describes in detail how and, in case it is a field study, where the research was conducted. This section may be subdivided into subsections describing experimental design, machines or other materials, and statistical methods.
Results: Summarize, analyze and present the data in sufficient detail to justify the conclusions.
Discussion: The authors explain how the data fits their original hypothesis, compare with other results, state their conclusions, and look at the theoretical and practical implications of their research.
A review article is an attempt by one or more scientists to sum up and analyze the current state of the research on a particular topic. Since a review article sums up results published in primary research articles, it is in most cases a secondary source. However, review articles are, unlike research articles, good places to get an overview of a topic. Reading a review article will also help you to identify key references and authors in the given topic.
Ideally, the author(s) of a review article searches for everything relevant to the topic, and then summarize and structure it into a coherent “state of the art” story. Review articles give you information on the background and context of a subject as well as the main people working in a field, recent major advances and discoveries, significant gaps in the research, current debates and ideas about where the research is heading.
There are three different types of review articles: narrative literature reviews, systematic literature reviews and meta-analyzes. You can read more about these three types in the box below.
|The systematic review - where the author(s) use a more rigorous and systematic approach when reviewing the literature. A systematic literature study should ideally capture all relevant material and the search process should be described in such detail as to be repeatable by other researchers with the same result.|
|The meta-analysis - which is a statistical approach where the results from multiple similar experiments or studies are combined in one analysis. This is a way to increase the power of the statistical test, by using a larger sample. It can also be used to resolve uncertainties when reports disagree, by testing if the overall effect is significant. The meta-analysis can function as a primary source, but only for the results from the statistical analysis performed in the article itself.|
A recently accepted paper is an article which has gone tru peer review and has been accepted for publication in a scientific journal. These articles can be labeled "Recently accepted paper", “Publication ahead of print”, “Early view paper” or “Post-print”. The only difference from a regular research article is that the recently accepted is in manuscript form (volume and page information missing) since it has not yet been published. Since a recently accepted paper has gone thru peer review, it is perfectly fine to use as a source for scientific information.
A preprint paper is a manuscript which has not gone tru peer review and has not yet been accepted for publication in a scientific journal. The practice of publishing preprints as a way for authors to rapidly spread their research results is getting more common in Science. The most common preprint server in Biology is called BioRxiv. Preprints can be found through Google and Google Scholar and they can be very similar to regular research articles. They are often in manuscript form, but will sometimes have the same setting as an article published in a scientific journal. The manuscript form can be hard to distinguish from the Recently accepted papers described in the section above.
Since preprint papers have not gone thru peer review, they should be used with caution! A preprint paper is a work in progress, and you should always try to find a published version of the research which usually differs quite a lot from the first manuscript. Even if the paper has been published later, the preprint will remain on the preprint-server (often more accessible than the published version!) so make sure that you have the right version. If there is no published version available and you still want to cite the research, you will need to judge the scientific quality yourself.
A retraction of an article is the public withdrawal of the article. The retraction may be initiated by the editor of the journal in which the article was published, or by the author(s) of the papers (or their institution). Possible reasons for retracting an article include falsification of data, plagiarism and honest mistake. The publisher usually add a page or note on the PDF stating that the article has been retracted and why. However, older versions (without the retraction page) may be found on Google Scholar.