LSAT 128 | Section 2 | Logical Reasoning: Q11

LR Question 11 Explanation

QUESTION TEXT: A recently completed study of several hundred subjects …

QUESTION TYPE: Strengthen

CONCLUSION: Exercise can increase one’s life span.

REASONING: A study found that people who exercised regularly were much less likely to die during the study.

ANALYSIS: The argument assumes that exercise is the cause of the lower death rate. Think about the basics of scientific experiments. To prove causation, you must rule out other possible explanations. This can be done through randomization, control groups, controlling other variables, etc. This ensures that the observed effect is actually due to the factor being tested (in this case, exercise).

Importantly, we don’t need to prove the claim beyond all doubt, just strengthen it. That means we’re looking for an answer that makes the study’s results more reliable by reducing the likelihood that something other than exercise caused the lower death rate.

___________

1. This would actually weaken the argument. If non-exercisers had worse diets, that could mean that their diets were responsible for higher death rates, not the lack of exercise.
2. This doesn’t really affect the argument. Why people did or didn’t exercise has no bearing on whether exercise itself increases your life span.
3. This would also weaken the argument. If many deaths were due to preexisting conditions, it means that the difference in death rate is not attributable to exercise.
4. CORRECT. If researchers randomly assigned subjects to exercise or not, this eliminates self-selection bias. Hence, it is much more likely that the observed effect was caused by exercise itself, rather than differences in initial health conditions.
5. Similar to B – the motivations for why people exercise or not isn’t necessarily informing us about the actual effects of exercise.