Guidelines for peer reviewers

Scientific journals at Thieme typically perform single-anonymized peer review where reviewers know who the authors are, but the reviewer's identity is not revealed to the authors. Many journals offer the option of double-anonymized peer review where the reviewer is not aware of the identity of the author and the author is not aware of the identity of the reviewers. Some journals use Select Crowd Review, an interactive and secure single- or double-anonymized review process that offers different perspectives by expert reviewers. In all cases, reviewer and author identity is visible to the decision-making editor. After referee comments have been submitted that allow for a decision on a manuscript to be made, the handling editor makes the final decision on the paper.

Some journals ask their authors to provide a short list of referees that they recommend review the paper, we also use the Web of Science Reviewer Locator to suggest potential reviewers, and reviewers who decline to review may suggest alternative reviewers. These suggestions may be useful, particularly for niche research topics. However, the assigned editor is ultimately in charge of the peer review process and chooses who to invite. For cases in which the editor deems the referee comments not to be satisfactory in terms of analytical depth, they can request the reviewer modify the report and give indications as to how to improve the quality of the report. Such requests are never made to modify the reviewer publishing recommendations.

After an initial screening by the editorial office (see the journal web pages for contact details), papers are typically reviewed by two independent expert referees. Editors are encouraged to seek at least two referees for each paper. In the event of conflicting reviewer reports, a third reviewer will be invited to resolve the dispute, or the handling editor may act as a third reviewer and make the final decision, taking into account his/her personal view. While all original research papers are peer-reviewed, some journals may have exceptions, as stated on their journal websites, and publish for example editorial-type articles that do not undergo peer review.

Invited senior reviewers, may review the paper together with a co-reviewer, who is usually an early-career researcher (e.g., PhD student or postdoc). When done correctly, it is a valuable learning experience. Reviewers should simply disclose collaboration with a co-reviewer and provide name and status upon submission of the review report. The principles relating to confidentiality and competing interests also apply to the co-reviewer, while the senior researcher will remain accountable for the review.

Peer reviewers are essential to ensuring the integrity of the scholarly record. The Committee on Publication Ethics (COPE) has published ethical guidelines for reviewers.

Reviewers should accept the invitation to review a paper only if they have sufficient subject expertise and enough time to complete the review. Any potential conflicts of interest should be declared before reviewing.

If reviewers cannot carry out a review, they should decline the invitation to review as soon as they can and suggest alternative reviewers if possible.

Supplementary materials and other supporting documentation such as primary data are accessible to reviewers and are used to form the basis of the decision. These comprehensive documents should however not be considered fully peer reviewed.

For a reviewer, a conflict of interest (COI) is a financial, material, personal, direct or indirect, gain or relationship that could be reasonably perceived as interfering with the objective peer review of a paper.

COIs are often unavoidable, and they need not automatically disqualify a reviewer from evaluating a paper. A perceived COI is as important as a real COI. Therefore, transparent disclosures of financial and non-financial relationships and activities is key. Editors are responsible for evaluating the bias and, depending on the situation, may ask the reviewer to evaluate the paper anyway and may then consider the COI statement when weighing the recommendation.

Before agreeing to review a paper, reviewers should disclose any relevant conflicts of interest by writing to the journal. Reviewers can recuse themselves when COIs are relevant by simply declining the invitation. If reviewers realize only during peer review, they should disclose relevant COIs or recuse themselves by writing to the journal.

• Financial COIs include that reviewers (or someone close to them) could profit or be negatively impacted financially if a paper is published or rejected (e.g., through stock ownership, patents, or consultancies). 
• Personal COIs include a close personal relationship or association, or a conflict and a direct academic competitive situation with the author. 
• Professional COIs include that reviewers have recently worked in the same department as the author, have closely collaborated, or have published with the author recently.
  
  

In double-anonymized peer review, reviewers may not be sure if they have a conflict of interest, but if they suspect there may be a reason, they should recuse themselves.

It is misconduct to delay the reviewing process to favour the publication date of a reviewer's own paper or patent.

Reviewed materials are subject to confidentiality. Details of unpublished manuscripts should not be revealed to anyone, and papers should not be uploaded to publicly available GenAI platforms, like ChatGPT, or other tools, that risk violating confidentiality, privacy, and copyright obligations. GenAI should be used only for language assistance.

The use of large language models and AI chatbots to assist in the writing of peer review reports may only be acceptable if:

• the use is declared
• the tools guarantee confidentiality, and
• reviewers take responsibility for the full contents of the report

Reviewers who are invited to review a paper either via conventional peer review or via Select Crowd Review receive an email with basic information, such as the title and the abstract of the paper, to help them decide on whether they have the expertise to review the paper. If the topic falls outside of their scope of expertise, they should simply decline the invitation.

Review invitations will also include a due date by which the report should be provided. In case reviewers would like to carry out a review of the paper, they should make sure they can accommodate time for the reviewing process in advance of the given date and provide a timely answer to the invitation to avoid any delay in the process. If they cannot do the review in the allotted time, they should decline the invitation.

If reviewers have a real or perceived conflict of interest (CoI) that would preclude them from judging the paper fairly, they should decline the invitation. If they accept to review the paper and have any CoI, they should simply declare it by writing to the journal before starting the review (see section above).

If the paper falls outside of the area of the reviewer's expertise or they do not have time, they should suggest alternative reviewers who could review the paper, if possible.

Otherwise, with our sincere gratitude, they should accept the invitation, download the paper, and set aside time to review it by the agreed due date.

When assessing a paper, please think about what areas may need improvement. These may include (but are not limited to) clarity of the title and paper text, paper structure, the graphical or tabular components, the choice and quality of referenced literature, or the contents and quality of any supporting information.

The following checklist might be useful:

• What is the research question the authors want to answer?
• Is this question important, and does this work contribute to advancing the field of research?
• How was the question answered? Are the tests done appropriately?
  
  

Theoretical aspects: 

• Can the study as designed answer the question?
•  Are statistics used appropriately? 
• Are necessary positive or negative controls included?
•  Are there fundamental flaws in the study?
  
  

Practical aspects: 

• Does the experimental or methods section clearly explain what the investigators did, and is enough detail provided to reproduce the study?
• Are the methods appropriate? Be reasonable when evaluating this: Please consider that different institutes have access to different resources. Not all authors have access to the latest instruments released in the market.

 
Paper aspects: 

• Are the figures and tables easy to understand and consistent with the text?
  • Do they properly describe the content of the paper? 
  • Are they misleading? 

  • If something is unclear or confusing, suggest ways to make it clearer. Further evaluation concerns the significance of the title and the abstract.  Check if sources are properly cited.

• Are the conclusions justified based on the results? 

• Do the authors consider alternative interpretations that are also justified by the results, and do they discuss limitations of the study?

Do not correct minor grammatical errors or typos, as those will be assessed during copyediting. If such errors make it difficult to assess the science, flag them to the editor so that the authors can adjust the paper accordingly before further peer-review. 

Review report should be fair, polite, and constructive. When summarizing observations on a paper, whether positive or negative aspects are summarized, the language must remain professional. Comments must be explained and claims supported so that the authors can use them to improve their work. Feedback should be as specific as possible to avoid that a comment remains unaddressed because of lack of clarity.

Due to the anonymity, reviewers can be honest with their thoughts on scientific questions, but the focus should be kept on the work (not on the individuals) and the assessment of the the validity of the submitted paper. Comments should not be sarcastic inappropriate. Reviewers should beware of the risks of conscious and unconscious positive or negative biases.

For Select Crowd Review assignments, if reviewers see opinions by other crowd members that they agree with, they don’t need to rephrase them but instead could simply comment with “agree”. If reviewers do not agree with a comment, they should also explain why.

At Thieme, reviewer reports are not published alongside the paper version of record. Editors may slightly edit a report to remove destructive, discriminatory, or defamatory comments and personal attacks. They may not alter the professional opinion about the quality, content, and intellectual validity of the paper. Reviewers may be asked to participate in the editing of the report before it is sent to the author.

Reviewer identities are anonymized throughout the process among the other referees, but reviewer comments are made visible to other reviewers. For Select Crowd Review, throughout the process all referee comments made to a paper are visible to other referees on the Filestage platform. In conventional peer review, the decision letter is accessible via the reviewer center to all reviewers. Visibility of referee comments may also occur in cases for which an adjudicating referee may be needed. In this case, the conflicting comments from all current reports may be sent to the adjudicating referee to assist them in their review of the paper.

Upon acceptance, reviewer comments are kept private to the editorial office and the author and are not made public alongside the version of record.

Peer review reports may be transferred to a Thieme sister journal to aid the editors in case of a ‘reject & transfer’ decision. We do not send reviewer reports to journals outside of Thieme.

When submitting a report, reviewers must make a recommendation that will help the editor evaluate the paper and make a decision.
The key recommendations that can be made are:

It is helpful if, in the Confidential Comments to the ED when necessary, reviewers explain whether their recommendation is based upon the level of scientific progress; or if there are serious problems in the study design, experiments, or conclusions; or if the paper is scientifically and ethically flawed.

Reviewers of a first manuscript version may have the option to agree or decline to review the revised version of the paper. Reviewers who have already assessed a manuscript may be invited to reassess revised versions of the same manuscript, either for the same journal, or in case of a reject and transfer, by the receiving journal. The decision about which referees are invited to assess a revised manuscript is at the discretion of the handling editor.

Reviewers who reassess a manuscript after revision should indicate whether they agree to the revisions made and whether the manuscript has been revised satisfactorily. If a reviewer has any further changes that are required before the manuscript can be accepted, these should be indicated in the report.

If a paper is rejected, authors have the right to appeal, as described in our journal polices, and reviewers may be invited to assess the author's appeal.