#11 - Cholesterol, which is a known factor in coronary heart

[Administrator]

Complete Question Explanation

StrengthenX-CE. The correct answer choice is (C)

The conclusion of the argument is that HDLs help prevent coronary heart disease and stroke. In support of her statement, the author makes the observation that exercising and being a woman are both positively correlated with lower risk of heart disease, and both either lead to, or are associated with, high levels f HDL.

Cause Effect

HDL → Lower risk of heart disease

To support a causal relationship in which the cause constitutes the conclusion, first look for answer choices that deny the existence of alternate causes. In this instance, the most plausible alternate explanation for the cited phenomenon would simply be that aerobic exercise and being a woman are themselves the actual causes for reduced risk of cardiac disease, and that the elevated levels of HDLs in both instances simply establish a positive correlation between HDL and heart disease.

Because this is a strengthen EXCEPT question, the correct answer will either weaken the causal relationship, or have no effect on it.

Answer choice (A): If HDLs help the body excrete cholesterol and cholesterol is a known factor in coronary heart disease (first sentence), the author's conclusion makes a lot of sense. This answer choice strengthens the argument and is therefore incorrect.

Answer choice (B): Associating overweight people who die of heart disease with lower levels of HDL establishes a closer correlation between HDL and coronary heart disease. Even though this answer choice offers no definitive proof that one is caused by the other, it strengthens the argument sufficiently well to be incorrect.

Answer choice (C): This is the correct answer choice. The relative ease of removing HDL from the bloodstream compared to LDL has no effect on the conclusion and therefore does not strengthen the argument.

Answer choice (D): If high levels of HDL mitigate the health risks associated with LDLs, this provides further support for the conclusion that HDL play a role in reducing the risk of heart disease. This answer choice strengthens the argument and is therefore incorrect.

Answer choice (E): This is perhaps the strongest decoy answer, as the relevance of the information provided is not immediately clear. However, remember that supporting causal relationships often entail denying the existence of alternate causes. This answer choice does precisely that: if men with levels of HDL equal to those of women have a lower risk of heart disease than most men, then perhaps gender is not a contributing factor to the risk of coronary heart disease. Otherwise, we would expect men with HDL levels equal to those of women to be at a higher risk because of their gender alone, which is refuted by the information provided in this answer choice. By eliminating a plausible alternate cause, answer choice (E) strengthens the argument and is therefore incorrect.

[yrivers]

Could you please further explain this part:

Otherwise, we would expect men with HDL levels equal to those of women to be at a higher risk because of their gender alone, which is refuted by the information provided in this answer choice. By eliminating a plausible alternate cause, answer choice (E) strengthens the argument and is therefore incorrect.

Why is it that we would expect men w/HDL levels equal to those of women to be at a HIGHER risk? I read this to mean that:
1) women have higher levels of HDL
2) so if men have as high a level of HDL as women, then they would have lower risk of heart disease and stroke because these have reached the higher average level of HDL that women have. So these men would have lower risk.

Am I understanding this correct?

I had eliminated C thinking if HDLs are less easily removed, they could stay in the bloodstream longer and do more good work. Am I assuming too much?

Thanks,
Yaesul

[AthenaDalton]

Hi Yaesul,

I think you are understanding answer choice (E) correctly.

The stimulus tells us that women have more HDLs in their bloodstream than men, and that women have a lower risk of coronary heart disease and stroke.

Answer choice (E) indicates that men who have HDL levels comparable to women (so, higher-than-average HDL levels for a male) also have a lower risk of heart disease and stroke compared to men. This reinforces the stimulus's causal reasoning by demonstrating that

Cause Effect
Higher HDL levels Reduced Risk of Coronary Heart Disease / Stroke

Answer choice (E) also eliminates the possibility that there is something inherent in being female other than higher HDL levels that reduces the risk of coronary disease and stroke, which my colleague explained above.

With respect to your reason for eliminating answer choice (C) -- the argument in the stimulus is that HDLs help prevent coronary heart disease and stroke. Your reasoning for eliminating answer choice (C) assumes the truth of this argument, but doesn't actually bolster it.

For example, imagine that a doctor tells you that "HDLs reduce the risk of coronary disease and stroke." You ask why, and he provides the explanation that "HDLs stay in the blood stream longer." You would probably be kind of baffled as to why HDLs staying in the blood stream longer reduces the risk of coronary disease or stroke.

By contrast, the other correct answer choices, for example answer choice (B) (people who are at high risk of coronary disease and stroke have low HDL levels), would make sense if the doctor offered it as evidence for his conclusion that higher HDL levels are good for you.

I hope this clarifies things for you. Good luck!

Athena Dalton

[cindyhylee87]

Hi,

I see how (E) has strengthened the argument differently. Here is my understanding:

1. Men whose level of HDLs is equal to the average level for women have lower risk of coronary heart disease and stroke than MOST men
----> this means men's average level of HDLs is lower than women's HDLs

2. Since higher HDLs is the cause of less risk of coronary heart disease and stroke, (E) has actually strengthened the last sentence that being female is positively correlated with lower risk of coronary heart disease and stroke.

Would this be a reasonable thought?

Thanks,
Cindy

[Adam Tyson]

I think you're just a little off on this, Cindy, by coming at it from the wrong angle. The claim that we are looking to strengthen with the wrong answers is the claim that HDLs help prevent heart disease and stroke. We are not trying to help the claim that being female correlates with less heart disease.

E strengthens the claim that HDLs are good (simple paraphrase there) by showing that men with higher HDLs have less heart disease than those with lower HDLs. The stimulus already told us that men have, on average, lower HDLs than women, so saying that men with the same HDLs as women is the same as saying men that have higher HDLs than the average man.

I hope that helps! Keep up the good work.

[crispycrispr]

Hi!

I have a clarification question re strengthen(/weaken) question types--for answer choices like (B), in which the writers make associations, are we supposed to always take those as strengthening/weakening the conclusion even though they are only correlations?

Thanks!

[Adam Tyson]

A correlation can strengthen an argument if it corresponds to the causal claim made by the author, crispycrispr, can weaken an argument if it conflicts with that claim, and can have no impact if it does neither. In answer B, low HDLs correlating with a higher risk of heart disease helps the argument, but an answer that said lower levels of HDLs were also correlated with, say, lower cholesterol levels would weaken the argument, and one which said high HDLs correlated with lower incidence of liver disease would have no effect on the argument.

Correlations aren't proof, which is why almost all causal arguments are flawed, but they can still be positive or negative evidence for a causal claim.

[mollylynch]

Hello, I am still confused about how E strengthens the argument. Isn't this the opposite of what the premise is stating?

[Jeff Wren]

Hi Molly,

The relevant premise in the argument states that "HDL levels are higher in women than in men." This should be read as a general statement that, on average, women have higher HDL levels than men. It's not implying that every woman has a higher HDL level than every man, which would be a much more extreme statement. For example, if I state that "women live longer than men" that means that, on average, women have a longer life span than men, not that every woman lives longer than every man.

As you can imagine, for both men and women, there is likely a large range of HDL levels.

For Answer E, the men who have HDL levels equal to the average level of women would presumably be men who are at the very top of the range for men (and certainly above average for men). In other words, Answer E is saying that the men who have the best (i.e. highest) HDL levels have lower risk of coronary heart disease and stroke than most men (who have relatively lower levels of HDL). This is further evidence linking high HDL levels to lowering risk of coronary heart disease and stroke.