Reviewers provide quality control and a seal of approval for the published scientific literature. They have considerable influence over what gets published, and can use this leverage to encourage more open practices.

• If you would like to commit to requiring open practices in the papers you review, you could consider joining the Peer Reviewers' Openness Initiative. Members of the PRO pledge to require open data and materials, or an explanation why either is not possible, before reviewing a paper. Morey et al. (2016) present and discuss this initiative in detail.