Peer review

This article refers to the scholarly process of screening papers. For the Wikipedia process of improving articles, see Wikipedia:Peer review.

Peer review (known as refereeing in some academic fields) is a scholarly process used in the publication of manuscripts and in the awarding of funding for research. Publishers and funding agencies use peer review to select and to screen submissions. The process also forces authors to meet the standards of their discipline. Publications and awards that have not undergone peer review are likely to be regarded with suspicion by scholars and professionals in many fields.

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A reviewer at the National Institutes of Health evaluates a grant proposal.

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Reasons for peer review

A rationale for peer review is that it is rare for an individual author or research team to spot every mistake or flaw in a complicated piece of work. This is not because deficiencies represent needles in a haystack, but because in a new and perhaps eclectic intellectual product, an opportunity for improvement may stand out only to someone with special expertise or experience. Therefore showing work to others increases the probability that weaknesses will be identified, and with advice and encouragement, fixed. The anonymity and independence of reviewers is intended to foster unvarnished criticism and discourage cronyism in funding and publication decisions.

How it works

Peer review subjects an author's work or ideas to the scrutiny of one or more others who are experts in the field. These referees each return an evaluation of the work, including suggestions for improvement, to an editor or other intermediary (typically, most of the referees' comments are eventually seen by the author as well). Evaluations usually include an explicit recommendation of what to do with the manuscript or proposal, often chosen from a menu provided by the journal or funding agency. Most recommendations are along the lines of the following:

  • to unconditionally accept the manuscript or proposal,
  • to accept it in the event that its authors improve it in certain ways,
  • to reject it, but encourage revision and invite resubmission
  • to reject it outright.

During this process, the role of the referees is advisory, and the editor is under no formal obligation to accept the opinions of the referees. Furthermore, in scientific publication, the referees do not act as a group, do not communicate with each other, and typically are not aware of each other's identities. There is usually no requirement that the referees achieve consensus. Thus the group dynamics is substantially different from that of a jury. In situations where the referees disagree about the quality of a work, there are a number of strategies for reaching a decision.

Traditionally reviewers would remain anonymous to the authors, but this is slowly changing. In some academic fields most journals now offer the reviewer the option of remaining anonymous or not; papers sometimes contain, in the acknowledgments section, thanks to (named) referees who helped improve the paper.

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.

In some disciplines, such as computer science, there exist refereed venues (such as conferences and workshops). To be admitted to speak, scientists must submit a scientific paper (generally short, often 15 pages or less) in advance. This paper is reviewed by a "program committee" (the equivalent of an editorial board), who generally requests inputs from referees. The hard deadlines set by the conferences tend to limit the options to either accept or reject the paper.

Typically referees are not selected from among the authors' close colleagues, relatives, or friends. Referees are supposed to inform the editor of any conflict of interests that might arise. Journals or individual editors often invite a manuscript's authors to name people whom they consider qualified to referee their work. Authors are sometimes also invited to name natural candidates who should be disqualified, in which case they may be asked to provide justification (typically expressed in terms of conflict of interest).

Editors solicit author input in selecting referees because academic writing typically is very specialized. Editors often oversee many specialties, and may not be experts in any of them, since editors may be full time professionals with no time for scholarship. But after an editor selects referees from the pool of candidates, the editor typically is obliged not to disclose the referees' identities to the authors, and in scientific journals, to each other. Policies on such matters differ between academic disciplines.

Scientific journals observe this convention universally. The two or three chosen referees report their evaluation of the article and suggestions for improvement to the editor. The editor then relays the bulk of these comments to the author (some comments may be designated as confidential to the editor), meanwhile basing on them his or her decision whether to publish the manuscript. When an editor receives very positive and very negative reviews for the same manuscript, the editor often will solicit one or more additional reviews 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, the editor 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. Even in these cases, however, editors do not allow referees to confer with each other, and the goal of the process is explicitly not to reach consensus or to convince anyone to change their opinions. Some medical journals, however, (usually following the open access model) have begun posting on the Internet the pre-publication history of each individual article, from the original submission to reviewers' reports, authors' comments, and revised manuscripts.

After reviewing and resolving any potential ties, there may be one of three possible outcomes for the article. The two simplest 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 referees are not paid, and reviewing takes time away from the referee's main activities, such as his or her own research. To the would-be recruiter's advantage, most potential referees are authors themselves, or at least readers, who know that the publication 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, similarly, tend to seek referees among their present or former grantees. Serving as a referee can even be a condition of a grant, or professional association membership.

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 frustrates 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 for a particular article. However, credit and reputation are principally established by publications, not by refereeing; and in some fields refereeing may not be anonymous.

Different styles of review

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. Conversely, when either funds or publication space is limited, peer review may be used to select an extremely small number of proposals or manuscripts.

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.

Some journals such as Science, Nature, and Physical Review have extremely stringent standards for publication, and will reject papers which are of good quality scientific work that they feel are not breakthroughs in the field. Others such as the Astrophysical Journal use peer review primarily to filter out obvious mistakes and incompetence. Different publication rates reflect these different criteria: Nature publishes about 5 percent of received papers, while Astrophysical Journal publishes about 70 percent. The different publication rates are also reflected in the size of the journals.

Screening by peers may be more or less laissez-faire depending on the discipline. Physicists, for example, tend to think 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.

To preserve the integrity of the peer-review process, submitting authors are not informed of who reviews their papers; sometimes, they might not even know the identity of the associate editor who is responsible for the paper. In many cases, alternatively called "blind" or "double-blind" review, the identity of the authors is concealed from the reviewers, lest the knowledge of authorship bias their review; in such cases, however, the associate editor responsible for the paper does know who the author is. Sometimes the scenario where the reviewers do know who the authors are is called "single-blind" to distinguish it from the "double-blind" process. In double-blind review, the authors are required to remove any reference that may point to them as the authors of the paper.

While the anonymity of reviewers is almost universally preserved, double-blind review (where authors are also anonymous to reviewers) is not always employed. Critics of the double-blind process point out that, despite the extra editorial effort to ensure anonymity, the process often fails to do so, since certain approaches, methods, notations, etc., may point to a certain group of people in a research stream, and even to a particular person. Proponents of the single-blind process argue that if the reviewers of a paper are unknown to each other, the associate editor responsible for the paper can easily verify the objectivity of the reviews. Double-blind review is thus strongly dependent upon the goodwill of the participants.

Criticisms of peer review

One of the most common complaints about the peer review process is that it is slow, and that it typically takes several months or even several years in some fields for a submitted paper to appear in print. In practice, much of the communication about new results in some fields such as astronomy no longer takes place through peer reviewed papers, but rather through preprints submitted onto electronic servers such as

In addition, some sociologists of science argue that peer review makes the ability to publish susceptible to control by elites and to personal jealousy. 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, which accords with Thomas Kuhn's well-known observations regarding scientific revolutions.

However, others have pointed out that there is a very large number of scientific journals in which one can publish, making control of information difficult. In addition, the decision-making process of peer review, in which each referee gives his opinions separately and without consultation with the other members, is intended to mitigate some of these problems.

History of peer review

Peer review has been a touchstone of modern scientific methodology apparently only since in the middle of the twentieth century.[1] ( Before then, its application was lax. For example, Albert Einstein's revolutionary "Annus Mirabilis" papers in the 1905 issue of Annalen der Physik were not peer-reviewed. The journal's editor in chief (and father of quantum theory), Max Planck, recognized the virtue of publishing such outlandish ideas and simply had the papers published; none of the papers were sent to reviewers. The decision to publish was made exclusively by either the editor in chief, or the co-editor Wilhelm Wien—both certainly ‘peers’ (who were later to win the Nobel prize in physics), but this does not meet the definition of "peer review" as it is currently understood. At the time there was a policy that allowed authors much latitude after their first publication. In a recent editorial in Nature, it was stated that "in journals in those days, the burden of proof was generally on the opponents rather than the proponents of new ideas."

Famous papers which were not peer-reviewed

Because of its relatively recent status as a fixture in the scientific enterprise, many of the major breakthroughs in the history of science ironically were published without having undergone peer review. However, even after peer review had become common practice, some famous papers have been published without review. These include:

  1. Publication of Watson and Crick's 1951 paper on the structure of DNA in Nature. This paper was not sent out for peer review. John Maddox stated that “the Watson and Crick paper was not peer-reviewed by Nature... the paper could not have been refereed: its correctness is self-evident. No referee working in the field (Linus Pauling?) could have kept his mouth shut once he saw the structure” (Nature 426:119 (2003)). The editors accepted the paper upon receipt of a “Publish” covering letter from influential physicist William Lawrence Bragg.


Peer review and fraud

Peer review, in scientific journals, assumes that the article reviewed has been honestly written, and the process is not designed to detect fraud. The reviewers usually do not have full access to the data from which the paper has been written and some elements have to be taken on trust (except perhaps in subjects such as mathematics).

The number and proportion of articles which are detected as fraudulent at review stage is unknown. Some instances of outright scientific fraud and scientific misconduct have got through review and were detected only after other groups tried and failed to replicate the published results.

An example is the case of Jan Hendrik Schn, in which a total of fifteen papers were accepted for publication in the top ranked journals Nature and Science following the usual peer review process. All fifteen were found to be fraudulent and were subsequently withdrawn. The fraud was eventually detected, not by peer review, but after publication when other groups tried and failed to reproduce the results of the paper.

An example of what can happen within academic publications without peer-review is that of NYU Physics Professor Alan Sokal's publication of Transgressing the Boundaries: Toward a Transformative Hermeneutics of Quantum Gravity ( in the journal Social Text ( The submission for publication by Sokal was a hoax known as the Sokal Affair.

Peer review and software development

A variety of kinds of peer review are used in various software development processes, including more formal and rigorous approaches termed software inspection. 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," meaning "If there are enough reviewers, all problems are easy to solve." Eric S. Raymond has written influentially about peer review in software development, for example in the essay The Cathedral and the Bazaar.

See also

External links

es:Revisin por pares he:ביקורת עמיתים it:Peer review ja:査読 nl:Collegiale toetsing


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