PrepTest 130, Section 3, Question 19
Recent studies have demonstrated that smokers are more(53 more words not shown)
The argument's reasoning is most(17 more words not shown)
- Asmokers who drink(18 more words not shown)
- Bsomething else, such(24 more words not shown)
- Cdrinking caffeinated beverages(13 more words not shown)
- Dit is only(22 more words not shown)
- Ethere is a(18 more words not shown)
Reading the argument
Smokers have more heart disease. That association alone doesn't tell us whether smoking causes it; smokers might also have other habits that matter. But the argument's conclusion is only about a correlation, so we need to watch the group comparisons rather than turn this into a different causal argument.
The second study says smokers are also more likely to drink caffeinated beverages. Are the smokers drinking caffeine the same smokers developing heart disease?
What we’re looking for
Picture the smoker group with two different subgroups inside it. One subgroup drinks caffeine; another develops heart disease. Those subgroups might overlap very little, or even not at all. Smoking could be associated with each characteristic without caffeine and heart disease being positively associated with one another. The rest of the population's pattern would matter too, and the premises haven't supplied that information. For the flaw question, I'd look for a possible distribution of people that breaks the claimed connection.
Working the answers
- ACorrect
Within the smoker group, the caffeine drinkers could have a lower rate of heart disease than the non-caffeine drinkers. That would fit the concern that the two characteristics don't belong to the same smokers in the way the author assumes. It leaves room for the heart-disease association with smoking to be concentrated among smokers who don't drink caffeine.
This doesn't prove that caffeine prevents disease or that there is no positive correlation anywhere in the population. It shows why the two stated associations with smoking don't establish the claimed association with each other. We need information about their actual distribution, not just their separate connections to smoking.
- B
Some other factor could be more important in causing heart disease while caffeine consumption still correlated with the disease. The conclusion doesn't rank causes or recommend the best way to reduce risk. An alternative important cause therefore doesn't identify the missing correlation between these two groups.
- C
A stronger correlation between caffeine and heart disease would support the conclusion that there is a positive correlation. The author doesn't claim that the correlation must be weaker than the one involving smoking. This possibility isn't a reason the inference fails.
- D
An association confined to a hereditary subgroup could still produce a positive association in the population overall. The author doesn't claim that caffeine and disease are associated in every subgroup. D therefore doesn't directly challenge the conclusion's modest scope, and we have no basis for assuming the hereditary group is small.
- E
A common cause could produce the very correlation the author concludes exists. For example, another factor might contribute to both the behaviors and the disease, leaving them associated even though caffeine itself doesn't cause the disease. Since the conclusion is about association rather than causation, that possibility doesn't expose this argument's mistake.
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