How to write a methods section
The methods section of a paper may be the least interesting part to write, but for the purposes of advancing science and facilitating replication attempts of your work, it’s crucial. Nevertheless, many journals have reduced the space they allow for methods or ask authors to create a summary version and provide details in supplemental materials. These requirements will be available in the journal’s “instructions to authors” guide.
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Writing the methods section of a scholarly paper
The purpose of a methods section is twofold. First, you are letting readers know what you did so that they can vet the study design and materials for themselves. With this information, they can determine for themselves whether the study seems to have any gaps or flaws or was done in with a solid design and appropriate materials. Preferably, peer-reviewers will catch any major issues during the pre-publication review and apprise authors (and editors).
The second reason that scholarly articles include a methods section is that they allow other researchers to reproduce the study or its methods, if they wish to do so. The drawback to current practices of reducing methods sections to summaries is that the lack of detail interferes with this goal. However, journals that require these summary methods usually offer authors the opportunity to provide more detail in supplemental material. Photo by CDC
What to include in your methods
Patients, animals, or cells: Methods sections usually open with a description of the people, animals, or organisms used in the study. This information should include numbers, groups that were created, including controls, and information about housing or clinical care, etc.
Laboratory processes and procedures: You also should include in a single section or several subsections the processes (methods) that you used in your study. For each of these methods, if space is allowed, you should include the materials that were required and where you obtained them (the company, city, state, country, etc.). Some authors include catalogue numbers or other specific information.
Ethics statement: Most journals require authors to include an ethics statement if the study involves humans or animals. With patients, confirmation that participants gave written, informed consent is usually required.
Statistical analysis: Methods sections usually close with a subsection on statistical analyses. This subsection should include the comparisons made, the tests used, how distributions were assessed, and the cutoff for statistical significance.
Special considerations: If you are submitting a case study, then you likely will not have a methods section. If you are submitting a systematic review or meta-analysis, then your process should follow existing guidelines (e.g., PRISMA for meta-analyses), and your methods should include details about search terms, databases searched, and number of hits returned, along with your process of excluding or including studies for consideration.
If you have long lists of reagents or materials, as in the case of a study involving many antibodies, you can refer readers to a table that lists this material.
Finally, if the procedure or procedures you use are standard practice, you do not have to detail every step. You can simply refer the reader to a publication (including one of your own) that describes the process in detail. The best way to do this is to phrase it as, e.g., “We performed PCR as described previously (reference citation).”
What not to include in your methods section
You should try to avoid including any results in your methods section. Furthermore, you should avoid discussion of results in this section. It is best to consider this section as the part of your paper where you explain to the reader “What we did.”