PrepTest 111, Section 4, Question 24
A recent study of 6,403 people showed that(71 more words not shown)
The argument's reasoning is flawed(3 more words not shown)
- Aneglects the possibility(7 more words not shown)
- Bfails to consider(19 more words not shown)
- Crelies on past(16 more words not shown)
- Ddraws a conclusion(25 more words not shown)
- Efails to consider(10 more words not shown)
Reading the argument
Even if the drug helps, how do we know cholesterol is the reason?
My first question about the study is whether the two groups differed in other ways. Perhaps people taking the drug also exercised more. We aren't told enough about the study's design to settle that concern. But there is a more direct problem with the conclusion: reducing cholesterol is only one of the drug's effects.
Suppose, just as a hypothetical, a drug both lowered cholesterol and produced a change in weight, and the weight change explained the improved heart outcomes. We could then see fewer heart problems among people taking it without showing that lowering cholesterol caused the improvement. The earlier studies don't settle this either. Finding high cholesterol alongside heart disease isn't the same as showing that reducing the cholesterol reduces the disease risk.
What we’re looking for
We're asked to identify the flaw. I'd look for the overlooked possibility that the drug's benefit comes from something other than its cholesterol-lowering effect.
Working the answers
- A
A drug could reduce a particular risk while also causing serious side effects. That would matter to a decision about whether to take it, but the argument isn't claiming the drug is safe overall. The conclusion concerns whether lowering cholesterol reduces heart disease risk. A doesn't identify the missing link between those two things.
- BCorrect
This separates the drug's overall effect from the effect of one particular thing the drug does. Even granting that pravastatin caused the better outcomes, we still need a reason to credit its cholesterol reduction for that benefit.
If another effect of the drug accounts for the lower risk, the study doesn't establish the proposed explanation. We don't have to show that lowering cholesterol has no benefit, or that only one factor could matter. The problem is that this evidence hasn't isolated lowering cholesterol as the reason the risk fell.
- C
The argument uses the current study as well as earlier findings. It doesn't ignore the study it cites. And using previous research isn't inherently a mistake; the issue is whether the combined evidence supports this particular causal conclusion. C misdescribes the reasoning instead of identifying that gap.
- D
We already know that lowering cholesterol is one of pravastatin's effects. Restating a relationship between the drug and cholesterol wouldn't resolve the disputed connection between cholesterol reduction and reduced heart disease risk. There's no rule requiring the conclusion to focus on the topic D prefers. We need to explain why the conclusion actually drawn is unsupported.
- E
How many people in the general population take the drug doesn't tell us which of its effects explains the outcomes among the study participants. A widely used drug and a rarely used drug could each have several effects. The population's usage rate doesn't address the mechanism the argument assumes.
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