1. There is substantial evidence that systemic biases influence the scholarly peer review process. Many scholars have advocated for double-blind peer review (also known as double-anonymous review) to reduce these biases. However, the effectiveness of double-blind peer review in eliminating biases is uncertain because few randomized trials have manipulated blinding of author identities for journal submissions and those that have are generally small or provide few insights on how it influences reviewer biases.2. In 2019, Functional Ecology began a large, randomized trial, using real manuscript submissions, to evaluate the various consequences of shifting to double-blind peer review. Research papers submitted to the journal were randomly assigned to be reviewed with author identities blinded to reviewers (double-blind review) or with authors identified to reviewers (single-blind review). In this paper, we explore the effect of blinding on the outcomes of peer review, examining reviewer ratings and editorial decisions, and ask whether author gender and/or location mediate the effects of review type.3. Double-blind review reduced the average success of manuscripts in peer review;
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| INTRODUC TI ONThe assessment of research by experts in the subject, commonly called peer review, is the primary means by which granting agencies and journal editors assess the quality and importance of scholarly research. Yet there is a widespread perception among researchers that systemic biases influence the outcomes of peer review. In particular, there is concern that the gender, nationality, location or reputation of authors may influence how manuscripts are assessed by reviewers due to unconscious, or sometimes conscious, biases (Lee et al., 2013). Of all of the possible biases that can occur during peer review, bias against women has received the most attention, although studies are inconsistent in their outcomes. Some find that papers authored by women are rated lower or have lower acceptance rates in academic journals Murray et al., 2018;Walker et al., 2015; and references therein), but others have failed to find gender differences in peer review outcomes, or have even found that papers authored by women perform better than those authored by men (Lerback & Hanson, 2017;Squazzoni et al., 2021). Other biases, such as favouring papers by authors from the same country or that speak the same language as the reviewer (