PrepTest 140, Section 2, Question 4
Physician: Stories of people developing serious health problems(55 more words not shown)
Which one of the following,(8 more words not shown)
- AFor the most(18 more words not shown)
- BSome of the(25 more words not shown)
- CPeople are no(18 more words not shown)
- DThe health problems(24 more words not shown)
- EIn a few(30 more words not shown)
Reading the argument
Someone developed a health problem after a vaccination. Would that person have developed the problem anyway?
That's the physician's response to these stories. Among millions of people, some will have health problems shortly after being vaccinated simply because health problems occur. The order of events alone doesn't show that the vaccination caused the illness.
Still, I'd want to know how often this happens. Expecting some coincidental cases doesn't excuse an unusually high rate. If the number of health problems jumped after vaccination, the physician couldn't dismiss that increase just by saying coincidences exist.
What we’re looking for
To strengthen the argument, show that the rate isn't higher than we'd otherwise expect. That would help explain why the individual stories can be true without giving us the reason for concern that people take them to provide.
Working the answers
- A
Recently introduced vaccines could attract more stories for several reasons. This doesn't tell us whether recipients actually have an unusually high rate of health problems. Being new is neither evidence that a vaccine caused a particular illness nor support for the physician's coincidence explanation.
- B
This concerns how likely people are to contract the illnesses that vaccines prevent. The argument concerns whether vaccination causes other health problems afterward. Even if a targeted illness has become rare, that doesn't tell us what caused the reported later problems.
- CCorrect
There is no higher average likelihood of serious health problems shortly after vaccination than shortly before it. The earlier period gives us a useful comparison: people were already developing such problems before the vaccination could have caused them. If the rate doesn't increase afterward, the stories fit the physician's point that some cases are expected by coincidence.
This supports the physician without proving that no vaccination could ever cause a health problem. The question asks which fact most strengthens the argument, and this one directly addresses the missing rate comparison.
- D
How severe are the later problems? That's different from what caused them. A serious condition can occur coincidentally just as a minor condition can. Comparing its severity with the illness the vaccine targets doesn't establish whether the vaccination contributed to it.
- E
These other medications turned out to cause problems that were initially dismissed as coincidences. That gives us a reason to be cautious about this kind of dismissal, rather than supporting it. It doesn't prove that vaccines caused the problems here, either: evidence about a different medication doesn't settle this case.
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