Epidemiologist: A study of residents in 116 of our nation's cities

Question

﻿Epidemiologist: A study of residents in 116 of our nation's cities found that, on average, the incidence of cardiovascular disease was significantly higher in residents of the cities whose air was more polluted with soot particles. This shows that reducing soot pollution in those cities would lower the risk of cardiovascular disease for the residents.

Which of the following, if true, would most weaken the epidemiologist's argument?

A. A high proportion of residents in the cities whose air is more heavily polluted with soot particles have lifestyles that lower the risk of cardiovascular disease.

B. The study failed to measure the incidence of cardiovascular disease in rural areas where there is little or no soot pollution.

C. On average, among the 116 cities, the residents of cities whose air has less soot pollution have diets much less likely to cause cardiovascular disease.

D. After soot pollution in one city was dramatically reduced, the incidence of cardiovascular disease in that city remained above the national average.

E. Reducing soot pollution would also involve reducing several other forms of air pollution that contribute more significantly to cardiovascular disease.

gmatophobia · Accepted Answer

Conclusion of the argument  : Reducing soot pollution in those cities would lower the risk of cardiovascular disease for the residents.

Support Provided  : A study of residents in 116 cities was conducted → Finding: On average, the incidence of cardiovascular disease was significantly higher in residents of the cities whose air was more polluted with soot particles.

Hence, the author concludes a causal relationship between the presence of the soot particles and the incidence of cardiovascular disease in the residents. We have to weaken the author's conclusion in the line of the reasoning provided-

Answer Choice Elimination

A. A high proportion of residents in the cities whose air is more heavily polluted with soot particles have lifestyles that lower the risk of cardiovascular disease.

This statement supports the conclusion as it removes an alternate cause. However, we need to weaken the conclusion of the argument. Hence, we can eliminate this option.

B. The study failed to measure the incidence of cardiovascular disease in rural areas where there is little or no soot pollution.

The author's argument and the conclusion that follows are related to those cities. Hence, the provided statement doesn't affect the conclusion.

The conclusion of the argument is -

This shows that reducing soot pollution in   those cities   would lower the risk of cardiovascular disease for the residents.

C. On average, among the 116 cities, the residents of cities whose air has less soot pollution have diets much less likely to cause cardiovascular disease.

This is a good one!

This statement gives us a piece of information to believe that the probably the presence of high soot pollution in the cities is a mere correlation with high incidences of cardiovascular diseases. This weakens the conclusion as the author believes that reducing soot pollution in those cities would lower the risk of cardiovascular disease for the residents while the actual cause could be the diets that tend to cause high incidences of cardiovascular diseases. We can keep this option.

D. After soot pollution in one city was dramatically reduced, the incidence of cardiovascular disease in that city remained above the national average.

This is a trap option.

The statement presents information that when the cause (soot pollution) was removed, the effect was still present. Hence, it sort of gives use a reason to not believe the conclusion of the argument. However, we need to be very careful in reading the argument. The argument presents a generalized observation -

" A study of residents in 116 of our nation's cities found that  on average , the incidence of cardiovascular disease was significantly higher in residents of the cities "

Hence, the effect of each city may not be the same. We can eliminate D.

E. Reducing soot pollution would also involve reducing several other forms of air pollution that contribute more significantly to cardiovascular disease.

This strengthens the argument. If other pollutants that contribute more significantly to cardiovascular disease get reduced in the process, we are more likely to believe that reducing soot pollution in those cities would lower the risk of cardiovascular disease for the residents. Eliminate E.

Option C

MartyMurray · Answer

﻿Epidemiologist: A study of residents in 116 of our nation's cities found that, on average, the incidence of cardiovascular disease was significantly higher in residents of the cities whose air was more polluted with soot particles. This shows that reducing soot pollution in those cities would lower the risk of cardiovascular disease for the residents.

The conclusion of the argument is the following:

reducing soot pollution in those cities would lower the risk of cardiovascular disease for the residents

The support for the conclusion is the following premise:

A study of residents in 116 of our nation's cities found that, on average, the incidence of cardiovascular disease was significantly higher in residents of the cities whose air was more polluted with soot particles.

We see that the epidemiologist's reasoning is basically that there is some kind of causal connection between pollution of air with soot particles and the incidence of cardiovascular disease in a city.

The question asks which of the choices would most weaken the argument. So, the correct answer will show that, even though the premise is true, the epidemiologist's conclusion may not be correct.

A. A high proportion of residents in the cities whose air is more heavily polluted with soot particles have lifestyles that lower the risk of cardiovascular disease.

This choice strengthens the argument.

After all, if what this choice says is true, then we know that the lifestyles of the people in the cities in question are not causing them to experience cardiovascular disease. In fact, their lifestyles would be expected to reduce the risk of cardiovascular disease.

So, this choice serves to eliminate the possibility that people's lifestyles are causing the higher incidences of cardiovascular disease, making it more likely that the soot pollution is causing it.

A choice that strengthens the argument will never be the correct answer to a Weaken question.

Eliminate.

B. The study failed to measure the incidence of cardiovascular disease in rural areas where there is little or no soot pollution.

This choice tempts us to choose it as a weakener by seeming to suggest that the methodology of the study was lacking a key element.

So, what we need to notice is that, since the study involves a comparison of what goes on in cities with more and less soot pollution, it does not need to also measure the incidence of cardiovascular disease in rural areas. It has already provided reason to believe that soot pollution causes cardiovascular disease.

In fact, by including statistics from rural areas, the study might become less valid since any pattern seen in rural areas could be the result of the fact that they are rural rather than of the levels of soot pollution in those areas.

Eliminate.

C. On average, among the 116 cities, the residents of cities whose air has less soot pollution have diets much less likely to cause cardiovascular disease.

This choice weakens the argument.

After all, if what this choice says is true, then it could be that the reason the incidences of cardiovascular disease are lower in the cities with less soot pollution is that people in those cities have diets much less likely to cause cardiovascular disease.

In that case, the evidence that the incidence of cardiovascular disease was significantly higher in residents of the cities whose air was more polluted with soot particles does not effectively support the conclusion. After all, even though that premise is true, we have reason to doubt that the conclusion is correct since there's another variable, diet, that could be the true cause of the difference in incidences of cardiovascular disease.

Keep.

D. After soot pollution in one city was dramatically reduced, the incidence of cardiovascular disease in that city remained above the national average.

This choice does seem to weaken the argument because it seems to indicate that, even without soot pollution, the risk of cardiovascular disease remained high.

Notice, however, that the fact that the incidence of cardiovascular disease in one city remained "above the national average" does not tell us much. After al, the national average includes EVERYONE that lives in the country, including people who do not live in cities at all.

So, the implications of the information provided by this choice are not clear. After all, it could be that the incidence of cardiovascular disease in ALL cities is higher than average in a nation in which people may also live in rural and suburban areas.

Also, the fact that this outcome occurred in one city does not really change what we know since the evidence in support of the conclusion is that "ON AVERAGE, the incidence of cardiovascular disease was significantly higher in residents of the cities whose air was more polluted with soot particles." So, even though this one city does not fit the overall pattern, that overall pattern that supports the conclusion still exists.

Eliminate.

E. Reducing soot pollution would also involve reducing several other forms of air pollution that contribute more significantly to cardiovascular disease.

The conclusion is that "reducing soot pollution in those cities would lower the risk of cardiovascular disease for the residents."

So, if what this choice says is true, then we have even more reason to believe the conclusion since the recommended action, "reducing soot pollution," would likely reduce the presence of multiple causes of cardiovascular disease in addition to soot pollution.

So, this choice strengthens, rather than weakens, the case for the conclusion.

Eliminate.

The correct answer is (C).

Paras96 · Answer

IMO C

Because the argument is a causal argument that assumes that only soot pollution causes cardiovascular diseases, any statement that states that there may be other possible causes for cardiovascular diseases will weaken the argument. Option C states that the city that has residents having diets much less likely to cause cardiovascular disease, meaning that the diets can also cause the risk of cardiovascular diseases.

GmatKnightTutor · Answer

﻿Epidemiologist: A study of residents in 116 of our nation's cities found that, on average, the incidence of cardiovascular disease was significantly higher in residents of the cities whose air was more polluted with soot particles. This shows that reducing soot pollution in those cities would lower the risk of cardiovascular disease for the residents.

Which of the following, if true, would most weaken the epidemiologist's argument?

A. A high proportion of residents in the cities whose air is more heavily polluted with soot particles have lifestyles that lower the risk of cardiovascular disease.

B. The study failed to measure the incidence of cardiovascular disease in rural areas where there is little or no soot pollution.

C. On average, among the 116 cities, the residents of cities whose air has less soot pollution have diets much less likely to cause cardiovascular disease.

D. After soot pollution in one city was dramatically reduced, the incidence of cardiovascular disease in that city remained above the national average.

E. Reducing soot pollution would also involve reducing several other forms of air pollution that contribute more significantly to cardiovascular disease.

The passage says that cities with a lot of soot in the air have residents that are worse off when it comes to cardiovascular disease. That it would therefore be good to reduce soot to reduce this disease.

We're asked to find something that weakens this.

(C) is the answer. If cities with less soot have residents that have a diet MUCH LESS likely to cause cardiovascular disease, you have an ALTERNATE explanation for why those residents are less likely to have the disease. Basically, it reduces the link between soot causing the disease.

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Raman109 · Answer

Understanding the argument - 
﻿Epidemiologist: A study of residents in 116 of our nation's cities found that, on average, the incidence of cardiovascular disease was significantly higher in residents of the cities whose air was more polluted with soot particles. - Fact. 
This shows that reducing soot pollution in those cities would lower the risk of cardiovascular disease for the residents. - Conclusion. It establishes the causal connection between "soot particles" and "risk of cardiovascular disease."

Which of the following, if true, would most weaken the epidemiologist's argument?

Option Elimination: We need to break or weaken the causal connection. Remember, we don't need to bury the argument; we need something that can move the needle - even if it is small or creates doubt.

A. A high proportion of residents in the cities whose air is more heavily polluted with soot particles have lifestyles that lower the risk of cardiovascular disease. - So, those lifestyles should ideally reduce the risk of cardiovascular disease, but they don't help. Why? It may be because of soot particles. This option removes the possible objection and further strengthens the conclusion. Opposite of what we need.

B. The study failed to measure the incidence of cardiovascular disease in rural areas where there is little or no soot pollution. - The scope of our argument is "116 of our nation's cities." Out of scope.

C. On average, among the 116 cities, the residents of cities whose air has less soot pollution have diets much less likely to cause cardiovascular disease. - so the soot pollution is less, and their diet is less likely to cause cardiovascular disease. So, diets may be responsible for lowering cardiovascular disease. It can very well be because of lower soot pollution, but this option now casts doubt on it, which is what we need as a weakened. Remember, we are not looking for a Thor's hammer to shatter the argument and bury it in the ground. We are just looking for an option that moves the needle, however small. Ok.

D. After soot pollution in one city was dramatically reduced, the incidence of cardiovascular disease in that city remained above the national average. - one city doesn't affect the conclusion, which is still valid. Distortion.

E. Reducing soot pollution would also involve reducing several other forms of air pollution that contribute more significantly to cardiovascular disease. - strengthener

KarishmaB · Answer

Premise: A study of residents in 116 of our nation's cities found that, on average, the incidence of cardiovascular disease was significantly higher in residents of the cities whose air was more polluted with soot particles. Conclusion: Reducing soot pollution in those cities would lower the risk of cardiovascular disease for the residents. When we read this argument, automatically correlation vs causation should come to mind. Study only found correlation between 'heart disease' and 'soot'. Does it mean soot causes more disease? No. Does it mean lowering soot would reduce heart disease? No. A and B exist together doesn't mean A causes B. How can we weaken this? -By saying that some other factor in these cities could be the cause. A. A high proportion of residents in the cities whose air is more heavily polluted with soot particles have lifestyles that lower the risk of cardiovascular disease. It seems that in cities with high soot another factor (lifestyle) lowers the risk of heart disease. We are looking for something that may increase the risk of heart disease in these cities. B. The study failed to measure the incidence of cardiovascular disease in rural areas where there is little or no soot pollution. The study was conducted on cities only and those with more soot had more heart problems. The conclusion focuses on cities only too. Rural areas are out of scope for us. Because rural areas were not included, it doesn't weaken the conclusion. C. On average, among the 116 cities, the residents of cities whose air has less soot pollution have diets much less likely to cause cardiovascular disease. It seems that cities with low soot have better diets. Well, then this could be the reason for lower heart disease incidence and not the soot. This weakens the causation of soot-heart problem. Then even if we reduce soot from high soot cities, it may not change their diet and hence the high heart disease incidence may continue. It weakens the conclusion. D. After soot pollution in one city was dramatically reduced, the incidence of cardiovascular disease in that city remained above the national average. Irrelevant. We are not comparing stats in these cities with National average. We are only comparing 116 city stats with each other. National average could be extremely low or extremely high due to other conditions in other regions. Ignore. E. Reducing soot pollution would also involve reducing several other forms of air pollution that contribute more significantly to cardiovascular disease. Whether there are other factors that contribute more significantly to cardiovascular disease, doesn't matter. Our argument focuses on only soot-heart relation and reducing soot, not reducing anything else. Answer (C) Here are some discussions on weaken questions: https://youtu.be/EhZ8FKkfy0k https://youtu.be/tnFX99OpyYs https://youtu.be/XCBp62o70Eg https://youtu.be/55QgRwZmFRo

anushree01 · Answer

Little tricky, couldnt get it right

samoll · Answer

I have a question about choice C.

if the healthier diets described in choice C were themselves a consequence of living in cities with less soot pollution, wouldn’t that actually support the epidemiologist’s conclusion rather than weaken it?

guddo · Answer

The argument assumes that the correlation between soot pollution and higher cardiovascular disease implies causation. To weaken this, we need to show that something else could explain the correlation.

Option C provides an alternative explanation: cities with less soot pollution also have residents with healthier diets, which could be the real reason for lower cardiovascular disease rates. This breaks the causal link between soot pollution and disease, thereby weakening the argument.

So, the  answer is C .

guddo · Answer

The epidemiologist assumes soot causes heart disease because they correlate. But correlation doesn't prove causation.

Option C says low-soot cities have much healthier diets. Heart disease is strongly influenced by diet.

Therefore, diet could be the real cause of the lower heart disease in low-soot cities, not the soot level. This breaks the epidemiologist's causal claim.

Your point, that diet could be a result of low soot, requires its own evidence. Without that evidence, C presents a credible alternative cause, which weakens the argument by showing the correlation could be coincidental, not causal.

Alexdb10 · Answer

Its clearly between C and D for the answer choices.

what helped me make my decision was this:

D states:  After soot pollution in one city was dramatically reduced, the incidence of cardiovascular disease in that city remained above the national average.

- note that with this answer choice, while the soot was reduced dramatically and the incidence of cardiovascular disease was still high in that city compared to the average, there is no mention to the actual change in the incidence of cardiovascular disease. Thus the incidence could have been lowered from way above the national average, to just above the national average.

Epidemiologist: A study of residents in 116 of our nation's cities

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Epidemiologist: A study of residents in 116 of our nation's cities

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