Some measures of impact are difficult to express numerically but nonetheless carry weight within research communities. Open peer-review initiatives—both pre- and post-publication—have varying goals: to accelerate the path to publication, allow more voices to contribute to assessment, and acknowledge the contributions of reviewers themselves. Several of the services mentioned above offer some form of nontraditional peer review, from informal discussions (such as various Mendeley forums) to explicit post-publication review (as offered by the new Open Review tool from ResearchGate).
PLOS ONE, through its comments functionality, has since inception allowed registered users to discuss articles published in their journals. The National Institutes of Health’s PubMed Commons is more rigorous in that it only allows comments from authors who have articles in the PubMed database. PubMed Commons also offers membership to journal-club discussion groups based on specialty research areas. PubPeer is another independent journal-club site that allows anonymous review, but it has been embroiled in scrapes related to suspect research data and article retractions. Peerage of Science aims to transform pre-publication review by providing a free platform where authors can submit their work and solicit comment from peers (volunteer scientist-reviewers who are vetted by virtue of their publication records in ranking international outlets—ironically, the journals indexed in Web of Science). Conceived in 2010 by a group of Finnish scientists, Peerage of Science has developed productive partnerships with both for-profit and open-access publishers, including Springer, BioMedCentral, and Brill, who benefit from timely reviews from self-selected (and thus, presumably, motivated) reviewers. Those reviewers themselves benefit by being able to choose what they review and then gain recognition for their contributions.
Publons goes even farther to put peer reviewers into the spotlight. Named as a joking reference to the “smallest publishable unit” and boasting more than 100,000 registered reviewers who have uploaded more than 500,000 reviews, the New Zealand and UK-based Publons peer review site offers “a measurable indicator of a researcher’s expertise and contributions” and provides a means for editors and publishers to identify expert reviewers. The site allows reviewers to rate one another and presents ranked lists of reviewers by field, by reviewer institution, or country. Altmetric incorporates Publons metrics into its Attention Score, described below. Another site, F1000: Faculty of 1000 and its F1000Prime component, goes beyond expert peer review to provide article recommendations from researchers in the fields of biology and medicine. While the core product (launched in 2002) is a subscription service, its F1000 Research: F1000 Faculty Reviews site commissions review articles on the life sciences as part of a new open-access publishing initiative. The subscriber portion provides article rankings that are updated daily, including a “Top 10 Hidden Jewels” list for less high-profile specialty journals.