A4 fiffAnswers
A2: A blog could be listed either under social media or under
secondary literature, depending on the quality of the content.
In the case of a science blog written by a practicing scientist, the
choice would depend on the subject matter, but it would likely be
listed under secondary literature. (Counterargument: The physicist
who thinks global climate change is a scientific conspiracy.)
Q3: Give an example of when you would rely on secondary literature
to evaluate a scientific claim and an example of when you would go
to the primary literature. What is the basis of that decision?
A3: You might go to the secondary literature only for something
that is not life-threatening—for example, what kind of exercise
to do, or whether to turn down the thermostat in your bedroom.
Primary literature is challenging reading, so it is usually left
for life-critical choices—for example, whether to vaccinate your
children, or possibly whether to eat a vegetarian or vegan diet.
Figure 2.6
Q1: How much did organic food sales grow during the period
covered in the graph? How much did the incidence of autism grow?
A1: 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 prevalence
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 increased
wealth affect these variables?
A2: 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 disorder).
Q3: In what way has the vaccine-autism debate been confused by
people misinterpreting correlation as causation?
A3: 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 typically appear.
Figure 2.7
Q1: State the hypothesis of the people who believe that vaccines
cause autism. What is an alternative hypothesis?
A1: Hypothesis: Vaccination harms a child’s immune system and
stimulates the development of autism. One alternative hypothesis:
Autism is caused by a genetic predisposition, and symptoms begin
to show up in the second year of a child’s life.
Q2: What part(s) of the figure show where Wakefield’s study failed
to meet the standards of the scientific method?
A2: 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: Why does only one arrow point to “real science,” whereas
multiple arrows point to pseudoscience?A3: All of the criteria listed in the figure must be met for a study to
meet the expectations of the scientific method.Figure 2.8
Q1: Why is it important to know the education and expertise of a
person making a scientific claim?A1: The opinion of a person who doesn’t really understand the
science behind a claim is not valid.Q2: List at least five possible biases that people making scientific
claims might have.A2: (1) They could make money if you buy a product related to the
claim. (2) They might win a lawsuit if the judge believes the claim.
(3) They could become famous if people accept the claim. (4) Their
religious beliefs might be supported if the claim is true. (5) Their
political beliefs might be supported if the claim is true.Q3: Describe a situation in which you might not dismiss the
scientific claim of a person who did not have appropriate
credentials, or who had a bias toward the claim.A3: Paul Offit’s case provides an example: He made a great deal
of money by selling a rotavirus vaccine he created. However, his
expertise is extremely strong, and he does not have an ongoing
financial interest in supporting vaccination.Figure 2.10
Q1: Why do vaccine manufacturers begin with tests on animals or
cell lines before moving on to adult human subjects?A1: They need to be sure of the safety of the vaccine before
exposing people to it.Q2: What ongoing testing and reporting are vaccines subjected to?A2: Manufacturers test all vaccine lots, the FDA regularly
inspects manufacturing facilities, the Advisory Committee on
Immunization Practices (ACIP) and the CDC director review
all test results before approving vaccines, and vaccine safety
is continually monitored through the Vaccine Adverse Event
Recording System (VAERS) and the Vaccine Safety Datalink
( VSD).Q3: What do ACIP, FDA, and CDC stand for, and what is the role
of each in evaluating vaccines?A3: ACIP = Advisory Committee on Immunization Practices;
FDA = Food and Drug Administration; CDC = Centers for Disease
Control and Prevention. All are involved in the initial approval and
ongoing monitoring of vaccines.Figure 2.11
Q1: What happens to an immunized person when a disease
spreads through a population? (Hint: In the graphic, follow an
immunized individual before and after a disease spreads.)A1: The immunized person does not contract the disease.Q2: Explain why a disease is less likely to spread to vulnerable
members of a population if most people are immunized.