Answers ■ A3Wall Street Journal is a respected newspaper, it tends to have
a conservative bias, especially since being bought by Rupert
Murdoch.(c) Real science. Practicing scientists have reported experi-
mental findings to their peers, but they do not yet appear to
have published in a peer-reviewed journal, which will need to
be the next step.(d) Pseudoscience. Astrologers are not scientists. There is no
scientific evidence that date of birth has any effect on personality.(e) Real science. The journal Diabetes is a peer-reviewed and
well-established scientific journal. We do not know, however,
the design of the study or the sample size.- (a) The first graph shows the incidence of pertussis (whooping
cough) cases in the United States from 1922 to 2012, with
the inset showing a zoomed-in view of 1990–2012. The x-axis
shows the year from which the pertussis cases were counted;
the y-axis shows the counts. Any point on the line shows the
total number of cases reported in the corresponding year on
the x-axis. The general trend of the graph is a decrease in
cases of pertussis over time.(b) The reason for the increase in cases in the first decade of
the twenty-first century is probably that parents were choos-
ing not to have their children vaccinated.(c) The second graph shows the incidence of pertussis (whoop-
ing cough) cases in the United States by age group from 1990
to 2012. The x-axis shows again the year from which the
pertussis cases were counted, and the y-axis shows the counts.
This graph’s y-axis shows not the total number of cases, but
rather the number of cases per 100,000 individuals in the
population of that particular age group. One point on each
line shows the number of cases per 100,000 individuals in the
population of that particular age group reported in the corre-
sponding year on the x-axis. The general trend is an increase
in cases of pertussis by age group over time. The lines differ by
age group. The younger the age group, the greater the increase
in pertussis cases per year.(d) The incidence of pertussis cases per 100,000 individuals
in the population of children under 1 year old is very high, and
in people over the age of 20 it is very low. Increase over time is
much greater in children under 1 year old and is very minimal
in people over the age of 20.(e) It appears to be very risky not to vaccinate. I would vaccinate!
- (1) Evaluate the credentials of the group members recom-
mending the vaccine (in this case it would be members of the
ACIP, FDA, and CDC).(2) Assess any possible biases of the people in step 1.
(3) Read the secondary literature (for example, recent articles
in Popular Science or the New York Times) for an overview of
the issue.(4) Read recent primary literature that was cited in the
secondary literature (for example, articles in JAMA or the New
England Journal of Medicine or Vacc ine).(5) Review papers from the primary literature for credentials
and biases of the authors, good research design, reasonable
sample size, and conclusions.ANSWERS TO FIGURE QUESTIONS
Figure 2.1
Q1: Describe in one sentence how a vaccine creates immunity to a
virus.A1: A vaccine causes the immune system to produce antibodies in
response to an inactive or harmless virus. Those antibodies then
immediately identify and attack any live virus (of that type) that
enters the body.Q2: Why is it impossible to become infected with a virus from a
vaccine composed of viral proteins?A2: Proteins don’t replicate; DNA or RNA is needed for a virus to
replicate.Q3: Natural immunity occurs without a vaccine, just by exposure
to a particular stimulus, like the chicken pox virus. Explain why
people don’t get chicken pox twice.A3: Your body creates antibodies when you are exposed to, for
example, chicken pox virus. If you are exposed a second time, those
antibodies immediately identify and attack the chicken pox virus
(just as in question 1 above).Figure 2.2
Q1: Before vaccinations, which diseases had the highest and
lowest mortality rates? What are these mortality rates?A1: Highest: Tetanus, 90%. Lowest: Pertussis, 5%.Q2: After vaccinations, which diseases have the highest and lowest
mortality rates? What are these mortality rates?A2: Highest: Tetanus, 14%. Lowest: Polio, diphtheria, and
smallpox, 0%.Q3: If there were a sudden outbreak of whooping cough at a
university where pertussis vaccinations were not required and no
one was protected, how many students would die? What is the
probability or chance that you would die if infected?A3: At California State University, Northridge, for example, which
has 40,000 students total, 40 students would die—a 0.1% chance
of death for any individual student.Figure 2.5
Q1: Why are we less confident of scientific claims made over social
media?A1: Claims made over social media are not subject to peer review
before being “published.” Therefore, people can—and do—make
ridiculous scientific claims in social media.Q2: Where would you place a blog in this figure? Would it matter
whether or not it was written by a practicing scientist? Explain
your reasoning.