PLOS Peer Review Toolkit
Evaluating competing interests
In order to uphold the integrity of the peer review process, everyone involved in research, writing and evaluation of a manuscript—including authors, editors, and reviewers—must declare potential competing interests. Practically, though, the scientific community is relatively small, and it’s not uncommon to know other researchers in your field. How close does a relationship have to be before it qualifies as a competing interest?
"Sunlight is said to be the best of disinfectants."
— Louis D. Brandeis
What’s a competing interest, anyway? The official definition.
A competing interest is anything that interferes with, or could reasonably be perceived as interfering with, the full and objective presentation, peer review, editorial decision-making, or publication of research.
What it means
Any relationship—personal, professional, or financial—can qualify as a competing interest. Common examples for reviewers include:
A friendship or mentor/mentee relationship with any of the authors
A current or recent collaboration with any of the authors
A recent co-publication with any of the authors
Working at the same institution as the authors
Belonging to rival or competing labs
Applying for or holding an open grant together with any of the authors
Holding stocks or owning a patent that could benefit or suffer from the results of the research
Accepting travel stipends or consulting fees from the company sponsoring the research
IMPORTANT: Having a competing interest doesn’t necessarily mean you are biased. It just means that the relationship between you and the authors could give the appearance of bias. That is, a reasonable person--someone who doesn’t know you or the authors--could look at the the situation and believe that a bias might exist.
Why it matters
Declaring competing interests serves three important functions:
1. Helping to ensure that the peer review process is fair and objective
2. Protecting the reputations of the people involved in the manuscript development and assessment
3. Supporting the integrity of the peer review process, so that the research is taken seriously after publication
What to do about it
In cases where you have a close relationship with the authors, such as an ongoing collaboration or active grants, or if you simply feel that you cannot fairly assess a particular manuscript, you should decline the invitation.
If the potential competing interest is more tenuous, consider checking with the editor or journal office. Depending on the situation, they may ask you to review, or decide to find a different reviewer.
If you are asked to complete a review, be prepared to declare your you simply feel that you cannot fairly assess a particular manuscript, you should decline the invitation.
Didn’t spot your competing interest until after you agreed to review? It happens all the time! Let the editor or journal office know as soon as possible. They will advise you on whether to complete the review.
Read the complete Guide to Competing Interests on the PLOS Reviewer Center.
TRY IT: Take our quiz, Is it a Competing Interest? and register for a chance to win one of 5 PLOS t-shirts

You’re invited to review a manuscript in your area of expertise. One of the coauthors works in the same department as you do, and although you aren’t collaborating on any projects at the moment, you are friendly. Is it a competing interest?
See you soon! We’re taking a short “spring break” after this issue, but never fear--the Peer Review Toolbox will be back in three weeks with a special announcement.
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