PrepTest 126, Section 3, Question 9
Among people who have a history of chronic(62 more words not shown)
Which one of the following,(6 more words not shown)
- APeople who do(22 more words not shown)
- BMost people who(24 more words not shown)
- CMany people who(15 more words not shown)
- DThe people who(25 more words not shown)
- EThe people who(27 more words not shown)
Reading the argument
What if the people taking pills had more severe sleep problems to begin with?
We know the behavior-modification group falls asleep faster now. We don't know that the two groups started with the same difficulty. Maybe people with relatively mild trouble can manage it by changing their habits, while people with much harder cases are more likely to try medication. Then the final difference could reflect the problems being treated, not which treatment works better.
Think about what we'd need for a fair comparison. A treatment facing an easier problem might leave its users doing better even if the other treatment produces a larger improvement from a worse starting point. Simply comparing where the groups end up leaves that possibility open.
What we’re looking for
We're asked to weaken the claim that behavior modification is more effective. My prediction is information about that starting difference: the pill group had more trouble, or the behavior group had less. Those are two ways to expose the same problem with this comparison.
Working the answers
- A
Total hours asleep isn't the same as how quickly someone falls asleep. We might separately wonder whether people fall asleep quickly but wake up soon afterward; A doesn't give us that objection, since the non-pill group sleeps at least as long. It supplies no reason to doubt the argument's comparison about falling asleep. We shouldn't treat a different sleep outcome as though it settled this one.
- B
This introduces the wrong comparison group. The argument compares people with chronic trouble falling asleep who use two different treatments. B compares the behavior-modification group with people who don't have that trouble. Those people might fall asleep faster than either treatment group, telling us nothing about which treatment is more effective.
- C
Never having tried pills doesn't establish whether pills would work better or worse for these people. Their treatment history alone doesn't show how much either method helps or whether the two current groups had comparable problems. We need more than the fact that some people haven't tried the alternative.
- DCorrect
The people most likely to take pills are those who previously had the most trouble falling asleep. That's the starting difference we were looking for. The pill group may still take longer because it faces more severe problems, not because pills are less effective. D doesn't prove which treatment is better; it undermines using these groups' present speed as a fair test of that question.
- E
A preference for avoiding drugs explains why someone might choose behavior modification. It doesn't tell us how difficult that person's sleep problem was or how well the treatment worked. A reason for choosing a treatment is useful here only if it helps explain why the groups' results don't fairly measure treatment effectiveness. This preference alone doesn't do that.
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