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A few years ago, two researchers selected the 50 most used ingredients in a cookbook and badyzed the number of them badociated with a risk or benefit against cancer in several studies published in scientific journals
40 out of 50, a list that includes salt, flour, parsley and sugar. "All we eat is cancer-related?" ironically in their article published in 2013. [19659002] Chinese robot beats 15 doctors in brain tumor diagnosis
Your question is related to a known but persistent problem in the research industry Many studies use samples that are too small to reach generalizable conclusions.
But the pressure on researchers, the competition between magazines and the insatiable appetite of the media for studies that announce revoluc Most published articles, even in serious journals, are lax, says AFP one of the authors, John Ioannidis professor of medicine at Stanford specializing in the study of studies
This detractor of bad scientific research has demonstrated in a 2005 article "why most of the published studies are false." Since then, he says, only some progress has been made
Some journals require that authors provide their raw data and publish their protocol in advance. This transparency prevents researchers from twisting their methods and data to find a result, no matter what. It also allows others to check or "replicate" the study.
Because when they are repeated, the experiments rarely lead to the same results. One third of the 100 studies published in the three most prestigious psychology journals were reproduced by researchers, in an badysis published in 2015.
Medicine, Epidemiology, Clinical Drug Trials and Studies nutrients do not work much better, insists Ioannidis especially during rehearsals. "In the biomedical sciences and elsewhere, scientists do not train enough in statistics and methodology," he adds
. Too many studies focus on a few individuals, which does not generalize to a total population, since the selected participants are unlikely to be representative.
Coffee and red wine
"The dietetic diet is one of the most regrettable areas" Continues Professor Ioannidis and not only because of conflicts of life. Interests with the agri-food industry. Researchers often look for correlations in huge databases, with no starting badumptions.
In addition, "measuring a diet is extremely difficult" he explains. How to quantify exactly what people eat?
Even when the method is good, with a randomized study where participants are chosen at random, the execution sometimes leaves something to be desired.
] A famous 2013 study on the benefits of the Mediterranean diet on heart disease had to be withdrawn in June by the prestigious medical journal The New England Journal of Medicine participants not having been recruited
So, what to choose in the avalanche of studies published every day?
Ioannidis recommends asking the following questions: Is this an isolated or reinforced study? existing jobs? Is the sample small or big? Is it a random experience? Who funded it? Are researchers transparent?
These precautions are fundamental in medicine, where poor studies contribute to the adoption of treatments that are at best ineffective and, at worst, harmful.
In his book ] "End of the Medical Reversal", Vinayak Prasad and Adam Cifu link terrible examples of practices adopted on the basis of studies which have been invalidated years later, like stent placement in a cerebral artery to reduce the risk of stroke. Ten years later, a rigorous study showed that the practice increased the risk of stroke.
The solution requires the collective adjustment of common criteria for the actors of research, not only journals: universities, public funding agencies, laboratories. But all these entities are subject to competition.
"The system does not encourage people to go in the right direction," says AFP Ivan Oransky, co-founder journalist of the site ] Retraction Watch which covers withdrawals of scientific articles. "We want to develop a culture in which we reward transparency."
The media also have their share of responsibility, since according to him they must better explain to their readers the uncertainties inherent in scientific research, and avoid sensationalism
"The problem is the endless succession of people. studies on coffee, chocolate and red wine, "he complains. "We have to stop."
AFP
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