Reese Richardson

“Salami slicing” is the practice of taking a set of research findings and splitting them up into as many publishable papers as possible. It is typically regarded as a tactic to inflate the authors’ CVs. As far as I can tell, the first reference to salami to describe this practice came in 1982 in an editorial in Geoscience Canada, following on a 1981 editorial in Science that apparently coined the closely-related concept of the “Least Publishable Unit”. Before that, “salami tactics” were previously described in politics, law and finance. The phrase was initially made popular by the Hungarian Stalinist leader Mátyás Rákosi, who described his use of szalámitaktika to slice apart the competing ruling party during the Communist Party’s rise to power in Hungary.

I never particularly liked this term as it is used in relation to scholarly publishing, for a few reasons:

1. I’m not the biggest fan of salami.
2. We already have one perfectly good sausage-related metaphor for suspect modes of production in “seeing how the sausage is made”. Two seems excessive.
3. When you are slicing salami, you at least get a different piece of salami every time.
4. There is a physical limit to how thin salami can be sliced. As will become apparent here, no such limit exists for data.

Here, I’ve compiled several examples across different fields of what could variously be described as salami slicing, reduction to the Least Publishable Unit, redundant publication, data re-use or just plain fraud. I’ll call it what I see: data stretched to such an extreme that it becomes translucent.

Case #1: Same study, different mandibular measurements

Here are six articles with mostly the same authorship lists published within 4 months of each other in the same journal. All share the same ethics approval number (“IHEC/SDC/FACULTY/22/FO/059”). All involve different measurements of the mandible from orthopantomograms (OPGs) and correlation of these measurements with sex (and in some cases, age).  Most use a sample of 500 OPGs (with the exception of the “Evaluation” and “Gender” articles, which use 100) and most take OPGs from patients 20-30 years old (with the exception of the “Quantifying” study, which uses patients 41-50 years).

1. Evaluation of Sexual Dimorphism Using Condylar and Coronoid Mandibular Parameters in Orthopantomograms: A Pilot Study, Cureus
2. Quantifying Sexual Dimorphism by Analyzing Ramus Flexure and Bigonial Width in Orthopantomography, Cureus
3. Analyzing Mandibular Characteristics for Age and Gender Variation Through Digital Radiographic Techniques: A Retrospective Study, Cureus
4. Forensic Gender Prediction by Using Mandibular Morphometric Indices: A Panoramic Radiograph Study, Cureus
5. Exploring Age and Gender Identification Through Mandibular Parameters Using Orthopantomography: An Observational Study, Cureus
6. Gender Determination Through Mandibular Features on Orthopantomograms: A Preliminary Study, Cureus

All six of these articles were published by authors from Saveetha Dental College in Chennai, India in its channel in Cureus, through which Saveetha can appoint its own editorial officers. Cureus maintains that these editors have no real authority, but still advertises that such channels “will help your organization become a medical research publishing powerhouse”. Saveetha was recently caught inflating its rankings through a massive self-citation scheme, along with offering payment for authors to list them as an affiliation, as well as publishing hundreds of useless commentaries and letters to the editor that cite other Saveetha authors. Despite these suspicious behaviors, at the time of writing, Saveetha’s channel in Cureus survives, although no new articles have been posted in it since October.

UPDATE 18 March 2025: Cureus has now removed Saveetha’s channel. At the time of removal, the channel had published over 600 articles.

Case #2: Same paper mill, same procedure, different subject, different authors

Another organization that benefits from Cureus’ detached approach to publication ethics is the Good Research Project, a business which describes itself as offering “virtual mentorship for medical research and publication”, “research for US residency aspirants” and “thesis assistant for Indian postgraduate residents”. The Good Research Project is one of many different services that have sprung up to squeeze money out of international applicants to US medical residency programs trying to beef up their CVs (see this Science story and my previous writing on this topic). At the Good Research Project, a small fee can purchase “Original Article Writing with Statistics”, although as the following articles demonstrate, “original” might be a stretch.

1. Study on the Analysis of Gender Trends Among the First Authors of Publications on Budd-Chiari Syndrome, Cureus
2. Breaking Barriers: Investigating Gender Representation in the First Authors of Cardiovascular Disease and Artificial Intelligence Publications, Cureus
3. Gender Disparities in First Authorship in Publications Related to Attention Deficit Hyperkinetic Disorder (ADHD) and Artificial Intelligence (AI), Cureus
4. Gender Trends in First Authorship of Academic Publications Related to Wolff-Parkinson-White Syndrome, Cureus
5. Gender Equality in Antiphospholipid Syndrome Publications: A Comprehensive Analysis of First Author Trends, Cureus
6. Gender Disparity of First Authors in Review Article Publications Related to Schizophrenia, Cureus
7. Gender Equality Trends of First Authors in Publications of Artificial Intelligence and Thyroid, Cureus
8. Gender Representation in Academic Publications of Tourette Syndrome Research: An Analysis of Authorship Trends, Cureus

Each article above follows the exact same procedure of picking a microfield in the medical literature (e.g. Wolf-Parkinson-White syndrome, covering a grand total of 138 articles since 1973) and analyzing the gender of first authors of articles in that field. The paltry sample of articles this analysis recovers then gets divided even further by journal and country. All of these articles also attempt to forecast where gender representation may be going in these microfields with an ARIMA model, sometimes with as few as four data points. All but one acknowledge assistance from the Good Research Project and several were listed on the Good Research Project’s Publications page.

As shown here, the scientific literature can be sliced up and scrutinized in any number of meaningless ways. This might also explain the proliferation of articles performing a “bibliometric analysis” of the 100 top cited articles in a given field. Do these articles tell us anything of particular import? No, but they are indeed articles, and the more articles, the better!

Case #3: Same histological images, different treatments

This case was discovered and shared with me by Sholto David. Here are 13 articles that repeatedly use the same images to represent different experimental conditions.

1. In Vivo Antioxidant and Antiulcer Activity of Parkia speciosa Ethanolic Leaf Extract against Ethanol-Induced Gastric Ulcer in Rats, PLOS One, Retracted
2. Gastroprotective effects of Corchorus olitorius leaf extract against ethanol-induced gastric mucosal hemorrhagic lesions in rats, Journal of Gastrenterology and Hematology, Retracted
3. Gastroprotective Activity of Polygonum chinense Aqueous Leaf Extract on Ethanol-Induced Hemorrhagic Mucosal Lesions in Rats, Evidenced-Based Complementary and Alternative Medicine, Corrected
4. Cytoprotective Effect of Benzyl N’-(5-Chloro-indol-3-yl-methylidene)-hydrazinecarbodithioate against Ethanol-Induced Gastric Mucosal Injury in Rats, Molecules, Retracted
5. Acute Toxicity and Gastroprotection Studies of a New Schiff Base Derived Copper (II) Complex against Ethanol-Induced Acute Gastric Lesions in Rats, PLOS One, Retracted
6. Gastroprotective effect of desmosdumotin C isolated from Mitrella kentii against ethanol-induced gastric mucosal hemorrhage in rats: possible involvement of glutathione, heat-shock protein-70, sulfhydryl compounds, nitric oxide, and anti-Helicobacter pylori activity, BMC Complementary Medicine and Therapies, Retracted
7. Antisecretory, Gastroprotective, Antioxidant and Anti-Helicobcter Pylori Activity of Zerumbone from Zingiber Zerumbet (L.) Smith, PLOS One, Retracted
8. Gastroprotective Activity of Ethyl-4-[(3,5-di-tert-butyl-2-hydroxybenzylidene) Amino]benzoate against Ethanol-Induced Gastric Mucosal Ulcer in Rats, PLOS One, Retracted
9. Effect of nano silver on gastroprotective activity against ethanol-induced stomach ulcer in rats, Biomedicine and Pharmacotherapy
10.  Anti-Ulcerogenic Effect of Methanolic Extracts from Enicosanthellum pulchrum (King) Heusden against Ethanol-Induced Acute Gastric Lesion in Animal Models, PLOS One, Retracted
11. Gastroprotective activity of a novel Schiff base derived dibromo substituted compound against ethanol-induced acute gastric lesions in rats, BMC Pharmacology and Toxicology, Retracted
12. Acute Toxicity and Gastroprotection Studies with a Newly Synthesized Steroid, PLOS One, Retracted
13. α-Mangostin from Cratoxylum arborescens (Vahl) Blume Demonstrates Anti-Ulcerogenic Property: A Mechanistic Study, Evidence-Based Complementary and Alternative Medicine

This is the rare case where retractions have actually been issued on the offending articles (well, most of them). Perhaps this would not have happened if not for the remarkable lack of consistency in how the images are labeled and how the experiments are described. In other words, these articles might have been passed over by the editors if the authors put a little more effort into describing these experiments identically. The effect would be the same (the same data used repeatedly across many articles without citation) but the offense would be significantly downgraded from falsification (research misconduct) to salami slicing (only in poor taste).

Case #4: Eight articles, 28 different materials, one diffraction pattern

Data can also be re-used within an article to meet the Least Publishable Unit threshold. For instance, the eight articles below, all on very similar materials and featuring two common co-authors, use the exact same X-ray diffraction (XRD) pattern 28 different times.

1. Enhanced luminescence from silver nanoparticles integrated Er3+-doped boro-tellurite glasses: Impact of annealing temperature, Journal of Alloys and Compounds
2. Band gap and polarizability of boro-tellurite glass: Influence of erbium ions, Journal of Molecular Structure
3. Reduction of non-radiative decay rates in boro-tellurite glass via silver nanoparticles assisted surface plasmon impingement: Judd Ofelt analysis, Journal of Luminescence
4. Near-infrared up-conversion emission from erbium ions doped amorphous tellurite media: Judd-Ofelt evaluation, Journal of Alloys and Compounds
5. Impact of annealing time on silver nanoparticles growth assisted spectral features of erbium-zinc-boro-tellurite glass, Journal of Luminescence
6. Opto-Dielectric Properties of TeO2-Li2O-LiCl-Eu2O3 Glasses, ECS Journal of Solid State Science and Technology
7. Impact of Annealing Time on the Optical Response of Zinc-Boro-Tellurite Glass, Solid State Phenomena
8. Tuning Surface Plasmon in Erbium-Boro-Tellurite Nanoglass via Thermal Annealing, Materials Science Forum

XRD data has lots of high-frequency noise. Because of this, one will never record the exact same diffraction pattern twice, even when measuring the same sample on the same instrument with the same settings. Nevertheless, identical XRD patterns appear frequently in the materials science and engineering literature, though seldom this frequently.

Case #5: A web of shared data across 50+ articles

The following case is perhaps the most ridiculous amount of data re-use attributable to a single set of authors that I have encountered to date. The 39 articles below all share one common co-author and all relate to engineering hydrophobic surfaces, removing dust from the surfaces of solar panels or both. These articles share images with one another so often that I ran out of unique colors to label shared images for PubPeer comments.

1. Water Droplet Dynamics on a Hydrophobic Surface in Relation to the Self-Cleaning of Environmental Dust, Scientific Reports
2. Reversible exchange of wetting state of a hydrophobic surface via phase change material coating, RSC Advances
3. Mobility of A Water Droplet on Liquid Phase of N-Octadecane Coated Hydrophobic Surface, Scientific Reports
4. Water droplet mobility on a hydrophobic surface under a thermal radiative heating, Applied Thermal Engineering
5. Solution Crystallization of Polycarbonate Surfaces for Hydrophobic State: Water Droplet Dynamics and Life Cycle Assessment towards Self-Cleaning Applications , Polymers
6. Sliding Water Droplet on Oil Impregnated Surface and Dust Particle Mitigation, Molecules
7. Stretchable Hydrophobic Surfaces and Self-Cleaning Applications, Scientific Reports
8. Self-cleaning of a hydrophobic surface by a rolling water droplet, Scientific Reports
9. Droplet Rolling and Spinning in V-Shaped Hydrophobic Surfaces for Environmental Dust Mitigation, Molecules
10. Dust mitigation from inclined hydrophobic and hydrophilic surfaces under electrostatic repulsion, Journal of Electrostatics
11. Environmental dust removal from inclined hydrophobic glass surface: avalanche influence on dynamics of dust particles, RSC Advances
12. Influence of dust and mud on the optical, chemical and mechanical properties of a pv protective glass, Scientific Reports
13. Laser processing of Ti6Al4V alloy: wetting state of surface and environmental dust effects. Heliyon
14. Environmental dust effects on aluminum surfaces in humid air ambient, Scientific Reports
15. Characterization of Environmental Dust in the Dammam Area and Mud After-Effects on Bisphenol-A Polycarbonate Sheets, Scientific Reports
16. Droplet fluid infusion into a dust layer in relation to self-cleaning, RSC Advances
17. Water droplet on inclined dusty hydrophobic surface: influence of droplet volume on environmental dust particles removal, RSC Advances
18. Heating Enhancement of a Droplet on a Superhydrophobic Surface, Scientific Reports
19. A novel method for dust mitigation from PV cell surfaces, Solar Energy
20. Chemo-Mechanical Characteristics of Mud Formed from Environmental Dust Particles in Humid Ambient Air, Scientific Reports
21. Avalanche effect for chemically modified dust mitigation from surfaces, Scientific Reports
22. On the mechanism of droplet rolling and spinning in inclined hydrophobic plates in wedge with different wetting states, Scientific Reports
23. Surface Characteristics of Silicon Nanowires/Nanowalls Subjected to Octadecyltrichlorosilane Deposition and n-octadecane Coating, Scientific Reports
24. Droplet Rolling Dynamics over a Hydrophobic Surface with a Minute Width Channel, Langmuir
25. Dynamics of droplet motion over hydrophobic surfaces with functionalized and non-functionalized ferro particles, RSC Advances
26. Environmental dust repelling from hydrophobic and hydrophilic surfaces under vibrational excitation, Scientific Reports
27. Laser texturing of Inconel 718 alloy surface: Influence of environmental dust in humid air ambient, Optics and Laser Technology
28. Effect of environmental dust particles on laser textured yttria-stabilized zirconia surface in humid air ambient, Optics and Laser Technology
29. Hydrophobic and optical characteristics of graphene and graphene oxide films transferred onto functionalized silica particles deposited glass surface, Applied Surface Science
30. Laser gas assisted texturing and formation of nitride and oxynitride compounds on alumina surface: Surface response to environmental dust, Optics and Lasers in Engineering
31. A water droplet-cleaning of a dusty hydrophobic surface: influence of dust layer thickness on droplet dynamics, Scientific Reports
32. Internal flow and heat transfer in a droplet located on a superhydrophobic surface, International Journal of Thermal Sciences
33. Characteristics of oil impregnated hydrophobic glass surfaces in relation to self-cleaning of environmental dust particles, Solar Energy Materials and Solar Cells
34. Water Droplet Adhesion on Hydrophobic Surfaces: Influence of Droplet Size and Inclination Angle of Surface on Adhesion Force, Journal of Fluids Engineering
35. Heat Transfer and Fluid Flow Characteristics in a Sessile Droplet on Oil-Impregnated Surface Under Thermal Disturbance, Journal of Heat Transfer
36. Solar energy harvesting and self-cleaning of surfaces by an impacting water droplet, International Journal of Energy Research
37. Droplet dynamics on a hydrophobic surface coated with N-octadecane phase change material, Colloids and Surfaces A
38. Nanowall Textured Hydrophobic Surfaces and Liquid Droplet Impact, Materials
39. Solvent-induced crystallization of a polycarbonate surface and texture copying by polydimethylsiloxane for improved surface hydrophobicity, Journal of Applied Polymer Science

Apropos of nothing, 14 of these articles are in Scientific Reports. An overlapping set of at least 25 articles with the same common co-author repeatedly use the same XRD pattern to characterize the minerals found in sampled environmental dust. This pattern can be found in the following articles:

1. Water Droplet Dynamics on a Hydrophobic Surface in Relation to the Self-Cleaning of Environmental Dust, Scientific Reports, Figure 2
2. A water droplet-cleaning of a dusty hydrophobic surface: influence of dust layer thickness on droplet dynamics, Scientific Reports, Figure 2C
3. Environmental mud adhesion on optical glass surface: Effect of mud drying temperature on surface properties, Solar Energy, Figure 2A, lower pattern
4. Environmental dust removal from inclined hydrophobic glass surface: avalanche influence on dynamics of dust particles, RSC Advances, Figure 4
5. Environmental dust effects on aluminum surfaces in humid air ambient, Scientific Reports, Figure 3
6. Characterization of Environmental Dust in the Dammam Area and Mud After-Effects on Bisphenol-A Polycarbonate Sheets, Scientific Reports, Figure 2
7. Droplet fluid infusion into a dust layer in relation to self-cleaning, RSC Advances, Figure 2A
8. Water droplet on inclined dusty hydrophobic surface: influence of droplet volume on environmental dust particles removal, RSC Advances, Figure 7
9. Environmental dust repelling from hydrophobic and hydrophilic surfaces under vibrational excitation, Scientific Reports, Figure 2D
10. Laser texturing of Inconel 718 alloy surface: Influence of environmental dust in humid air ambient, Optics and Laser Technology, Figure 4
11. Laser gas assisted texturing and formation of nitride and oxynitride compounds on alumina surface: Surface response to environmental dust, Optics and Lasers in Engineering, Figure 6
12. Solar energy harvesting and self-cleaning of surfaces by an impacting water droplet, International Journal of Energy Research, Figure 4
13. Characteristics of a solar selective absorber surface subjected to environmental dust in humid air ambient, Solar Energy Materials and Solar Cells, Figure 3
14. Environmental Dust Particles Repelling from A Hydrophobic Surface under Electrostatic Influence, Scientific Reports, Figure 8
15. Laser gas assisted nitriding and sol-gel coating Of alumina surfaces: Effect Of environmental dust on surfaces, Surface and Coatings Technology, Figure 9
16. Laser fabricated tungsten oxide surface for solar energy harvesting and dust effects, Solar Energy Materials and Solar Cells Figure 10
17. Dust removal from a hydrophobic surface by rolling fizzy water droplets, RSC Advances, Figure 1C
18. Laser processing of Ti6Al4V alloy: wetting state of surface and environmental dust effects, Heliyon, Figure 9
19. Effect of mud drying temperature on surface characteristics of a polycarbonate PV protective cover, Solar Energy, Figure 2
20. Mechanics of dust removal from rotating disk in relation to self-cleaning applications of PV protective cover, Solar Energy, Figure 5
21. Flow Field Inside a Sessile Droplet on a Hydrophobic Surface in Relation to Self Cleaning Applications of Dust Particles, Journal of Heat Transfer, Figure 8
22. Internal fluidity of a sessile droplet with the presence of particles on a hydrophobic surface, Numerical Heat Transfer, Part A: Applications, Figure 10
23. Carbonated water droplets on a dusty hydrophobic surface, Soft Matter, Figure 3
24. Why environmental dust influences solar energy harvesting, International Journal of Energy Research, Figure 1B
25. Dust mitigation strategies concerning solar energy applications: A comprehensive review, Solar Energy, Figure 4

This pattern and its labels have been used so often that you can actually tell exactly when the authors became aware of each of the typos and decided to fix them.

Typos and extensively recycled data notwithstanding, the labels are also seriously wrong. Most of the peaks labeled as representing a particular mineral are nowhere close to the expected peaks for that mineral.

I only discovered this case because of another hallmark of mass-produced articles: misidentified instruments. Three of the above articles were among the 2,000+ articles we found that claim to use one model of scanning electron microscope in the Methods section while the figures imply that a completely different model was used (preprint here).

To keep with the theme of saying nothing new, I’ll conclude with this: counting papers is meaningless if this is what counts as a paper. If we continue to rely on quantitative heuristics for research assessment and reward those that excel in these metrics, this kind of publishing behavior will only become more commonplace and more extreme.