Since peer review week has made an entrance, I’ve been thinking about the nature of this process with both my editor and researcher hats on. Perhaps you’ve recently been asked to review a paper for a journal? I remember the first time I was ask to perform this role when I was still working on my PhD. It felt like a considerable honour and was also a little scary; was I really in a position to evaluate someone else’s work?
Don’t worry. You are. Editors don’t just ask random people to work on papers as peer-reviewers, and there will be a good reason (or reasons) why you have been selected. Reviewers are selected for one (or more) of three reasons: (i) you have been suggested by the authors of the study in question; (ii) you have been identified by a member of the journal’s editorial board, or (iii) a reviewer search engine has found you because of your previous work in the field. Being selected to review a paper can therefore be taken as a positive because at least it means you are ‘known’ in the field. This is particularly the case for Early Career Researchers; it’s a good idea to keep a record of such invitations so you can add them to your CV (‘performed peer-review for the following high-profile journals’).
What comes next? Having agreed to perform a review of someone else’s paper, it’s important to bear four things in mind: please try to be constructive, positive, thoughtful, and on time. And don’t be afraid to discuss your views of a paper with the editor; this will be much appreciated. Also, if you need more information about the study (or authors) from the editor, please ask; perhaps you need additional supplementary data from the authors, or copies of work cited as ‘in press’ in order to properly comment. Peer review should be a collaborative process between you, the editor, and then the authors as papers are returned, revised, and updated in light of your comments.
Similarly, it’s also important to be aware of your limitations and thus to not provide comments on an area of a study if you simply don’t have the expertise. As an example, although I’ve reviewed lots of papers in my field I would also baulk at sections containing analyses of numbers or statistics and flag these areas to the editor: ‘I am not a mathematician and so sections of this study should be looked at by someone with more appropriate expertise’. It's also well worth bearing in mind that, unless you choose to remain anonymous (or if that is journal policy), your name is likely to appear in the Acknowledgements section of this paper; ‘how did that paper get published?’, ‘oh, because Smith and Jones were peer reviewers’ is a situation best avoided.
My suggestions: Try to be positive and find reasons to be supportive, constructive, and work to make suggestions that will eventually lead to the acceptance of a paper (even after multiple rounds of revision) rather than trying to find reasons to reject. This is good advice in all cases apart from rare examples of studies that are simply so terrible there is no chance of acceptance (and which should have been filtered out by the journal or editor in pre-peer-review). Also, please don’t take on a review if you don’t have the time.