Peer review · practical

Peer-reviewed journals and articles: what counts, and how to check

A peer-reviewed journal sends research manuscripts to independent experts before deciding to publish. How to check a journal in five steps, what PubMed, MEDLINE, Scopus, DOAJ and Google Scholar actually guarantee, and how to check a single article.

Check a journalWhat the databases guarantee
Sources captured 13 September 2026 · 20 references
Key takeaways
  • A journal must state whether content is peer reviewed, by whom, what type, and the exceptions by article type.[5]
  • MEDLINE journals are reviewed by at least two NLM consultants against five criteria, including an explicit peer review process.[6] Scopus requires peer-reviewed content with a public description.[10] DOAJ requires at least two independent reviewers per article.[13]
  • PubMed is not MEDLINE: its 40 million citations include PubMed Central, which holds preprints "made public prior to peer review".[8][9]
  • Google Scholar includes preprints, dissertations and technical reports[18]; F1000Research lists all its articles there "irrespective of peer review status".[19]
  • Peer reviewed is not the same as correct: BMJ reviewers found 2.58 of nine planted errors[1]; retractions passed 10,000 in 2023.[4]
Five steps

Check a journal in five minutes.

Each step is a public source you can open yourself.
#StepWhat to look for
01The journal's policy pagePrinciple 8 of the Principles of Transparency (COPE, DOAJ, OASPA, WAME, v4.0, 2022): the journal must state "whether or not the content is peer reviewed", "who conducts the peer review", "the type of peer review process(es) used", whether "reviews are posted with articles" and "signed or anonymous", and "exceptions to the peer review process, such as specific article types".[5] No such page is a red flag.
02IndexingMEDLINE: "at least two consultants, usually one scientist … and one medical librarian review each journal" against five elements, asking "Is the peer review process explicit and sufficiently detailed".[6] Scopus: titles must "consist of peer-reviewed content and have a publicly available description of its peer review process".[10] Web of Science: "24 quality criteria designed to select for editorial rigor and best practice, and four impact criteria".[11] DOAJ: "All articles must pass through a quality control system (peer review) before publication"; "at least two independent reviewers".[13]
03A directoryUlrichsweb covers 383,000 serials with "bibliographic and provider details"; library subscription required.[14] Your library's database "peer reviewed" limiter draws on the same kind of directory data.
04The Think. Check. Submit. questions"Do you or your colleagues know the journal?" "Can you easily identify and contact the publisher?" "Is the journal clear about the type of peer review it uses?" "Are articles indexed and/or archived in dedicated services?" "Is it clear what fees will be charged?" "Are guidelines provided for authors on the publisher website?" "Is the publisher a current member of a recognized industry initiative?"[15]
05The predatory definitionAgreed in 2019 by "leading scholars and publishers from ten countries": "entities that prioritize self-interest at the expense of scholarship and are characterized by false or misleading information, deviation from best editorial/publication practices, lack of transparency, and/or use of aggressive and indiscriminate solicitation practices".[17][16] Unsolicited invitations, fees revealed late and no named editorial board match the definition.
What inclusion means

What each database guarantees.

Sizes and criteria quoted from each database's own pages.
DatabaseSizeWhat inclusion means
MEDLINE"more than 31 million references"[7]Journal selected by NLM after review by at least two consultants against five criteria, including an explicit peer review process.[6] The strongest routine signal for biomedicine.
PubMed"more than 40 million citations"[8]Three components: MEDLINE (the largest), PubMed Central, and Bookshelf.[8] Inclusion alone does not mean MEDLINE selection.
PubMed Central"more than 10 million full-text article records"[9]Published articles, "author manuscripts that have been peer-reviewed and accepted", and "preprint versions of articles that have been made public prior to peer review".[9] Check which version you are reading.
Scopus"titles from more than 7,000 publishers"[10]Peer-reviewed content with a public description of the process is a minimum criterion; the Content Selection and Advisory Board evaluates titles.[10]
Web of Science Core Collection"over 20,000 peer reviewed, high-quality scholarly journals" (Clarivate, 2018)[12]24 quality criteria and four impact criteria.[11]
DOAJOpen-access journalsEditor and editorial board listed; "at least two independent reviewers must review each article"; the peer review process "must be stated clearly on the website".[13]
Google ScholarNot statedContent "must consist primarily of scholarly articles - journal papers, conference papers, technical reports, or their drafts, dissertations, pre-prints, post-prints, or abstracts".[18] No peer review filter.
One article

Check a single article.

  • Article type. Journals must state their "exceptions to the peer review process, such as specific article types".[5] Editorials, news, commentaries and letters are the usual exceptions; original research and systematic reviews are reviewed.
  • Version. A preprint is "made public prior to peer review".[9] On review-after-posting platforms, look for the reviews: eLife publishes "Public Reviews" and an assessment on every Reviewed Preprint[20]; F1000Research indexes only articles that pass peer review in PubMed and Scopus.[19]
  • Dates. Received, revised and accepted dates on the article page show that a review cycle happened.
  • Published review history. Where the journal posts reports, read them. Which journals do is on open peer review.
The limit

Peer reviewed is not the same as correct.

Peer review screens; it does not verify. The numbers, from the studies that measured it.
2.58 of 9

BMJ reviewers found an average of 2.58 of nine major errors deliberately inserted into a test paper; training raised this only to about 3. [1]

kappa 0.17

Across 48 studies and 19,443 manuscripts, agreement between reviewers is low: mean intraclass correlation 0.34 and mean Cohen's kappa 0.17. [2]

8 of 9 rejected

When 12 already-published articles were resubmitted to the journals that had published them, only 3 of 38 editors and reviewers noticed, and 8 of the 9 that went through review were rejected. [3]

10,000+

Retractions of research articles passed 10,000 in 2023, an annual record. [4]

What this means for a reader

Treat "peer reviewed" as a floor, not a verdict. Read the methods, check the references, and see how to peer review a paper for the checks reviewers are supposed to run.

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Sources

References and sources

Every figure on this page is quoted from the primary source listed here. Verification dates are recorded per source.
  1. [1]Schroter S et al. What errors do peer reviewers detect, and does training improve their ability to detect them?. Journal of the Royal Society of Medicine 2008. doi:10.1258/jrsm.2008.080062 PMID 18840867.peer-reviewed article (Europe PMC / Crossref record) · verified 2026-09-12
  2. [2]Bornmann L, Mutz R, Daniel HD. A reliability-generalization study of journal peer reviews: a multilevel meta-analysis of inter-rater reliability and its determinants. PloS one 2010. doi:10.1371/journal.pone.0014331 PMID 21179459.peer-reviewed article (Europe PMC / Crossref record) · verified 2026-09-12
  3. [3]Peters Douglas P., Ceci Stephen J. Peer-review practices of psychological journals: The fate of published articles, submitted again. Behavioral and Brain Sciences 1982. doi:10.1017/s0140525x00011183peer-reviewed article (Europe PMC / Crossref record) · verified 2026-09-12
  4. [4]Van Noorden R. More than 10,000 research papers were retracted in 2023 - a new record. Nature 2023. doi:10.1038/d41586-023-03974-8 PMID 38087103.peer-reviewed article (Europe PMC / Crossref record) · verified 2026-09-12
  5. [5]COPE, DOAJ, OASPA, WAME. Principles of Transparency and Best Practice in Scholarly Publishing, version 4.0, September 2022. Captured 13 September 2026. doaj.org/apply/transparency/joint industry standard · verified 2026-09-13
  6. [6]National Library of Medicine. MEDLINE journal selection (Literature Selection Technical Review Committee). Captured 13 September 2026. www.nlm.nih.gov/medline/medline_journal_selection.htmlNLM policy page · verified 2026-09-13
  7. [7]National Library of Medicine. MEDLINE overview. Captured 13 September 2026. www.nlm.nih.gov/medline/medline_overview.htmlNLM fact page · verified 2026-09-13
  8. [8]National Library of Medicine. About PubMed. Captured 13 September 2026. pubmed.ncbi.nlm.nih.gov/about/NLM fact page · verified 2026-09-13
  9. [9]National Library of Medicine. PubMed Central: introduction and content. Captured 13 September 2026. pmc.ncbi.nlm.nih.gov/about/intro/NLM fact page · verified 2026-09-13
  10. [10]Elsevier. Scopus content policy and selection. Captured 13 September 2026. www.elsevier.com/products/scopus/content/content-policy-and-selectiondatabase policy page · verified 2026-09-13
  11. [11]Clarivate. Web of Science Core Collection editorial selection process. Captured 13 September 2026. clarivate.com/academia-government/scientific-and-academic-research/research-discovery-and-referencing/web-of-science/web-of-science-core-collection/editorial-selection-process/database policy page · verified 2026-09-13
  12. [12]Publons. 2018 Global State of Peer Review. Clarivate Analytics; 2018. publons.com/static/Publons-Global-State-Of-Peer-Review-2018.pdfindustry report (PDF on file) · verified 2026-09-12
  13. [13]DOAJ. Guide to applying: basic criteria for inclusion. Captured 13 September 2026. doaj.org/apply/guide/directory criteria page · verified 2026-09-13
  14. [14]ProQuest (Clarivate). Ulrichsweb Global Serials Directory: product description. Captured 13 September 2026. about.proquest.com/en/products-services/Ulrichsweb/vendor product page · verified 2026-09-13
  15. [15]Think. Check. Submit. Journal checklist (ALPSP, AUP, COPE, DOAJ, ISSN, LIBER, OAPEN, OASPA, STM, UKSG). Captured 13 September 2026. thinkchecksubmit.org/journals/industry checklist · verified 2026-09-13
  16. [16]Cukier S, Helal L, Rice DB, et al. Checklists to detect potential predatory biomedical journals: a systematic review. BMC Medicine 2020;18:104. doi:10.1186/s12916-020-01566-1 PMID 32375818.peer-reviewed article (Europe PMC open-access full text; quotes the 2019 consensus definition) · verified 2026-09-13
  17. [17]Grudniewicz A, Moher D, Cobey KD, et al. Predatory journals: no definition, no defence. Nature 2019;576:210-212. doi:10.1038/d41586-019-03759-y PMID 31827288.journal comment (paywalled; definition quoted from Cukier 2020) · verified 2026-09-13
  18. [18]Google Scholar. Inclusion guidelines for webmasters: content. Captured 13 September 2026. scholar.google.com/intl/en/scholar/inclusion.htmlsearch-engine documentation · verified 2026-09-13
  19. [19]F1000Research. How it works: open peer review and indexing. Captured 13 September 2026. f1000research.com/aboutpublisher policy page · verified 2026-09-13
  20. [20]eLife. Peer review: the eLife model (Reviewed Preprints). Captured 13 September 2026. elifesciences.org/about/peer-reviewjournal policy page · verified 2026-09-13

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