Logical reasoning PrepTest 113 · Section 4 · Question 13

Question prompt

When several of a 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

Bizarro / Strengthen Questions

Stimulus Summary

Phenomenon - Patients had a rash on just one side of their face
Correlation - The rash was on the side of the face where the patient holds their phone
Conclusion - The phone contact caused the rash

Answer Anticipation

This argument highlights the intersection of a few trends on the LSAT.
It falls into a phenomenon/explanation pattern. The dermatologist witnessed patients having a certain rash, and she worked to explain it. Explanations for phenomena are almost always causal, so they tend to have Correlation/Causation flaws. Strengthen questions also tend to feature Correlation/Causation flaws. And both Strengthen questions with Correlation/Causation flaws and arguments that fall into the phenomenon/explanation pattern tend to have answers that eliminate other explanations/causes.
These are all the trends that should be going through your head as you read this stimulus, allowing for a pretty solid anticipation of answers that rule out alternative causes of the rash.
Also, we should anticipate the other common strengthen answers with a Correlation/Causation flaw:
Eliminate an alternative cause (already anticipated) More correlative data (more people with the rash on the side of their face to which they hold the phone) A control (no cause, no effect)

Answer choices

  1. A
    Many telephones are now Remaining source text redacted.
    Why choice A is not credited
    This answer explains how the proposed explanation could lead to the phenomenon it’s meant to explain. If people are allergic to the material in phones, then it makes sense that it would cash a rash.
  2. B
    Contact between other devices Remaining source text redacted.
    Why choice B is not credited
    This answer essentially rules out alternative causes. If other items that could have caused the rash touched both sides of the face equally, then if they were the cause, you’d expect the rash on both sides of their face. This doesn’t match the observed phenomenon, so it rules these other items out, strengthening the phone as the cause.
  3. C
    Most of the patients Remaining source text redacted.
    Why choice C is not credited
    This answer establishes that people who had the most exposure to the supposed cause were the ones who saw the effect. That’s essentially strengthening the correlation, which strengthens the argument for causality.
  4. D
    Telephones are used by Remaining source text redacted.
    Why choice D matches the stem
    The stimulus notes that “several” of a dermatologist’s patients had this rash. If most people use telephones, and those phones are a potential cause of rash, this answer would suggest that more than “several” people should have the rash! That said, it doesn’t address the side-of-the-face evidence that the dermatologist notes, so this answer is between doing nothing to the argument to weakening it, making it the correct answer.
  5. E
    The complaints occurred after Remaining source text redacted.
    Why choice E is not credited
    An increase in the supposed cause preceded the effect? That establishes a timeline that makes sense for causality to be present and adds to the correlation, strengthening the conclusion.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A 4%
  2. B 29%
  3. C 2%
  4. D Credited 63%
  5. E 3%

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