Logical reasoning PrepTest 130 · Section 3 · Question 23

Incorrect. Very tempting. However, this answer falls short of affecting the argument in that it doesn't connect members of the studies to specific outcomes, so we can't attribute the correlation to the insomniacs or non-insomniacs. Comparisons like this are also very weak—"a weaker correlation" could mean a .003 vs. a .004 correlation. When it's noted that "only a few" subjects were affected by the melatonin, a single non-insomniac being affected by melatonin could be enough to change that number. In short, this answer is too weak and non-specific to affect the argument.

Incorrect. Because the conclusion of this argument is about possibility ("can induce"), it can be supported by a certain subset of the population being affected by melatonin. After all, if it's only people with sleep issues who are affected by melatonin, then it's true that it can induce sleep. As such, the sample doesn't need to be representative. Especially since the stimulus even notes that only a few people in any given study saw the effect.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen

Stimulus Summary:
Studies - Suggest that melatonin can help with sleep
Shortcomings - 1) Mostly didn't feature insomniacs; 2) Many showed only a few people affected by it
Conclusion - We can't conclude that melatonin helps with insomnia

Answer Anticipation:
The conclusion of this argument is interesting. Usually, in a stimulus that features studies, the conclusion is a causal hypothesis—one thing causes another. This one, however, rules out a hypothesis. Based on the studies, one might believe that melatonin can treat insomnia, but the author concludes that we can't conclude that. Note that it doesn't conclude that melatonin doesn't help with insomnia—just that the studies don't support that.

Why not? Because the studies mostly didn't feature insomniacs, and many of the studies showed very few people were affected by melatonin. So the former studies wouldn't tell us anything about insomniacs, and the latter ones don't necessarily have an overlap between the insomniacs in the study and the people who were helped by melatonin.

Let's break these studies into two groups—the ones that didn't have insomniacs, and the ones that did, as the interaction between those studies and the conclusion are different.

The ones without insomniacs definitely can't support a conclusion about insomniacs, so there's no assumption there. Those studies don't, in fact, allow the hypothesis the argument rules out to be drawn, so there's no gap there.

The ones with the insomniacs, however, could prove that melatonin can help with insomnia. If the "few" individuals in those studies who were significantly affected by the melatonin were the insomniacs, then the studies do support using it as a cure. If they weren't, then the conclusion holds. Let's find an answer establishing that in these studies, it wasn't the insomniacs who were helped out by the melatonin.

Answer Explanation:
This answer establishes that the insomniacs were not the ones affected by melatonin. If that's the case, then that supports the conclusion that melatonin doesn't help with insomnia, which would support the conclusion that the studies don't support such a relationship.

Key Takeaway:
When more than one study is mentioned in a stimulus, make sure to look at each one and how it aligns with the conclusion. Here, doing so showed us that the first study could essentially be ignored since it aligned perfectly with the conclusion—if a study doesn't include insomniacs, then it can't support a conclusion about insomniacs!

Incorrect. Without knowing if these control groups had insomniacs or not makes it hard for this answer to affect the argument.

Incorrect. Since the stimulus doesn't tell us whether the "few" people significantly affected by the melatonin in the studies were the ones with insomnia, we don't know if this answer allows us to reach the conclusion, and thus we don't know if this answer strengthens the argument.