PrepTest 146, Section 1, Question 22
In 2005, an environmental group conducted a study(69 more words not shown)
The reasoning in the argument(11 more words not shown)
- Atakes an inconsistent(14 more words not shown)
- Boverlooks the possibility(9 more words not shown)
- Cconcludes that a(16 more words not shown)
- Dtakes something to(16 more words not shown)
- Edoes not consider(14 more words not shown)
Reading the argument
You just said this study couldn't support scientifically valid inferences. Now it 'proves' the ban worked?
Eleven volunteers might give us interesting observations, but I'd immediately wonder whether they represent a broader population. The author acknowledges the limitation: the sample is too small for scientifically valid inferences. Seeing lower PCB levels in the younger volunteers could still be worth investigating. Interesting results and conclusive proof are different things.
What we’re looking for
The problem is that the final sentence abandons the earlier caution. It uses those very results to declare that the regulation reduced human exposure. For the flaw question, I'd look for that conflict in how the author treats the study: too limited to support valid inferences, yet strong enough to prove the claimed effect.
Working the answers
- ACorrect
The author takes two incompatible positions about the study's evidentiary value. First, we cannot draw scientifically valid inferences from it. Then, it proves that the ban was effective. The argument can't use its own stated limitation and simply ignore it when announcing the result it wants.
- B
We are measuring how much of a chemical is present in people's bodies, not identifying the chemical by the symptoms it produces. Two chemicals causing the same effect wouldn't explain the inconsistency in how the author uses these measurements.
- C
The author doesn't say, 'Nobody has disproved the ban's effectiveness, so it must be effective.' The argument cites an observed difference in PCB levels as evidence. Its own description of that evidence undermines the claim of proof, but that isn't the same as treating an absence of disproof as proof.
- D
This would question whether the reduction led to the regulation rather than the regulation causing the reduction. The passage doesn't give us a reason to identify that reversed sequence as its problem. Whatever other questions we might ask about the causal claim, A directly captures the stated inconsistency: evidence declared insufficient is then treated as conclusive.
- E
The conclusion concerns reducing exposure, not eliminating every later health effect of past exposure. PCBs could cause harm years later even if a regulation successfully reduced newer exposure. E doesn't undermine the specific conclusion or explain the contradiction in the treatment of the study.
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