Peer review (known as refereeing in some academic fields) is a scholarly process used in the publication of manuscripts and in the awarding of money for research. Publishers and agencies use peer review to select and to screen submissions. At the same time, the process assists authors in meeting the standards of their discipline. Publications and awards that have not undergone peer review are liable to be regarded with suspicion by scholars and professionals in many fields.

Table of contents
1 How it works
2 Recruiting referees
3 Different styles of review
4 Alleged abuses of peer review
5 Peer review and software development

How it works

Peer review subjects an author's work or ideas to the scrutiny of two or more others who are experts in the field of the subject at hand. Referees return a text to its author with edits, annotation and suggestions for improvement. Typically referees remain anonymous to the authors and are not selected from among the authors' close colleagues, relatives or friends.

A chief rationale for peer review is that rarely is just one person, or one closely working group, able to spot every mistake or weakness in a complicated piece of work. This is not necessarily because these deficiencies represent needles in a haystack, but because in a new and creative and perhaps eclectic intellectual product, any one of these opportunities for improvement may stand out only to someone with a particular expertise and/or history of experience. Therefore showing a work to various others increases the odds that the weakness will be identified--and with advice and encouragement fixed. The anonymity and independence of reviewers fosters unvarnished criticism and discourages cronyism in granting and publication decisions.

At a journal or book publisher, the task of picking reviewers typically falls to an editor. When a manuscript arrives, an editor solicits reviews from scholars or other experts who may or may not have already expressed a willingness to referee for that journal or book division. Granting agencies typically recruit a panel or committee of reviewers in advance of the arrival of applications.

As a policy, editors often invite a manuscript's authors to name people who they consider qualified to referee their work. Authors are also invited to name natural candidates who should be disqualified; with regard to which the authors are asked to provide justification (typically expressed in terms of conflict of interest).

Editors solicit author input in selecting referees, because adademic writing typically is very specialized. Editors often oversee many specialties, and may not be experts in any of them, since editors may be fulltime professionals with no time for scholarship. But after an editor selects referees from the pool of candidates, he or she typically is obliged not to disclose their identity to the authors.

Scientific journals observe this convention universally. To the editor, the two or three chosen referees report their evaluation of the article and suggestions for improvement. The editor then transmits these comments to the author, meanwhile basing on them his or her decision whether to publish the manuscript. When an editor receives both very positive and very negative reviews for the same manuscript, as sometimes happens, he or she often will solicit one or more additional review as a tie-breaker.

As another strategy in the case of ties, editors may invite authors to reply to a referee's criticisms and permit a compelling rebuttal to break the tie. If an editor does not feel confident to weigh the persuasiveness of a rebuttal, he or she may solicit a response from the referee who made the original criticism. In rare instances, an editor will convey communications back and forth between authors and a referee, in effect allowing them to debate a point.

During this process, the role of the referees is advisory, and the editor under no formal obligation to accept the opinions of the referees.

After reviewing and resoving any potential ties, there may be one of three possible outcomes for the article. The two simplest which are uncommon for most journals are outright rejection and unconditional acceptance. In most cases, the authors may be given a chance to revise, with or without specific recommendations or requirements from the reviewers.

Recruiting referees

Recruiting referees is a political art, because refereeing is unpaid, and because at the institutions where potential referees work, they must improvise a time to do it. To the would-be recruiter's advantage, most potential referees are authors themselves, or at least readers, who are familiar with the system of publication. They know the system requires that experts donate their time. Editors are at an especial advantage in recruiting a scholar when they have overseen the publication of his or her work--or if the scholar is one who hopes to submit manuscripts to that editor's publication in the future. Granting agencies, relatedly, tend to seek referees among their present or former grantees.

Another difficulty that peer-review organizers face is that, with respect to some manuscripts or proposals, there may be few scholars who truly qualify as experts. Such a circumstance often flusters the goals of reviewer anonymity and the avoidance of conflicts of interest. It also increases the chances that an organizer will not be able to recruit true experts--people who have themselves done work like that under review, and who can read between the lines. Low-prestige journals and granting agencies that award little money are especially handicapped with regard to recruiting experts.

Finally, anonymity adds to the difficulty in finding reviewers in another way. In scientific circles, credit and reputation are important, and while being a referee for a prestigious journal is considered an honor, the anonymity restrictions make it impossible to publicly state that one was a referee.

Different styles of review

It's worth noting that peer review can be rigorous, in terms of the skill brought to bear, without being highly stringent. An agency may be flush with money to give away, for example, or a journal may have few impressive manuscripts to choose from. So there may be no use to being picky. Often the decision of what counts as "good enough" falls entirely to the editor or organizer of the review. In other cases, referees will each be asked to make the call, with only general guidance from the coordinator on what stringency to apply.

Screening by peers may be more or less laissez-faire, and in this as well as other regards it is prone to differ between disciplines. Physicists, for example, are liable to opine that decisions about the worthiness of an article are best left to the marketplace. Yet even within such a culture peer review serves to ensure high standards in what is published. Outright errors are detected and authors receive both edits and suggestions.

Alleged abuses of peer review

Some sociologists of science argue that peer review makes the ability to publish susceptible to control by elites. Reviewers tend to be especially critical of conclusions that contradict their own views, and lenient towards those that accord with them. At the same time, elite scientists are more likely than less established ones to be sought out as referees, particularly by high-prestige journals or publishers. As a result, it has been argued, ideas that harmonize with the elite's are more likely to see print and to appear in premier journals than are iconoclastic or revolutionary ones.

Patrick Michaels claims that in regards to global warming, an egregious case of statistical manipulation managed to pass one of the world's most influential journals. He claims the article authors calculated a false trend line, by selecting a subset of data especially chosen to support their hypothesis; he further argues that if they had used all available data the calculations would not have supported their hypothesis and implies that the journal editors were well aware of this and thus in on the deception:

In 1996, conveniently a day before the U.N. conference that gave birth to the Kyoto Protocol, Nature published a paper purporting to match observed temperature with computer models of disastrous warming. It used weather balloon data from 1963 through 1987. The actual record, however, extended (then) from 1958 through 1995, and, when all the data were used, the troubling numbers disappeared. Since that famous incident, people have been very leery of what major scientific journals publish on global warming. [1]

However, others have pointed out that there are a very large number of scientific journals that one can be published in, making control of information difficult. In addition, most peer review is now done after the scientific results have been circulated via preprints.

Peer review and software development

In the open source movement, something like peer review has taken place in the engineering and evaluation of computer software. In this context, the rationale for peer review has its equivalent in Linus's law, often phrased: "Given enough eyeballs, all bugs are shallow." Eric S. Raymond has written influentially about peer review in software development, for example in the essay The Cathedral and the Bazaar.

See also: preprint, Wikipedia:Peer review