GRE General TestAnalytical WritingHard
A public health official proposes a city-wide ban on sugary drinks in schools, arguing that this measure will significantly reduce childhood obesity rates. The official cites a study from a small town where a similar ban was implemented, followed by a noticeable decrease in the town's average childhood obesity rate. Which of the following, if true, would most seriously weaken the official's argument?
- AThe small town's ban also included a mandatory daily physical education program, which was not part of the official's proposal.
- BMany children in the city can easily purchase sugary drinks from stores outside of school premises.
- CSome parents argue that banning sugary drinks infringes on their right to choose what their children consume.
- DThe official's proposal does not include a plan to address other contributing factors to childhood obesity, such as diet at home.
Show answer & explanationAnswer & explanation
Correct answer: A. The small town's ban also included a mandatory daily physical education program, which was not part of the official's proposal.
The official uses the small town's success to support the city-wide ban. If the small town's success was also due to a mandatory physical education program (a confounding variable), then the causal link between *just* the sugary drink ban and reduced obesity is weakened, making the official's argument for the city-wide ban less compelling.
Why the other options are wrong
- B. This points to an external factor that could limit the effectiveness of the ban, but doesn't directly challenge the *argument's logic* based on the cited study as much as option A.
- C. Parental rights are a political/ethical concern, not a factor that weakens the scientific or causal argument about the ban's effectiveness on obesity.
- D. While important, the argument is about the effectiveness of *this specific measure*. The failure to address *other* factors doesn't directly weaken the claim about the ban's effectiveness, but rather its comprehensiveness.
Confounding Variable
A confounding variable is an unmeasured factor that influences both the supposed cause and effect, leading to a spurious correlation or misleading causal inference.
- Can create an illusion of causation where none exists.
- Must be controlled for in studies to establish true causation.
- Often explains why two correlated events might not be causally linked.
Memory trick: Confounding is like two paths crossing because of a hidden third path.