In a study, researchers repeatedly measured the thickness of

Question

In a study, researchers repeatedly measured the thickness of a specific artery in each of thousands of volunteers over several years. The researchers found during the study that the artery became thicker more quickly in individuals who lived in cities with significant air pollution. Since thick arterial walls are associated with heart disease, the researchers concluded that exposure to significant urban air pollution contributes to heart disease.

The stem: the volunteers lived in cities with a high concentration of pollutants. The higher they are , the more the arteries are thick

Pretty straight. What help us to evaluate if this is true or not ?

In order to assess the force of the researchers' evidence for their conclusion, it would be most helpful to know whether

A )  any of the volunteers whose arteries became thicker during the study lived in areas without urban air pollution

This will not help us because we could have other factors that would influence the thickness of the arteries

B )  the specific artery the researchers examined is fairly typical of arteries in the human body with respect to the thickness of its walls

B has no sense. we need to see if the pollutant is the real reason not the specifics of the arteries or what kind of arteries we are dealing with

C )  any factors that are more common in urban areas contribute to heart disease without contributing to the thickening of arterial walls

this could be the object of a separate study or investigation. Not in our case

D )  any of the volunteers whose arteries were among the thickest at the end of the study had arteries that were among the thickest when the study began

this not helps us to understand the influence of the pollutants. also : arteries were among the thickest is not of any help

E )  any other environmental factors tend, in cities with significant amounts of air pollution, to act to thicken arterial walls more quickly than they do in cities with lower amounts of air pollution

Yes this is correct. If we have OTHER elements that influence the thickness, then our study is invalid. If yes our study is correct

I hope this helps

PS:- the GMAT could change in a new vest but at the end of the day is always the same test

MartyMurray · Accepted Answer

In a study, researchers repeatedly measured the thickness of a specific artery in each of thousands of volunteers over several years. The researchers found during the study that the artery became thicker more quickly in individuals who lived in cities with significant air pollution. Since thick arterial walls are associated with heart disease, the researchers concluded that exposure to significant urban air pollution contributes to heart disease.

The researchers conclude the following:

exposure to significant urban air pollution contributes to heart disease

The support for that conclusion is the following:

the artery became thicker more quickly in individuals who lived in cities with significant air pollution

and

thick arterial walls are associated with heart disease

We see that the researchers have reasoned that, since something associated with heart disease, "thick arterial walls," is correlated with urban air pollution, urban air pollution contributes to heart disease.

Simply put, the researcher have used a correlation between two events as support for the conclusion that one causes the other.

In order to assess the force of the researchers' evidence for their conclusion, it would be most helpful to know whether

This question is an Evaluate question. So, the correct answer will present a question such that different answers to that question will weaken or strengthen the support for the conclusion provided by the evidence.

A)  any of the volunteers whose arteries became thicker during the study lived in areas without urban air pollution

The evidence that supports the conclusion is a general pattern: "the artery  became thicker more quickly  in individuals who lived in cities with significant air pollution."

Notice that the evidence is not that the artery simply became thicker. It's that it "became thicker more quickly" in individuals in cities with significant air pollution.

Thus, even if some of the volunteers whose arteries became thicker lived in areas without urban air pollution, it would still be true that the artery became thicker  more quickly  in individuals who lived in areas with air pollution.

So, a yes answer to the question presented by this choice does not weaken the support provided by the evidence.

On the other hand, a no answer to this question could seem to strengthen the argument. After all, if none of the volunteers whose arteries became thicker lived in areas without urban air pollution, then we have more reason to believe that urban air pollution causes thickening of arteries.

So, since at least a no answer to the question presented by this choice seems to affect the strength of the argument, let's keep this choice and see whether any other choice is better.

B)  the specific artery the researchers examined is fairly typical of arteries in the human body with respect to the thickness of its walls

Neither a yes nor a no answer to the question presented by this choice affects the strength of the argument.

After all, the support for the conclusion isn't that the specific artery the researchers examined is thicker than other arteries. It's that  the artery's thickness increased faster  in people living in areas with air pollution.

In other words, the evidence doesn't involve simply the thickness of the artery. It involves a change in the thickness, and that change would have the same support for the conclusion regardless of how that artery compares with other arteries.

Eliminate.

C)  any factors that are more common in urban areas contribute to heart disease without contributing to the thickening of arterial walls

Notice that the conclusion is not that "urban areas" contribute to heart disease. It's that "exposure to significant urban air pollution contributes to heart disease."

So, whether other factors common in urban areas contribute to heart disease in other ways is irrelevant.

Another way of seeing that this choice is wrong is that the conclusion is based on the fact that thickening of arterial walls is  one  path or factor associated with to heart disease. That reasoning doesn't depend on it being the case that thickening of arterial walls is the  only  thing that results in heart disease. There could be other factors that cause heart disease in other ways and that fact would not change the fact that one path to heart disease is thickening of arteries.

So, neither a yes answer nor a no answer to the question presented by this choice has any effect on the force of the evidence.

Eliminate.

D)  any of the volunteers whose arteries were among the thickest at the end of the study had arteries that were among the thickest when the study began

The answer to the question presented by this choice has no effect on the force of the evidence. After all, the evidence involves the fact that the arteries became  thicker than they were before , not the fact that they were simply thick.

So. regardless of whose were the thickest, as long as arteries became thicker more quickly in those who lived in areas with air pollution, the argument still works.

Eliminate.

E)  any other environmental factors tend, in cities with significant amounts of air pollution, to act to thicken arterial walls more quickly than they do in cities with lower amounts of air pollution

The answer to the question presented by this choice makes or breaks the force of the evidence that supports the conclusion.

After all, if the answer is "Yes" and there are other factors that act to thicken arterial walls in cities with air pollution, then the correlation between air pollution artery thickening doesn't support the conclusion as well as it would otherwise.

After all, it could be that those other factors, which are correlated with both air pollution and thickening, are actually causing the thickening, rather than the pollution. In other words, some other factor could be causing the thickening, and the pollution could just happen to be present at the same time but not causing the thickening.

On the other hand, if the answer to the question presented by this choice is "No," then we have confirmation that there is not some other factor causing the thickening. So, in that case, we can be more confident that pollution causes the thickening, and in that case, the support provided by the evidence is strong.

So, this choice is looking great.

The only issue is that a no answer to (A) seems to strengthen the argument as well. So, which choice is correct, (A) or (E)?

Here's the thing.

We are not looking for a choice that simply strengthens the case for the conclusion. The question stem asks for information that can be used "to assess  the force of the researchers' evidence  for their conclusion."

So, we can roll with (E) rather than (A) because of the following difference.

A no answer to the question presented by (A) adds some  new evidence  in support of the conclusion. On the other hand, (E) helps to confirm whether the evidence we already have supports the conclusion.

Simply put, (A) is more about new evidence whereas (E) is about the force of the researchers' evidence.

Correct answer:  E

Carcass · Answer

In a study, researchers repeatedly measured the thickness of a specific artery in each of thousands of volunteers over several years. The researchers found during the study that the artery became thicker more quickly in individuals who lived in cities with significant air pollution. Since thick arterial walls are associated with heart disease, the researchers concluded that exposure to significant urban air pollution contributes to heart disease.

The stem: the volunteers lived in cities with a high concentration of pollutants. The higher they are , the more the arteries are thick

Pretty straight. What help us to evaluate if this is true or not ?

In order to assess the force of the researchers' evidence for their conclusion, it would be most helpful to know whether

A )  any of the volunteers whose arteries became thicker during the study lived in areas without urban air pollution

This will not help us because we could have other factors that would influence the thickness of the arteries

B )  the specific artery the researchers examined is fairly typical of arteries in the human body with respect to the thickness of its walls

B has no sense. we need to see if the pollutant is the real reason not the specifics of the arteries or what kind of arteries we are dealing with

C )  any factors that are more common in urban areas  contribute to heart disease  without contributing to the thickening of arterial walls

this could be the object of a separate study or investigation. Not in our case

D )  any of the volunteers whose arteries were among the thickest at the end of the study had arteries that were among the thickest when the study began

this not helps us to understand the influence of the pollutants. also :  arteries were among the thickest is not of any help

E )  any other environmental factors tend, in cities with significant amounts of air pollution, to act to thicken arterial walls more quickly than they do in cities with lower amounts of air pollution

Yes this is correct. If we have OTHER elements that influence the thickness, then our study is invalid. If yes our study is correct

I hope this helps

PS:- the GMAT could change in a new vest but at the end of the day is always the same test

OmerKor · Answer

Hi  MartyMurray ,
Thank you for your elaborate response.

I chose the first answer choice because I could not think of a better answer to that question.
From my perspective (based on what I have learned so far), I believe there is a relation between air pollution   and heart disease  .
However, they did not conclude that  *ONLY*    ->  . 
I encountered both types of questions with these relations, such as Only X -> Y or X -> Y (which implies that  other factor s can lead to Y and is valid for our argument).

There may be additional factors that can increase HD, which is legitimate, (right -_-?)
So, why would any other factors strengthen or weaken the argument? -> As Answer choice E.

MartyMurray · Answer

It'a true that the conclusion could be correct even if other factors cause thickening of arteries and heart disease.

At the same time, the force of the evidence comes from the fact that there is a correlation between degree of thickening and air pollution.

Seeing that correlation, the researchers conclude that air pollution causes the thickening.

So, the issue that (E) brings up is that it could be that, EVEN THOUGH THERE IS A CORRELATION BETWEEN DEGREE OF AIR POLLUTION AND DEGREE OF THICKENING, the conclusion may not be correct because the thickening may be caused by another factor that's associated with air pollution rather than by air pollution.

If a different factor could be causing the thickening, then it could be that air pollution is present when thickening exists but does not cause the thickening. In that case, the evidence is not convincing, and the conclusion is questionable.

So, we can see that knowing whether "any other environmental factors tend, in cities with significant amounts of air pollution, to act to thicken arterial walls more quickly than they do in cities with lower amounts of air pollution" would help with determining whether the conclusion is effectively supported by the evidence.

KumarRishav · Answer

It says, urban pollution contributes to artery thickness, but  not only  the contributor. Hence E is also not completely accurate. Other factors can also be reason along with urban pollution which does not break the reasoning.

egmat · Answer

Let me help you tackle this evaluate question systematically. The key to these questions is identifying what assumption the argument relies on and finding the answer choice that tests that assumption.

Argument Structure: 
The researchers present a logical chain:

Observation:  Arteries thickened faster in people living in polluted cities
 Medical fact:  Thick arteries are associated with heart disease
 Conclusion:  Air pollution contributes to heart disease

The Critical Gap: 
The argument assumes that air pollution is  the cause  of the faster artery thickening observed in polluted cities. But correlation doesn't equal causation! What if something else about polluted cities causes the artery thickening?

Evaluating the Answer Choices:

Option A  Whether some people in clean areas also had artery thickening doesn't tell us if pollution caused the effect in polluted cities. This is a distractor.
 Option B  Whether this artery is typical affects generalizability but doesn't address whether pollution actually causes the thickening. The causal claim remains equally strong or weak.
 Option C  This asks about alternative pathways to heart disease, but we need to know about alternative causes for the artery thickening itself.
 Option D  This is about baseline measurements vs. change over time - a study design issue that doesn't address the causal relationship.
 Option E ✓  This directly targets the assumption! If other environmental factors in polluted cities (like stress from traffic, diet differences, less exercise space) also cause artery thickening, then pollution might not be the culprit.

If YES (other factors exist) → Weakens the conclusion significantly
If NO (pollution is the only factor) → Strengthens the conclusion

Why E is Correct: 
Option E is the only choice that helps us determine whether the correlation between pollution and artery thickening represents actual causation. It tests whether alternative explanations exist for the observed pattern.

The Answer:   E

Want to master the systematic framework for tackling all Evaluate questions and learn the advanced patterns that help you spot the correct answer in under 90 seconds? Check out the  complete solution on Neuron by e-GMAT , which includes 3 alternative approaches and shows how this question connects to other CR question types. Access detailed explanations for official questions  here .

Tucky · Answer

MartyMurray  @ KarishmaB  
Although I got this correct, I have a question about (B):

What if the specific artery discussed in the passage is not typical of the human body and is especially susceptible to air pollution, causing it to thicken much more quickly than a normal human artery? 
Wouldn’t this possibility weaken the argument? I understand that choice (E) clearly weakens it, but wouldn’t choice (B) also weaken the argument?

MartyMurray · Answer

Notice how much of a story you created.

(B) is about only whether the "thickness" of the artery's walls is "typical."

You added "especially susceptible to air pollution" and "thicken much more quickly," neither of which is mentioned by (B) or properly inferable if the answer to the question posed by (B) is that the specific artery is not typical.

After all, not fairly typical with respect to  "thickness" does not really mean "thicken."

So, for (B) to weaken the argument, we have to come up with a story that doesn't logically follow from the information in the passage or any possible answer to choice (B).

Tucky · Answer

Thanks  MartyMurray . I think I got my answer at '' Notice how much of a story you created ''
Typical or no-typical, it is equally probable that both types of Arteries may behave in the same way.

liberoasperiores · Answer

The catch is correlation with city not actually with the air pollution. The jump in the conclusion is the air pollution. 
Now the other options can be easily eliminated.

Borrat · Answer

MartyMurray , Can you help me understand this: multiple factors can cause arterial thickening , and the researcher never claims a true causal claim, just a contribution (in other words lots of causes with varying strengths lead to heart disease) - so why does E hurt the argument? I've used the above reasoning to cross off answer choice E here: https://gmatclub.com/forum/economist-in ... l#p3751116 - E. It fails to address adequately the possibility that a severe economic recession may itself cause more homes to remain on the market unsold. -- also wrong because it doesn't break the causal claim: it says yeah the direction is stronger for recession -> unsold homes (by using " cause more unsold homes ") but it doesn't wreck the (weaker) unsold -> recession causal claim What am i missing here, these seems similar.

In a study, researchers repeatedly measured the thickness of

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In a study, researchers repeatedly measured the thickness of

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