Peer review, preprints and retractions

The core idea

Preprints are complete, publicly available versions of scientific research that have not yet been approved through peer review; approval through peer review is the key difference between them and an article published in a journal.

A retraction is a formal announcement that a published article, in whole or in part, is withdrawn, by its authors or by an authorised body, and journals retract articles because of major errors or data that are unverified or cannot be reproduced.

Why it matters to you

Any aspect of research in a preprint, including the results and conclusions, may change as a result of peer review; so it is not treated as a final result.

The NLM links the retraction notice to the original article so the reader knows it was retracted.

States a study can be in

Preprint: available before peer review, and carries in PMC a notice that it is a preprint that has not yet undergone peer review in a journal. Its results and conclusions may change after peer review, and the authors may publish updated versions of it.

Article published after peer review: approved by a journal through peer review, but it remains open to debate and correction.

Erratum: a formal acknowledgement by the publisher, editor or author of an error in a published article, specifying where it is.

Expression of Concern: a notice from the editor about the integrity of an article, followed by an investigation that may end in retraction.

Retracted article: classified in PubMed with the publication type "Retracted Publication", and the retraction notice itself is classified "Retraction Notice", and each is linked to the other.

How to check a study’s status

Enter a DOI in the Study Reader: it checks the update notices linked to the article in Crossref, which includes Retraction Watch data, and the publication types in Europe PMC.

In PubMed, a retracted article appears with the publication type "Retracted Publication" and a link to the retraction notice.

Common pitfalls

Citing a preprint as if it were a final peer-reviewed result.

Assuming every retraction means fraud: the NLM does not distinguish in its linking between retraction for an honest error and retraction for misconduct or plagiarism.

Limits of this page

The data on corrections and expressions of concern in Retraction Watch are less comprehensive than the retraction data, according to Crossref.

The absence of a retraction notice does not guarantee that a study is sound or strong; it only means that no retraction has been recorded in the sources checked.

Common questions