Logical reasoning PrepTest 126 · Section 3 · Question 9

Question prompt

Among people who have Remaining source text redacted.
Why the credited answer is right

Credited answer: D

The notes below walk through why it fits the stem and how to eliminate the rest.

Argument or Facts

Argument

Valid or Flawed

Flawed

Question Type

Weaken Questions

Answer Anticipation

This entire argument is based on a study, so we should consider the two most common flaws in studies - a sampling flaw, and a correlation/causation flaw.
For the sampling flaw, while there’s no indication that the sample is too small, there are other problems.
First, the study was done on people with sleep issues, while the conclusion is about people generally. If those with chronic sleep issues respond differently to pills and behavior modification than the general public, they are unrepresentative and thus could skew the results. Any answer highlighting this possibility would weaken the argument.
Second, the two groups weren’t randomly assigned. For this study to draw valid conclusions, it would need to find people with sleep problems and randomly assign them to receive pills or behavior modification (and also establish a control group). By starting with people who are using pills or behavior modification, the study leaves open the possibility that people “self-selected” into those groups - in other words, maybe those with bigger sleep issues take sleeping pills because behavior modification doesn’t work. Any answer highlighting an inherent difference between Groups 1 and 2 that weren’t accounted for by randomly assigning the groups will weaken this argument.
For the correlation/causation flaw, the argument does jump from a correlation between people treating their sleep conditions with different treatments and difficulty falling asleep to draw a causal conclusion. However, since the argument’s conclusion compares the effectiveness (“more effective”) of the two, it’s unlikely that the answer will weaken the argument by addressing it. It’s that comparison that serves as the basis for the conclusion, and calling the causality itself into question makes the entire argument meaningless. We can still look for it, but we shouldn’t expect it.

Answer choices

  1. A
    People who do not Remaining source text redacted.
    Why choice A is not credited
    The issue is falling asleep, not how long one sleeps once they do so, so this answer is out of scope.
  2. B
    Most people who have Remaining source text redacted.
    Why choice B is not credited
    The conclusion compares behavior modification techniques to sleeping pills for falling asleep, and the study established that those using the former fall asleep faster than those taking the latter. As such, comparing the former group to those who don’t have sleep problems doesn’t change anything about the relative time for the two groups in question to fall asleep - this answer is out of scope.
  3. C
    Many people who use Remaining source text redacted.
    Why choice C is not credited
    First, this answer is relatively weak in discussing “[m]any” people, so it’s not really strong enough to affect an argument about average time to fall asleep. Additionally, even if most had taken sleeping pills, without knowing why they switched, it’s hard to know whether it had to do with effectiveness.
  4. D
    The people who are Remaining source text redacted.
    Why choice D matches the stem
    This answer highlights an inherent difference between the two groups that calls the sample into question. If those who take sleeping pills have the most serious sleeping issues, then it’s possible sleeping pills work better than behavior modification techniques, but they’re working against a harder problem. For example, let’s say, those who take sleeping pills usually take 2 hours to fall asleep, and the sleeping pills get it down to 30 minutes. And those who use behavior modification techniques usually take 45 minutes to fall asleep, and the behavior techniques get that down to 28 minutes. Sure, the latter group is falling asleep faster, but the sleeping pills are shaving 1:30 off of the time to fall asleep, not just 17 minutes! In any case, by questioning the sample - by pointing out that the groups aren’t random, and that there’s a relevant difference between them other than the treatment - this answer weakens the argument.
  5. E
    The people who are Remaining source text redacted.
    Why choice E is not credited
    This answer does highlight a difference between the two groups in the study, but that difference isn’t relevant to the conclusion of the argument. Contrast this with answer choice (D), which also points out a difference between the groups. That difference was related to the seriousness of the illness, which speaks directly to how effective treatments are. The difference in this answer has to do with people’s preferences towards pills, which could be split evenly between people with more and less serious sleeping problems.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A 9%
  2. B 4%
  3. C 6%
  4. D Credited 77%
  5. E 4%

Deeper help

Ask follow-ups on any step

Optional AI tutor mode will let you interrogate assumptions, compare answers, and drill weak patterns without leaving the page.

Human-written explanations stay primary; AI is an add-on when you want it.

Discussion

View all discussions Start a discussion