PrepTest 137, Section 3, Question 4
In a study of patients who enrolled at(63 more words not shown)
Which one of the following,(8 more words not shown)
- ASeveral studies have(21 more words not shown)
- BThe patients who(25 more words not shown)
- CBecause the scents(34 more words not shown)
- DSome of the(16 more words not shown)
- ESeveral studies have(21 more words not shown)
Reading the argument
The peppermint group had more trouble falling asleep. Was that because of the peppermint?
At first, we could imagine several explanations: peppermint makes sleep harder, bitter orange makes it easier, or something else differs between the groups. The argument rules out the second explanation by telling us bitter orange doesn't help people fall asleep. We should accept that, but it doesn't leave peppermint as the only possible cause.
What if the peppermint patients were also given caffeine? Then we'd have a reason they struggle to fall asleep that has nothing to do with the scent. That's a hypothetical example of the comparison problem: different outcomes don't establish a peppermint effect unless we can deal with other relevant differences.
What we’re looking for
For a weakener, I'd look for another reason the peppermint group would have more trouble. We can accept the study's results while questioning what caused them.
Working the answers
- A
These studies concern people without insomnia, while our argument concerns people with insomnia. Peppermint could affect those groups differently. Also, feeling relaxed doesn't automatically mean falling asleep more easily. A doesn't establish that peppermint fails to worsen the particular problem studied here.
- BCorrect
The peppermint patients already had more severe insomnia on average. That gives us a direct alternative explanation: they may have had more trouble sleeping because their sleep problem was worse to begin with.
My hypothetical involved caffeine; B supplies a different relevant difference between the groups. If neither scent changed anyone's sleep, the more severely affected group could still have worse results. That undermines the attempt to attribute the difference to peppermint. It doesn't prove that peppermint has no effect at all.
- C
Knowing that you're participating in a scent study doesn't tell us why one group would have more difficulty than the other. Perhaps expectations could matter, but C doesn't say the groups had different expectations about their scents or that those expectations affected sleep. We shouldn't supply that extra causal story for the answer.
- D
Trouble staying asleep is different from trouble falling asleep. More importantly, this doesn't distinguish the peppermint group from the bitter-orange group. Some patients having an additional sleep problem gives us no specific alternative explanation for the observed difference.
- E
Some pleasant scents can affect insomnia, but which scents, and in which direction? An effect could be improvement or worsening. The answer is compatible with peppermint making insomnia worse and gives us no reason to doubt that particular claim.
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