Details to include in your methods:
- Where – from which population and where were adverts distributed
- When – actual date ranges
- How – email, flyers, advert, targeted messages etc
- Inclusion and exclusion criteria – even if there were no exclusion criteria you should explicitly state that!
- Ethical approval – who awarded it, what were the reference numbers for people to check,
- How consent was obtained – “written informed consent”, parent/guardian etc
- How participants were segregated into groups – how was randomisation achieved, what were the demographic boundaries or other criteria used for segregation
- How sample sizes were decided – details of your power analyses etc
- Anything else relevant to data analysis
The actual demographics of who was recruited is usually better placed in the results section rather than methods.
Most of my work has not been involved extensive patient recruitment, however, here is an excerpt from our sunscreen paper;
I have added annotations in bold and italics eg (#6) to indicate what I am describing (using the numbering system above).
Note: I’m not saying this example is the best possible way to write methods. Methods section can be really dry so I have added a few softer linkers between sentence to make it a little more narrative, a little easier to digest. Not more than a couple of words longer, but less stark.
The study was approved by University of Liverpool Ethics Review Board with approval number 201606181 (#5). Written consent was obtained from all participants prior to both phases of the trial (#6). The individuals whose images have been used in this manuscript have given written informed consent (as outlined in PLOS consent form) to publish their case details here (#6).
Sample sizes were determined based on preliminary data where 4 participants were analysed from two identical non-intervention visits and one intervention visit (SD = 8) . Power analyses were performed based on 95% power and 5% type I error rate; to detect an increase of at least 5% after intervention requires 57 participants assuming paired t-test (#8). 57 people (27 male and 30 female) were recruited in October to December (#2) through poster advertising and an email cascade to all staff and students of the Institute of Ageing and Chronic Disease, University of Liverpool (#1 and 3). There were no exclusion criteria based on demographics, ethnicity or other personal criteria, however, excluded from the study were volunteers who self-identified as having allergies to sun lotion (#4). Volunteers were required to fill in a pre-questionnaire before participating in the study (S1 Fig), requiring them to confirm whether they had used any form of sun protection previously, and whether they had any known allergies. Participants were also requested to self-identify their skin-type based on provided Fitzpatrick scale diagram.
Participants were then allowed to self-select (#7) from either SPF50 spray or SPF50 cream sunscreen formulations (both Nivea, Birmingham, UK) and instructed to apply sunscreen in their usual manner. No instructions were provided regarding volume of solution to use.(#9)