Salami Slicing or Salami publication or segmented publication is a distinct form of redundant publication usually characterized by similarity of hypothesis, methodology, or results but not text similarity. Based on an ethical point of view, a "Salami Slicing" case is even worse than a duplicate publication because it cannot be easily detected, gives undeserved credit to authors, misleads the scientific community, and directly influences clinical practice by distorting medical evidence (1).

How to detect salami publication?

There is no software application or algorithm for the detection of salami publications. Identifying this type of publication misconduct is complex because salami publications do not often include text plagiarism, so manuscripts can easily evade strict software checking. Only under the rare circumstances of encountering both the original and the salami manuscript can some editors or reviewers suspect salami publication. Even though there are no objective ways to detect this sort of redundant publication, manuscripts suspected of being salami publications often report identical or similar sample sizes, hypotheses, research methodology, and results and often have the same authors (1).

Is it unethical? 

Yes. Salami slicing can distort the literature by leading unsuspecting readers to believe that data presented in each 'slice' is derived from a different subject sample (2).

Advice to Authors (2):

• Avoid inappropriately breaking up data from a single study into two or more papers.
• When submitting a paper, be transparent. Send copies of any manuscripts closely related to the manuscript under consideration.
• This includes any manuscripts published, recently submitted, or already accepted.

What does the COPE flowchart say about the redundant publication (3):

• Assess the degree of overlap between the two papers by EIC
  1. In case of "Major overlap": Reject the paper
  2. In case of "Minor overlap": Ask authors for more explanations and perhaps publish a "corrigendum" or "erratum" or "Commentary"
     note: It is suggested that the editor could consult the "sample letters" on the COPE website, which deal with the "Overlap of figures or text with a manuscript submitted or published elsewhere."
• Because of no transparency from the authors in their submission, this case must be reported to the authors' institution.
• In case of any threat to the community's health, the article must be retracted after careful investigations and enough evidence.
• Because of the risk of litigation and the danger of harming other innocent associated authors, COPE strongly recommends not blacklisting authors or sharing alert lists with other editors.

When is salami publication allowed?

In some rare cases and under specific circumstances, authors are allowed to publish more than one article from their studies. However, in all such cases, authors must provide all necessary information to the editor to evaluate the justification for publishing such a manuscript. Authors must clearly state which of the presented results are already published and give the full source and consent of the original author when applicable. The added value of the new manuscript has to be correctly described in the second manuscript, and the extent to which the two manuscripts are similar has to be easily determined. Citing the original manuscript solely by listing it in the reference section is not enough (1).

• Articles for different readers
• Guidelines in two or more different languages
• Follow-up investigations:
  They can be published using parts of already published results when the new manuscript largely contributes new scientific knowledge.
• Extensive epidemiological studies or randomized controlled trials:
  When a large amount of data is collected, it is almost impossible to present all results in a single manuscript. The number of subjects included in the study can be greater than a few thousand, and longitudinal cohort studies can last for a few decades. 

References:

1. https://dx.doi.org/10.11613%2FBM.2013.030
2. https://www.elsevier.com/__data/assets/pdf_file/0011/653888/Salami-Slicing-factsheet-March-2019.pdf
3. https://publicationethics.org/case/duplicate-publication-or-salami-publication
4. https://publicationethics.org/resources/flowcharts-new/what-do-if-you-suspect-redundant-duplicate-publication
   (https://doi.org/10.24318/cope.2019.2.12)
5. https://publicationethics.org/case/case-salami-slicing
6. https://publicationethics.org/case/self-plagiarism-and-suspected-salami-publishing

Read more:

1. https://brieflands.com/scinews/articles/88066.html
2. https://brieflands.com/scinews/articles/84293.html