PrepTest 148, Section 3, Question 14
Researchers recently studied the relationship between diet and(38 more words not shown)
The argument is most vulnerable(9 more words not shown)
- AIt improperly infers(26 more words not shown)
- BIt draws a(22 more words not shown)
- CIt draws a(21 more words not shown)
- DIt confuses a(24 more words not shown)
- EIts conclusion is(17 more words not shown)
Reading the argument
Maybe feeling depressed makes people reach for chocolate. Or perhaps something else explains both: a person goes through a breakup, feels miserable, and eats more chocolate for comfort.
What we’re looking for
In either case, chocolate and low mood could appear together without chocolate causing the low mood. Cutting the chocolate wouldn't necessarily remove the underlying problem. The study gives us an association; the recommendation needs a causal effect. That's the flaw to look for. We don't need to prove chocolate never affects anyone's mood. We need to explain why these observations don't establish that reducing it will almost certainly improve mood.
Working the answers
- A
This starts with an established causal contribution, which the study hasn't given us. It also describes a conclusion about eliminating the condition, while the argument only claims mood will improve. The actual mistake comes earlier: inferring the causal relationship from the observed association.
- B
A large, diverse sample isn't guaranteed to be perfect, but nothing here identifies a reason it is unlikely to represent adults. We shouldn't invent a sampling defect when the stated observations already reveal a different problem. Even a representative sample could show this association without establishing that chocolate causes low mood.
- CCorrect
The evidence shows that the people who ate the most chocolate were most likely to feel depressed. The conclusion assumes that cutting chocolate will improve mood, which requires treating chocolate as a cause. The breakup example shows why the pattern alone doesn't establish that direction: another experience could explain both the sadness and the chocolate eating.
- D
This describes mistaking a requirement for something that guarantees an outcome. For example, knowing that an improvement requires a dietary change wouldn't mean every dietary change guarantees improvement. But the study doesn't give us a requirement of that kind. The mistake is using an observed association to infer a causal benefit from an intervention.
- E
The conclusion is clear enough to test: reducing excessive chocolate consumption will almost certainly improve mood. We can identify precisely what evidence is missing—a reason to believe the chocolate causes the mood problem. Unconvincing support doesn't make the conclusion too vague to evaluate.
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