Cherry-picking: choosing facts that confirm what you want!

The scientific literature isn’t a cherry tree. You can pick the red cherries off a tree and leave the ones that are green and unripe. But scientific rigour requires that all studies dealing with a subject be considered to obtain an overview.  

Cherry-picking is a common practice. Various movements and industries have practiced it, taking care to exclude studies that don’t go their way, They only select studies that support their position. 

Here are some famous cases of cherry-picking. 


Climate deniers  

Everyone knows how easy it is to make numbers say what we want to hear. Just select the data that agrees with our ideology and isolate the other values. That’s how some climate deniers have contradicted the science of climate change. They invoke a temperature plateau observed from 2000 to 2010 and ignore the other scientific data.  

By concentrating only on temperature fluctuations in that decade, the trend seems to be pausing instead of rising. But climate deniers forget to mention that this apparent pause is explained  by the El Niño phenomenon of 1998. A particularly warm seasonal air current occurred that year. The 1998 temperature peak exceeded the fluctuations observed in the following years, giving the appearance of a plateau. It was only in 2007 and 2010 that new peaks reached the 1998 level. Since then, the temperature curve has started rising again.  

Cherry-picking can also be geographic, That’s when only the localities recording cool temperature are chosen, while the temperature is rising everywhere else.  

Another strategy for sowing doubt is to brandish an opinion letter or a petition signed by a multitude of scientists. Client deniers attach more importance to this document than to all the data on the subject. In September 2019, a letter entitled “There is No Climate Emergency”, signed by over 500 scientists, was sent to the United Nations. 

Barely 3% of these 500 scientists had expertise in climate science. Furthermore, an opinion or a petition isn’t a scientific study. But the scientific consensus on climate change is based on the results of the collective efforts of thousands of scientists over the past fifty years. 


Anti-vaccination, from one adjuvant to another 

The anti-vaccination movement has also practiced cherry-picking, relying on a single 1998 study, published by Dr. Andrew Wakefield in The Lancet. This fraudulent study claimed to show how the addition of the adjuvant thiomersal to the MMR (measles, mumps and rubella) vaccine increased the rate of autism spectrum disorders.  

The anti-vaccination movement used this as its sledgehammer argument against vaccination. That’s even though many studies had proved the safety of MMR since its use began in the 1970s.  

An investigation by journalist Brian Deer in 2011 revealed Dr. Wakefield’s frauds and conflicts of interest. As a result, his co-authors issued a retraction and The Lancet removed the article from its archives. But the anti-vaccination movement had taken root. It rejected the verdict of the journalistic investigation or cherry-picked other scientific studies that agreed with their point of view. They invoked studies suspecting another adjuvant, aluminium, of causing autism or macrophage myofasciitis at the injection site, leading to various muscular or neurological disorders. The studies were funded by the Dwoskin Family Foundation, which was openly anti-vaccination. 

Yet many systematic reviews have proved the efficacy and safety of these vaccines. One of the latest was published in April 2020 in the Cochrane Library. It surveys 138 studies (nearly 23.5 million participants) and concludes that the vaccines are effective and do not cause autism. These studies attest to a scientific consensus supporting the national vaccine recommendations.  


Smoking: instilling doubt 

By the 1950s, the tobacco industry knew that successive studies were denouncing the harm that cigarettes caused to health. To oppose this, the industry didn’t cherry-pick studies that relativized or denied the harmful effects of cigarettes. It simply manufactured them! 

More specifically, the tobacco industry subsidized university scientists through the Council for Tobacco Research (CTR), which it had created in 1954. As the evidence mounted against cigarettes, the cigarette manufacturers couldn’t hope to conceal it by only promoting its own studies. The strategy was to instill doubt regarding the scientific consensus on the carcinogenic nature of tobacco. The industry paid scientists to give an opposite opinion. This created the illusion that there was still a debate in the scientific community, even though this wasn’t true. A systematic review of the studies on the health effects of second-hand smoke, backed up by statistical analyses, showed that all the studies minimizing the harmful effects of second-hand smoke were conducted by researchers affiliated with the tobacco industry! 

Sowing doubt turned out to be such an effective strategy that it was later copied by the food industry (soft drinks, sugar) and the oil industry


Creationists… also create their own studies 

Creationists are very familiar with the art of cherry-picking. This is shown by the pseudoscientific articles published on the website of the Discovery Institute, a think tank linked to the American right-wing conservatives and a major promoter of creationism. To produce reports that look like “peer-reviewed scientific articles” and give their ideas a scientific veneer, creationists created their own science, their own scientific journals (Answers Research JournalCreation Research Society Quarterly) and their own body of studies! Creationism has now spun off into several disciplines, with biologists, geologists and even astronomers. In their own production, they cherry-pick pseudoscientific reports and set them up in opposition to science.  


COVID-19, conducive to cherry-picking 

All the scientific, social and economic uncertainties make COVID-19 a subject conducive to polemics and cherry-picking. This is especially true, given that the body of scientific evidence on this subject is being constructed while the pandemic goes on. We’ve seen some politicians rely on Dr. Raoult’s study to certify that hydroxychloroquine could curb the disease. That’s even though the scientific community called for more caution due to the lack of data. What about the document by Canadian physicist Denis Rancourt, claiming that masks are useless? It was picked up by various groups to oppose mask wearing.  As this article shows, these groups ignored the biases in the physicist’s report and the scientific studies that confirm how masks are useful. 


This article was originally published on the website of L'Agence Science-Presse (French only)


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