Scientific Salami Slicing: 33 Papers From One Study

“Salami slicing” is a recognised research-integrity problem in which authors divide data from a single study into multiple smaller publications. The result can be more papers, more citations and a stronger publication record, but the science becomes diluted. This practice has been discussed for years by research-ethics bodies, including international publication committees and national integrity offices. Many of them classify it as questionable research practice when used to inflate output rather than communicate meaningful insights.

The phrase “33 papers from 1 study” is often used to illustrate how far the problem can go. In several documented cases, very large datasets have been broken into dozens of papers, each offering only a small fraction of the findings. While this may not always violate strict rules, it can limit the clarity of the evidence, confuse the literature and make replication harder.

How Salami Slicing Works

Salami slicing occurs when authors divide one research project into multiple papers, even when the results could be reported together. The objective is usually to increase the number of publications without adding new scientific knowledge.

Typical forms include:

• Publishing subsets of the same dataset as separate papers
• Splitting demographic groups or outcomes into stand-alone articles
• Repeating similar methods with slight variations
• Presenting “preliminary,” “secondary”, and “exploratory” results as separate works

Ethics organisations state that it becomes a problem when these fragments create unnecessary duplication or when readers are not clearly told that the data come from the same underlying study. Publishing multiple papers from one large dataset is not automatically wrong; it becomes questionable when the division adds little value.

Why It Happens

One of the strongest drivers is academic reward systems. Promotion, funding and hiring often rely on publication numbers, citation counts and journal visibility. Producing many small papers can help researchers meet those expectations faster than producing a single comprehensive article.

Other reasons include:

• Pressure to present results quickly
• Journals favouring shorter papers
• Collaborators wanting authorship credit
• Fragmented research teams working on different parts of a dataset

These factors create an environment where dividing findings seems efficient, even when it weakens the full picture.

Documented Examples of Large-Scale Slicing

Research integrity offices and peer-review organisations have reported cases in which a single study has produced dozens of papers. Some investigations have identified more than 30 outputs stemming from one dataset.

Common features of such cases include:

• A shared sample population
• Overlapping methods and measures
• Minimal differences between papers
• Repetition of tables or figures
• Lack of acknowledgement that the data were reused

In several instances, journals have issued corrections or combined papers once overlap was identified. These actions reflect guidance from publication-ethics authorities to avoid redundant or fragmented research outputs.

Why It Damages Science

Salami slicing may appear harmless, but it has several negative effects.

It weakens scientific clarity

When findings are split, readers cannot easily understand the full picture. A dataset that should produce a single strong conclusion becomes scattered across many articles. This makes interpretation difficult, especially in fields such as medicine and psychology where integrated results matter.

It inflates the literature

Multiple papers from one dataset can make a research topic appear more thoroughly studied than it is. This misleads future reviewers, policymakers and meta-analysts, who may unknowingly treat overlapping papers as independent evidence.

It creates repetition

Fragmented studies can contain overlapping methods, duplicated text and similar results. Journals and ethics bodies identify such repetition as a form of redundant publication when transparency is lacking.

It wastes resources

Editors, reviewers and readers spend time evaluating multiple small papers rather than one comprehensive analysis. This increases strain on the research ecosystem.

Official Guidance on the Issue

Research-ethics committees and journal-governance bodies provide clear positions on salami slicing. Their guidance includes:

• Publishing multiple papers from a single dataset is only acceptable if each paper addresses a distinct research question
• Authors must be transparent about related papers using the same data
• Results should not be divided artificially
• Journals should be informed when overlapping manuscripts exist
• Fragmentation that limits scientific clarity is considered questionable practice

These organisations also encourage authors to produce unified articles whenever possible, emphasising that the primary goal of research is to communicate findings accurately.

When Multiple Papers Are Acceptable

Large datasets can support multiple publications in some circumstances. For example:

• Longitudinal studies that track participants over many years
• National surveys with diverse research angles
• Trials that include distinct sub-analyses with separate outcomes
  
• Multidisciplinary projects where different teams investigate independent questions

In these cases, dividing results may help specialists access the information they need. Transparency remains essential so that readers understand how the papers relate.

How to Reduce Salami Slicing

Institutions and journals can help limit the problem through:

• Clear authorship and data-sharing policies
• Stronger editorial screening for overlapping manuscripts
• Training in research integrity
• Incentives that reward high-quality papers over quantity
• Requirements for preregistration and full disclosure of data use

Authors can also help by designing publication plans early, documenting related papers and aiming for comprehensive analysis rather than splitting results unnecessarily.