After Laura’s appearance on The Late Late Show, the World Health Organization (WHO) invited her to spread the message about the HPV vaccine across Europe to help combat misinformation being spread about the vaccine. Instead of turning to reputable sources, parents were being guided by pseudoscience.
A claim that superficially looks as though it is backed by science is called pseudoscience. Pseudoscience is characterized by scientific-sounding statements, beliefs, or practices that are not actually based on the scientific method. Asking a series of simple questions related to the scientific method can help you distinguish science from pseudoscience (Figure 2.9). As an example, let’s look at two real-world examples of pseudoscience: a 1998 claim that vaccines cause autism and a 2016 claim that the HPV vaccine causes brain damage.
Figure 2.9Science or pseudoscience? A series of simple questions based on the scientific method can help you determine whether a “scientific” study is real science or pseudoscience.
Q1: Why do all the green arrows continue down to “real science,” whereas each red arrow points directly to “pseudoscience”?
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All of the criteria listed in boxes 1–6 must be met for a study to meet the expectations of the scientific method and therefore be real science. By contrast, any single item in a red box indicates pseudoscience.
Q2: Return to the main text and read the rest of this section and the following section, “Real or Pseudo?” Then come back and answer this question: What part(s) of the figure show where Wakefield’s study failed to meet the standards of the scientific method?
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Wakefield’s study really falls apart in steps 4–6. It was not carefully designed and definitely not reproducible. The sample studied was not of sufficient size and did not include a random control group. The conclusions did not follow from the analysis of the experimental results, and the study was published without adequate review from scientists in the field.
Q3: What is the scientific claim behind the vaccine-autism controversy? What is an alternative scientific claim?
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The original scientific claim was that the MMR vaccine leads to the development of autism (specifically, some said, by harming a child’s immune system). One alternative claim is that autism is caused by multiple factors that include a genetic predisposition but do not include vaccination.
You can also see Appendix A for answers to the figure questions.
In 1998, the Lancet, a well-known peer-reviewed medical journal and therefore a reputable source, published a paper unremarkably titled “Ileal-Lymphoid-Nodular Hyperplasia, Non-specific Colitis, and Pervasive Developmental Disorder in Children.” The paper presented a study of 12 children ranging in age from 3 to 10 who had experienced a loss of language skills—a symptom of autism spectrum disorders—as well as diarrhea and abdominal pain. Parents of 8 of the 12 children said the onset of symptoms occurred shortly after the children’s immunization with the measles, mumps, and rubella (MMR) vaccine.
The authors of the paper, a team of 12 researchers, concluded that more research was needed, but in a press conference when the paper was published, one of the authors, a British doctor named Andrew Wakefield, made the claim that single vaccines, rather than the MMR triple vaccine, were likely to be “safer” for children. The study and press conference sparked widespread fear among parents that the MMR vaccine could cause autism. This fear has led directly to the anti-vaccination, or anti-vax, movement, which continues to generate controversy and headlines.
The Wakefield et al. study was published around the time that officials began documenting an increase in the rate of autism. The CDC, which funds basic research to follow trends of disease in the United States, said that the rise was likely due to heightened awareness of autism, more screening within schools, and a willingness to label the condition. But after Wakefield publicly suggested that the MMR vaccine might be causing autism, the press and other organizations began to report that the rise in autism cases was caused by the increased use of vaccines.
Linking the rising rate of autism with increased use of vaccines is a correlation. Correlation means that two or more aspects of the natural world behave in an interrelated manner. That is, if one aspect shows a particular value, we can predict a value for the other aspect(s). But correlation does not prove causation. In other words, just because two aspects are correlated does not mean that a change in one aspect causes a change in another. A correlation may suggest possible causes for a phenomenon or phenomena, but it does not establish a cause-and-effect relationship. For example, there is a correlation between organic food sales and the increase in autism. From 1998 to 2007, organic food sales increased hand in hand with the number of autism diagnoses. These changes are correlated, but there is no scientific evidence that eating organic food causes autism (Figure 2.10).
Figure 2.10Correlation is not causation: organic food and autism Reddit user Jasonp55 created a tongue-in-cheek demonstration of why it is important not to assume that correlation means causation. Jason used real data on organic food sales and the increase of autism from 1998 to 2007. As this graph shows, the two phenomena are highly correlated. However, the graph cannot show scientific evidence that one causes the other.
Q1: How much did organic food sales grow during the period covered in the graph? How much did the autism diagnoses grow?
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Organic food sales grew from $5 billion to $25 billion (a fivefold increase). Autism diagnoses grew from about 50,000 individuals to over 250,000 (also a fivefold increase).
Q2: Why might both organic food sales and autism diagnoses have increased during this time period? A Reddit user in the original discussion thread suggested that both might be affected by increasing wealth in the United States. How might an increase in wealth affect these variables?
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People with more disposable income are able to spend more on food (hence, the rise in organic food sales), and they are also better able to take their children in for advanced medical care (possibly the reason for increased identification of autism spectrum disorder).
Q3: How has the vaccine-autism debate been confused by people misinterpreting correlation as causation?
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Because vaccination was increasing at the same time that autism rates were rising (correlation), people suggested that the former caused the latter (causation). In addition, the time at which children are typically vaccinated is about the same age at which autism symptoms often appear.
You can also see Appendix A for answers to the figure questions.
Another correlation that spurred fears about vaccines is that the onset of autism symptoms occurs at about the same age that children receive vaccinations. Most children receive the MMR vaccine at about 15 months old, which is shortly before the first symptoms of autism are often noticed. Parents of children with autism saw their children begin to exhibit symptoms of the illness after their vaccinations and therefore directly observed a correlation between the injection of the vaccine and the onset of autism spectrum disorder.
Yet, again, correlation does not prove causation. Only scientific experiments can demonstrate causation. So was Wakefield’s claim about the link between MMR vaccine and autism based on good science or pseudoscience? Did the MMR vaccine cause autism?
A statistical relation indicating that two or more aspects of the natural world behave in an interrelated manner: if one shows a particular value, we can predict a particular value for the other aspect. Compare causation.
