Every now and then, some jarring scams emerge that stun the scientific world—from a portion of papers flagged as potentially fake to studies containing problematic images. While serious integrity breaches such as fabrication, falsification, and plagiarism grab significant attention, some wrongdoings are not as obvious.
Every day, researchers face choices that live in the murky space between good science and outright fraud. These decisions shape what ultimately becomes the scientific truth. In global surveys, several researchers admit to engaging in subtle behaviors of potential misconduct—such as falsely attributing authorship, not reporting conflicts of interest, or citing papers only because of friendship—commonly referred to as questionable research practices (QRPs).
“It’s a very important question that is worrying the scientific community in many aspects,” said Marta Entradas, who studies research integrity at Iscte–University Institute of Lisbon. While studies from other parts of the world have shed light on how prevalent such practices are, “We actually didn’t know anything about this questionable research practice or misconduct in Portugal,” said Entradas. This is particularly relevant, since some factors such as the researchers’ country and the resources they get determine the prevalence of QRPs, she explained.
Recently, Entradas and her colleagues surveyed more than 1,500 researchers in Portuguese universities to gauge their perception and participation in such dubious practices.1 The findings, published in PLoS One, revealed that 91 percent of the researchers have participated in at least one practice that lies in the grey zone of scientific integrity, indicating that widespread QRPs may pose a threat to ethical research.
“They did a pretty comprehensive study,” said Gowri Gopalakrishna, an epidemiologist at Maastricht University, who previously led a similar study investigating the prevalence of QRPs in the Netherlands.2 “They had a well-rounded profile of their respondents.”
How Many Researchers Admit to Breaching Scientific Integrity?
Entradas and her colleagues started out by looking at practices that are generally construed as breaches in scientific integrity but are not as obvious as absolute fraud. Some of these include not conducting a thorough literature review, developing hypotheses after seeing the results, and using another researcher’s idea without giving credit.
Next, Entradas and her team asked researchers how serious they perceived these practices to be. Almost an equal percentage of researchers thought that developing a hypothesis after seeing the results was either “not very serious” or “very serious.”. In contrast, a majority of them—nearly 91 percent—agreed that using a researcher’s idea without giving credit was a “very serious” breach of integrity.
“I was happy to see that people have consciously [admitted] that they recognize the seriousness of some of these practices,” said Entradas.
Finally, Entradas and her team asked the researchers how many of them had participated in these dubious practices. While 91 percent of them had participated in at least one QRP, 32 percent had participated in six or more.
The prevalence of various questionable research practices differs significantly. While nearly 73 percent of the researchers surveyed admitted to including authors who had not contributed significantly to a study, only four percent of them used a researcher’s idea without giving credit.
Designed by Erin Lemieux; data from Entradas M, et al. PLoS One. 2026;21(1):e0339056.
These numbers are significantly higher than previously reported QRP prevalence through meta-analyses, which revealed that anywhere between 13 to 34 percent of researchers participated in QRPs.3,4 “I was indeed very surprised to see such a large expression of some of these practices in Portuguese universities,” admitted Entradas.
Gopalakrishna agreed. “I’m surprised that they managed to actually get such an honest answer [from researchers], reflecting that percentage,” she said. “But on the other hand, [I’m] also not [surprised] because I think QRPs are just prevalent.”
Data Reveal Which Researchers Are More Likely to Engage in Questionable Practices
In the present study, comparing the percentage of people who thought a practice was “very serious” with how prevalent it was yielded mixed insights. For instance, in line with nearly 91 percent of the researchers perceiving using others’ idea without crediting “very serious,” only about four percent of those who answered the survey ever participated in it. In contrast, despite nearly a third of the researchers believing that not conducting a thorough literature review was “very serious,” almost 65 percent of the surveyed did it anyway.
In a survey where researchers were asked how serious they deemed a practice and how many of them had done it, the results were mixed. Despite 23 percent people believing that developing hypotheses after seeing the results was a “very serious” questionable practice, nearly 46 percent of the researchers did it anyway. About 91 percent of the researchers perceived using a researcher’s idea without giving credit as very serious, and only about four percent of them engaged in it.
Designed by Erin Lemieux; data from Entradas M, et al. PLoS One. 2026;21(1):e0339056.
Finally, Entradas and her team examined the factors affecting engagement in dubious practices. Through regression analyses, they discovered that questionable research practices were more prevalent among those who dismissed their seriousness and those who produced more research.
Younger researchers were also more likely to engage in questionable methods. “At least, they are more likely to admit [it],” noted Entradas. She believes that conditions such as temporary contracts and pressure to publish quickly could be factors in this.
However, Gopalakrishna was skeptical about using a general model to predict questionable research practices, “because I think a lot of how researchers behave is set by the research group in which they belong and the pressures that they face within, actually, that group,” she said.
She added, “I was struck by the fact that they didn’t ask questions around artificial intelligence and how it is actually used, since that’s the top of the mind of every researcher at the moment.”
Expanding on the Initial Survey and its Results
According to Entradas, this survey is just the beginning. “You do a study, and [many] more questions come that open your eyes and curiosity,” she said. The results opened her eyes to the need for clear codes of conduct and research integrity policies, especially on ethical grey zone decisions. While she hopes institutions can work on this, she has already planned her future work based on this study.
“We will be designing some methodologies to actually explore the way scientists think about the practices and how they classify them,” said Entradas. While the initial survey offered some clues, “We need to go deeper now and talk to [researchers].”