Structure of a scientific paper
George M. Hall
Professor of Anaesthesia, St George's Hospital Medical School and Chairman of the Board of British Journal of Anaesthesia
Structure of a Scientific paper
The research you have conducted is obviously of vital importance and must be read by the widest possible audience. It is probably safer to insult a colleague's spouse, family, and driving rather than the quality of his or her research. Fortunately, there are now so many medical journals that your chances of not having the work published somewhere are small. Nevertheless the paper must be constructed in the approved manner and presented to the highest possible standards.
There is no doubt that editors and assessors look adversely on scruffy manuscripts regardless of the quality of the science. All manuscripts are constructed in a similar manner, although there are some notable exceptions such as the format used by Nature.
These exceptions are unlikely to trouble you in the early stages of your research career.
Introduction
The introduction shouid be brief and must state clearly the question that you tried to answer in the study. To lead the reader to this point it is necessary to review briefly the relevant literature.
Many junior authors have difficulties in writing the introduction. The most common problem is the inability to state clearly what question was asked. This should not occur if the study was planned correctly. It is too late to rectify basic errors when attempting to write the paper. Nevertheless, some studies seem to develop a life of their own and the original objectives can easily be forgotten. I find it useful to ask collaborators from time to time what question we hope to answer. If I do not receive a short clear sentence as an answer, then alarm bells ring.
A review of the literature must not appear in the introduction. Only cite those references that are essential to justify your proposed study. Three citations from different groups are usually sufficient to convince most assessors that some fact is "well known" or "well recognised", particularly if the studies are from different countries.
Many research groups write the introduction to a paper before the work is started, but you must never ignore pertinent literature published during the conduct of the study. For example: It is well known that middle-aged male runners have diffuse brain damage [1,2,3], but whether this was present before running, or arises as a result of repeated cerebral contusions during exercise, has not been established. In the present study we exa mined cerebral function in a group of sedentary middle-aged men before and after a 6 month exercise programme. Cerebral function was assessed by …
Methods
This important part of the manuscript has become increasingly neglected and yet the methods section is the most common cause of absolute rejection of a paper. If the methods used to try to answer the question were inappropriate, or flawed, then there is no salvation for the work.
The main purposes of the methods section are to describe, and sometimes defend, the experimental design and to provide sufficient detail so that a competent worker can repeat the study. The latter is particularly important when you are deciding how much to include in the text. If standard methods of measurement are used then appropriate references are all that is required. In many instances "modifications" of published methods are used and it is these that cause difficulties for other workers.
To ensure reproducible data, authors should:
- Give complete details of any new methods used
- Give the precision of the measurements undertaken
- Use statistical analysis sensibly
The help of a statistician should be sought at the planning, stage of any study. Statisticians are invariably helpful and have contributed greatly to improving both the design and analysis of etica investigations. They cannot be expected, however, to resurrect a badly designed study.
Results
The results section of a paper has two key features: there should be an overall description of the major findings of the study; and the data should be presented clearly and concisely.
It is not necessary to present every scrap of data that you have collected. There is a great temptation to give all the results, particularly if they were difficult to obtain, but this section should contain only relevant, representative data. The statistical analysis of the results must be appropriate. The easy availability of statistical software packages has not encouraged young research workers to understand the principles involved. The analysis presented must pass what is called the "Mark I Eyeball Test," sometimes known as the "BOT" (b... obvious test).
An assessor is only able to estimate the validity of the statistical tests used, so if your analysis is complicated or unusual expect your paper to undergo apprasal by a statistician.
You must strive for clarity in the results section by avoiding unnecessary repetition of data in the text, figures, and tables. It is worthwhile stating briefly what you did not find, as this may save other workers in this area from undertaking unnecessary studies.
Discussion
The initial draft of the discussion is almost invariably too long. It is difficult not to write a long, detailed analysis of the literature that you know so well. However, a rough guide to the length of this section is that it should not be more than one third of the total length of the manuscript (Introduction + Methods + Results+Discussion). Ample scope often remains for further pruning.
Many beginners find this section of the paper difficult. It is possible to compose an adequate discussion around the points outlined below. Writing the discussion:
- Summarise the major findings
- Discuss possible problems with the methods used
- Compare your results with previous work
- Discuss the clinical and scientific (if any) implications of your findings
- Suggest further work
- Produce a succinct conclusion
Common errors include repetition of data already given in the results section, the belief that your methods were beyond criticism, and the preferential citing of previous work to suit your conclusions. Good assessors will seize upon such mistakes, so do not even contemplate trying to deceive them.
Although IMRAD describes the basic structure of a paper, there are other important parts of a manuscript. It is salutary to remember that many people will read the title of the paper, and some will read the summary, but very few will read the complete text.
The title and summary of the paper are of great importance for indexing and abstracting purposes, as well as enticements to persuade the reader to peruse the complete text.
The use of appropriate references for a paper is essential, this an area commonly full of mistakes. A golden rule is to list only relevant, published references and present them in a manner that is appropriate for the particular journal. The citation of large numbers of references is an indicator of insecurity, not of scholarship. An authoritative author knows the important references that are appropriate to the study.
Before you start the fírst draft of the manuscript, read carefully the "Instructions to authors" which every journal publishes and prepare the paper accordingly. Some journals give detailed instructions, often annually, and these can be a valuable way of learning some of the basic rules. It is a grave mistake to submit a paper in the style of another journal; this suggests that it has been rejected recently. At all stages of preparation of the paper, go back and check with the instructions to authors and make sure that your manuscript conforms. It seems very obvious, but if you wish to publish in the European Annals of Andrology do not write your paper to conform wit the Swedish Journal of Androgen Research. Read and reread the instructions to authors.
Variations on the IMRAD system are sometimes necessary in specialised circumstances, such as a letter to the editor, an abstract for presentation at a scientific meeting, or a case report. Nevertheless, it is a fundamental system that is the basis of all scientific papers.
Hall G: Structure of a Scientific Paper. How to write ti paper. BMJ, Editor George M. Hall
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