In plain English
When a scientist sends a paper to a journal, the editor usually asks other experts to read it and comment. This is peer review. It can catch errors and often improves how a paper is reported, but it is not a guarantee [1, 2]. Reviewers usually work from the manuscript and cannot repeat the experiments.
After publication, problems can still come to light. A journal may then publish a correction, an expression of concern or a retraction [4, 5]. Retracted papers stay visible, marked as retracted, and they continue to be cited [9].
Some outlets look like journals but do not do the work of one. They are called predatory or pseudo-journals. They take a fee and publish almost anything [1, 11].
The short version
- Peer review is a filter, not a proof of correctness [1, 2].
- Corrections fix limited errors; retractions withdraw unreliable findings [4, 5].
- Check every key paper’s record for retraction, correction and expression-of-concern notices [6].
- Check that a journal is what it claims to be before trusting what it publishes [1, 11, 12].
What peer review is
The International Committee of Medical Journal Editors (ICMJE) describes peer review as the critical assessment of submitted manuscripts by experts who are usually not part of the editorial staff. It notes that the actual value of peer review is widely debated, but that the process facilitates a fair hearing for a manuscript, helps editors decide which manuscripts suit their journals and often helps improve the quality of reporting [1]. A peer-reviewed journal is not obliged to send every submission out for review [1].
Common models of peer review
| Model | Who knows whose identity | Notes |
|---|---|---|
| Single-anonymised | Reviewers know the authors; authors do not know the reviewers | Reviewer identities stay confidential |
| Double-anonymised | Neither side knows the other | Studies of concealing identities have given ambiguous results [2] |
| Open peer review | Varies | An umbrella term: open identities, published review reports, wider participation, or combinations of these [3] |
Open peer review has no single meaning. A systematic review of 122 definitions found 22 distinct configurations of seven traits, in effect 22 different definitions of the term in the literature reviewed [3].
What the evidence says about peer review
A systematic review of editorial peer review in biomedical journals found that only 19 of 135 identified studies met its criteria. Two studies showed that editorial processes make articles more readable and improve the quality of reporting, but the authors concluded that editorial peer review, although widely used, is largely untested and its effects are uncertain [2].
Peer review also has blind spots. In a visual screen of 20,621 papers published in 40 scientific journals from 1995 to 2014, 3.8% contained problematic figures, and at least half of those showed features suggestive of deliberate manipulation. The marked variation between journals suggested that practices such as image screening before publication influence the quality of the literature [8].
Preprints are not peer-reviewed papers
A preprint is a manuscript shared before journal peer review. Preprints appear in some databases alongside published papers: PubMed Central, for example, contains author manuscripts and preprints collected through the NIH Preprint Pilot as well as journal articles [14]. A preprint should be read as a draft, and its later published version, if there is one, checked for changes.
Corrections, expressions of concern and retractions
Not every problem leads to a retraction. The Committee on Publication Ethics (COPE) guidance sets out when each response is appropriate [4].
| Notice | When COPE says editors should consider it [4] |
|---|---|
| Retraction | Clear evidence that the findings are unreliable, through misconduct (for example data fabrication) or honest error (for example miscalculation or experimental error); redundant publication; plagiarism; unethical research |
| Expression of concern | Inconclusive evidence of misconduct; evidence that findings are unreliable but the authors’ institution will not investigate; doubts that an investigation would be fair; an investigation under way with no judgement expected for a considerable time |
| Correction | A small portion of an otherwise reliable publication proves misleading, especially through honest error; an incorrect author list |
COPE also says retraction notices should be linked to the retracted article, clearly identify it, be published promptly, be freely available, state who is retracting the article and state the reasons, so that misconduct can be distinguished from honest error [4].
The ICMJE adds that honest errors are a part of science and publishing and require a correction when detected, while matters of debate and evolving science are not errors. Errors serious enough to invalidate a paper’s results and conclusions may require retraction, and where an honest error leads to a major change in results, retraction with republication of the changed paper can be considered [5].
Why papers are retracted
Two studies of PubMed-indexed retractions give different pictures, partly because retraction notices are often vague.
- Fang, Steen and Casadevall (2012) reviewed all 2,047 biomedical and life-science articles indexed as retracted on 3 May 2012. Only 21.3% of retractions were attributable to error. Misconduct accounted for 67.4%: fraud or suspected fraud 43.4%, duplicate publication 14.2% and plagiarism 9.8%. The percentage of articles retracted for fraud had increased about tenfold since 1975. The authors noted that incomplete or misleading retraction notices had led to underestimates of the role of fraud [7].
- Steen (2011) evaluated 742 English-language papers retracted from PubMed between 2000 and 2010. Based on the notices, error or an undisclosed reason (73.5%) was more common than fraud (26.6%). The most common single reason was scientific mistake (31.5%), and 18.1% were retracted for ambiguous reasons. Retractions per year rose sharply over the decade, and 31.8% of retracted papers were not noted as retracted in any way [13].
The difference matters for a reader. A retraction says the findings should not be relied on. It does not by itself say whether the cause was misconduct or an honest mistake, so the notice should be read.
Retracted papers keep being cited
In a database-wide study of 7,813 retracted papers indexed in PubMed, retracted papers continued to be cited, and retraction did not change the way they were cited. Of 13,252 citation contexts written after retraction, only 722 (5.4%) acknowledged the retraction [9]. A citation in a newer paper is therefore no evidence that the cited work still stands.
How to check whether a paper has been retracted
- Open the PubMed record. NLM creates links in PubMed between citations for original articles and citations for retraction and erratum notices, expressions of concern, corrected and republished articles and comments [6]. A retracted article carries a “Retraction in:” link and the Retracted Publication publication type. On 25 October 2026, the PubMed search
"Retracted Publication"[pt]returned 35,220 records. The mechanics are covered in How to Search PubMed. - Check the journal’s own page for the current version and any notices. The ICMJE expects journals to post corrected versions with the dates of changes and to keep prior versions archived [5].
- Check the Retraction Watch Database. In September 2023 Crossref acquired the Retraction Watch database and made it a public resource. At the time, Crossref recorded about 14,000 retractions and the Retraction Watch database about 43,000, around 50,000 in total once overlaps were removed. The Retraction Watch blog and its journalism remain separate from Crossref [10].
- Check citing reviews. If the paper underpins a systematic review, the review’s conclusions may need to be read without it; see Systematic Reviews and Meta-Analyses.
Predatory journals
What they are
The ICMJE describes predatory or pseudo-journals as entities that advertise themselves as scholarly journals yet do not function as such. They accept and publish almost all submissions and charge article processing fees, often telling authors about the fee only after acceptance. They often claim to perform peer review but do not, may use names similar to well-established journals, and may falsely claim membership of ICMJE or that they follow the recommendations of ICMJE, COPE and WAME [1]. The ICMJE states that authors have a responsibility to evaluate the integrity, history, practices and reputation of journals they submit to [1].
There is no standardised definition. A scoping review of the literature on predatory journals found 344 eligible records, most of them commentaries, viewpoints, letters or editorials (78.4%). Only 38 were empirical studies, and from these the authors extracted 109 unique characteristics, grouped into six categories: journal operations; article; editorial and peer review; communication; article processing charges; and dissemination, indexing and archiving [11].
Elmore and Weston summarise common predatory practices: falsely claiming to provide peer review, hiding information about article processing charges, misrepresenting members of the editorial board, and other violations of copyright or scholarly ethics [12].
Warning signs
| Sign | What to check |
|---|---|
| Peer review claimed but implausible | Almost every submission accepted; review claimed but no sign it took place [1, 12] |
| Fees hidden or revealed late | Article processing charges stated only after acceptance [1, 12] |
| Editorial board | Board members listed whose connection to the journal cannot be verified [12] |
| Borrowed identity | A title closely resembling an established journal; claimed ICMJE membership or adherence to ICMJE, COPE or WAME recommendations that cannot be confirmed [1] |
| Indexing claims | Claimed indexing that cannot be confirmed in the database named; check the database directly [11] |
| Solicitation | Unsolicited invitations to submit; the scoping review groups such features under communication [11] |
No single sign is proof. Some legitimate new journals are small and some have weak websites. The point is to check claims directly rather than accept them.
Why it matters for peptide research
Research peptides attract papers from many sources. A paper in a predatory outlet may never have been reviewed by anyone with relevant expertise, so its methods, identity testing and statistics deserve extra scrutiny. Statistical red flags are covered in Statistics in Research Papers, and marketing claims that lean on weak sources in Spotting Misleading Peptide Claims.
A checklist for judging a paper’s standing
- Is it a peer-reviewed article, a preprint or an author manuscript [14]?
- Is the journal what it claims to be, with verifiable indexing, editors and fees [1, 11, 12]?
- Is there a “Retraction in:”, “Erratum in:” or “Expression of concern in:” link on its PubMed record [6]?
- Is it in the Retraction Watch Database [10]?
- If corrected, which version is being cited [5]?
- Do the figures and data look consistent, with methods detailed enough to repeat [8]?
- Have the findings been repeated by an independent group? Evidence levels are explained in How to Read Peptide Research.
What this means in Australia
- The Australian Code. The Australian Code for the Responsible Conduct of Research, 2018 is a principles-based document developed jointly by the National Health and Medical Research Council (NHMRC), the Australian Research Council (ARC) and Universities Australia. Adherence is a prerequisite for NHMRC funding, and supporting guides cover peer review, publication and dissemination of research, and the investigation of potential breaches [15].
- Shared oversight. The ARC states that there is no single Commonwealth agency with regulatory powers for the oversight of research integrity in Australia. Responsibility is shared among research institutions, funding agencies and other bodies. The Australian Research Integrity Committee reviews the institutional processes used to manage and investigate potential breaches of the Code [16].
- A publication is not an approval. A published paper, peer reviewed or not, does not change whether a substance may be supplied in Australia. The TGA states that unapproved peptide products have not been assessed by the TGA for safety, quality or effectiveness, and that a “research use only” disclaimer does not make supply lawful [17].
This is general information, not legal advice. Laws change; check the current Poisons Standard and TGA guidance.
Frequently asked questions
What is a predatory journal?
It is an outlet that presents itself as a scholarly journal but accepts almost all submissions for a fee, often without the peer review it claims. There is no single agreed definition, but common features include hidden fees, unverifiable editorial boards and false indexing or membership claims [1, 11, 12].
Does peer review mean a paper is correct?
No. Peer review is expert assessment that helps editors decide what to publish and often improves reporting, but it cannot repeat the experiments, and the evidence on its effects is limited [1, 2].
What is the difference between a correction and a retraction?
A correction fixes a limited error in an otherwise reliable paper. A retraction withdraws a paper whose findings are unreliable, whether through misconduct or honest error, or because of plagiarism, redundant publication or unethical research [4, 5].
What is an expression of concern?
It is a notice a journal can publish when there are serious doubts about a paper but the evidence is inconclusive or an investigation is incomplete [4].
Are most retractions due to fraud?
In a 2012 review of 2,047 PubMed-indexed retractions, 67.4% were attributable to misconduct, including fraud or suspected fraud, duplicate publication and plagiarism, and 21.3% to error [7]. Earlier work based on the stated reasons found error more common, partly because many notices are vague [13].
How can a reader tell if a paper has been retracted?
Check its PubMed record for a “Retraction in:” link, the journal’s own page and the Retraction Watch Database, which Crossref has made publicly available [6, 10].
References
- International Committee of Medical Journal Editors. Responsibilities in the submission and peer-review process. Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals. icmje.org. Accessed 25 October 2026.
- Jefferson T, Alderson P, Wager E, Davidoff F. Effects of editorial peer review: a systematic review. JAMA. 2002;287(21):2784–2786. doi:10.1001/jama.287.21.2784. PMID: 12038911
- Ross-Hellauer T. What is open peer review? A systematic review. F1000Res. 2017;6:588. doi:10.12688/f1000research.11369.2. PMID: 28580134
- Wager E, Barbour V, Yentis S, Kleinert S. Retractions: guidance from the Committee on Publication Ethics (COPE). Croat Med J. 2009;50(6):532–535. doi:10.3325/cmj.2009.50.532. PMID: 20017220
- International Committee of Medical Journal Editors. Corrections and version control. Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals. icmje.org. Accessed 25 October 2026.
- US National Library of Medicine. Errata, retractions, and other linked citations in PubMed. nlm.nih.gov. Accessed 25 October 2026.
- Fang FC, Steen RG, Casadevall A. Misconduct accounts for the majority of retracted scientific publications. Proc Natl Acad Sci U S A. 2012;109(42):17028–17033. doi:10.1073/pnas.1212247109. PMID: 23027971
- Bik EM, Casadevall A, Fang FC. The prevalence of inappropriate image duplication in biomedical research publications. mBio. 2016;7(3):e00809-16. doi:10.1128/mBio.00809-16. PMID: 27273827
- Hsiao TK, Schneider J. Continued use of retracted papers: temporal trends in citations and (lack of) awareness of retractions shown in citation contexts in biomedicine. Quant Sci Stud. 2022;2(4):1144–1169. doi:10.1162/qss_a_00155. PMID: 36186715
- Hendricks G, Lammey R, Ofiesh L, Bilder G, Pentz E. News: Crossref and Retraction Watch. Crossref blog, 12 September 2023. doi:10.13003/c23rw1d9. Accessed 25 October 2026.
- Cobey KD, Lalu MM, Skidmore B, Ahmadzai N, Grudniewicz A, Moher D. What is a predatory journal? A scoping review. F1000Res. 2018;7:1001. doi:10.12688/f1000research.15256.2. PMID: 30135732
- Elmore SA, Weston EH. Predatory journals: what they are and how to avoid them. Toxicol Pathol. 2020;48(4):607–610. doi:10.1177/0192623320920209. PMID: 32319351
- Steen RG. Retractions in the scientific literature: is the incidence of research fraud increasing? J Med Ethics. 2011;37(4):249–253. doi:10.1136/jme.2010.040923. PMID: 21186208
- National Center for Biotechnology Information. About PMC. US National Library of Medicine. pmc.ncbi.nlm.nih.gov. Accessed 25 October 2026.
- National Health and Medical Research Council. Australian Code for the Responsible Conduct of Research, 2018. nhmrc.gov.au. Accessed 25 October 2026.
- Australian Research Council. Research integrity. arc.gov.au. Accessed 25 October 2026.
- Therapeutic Goods Administration. Understanding your responsibilities when importing, compounding and supplying unapproved peptide products. Safety advisory, 13 April 2026. tga.gov.au. Accessed 25 October 2026.
