A recent study found that people who use public transportation to comm

Question

A recent study found that people who use public transportation to commute to work are more likely to be overweight or obese than those who drive to work. The study's authors conclude that using public transportation must therefore be a contributing factor to weight gain.

Which of the following, if true, would most strengthen the study's conclusion?

A) The study controlled for other factors that might influence weight, such as diet and exercise habits.
B) People who use public transportation tend to have lower incomes than those who drive to work.
C) The study found that people who use public transportation are more likely to work in sedentary jobs.
D) Other studies have found similar links between public transportation use and weight gain.
E) The study's authors are experts in the field of transportation policy, but not in nutrition or public health.

leyermo1234 · Answer

Correct answer: A)  The study controlled for other factors that might influence weight, such as diet and exercise habits.

Explanation:  This answer choice strengthens the study's conclusion by  ruling out alternative explanations  for the observed correlation between public transportation use and weight gain. By controlling for other factors that might influence weight, the study can be more confident that the observed effect is actually caused by using public transportation, rather than by some other factor.

SiddharthPhalke · Answer

Why not C as the conclusion public transportation must be a contributing factor to weight gain

ashutosh_73 · Answer

SiddharthPhalke  This ques uses the classic correlation to causation way.

people who use public transportation are more likely to be overweight than those who drive to work ----> Hence, using public transportation must therefore be a contributing factor to weight gain.
 
This option WEAKENS the argument by point out that NOT public transportation BUT sedentary jobs may the cause behind obesity.

HarishD · Answer

I understand how option A is correct. But why not D?????
In some cases, I have selected such answers where other studies showed similar results, why not in this case.

When I should go for a similar study-type answer?

divyansh843 · Answer

Why is D wrong... If other studies have shown similar results then this strengthens the author's conclusion

Against A, the choice says that they have controlled other factors but not all factors. So there is a possibility that other factors may have an effect on weight

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DmitryFarberMPrep · Answer

Two things to watch for:

This question is making a classic error--moving from correlation to causation. We accept the study that found a connection between using public transportation and being overweight. What we don't have to accept is the conclusion, which says that using public transportation CONTRIBUTES to a gain in weight. What if the causation goes the other way, and people who are overweight are simply more likely to choose the bus? It could also be more complicated. For instance, maybe people who ride the bus have lower incomes, and thus don't have as much time and money to put into exercise, etc.? We don't need to figure all that out, nor do we have to assume that being overweight has a behavioral cause. Maybe it's all the the genes! We just have to identify that we don't know which way the causation runs. If we can rule out some other potential causes of the difference in weight, then that strengthens the idea that using the bus is the cause.

So why does D fail? Because it just supports the premise we've already accepted--that these factors are linked. We already knew that! It doesn't tell us anything about the CAUSE behind this link, so it does nothing for our argument. We often call this kind of statement a "premise booster," since it's just supporting the premise, and we already believe the premise by default.

One other note: the goal here is just to strengthen, not to prove, so we need to apply that same standard to all answers. We can't cut A because it doesn't cover *everything.* None of the answers do, and in fact you'll almost never find a strengthen answer that fills all the holes in the argument.

A recent study found that people who use public transportation to comm

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