Peer reviewers play a role in ensuring the integrity of the scholarly record. The peer review process depends to a large extent on the trust and willing participation of the scholarly community and requires that everyone involved behaves responsibly and ethically. Peer reviewers play a central and critical part in the peer review process but may come to the role without any guidance and be unaware of their ethical obligations. Journals have an obligation to provide transparent policies for peer review, and reviewers have an obligation to conduct reviews in an ethical and accountable manner. Clear communication between the journal and the reviewers is essential to facilitate a consistent, fair and timely review.
Peer review, for the purposes of these guidelines, refers to reviews provided on manuscript submissions to journals, but can also include reviews for other platforms and apply to public commenting that can occur pre- or post-publication. Reviews of other materials such as preprints, grants, books, conference proceeding submissions, registered reports (pre-registered protocols), or data will have a similar underlying ethical framework, but the process will vary depending on the source material and the type of review requested. The model of peer review will also influence elements of the process.
Being a reviewer
Professional responsibility: Authors who have benefited from the peer review process should consider becoming peer reviewers as a part of their professional responsibilities. Some journals require a formal process of appointment to the review panel, and some require specific expertise; anyone interested in becoming a reviewer should look for the journal guidelines on peer review and follow any requirements posted. In order to assign appropriate reviewers, editors must match reviewers with the scope of the content in a manuscript to get the best reviews possible. Potential reviewers should provide journals with personal and professional information that is accurate and a fair representation of their expertise, including verifiable and accurate contact information. It is important to recognize that impersonation of another individual during the review process is considered serious misconduct (e.g. see COPE Case 12-12: Compromised peer review in published papers). When approached to review, agree to review only if you have the necessary expertise to assess the manuscript and can be unbiased in your assessment. It is better to identify clearly any gaps in your expertise when asked to review.
Competing interests: Ensure you declare all potential competing, or conflicting, interests. If you are unsure about a potential competing interest that may prevent you from reviewing, do raise this. Competing interests may be personal, financial, intellectual, professional, political or religious in nature. If you are currently employed at the same institution as any of the authors or have been recent (e.g., within the past 3 years) mentors, mentees, close collaborators or joint grant holders, you should not agree to review. In addition, you should not agree to review a manuscript just to gain sight of it with no intention of submitting a review, or agree to review a manuscript that is very similar to the one you have in preparation or under consideration at another journal.
Timeliness: It is courteous to respond to an invitation to peer review within a reasonable time-frame, even if you cannot undertake the review. If you feel qualified to judge a particular manuscript, you should agree to review only if you are able to return a review within the proposed or mutually agreed on time-frame. Always inform the journal promptly if your circumstances change and you cannot fulfill your original agreement or if you require an extension. If you cannot review, it is helpful to make suggestions for alternative reviewers if relevant, based on their expertise and without any influence of personal considerations or any intention of the manuscript receiving a specific outcome (either positive or negative).
Conducting a review
Initial steps: Read the manuscript, supplementary data files and ancillary material thoroughly (e.g., reviewer instructions, required ethics and policy statements), getting back to the journal if anything is not clear and requesting any missing or incomplete items you need. Do not contact the authors directly without the permission of the journal. It is important to understand the scope of the review before commencing (i.e., is a review of raw data expected?).
Confidentiality: Respect the confidentiality of the peer review process and refrain from using information obtained during the peer review process for your own or another’s an advantage, or to disadvantage or discredit others (e.g. see COPE Case 14-06: Possible breach of reviewer confidentiality). Do not involve anyone else in the review of a manuscript (including early career researchers you are mentoring), without first obtaining permission from the journal (e.g. see COPE Case 11-29: Reviewer asks the trainee to review manuscript). The names of any individuals who have helped with the review should be included so that they are associated with the manuscript in the journal’s records and can also receive due recognition for their efforts.
Bias and competing interests: It is important to remain unbiased by considerations related to the nationality, religious or political beliefs, gender or other characteristics of the authors, origins of a manuscript or by commercial considerations. If you discover a competing interest that might prevent you from providing a fair and unbiased review, notify the journal and seek advice (e.g. see COPE Case 15-05: Reviewer requests to be added as an author after publication). While waiting for a response, refrain from looking at the manuscript and associated material in case the request to review is rescinded. Similarly, notify the journal as soon as possible if you find you do not have the necessary expertise to assess the relevant aspects of a manuscript so as not to unduly delay the review process. In the case of double-blind review, if you suspect the identity of the author(s) notify the journal if this knowledge raises any potential competing or conflict of interest.
Suspicion of ethics violations: If you come across any irregularities with respect to research and publication ethics do let the journal know (e.g. see COPE Case 02-11: Contacting research ethics committees with concerns over studies). For example, you may have concerns that misconduct occurred during either the research or the writing and submission of the manuscript, or you may notice the substantial similarity between the manuscript and a concurrent submission to another journal or a published article. In the case of these or any other ethical concerns, contact the editor directly and do not attempt to investigate on your own. It is appropriate to cooperate, in confidence, with the journal, but not to personally investigate further unless the journal asks for additional information or advice.
Transferability of peer review: Publishers may have policies related to transferring peer reviews to other journals in the publisher’s portfolio (sometimes referred to as portable or cascading peer review). Reviewers may be asked to give permission for the transfer of their reviews if that is journal policy. If a manuscript is rejected from one journal and submitted to another, and you are asked to review that same manuscript, you should be prepared to review the manuscript afresh as it may have changed between the two submissions and the journal’s criteria for evaluation and acceptance may be different. In the interests of transparency and efficiency, it may be appropriate to provide your original review for the new journal (with permission to do so from the original journal), explaining that you had reviewed the submission previously and noting any changes. (See discussion2 with Pete Binfield and Elizabeth Moylan highlighting some of the issues surrounding portable peer review).
Preparing a report
Format: Follow journals’ instructions for writing and posting the review. If a particular format or scoring rubric is required, use the tools supplied by the journal. Be objective and constructive in your review, providing feedback that will help the authors to improve their manuscript. For example, be specific in your critique, and provide supporting evidence with appropriate references to substantiate general statements, to help editors in their evaluation. Be professional and refrain from being hostile or inflammatory and from making libelous or derogatory personal comments or unfounded accusations (e.g. see COPE Case 08-13: Personal remarks within a post-publication literature forum).
Appropriate feedback: Bear in mind that the editor requires a fair, honest, and unbiased assessment of the strengths and weaknesses of the manuscript. Most journals allow reviewers to provide confidential comments to the editor as well as comments to be read by the authors. The journal may also ask for a recommendation to accept/revise/reject; any recommendation should be congruent with the comments provided in the review. If you have not reviewed the whole manuscript, do indicate which aspects of the manuscript you have assessed. Ensure your comments and recommendations for the editor are consistent with your report for the authors; most feedback should be put in the report that the authors will see. Confidential comments to the editor should not be a place for denigration or false accusation, done in the knowledge that the authors will not see your comments.
Language and style: Remember it is the authors’ paper, so do not attempt to rewrite it to your own preferred style if it is basically sound and clear; suggestions for changes that improve clarity are, however, important. In addition, be aware of the sensitivities surrounding language issues that are due to the authors writing in a language that is not their first or most proficient language, and phrase the feedback appropriately and with due respect.
Suggestions for further work: It is the job of the peer reviewer to comment on the quality and rigor of the work they receive. If the work is not clear because of missing analyses, the reviewer should comment and explain what additional analyses would clarify the work submitted. It is not the job of the reviewer to extend the work beyond its current scope. Be clear which (if any) suggested additional investigations are essential to support claims made in the manuscript under consideration and which will just strengthen or extend the work.
Accountability: Prepare the report by yourself, unless you have permission from the journal to involve another person. Refrain from making unfair negative comments or including unjustified criticisms of any competitors’ work that is mentioned in the manuscript. Refrain from suggesting that authors include citations to your (or an associate’s) work merely to increase citation counts or to enhance the visibility of your or your associate’s work; suggestions must be based on valid academic or technological reasons. Do not intentionally prolong the review process, either by delaying the submission of your review or by requesting unnecessary additional information from the journal or author. If you are the editor handling a manuscript and decide to provide a review of that manuscript yourself (perhaps if another reviewer could not return a report), do this transparently and not under the guise of an anonymous additional reviewer.
What to consider after peer review
If possible, try to accommodate requests from journals to review revisions or resubmissions of manuscripts you have reviewed previously. It is helpful to respond promptly if contacted by a journal about matters related to your review and to provide the information required. Similarly, contact the journal if anything relevant comes to light after you have submitted your review that might affect your original feedback and recommendations. Continue to respect the confidential nature of the review process and do not reveal details of the manuscript after peer review unless you have permission from the author and the journal (e.g. see COPE Case 13- 05: Online posting of the confidential draft by peer reviewer). See the COPE discussion document Who “owns” peer reviews ? for a fuller discussion of the issues.
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