PrepTest 123

[lcid:3590] Prep Test 123 LSAT — Logical Reasoning — S3 Logical reasoning

Question prompt

A consumer magazine surveyed Remaining source text redacted.
Why the credited answer is right

Credited answer: C

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

Cause & Effect / Weaken Questions

Stimulus Summary

A survey showed almost twice as many people who went to a psychologist for over 6 months said the treatment helped compared to those who went for six months or less. Therefore, longer treatment is more effective.

Answer Anticipation

When a survey is featured in a stimulus, there are two important things to check—does the conclusion reflect the data, and was the survey set up correctly especially with respect to the sample?
The conclusion here does seem to reflect the data mostly. Nearly twice as many long-term patients found treatment helped them. There might be a problem with self-reporting here, or a jump between people reporting things getting better and effectiveness (maybe they just said that because they didn't want to seem like they were wasting time), so we should be on the lookout for those as answers.
What about the survey and the sample? In general, a survey needs a large, random, representative sample. There's no indication of the size here, so there's no reason to question that unless an answer tells us it was limited. There's also no reason to believe it's unrepresentative, since it's from a general survey in a consumer magazine. However, the sample wasn't random—a random sample would require that a bunch of people are randomly assigned between a group that had fewer than six months of therapy and another group that had therapy for over six months.
Here, it's possible that the groups are fundamentally different, and the length of therapy itself didn't play into its effectiveness. If the short-term therapy group is made up of people who wouldn't respond well to therapy (explaining why they quit), then it wasn't the length of the therapy but the person in it that explains the ineffectiveness.

Answer choices

  1. A
    Of the respondents who Remaining source text redacted.
    Why choice A is not credited
    Incorrect. Without a baseline of what percent said something similar in the under 6 month group, this information doesn't help us to analyze the effectiveness of treatment. Maybe 10% is very low; maybe it's high. Since we can't be sure, this answer doesn't present enough information to evaluate its impact on the argument.
  2. B
    Patients who had received Remaining source text redacted.
    Why choice B is not credited
    Incorrect. The percents reporting improvement were of those who responded. Even if the group who received over 6 months of treatment was bigger, as long as the number of responses for each group were large enough to guarantee representative samples (which this answer doesn't provide enough information to question), the argument is still in good shape.
  3. C
    Patients who feel they Remaining source text redacted.
    Why choice C matches the stem
    Correct. This answer choice points out a difference between the two groups that could have skewed the results. This answer suggests an alternative to long-term therapy being more effective—mainly, that the reverse is true, in that effective therapy tends to cause people to stick with it for the long-term.
  4. D
    Patients who were dissatisfied Remaining source text redacted.
    Why choice D is not credited
    Incorrect. This answer choice would provide a consideration for those who were in short-term and long-term therapy, and there's no information as to how this skewed both groups. Since it may have affected the responses from both groups equally, it wouldn't skew the data and thus wouldn't call the argument into question.
  5. E
    Many psychologists encourage their Remaining source text redacted.
    Why choice E is not credited
    Incorrect. The argument is about the effectiveness of short-term vs. long-term therapy, not what psychologists believe. The psychologists could be making this recommendation for any number of reasons, including wanting to have a more stable practice.

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