PrepTest 131

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen

Stimulus Summary:
Group A—Free nutritious breakfasts every day
Group B—Didn't receive free breakfast
Results: Group A productivity went up; Group B productivity didn't
Conclusion: Nutritious breakfasts increase productivity

Answer Anticipation:
A study was done, so we need to start by considering a sampling flaw and a correlation/causation flaw, the two most common flaws in study-based arguments.

Starting with the sample, we should ask if it was large, representative, and random? There's no indication that the sample was too small. However, it could very well have been unrepresentative, and it wasn't random. The workers at these plants aren't necessarily representative of all workers, as the argument concludes. Additionally, the groups weren't randomly assigned—they were assigned based on the plants. It's possible that the two plants attract workers who are relevantly different. Since there are sampling flaws, any answer that makes the sample better will strengthen the argument.

Next, we consider if there's a correlation/causation flaw. And, as with most causal conclusions ("make . . . more productive") derived from studies, it is based on a correlation. As such, we can look for our regular correlation/causation strengthen answers—eliminate an alternative cause; bring up more examples of the cause and effect going together; bring up examples of no cause/no effect.

Answer Explanation:
We didn't note this in our summary because we wouldn't expect to note it when reading through the argument, but there was a missing piece of information that was needed for the argument to work—Group A received free, nutritious breakfasts, but that doesn't guarantee that Group B didn't eat a nutritious breakfast. This answer, on the other hand, establishes that. To fit it into our framework, this is essentially guaranteeing a control group—Group B didn't see an increase in productivity and, according to this answer, didn't eat a nutritious breakfast. Establishing Group B as a true control group (no cause/no effect) strengthens the argument.

Key Takeaway:
Whenever an argument-based LSAT question features a study, start with thinking about the sampling and, if it has a causal conclusion, whether it jumps from a correlation. One or both of these flaws is generally present and generally related to the correct answer, so it's a great trend for saving time.

Incorrect. Since the argument is about increases to productivity, similarities between Plant A and B are out of scope. Instead, what matters is comparing each plant to itself in earlier months.

Incorrect. The argument specifically notes that productivity increased for Group A but not Group B. Since the results show a relative jump in productivity and conclude a relative jump, the actual productivity levels are out of scope.

Incorrect. This answer is out of scope in bringing up vacation days since productivity can be measured based on hours worked instead of just total output. Additionally, it wouldn't explain an increase in productivity at Plant A—at most it explains a higher level of productivity at Plant A (comparing vacation days from Plant A before the study to during the study would be needed to show an increase in one plant's productivity). Finally, even if we missed those reasons to eliminate this answer, in raising that the workers at Plant A were working more hours than in Plant B, this answer suggests another reason that they had more output unrelated to breakfast, which would cut against the argument.

Incorrect. Again, the effect raised in the argument is an increase in productivity, not high productivity. Even if Plant B has a higher productivity level, they didn't see it increase during this month, whereas Plant A's workers were more productive.