Logical Reasoning

PT124 · S1 · Q8 Doctor: In three separate

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Doctor: In three separate studies, researchers compared children who had slept with night­-lights in their rooms as infants to children who had not.

Evidence

In three separate studies, researchers compared children who had slept with night-lights in their rooms as infants to children who had not.

In the first first study, the children who had slept with night-lights proved more likely to be nearsighted.

The later studies found no correlation between night-lights and nearsightedness.

However, the children in the first study were younger than those in the later studies.

Conclusion

This suggests that if night-lights cause nearsightedness, the effect disappears with age.

Evaluate

At first glance this appears to be a standard question structured on correlation vs. causation. But the conclusion does not actually assert that night-lights cause nearsightedness, nor does it assert that they do not cause nearsightedness. Instead the conclusion focuses on the chance that they do, suggesting that if night-lights do cause nearsightedness, the effect disappears with age.

8.

Which one of the following, if true, would most weaken the doctor's argument?

  1. A fourth study comparing infants

    Too Weak

    This might weaken a conclusion that night-lights cause nearsightedness, but that’s not the conclusion the argument reached.

    13% picked this

  2. On average, young children who

    Too Weak

    This might weaken a conclusion that night-lights do not cause nearsightedness, but that’s not the conclusion the argument reached.

    5% picked this

  3. In a study involving children

    Too Weak

    That most of the children studied were not nearsighted is not strong enough to weaken an argument that includes a study showing that young children who slept with night-lights are more likely than than those who do not sleep with night-lights to be nearsighted. This relative comparison leaves room for most young children who slept with night-lights not to develop nearsightedness.

    4% picked this

  4. Correct

    The two studies in which

    Why this is right

    This weakens the conclusion by suggesting that the latter two studies were insufficient to reach the conclusion in the argument.

    Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.

    38% picked this

  5. In a fourth study involving

    Too Weak

    Several children could still amount to very few children. This answer is too weak to establish a correlation between night-lights and nearsightedness.

    40% picked this

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