Double-blind reviewed manuscripts — where both authors and referees remain anonymous — have accounted for between 12 and 30% of total monthly submissions to Nature Climate Change, with the six-month average around 22%. This is somewhat lower than we might have expected on the basis of a reader survey run by Nature Geoscience in June 2012, where three-quarters of respondents agreed that double-blind peer review is a good idea.

As part of our monitoring effort, both journals involved in the trial (Nature Climate Change and Nature Geoscience) have been inviting all submitting authors to fill out a short survey to provide feedback on why they do or don't choose double-blind peer review. Completed surveys have been pooled to compensate for the relatively low number of respondents so far (47; 12 double blind, 35 traditional at the time of writing). The survey responses, although imperfect and self-selecting to some extent, indicated strong support for double-blind review in principle, with over 80% of respondents agreeing that it is a good (or very good) idea and 95% supporting (or strongly supporting) the continuation of the trial. These numbers are encouraging, but pose the question: given such a high level of support in principle, why aren't the same numbers of authors choosing this option in practice?

The explanation seems to relate to levels of awareness about the trial, with about 60% of respondents unaware of the double-blind option before submission. Of those who did not have previous knowledge of the trial, three-quarters said they would be more likely to choose the option if they knew about it before they started to write their paper. Reluctance to delay submission owing to the extra time it can take to retrospectively anonymize a manuscript accounts for this difference.

Preliminary records also indicate that referees do not seem significantly more reluctant to review double-blind manuscripts.

Interestingly, the perceived areas of bias that authors hoped double-blind review might mitigate were primarily concerned with author affiliations, influence and reputation. Gender and age were not perceived to be as significant as sources of bias. Two recurring concerns were expressed in the survey. First that double blind is most effective when mandatory, otherwise perceived bias might be introduced if referees assume those that select double blind are not from prestigious institutions, do not have an established reputation and so on. A number of authors also feel that their identities could be guessed anyway.

In summary, although uptake has been lower than we expected, early indications are that the trial is going well and that double-blind review will increase in popularity as awareness of the option grows. An interesting question is whether we should indicate on published papers whether the review was single- or double-blind, but there are no plans to do this at present. In the next phase of monitoring we are aiming to investigate how often referees believe that they can identify authors, as well as their skill in doing so.