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Clinical article

Laboratory investigation

Literature review (including systematic review)

Case report

Technical note

Historical vignette


Letter to the editor or response

1. Original research: These are detailed studies reporting original research and are classified as primary literature. They include hypothesis, background study, methods, results, interpretation of findings, and a discussion of possible implications. Original research articles are long, with the word limit ranging from 3000 to 6000,2,3 and can even go up to 12000 words for some journals.1 These require a significant investment of time.

2. Review article: Review articles give an overview of existing literature in a field, often identifying specific problems or issues and analysing information from available published work on the topic with a balanced perspective.1 These are considered as secondary literature and can be a particularly efficient way for early career researchers to begin publishing. Review articles can be of three types, broadly speaking: literature reviews, systematic reviews, and meta-analyses. Review articles are usually long, with the maximum word limit being 3000-5000 or even more, depending on the journal.1-3 However, some journals also publish short reviews.

3. Clinical case study: Clinical case studies present the details of real patient cases from medical or clinical practice. The cases presented are usually those that contribute significantly to the existing knowledge on the field. The study is expected to discuss the signs, symptoms, diagnosis, and treatment of a disease.1,5 These are considered as primary literature and usually have a word count similar to that of an original article. Clinical case studies require a lot of practical experience and may not be a suitable publication format for early career researchers.5

4. Clinical trial: Once again, specific to the field of medicine, clinical trials describe the methodology, implementation, and results of controlled studies, usually undertaken with large patient groups.1,5 Clinical trial articles are also long, usually of about the same length as an original research article. Clinical trials also require practical work experience, as well as, high standards of ethics and reliability.5 So this format is more useful for experienced researchers.

5. Perspective, opinion, and commentary: Perspective pieces are scholarly reviews of fundamental concepts or prevalent ideas in a field. These are usually essays that present a personal point of view critiquing widespread notions pertaining to a field.1-3 A perspective piece can be a review of a single concept or a few related concepts. These are considered as secondary literature and are usually short articles, around 2000 words.2

Opinion articles present the author’s viewpoint on the interpretation, analysis, or methods used in a particular study. It allows the author to comment on the strength and weakness of a theory or hypothesis. Opinion articles are usually based on constructive criticism and should be backed by evidence.1 Such articles promote discussion on current issues concerning science. These are also relatively short articles.

Commentaries are short articles usually around 1000-1500 words long that draw attention to or present a criticism of a previously published article, book, or report, explaining why it interested them and how it might be illuminating for readers.

6. Book review: Book reviews are published in most academic journals. The aim of a book review is to provide insight and opinion on recently published scholarly books. Book reviews are also relatively short articles and less time-consuming. Book reviews are a good publication option for early-career researchers as it allows the researcher to stay abreast of new literature in the field, while at the same time, adding to his publication list


1. Frontiers in group. Frontiers in Neuroscience [Accessed Feb 18, 2015] Available from

2. Sage Publications. Manuscript Submission Guidelines [Accessed Feb 18, 2015] Available from

3. Nature Publications. Author Resources [Accessed Feb 18, 2015] Avaialable from

4. AcademyHealth. Writing Articles for Peer-review Publications: A Quick Reference Guide [Accessed Feb 19, 2015] Available from

5. University of Colorado Libraries. Publish, Not Perish: The Art & Craft of Publishing in Scholarly Journals, Module 1, Overview of Scholarly Publishing [Accessed Feb 18, 2015] Available from

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