Last year we published 44 review-type articles written by 225 authors, of whom only 28 (or 12.4%) are women. We were advised by 129 referees, only 10% of whom were women. The majority of corresponding authors and referees work in North America or Western Europe. But data are not the whole story and as scientists we need to interpret and understand these numbers.

To obtain three referee reports we had to invite seven reviewers on average, with as many as 12–15 experts for some manuscripts. The success in recruiting referees is extremely variable and depends on a number of factors such as field, topic and timing (conferences, teaching, grant applications, holidays). It is therefore challenging to obtain the desired mixture of expertise, seniority, geographical and gender diversity. We are left with a difficult optimization problem and the referees’ expertise is the component we must give most weight to.

Our percentage of women referees is low, lower than the 11–16% representation of women at senior faculty level. We should certainly strive to improve this number, but at the same time we are acutely aware that overburdening female researchers with extra tasks can have negative consequences. Therefore, we are keen to explore how to promote women scientists, raise their profiles and amplify their voices in other ways.

Another challenge is to improve the geographical representation of both authors and referees. Perhaps the major hurdle in this sense is the lower visibility of researchers from other countries compared with those in North America and Western Europe. For example, name disambiguation can be a challenge when looking for Asian scientists. The lack of personal webpages or Google Scholar accounts is another. Editors are required to do a lot of detective work to expand the pool of potential authors and referees.

We clearly have work to do to improve, and next year we hope to be able to report more encouraging diversity figures.