PrepTest 121

Incorrect. This answer would explain the data on the group receiving the medication, but not on the group receiving the placebo. It doesn't explain why the placebo was as effective as the medicine, nor why people on it had the same reversion as the drug to which others developed a tolerance (presumably, you can't develop a tolerance to a placebo).

Incorrect. This answer explains the data for the improvement over the past 2 weeks but not the reversion back at the three-week mark, since the patients were still taking something for their insomnia and thus would still be receiving comfort from it.

Incorrect. First, something being "less effective than expected" doesn't tell us much—was it expected to cure 100% of cases but actually cured only 80%, or was it expected to cure 80% and actually cured only 20%? One of those aligns with the situation better than the other. Second, even if it aligned with the situation, it wouldn't explain the placebo. Third, it certainly wouldn't then explain the reversion after a few weeks as there would be no change to explain the rapid descent back into insomnia.

Correct. Argument or Facts:
Facts

Question Type:
Paradox

Stimulus Summary:
In a one-month sleep study of insomniacs:
(1) Group 1 was given a drug; Group 2 was given a placebo
(2) First two weeks - 80% of both groups reported better sleep
(3) Third week - 90% of that 80% reported their insomnia returned

Answer Anticipation:
As with all Paradox questions, we should start by identifying the paradox. And we also have to be careful because the question stem asks us to explain all the data in the study. In other words, we need to explain the data from the first two weeks, as well as the data from the third week. So there are two things we need to explain.

What's paradoxical about the data from the first two weeks? There was a drug meant to treat insomnia, but those receiving the placebo saw the same reduction in insomnia as the other group. We need an answer that explains how this could be—either it's the placebo effect, or the medicine doesn't work, or something else that highlights why the placebo and medicine had the same effect.

What's paradoxical about the data from week three? If something was helping the insomnia, and nothing changed, then why was there a reversion back to insomnia? The answer should highlight something that changed about the study or those in it that can explain this shift back to having sleep issues.

We need an answer that does both of these things, so it's likely we'll see wrong answers that do only one—we need to watch out for those.

Answer Explanation:
If the new drug has no effect on sleep, then it'd be expected that the group on the drug and the group on the placebo would see the same results (since neither drug affects sleep). If most insomniacs sleep better in a new environment, that explains why 80% of both groups saw improved sleep during the study—as they were now sleeping in a new location (the institute). And it also explains why they ended up with sleep issues again at the three-week mark—they were no longer sleeping somewhere new, having acclimated to the environment over the prior 2 weeks. This answer explains all the data and is thus the correct answer.

Key Takeaway:
Be sure to clearly define the paradox in Paradox questions. And always read the question stem carefully—sometimes, it'll break out of the usual mold, and when it does, noting it will be key to avoiding trap answers. Here, you were tasked with explaining all the data, and trying to explain just the similar outcomes for those receiving the medication and the placebo or just the reversion after 2 weeks could have led you to a wrong answer.

Incorrect. That's why the study was being done in an institute instead of relying on people's self-reported sleep!