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Citing the frequency with which gum disease and heart disease occur in

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Citing the frequency with which gum disease and heart disease occur in [#permalink]

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Citing the frequency with which gum disease and heart disease occur in the same patients, many dentists believe that periodontal disease is a cause of a variety of cardiovascular problems, including Coronary Artery Disease.

Which of the following, if true, would most weaken the claim that periodontal disease is a cause of Coronary Artery disease?


A) Bacteria present in infected gums can become mobile and enter the bloodstream, causing arterial plaque to accumulate.

B) People who brush and floss their teeth regularly are also more likely to exercise and eat a healthy diet.

C) Infected gums are more prone to bleeding, which allows bacteria to escape the mouth and irritate arteries.

D) People who experience loss of teeth due to periodontal disease usually cut back on many foods that are harder to chew, such as lean meats and vegetables, and increase their consumption of processed foods like pudding and ice cream.

E) Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.

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Originally posted by enigma123 on 29 Jan 2012, 14:33.
Last edited by Bunuel on 10 May 2018, 00:14, edited 3 times in total.
Renamed the topic and edited the question.
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 21 Mar 2013, 11:15
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agdimple333 wrote:
Citing the frequency with which gum disease and heart disease occur in the same patients, many dentists believe that periodontal disease is a cause of a variety of cardiovascular problems, including Coronary Artery Disease.

Which of the following, if true, would most weaken the claim that periodontal disease is a cause of Coronary Artery disease?
A. Bacteria present in infected gums can become mobile and enter the bloodstream, causing arterial plaque to accumulate.
B. People who brush and floss their teeth regularly are also more likely to exercise and eat a healthy diet.
C. Infected gums are more prone to bleeding, which allows bacteria to escape the mouth and irritate arteries.
D. People who experience loss of teeth due to periodontal disease usually cut back on many foods that are harder to chew, such as lean meats and vegetables, and increase their consumption of processed foods like pudding and ice cream.
E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.


Another strange question... Is it just me or do you guys also think these questions are not true representation of actual GMAT style questions..

fameatop wrote:
I am not able to understand why option B is correct & E is incorrect. Can you kindly throw some light on the same. Waiting eagerly for your detailed explanation.

So far as I can tell, this is a Knewton question, and the OA is (B). First, as to agdimple333's point, while this prompt is perhaps a little on the short side, I would say the logic of the question very much captures the kind of logic you will see on GMAT CR questions. This is, in essence, a very good question --- not least because it has a very clear and well-defined OA, and yet, many folks on this page have fallen for one of the trap answers, most notably, (E).

The big underlying idea of this question is ---- correlation does not imply causality. This blog
http://magoosh.com/gmat/2012/gmat-integ ... tterplots/
is primarily about regression and correlation, but it does touch on this issue.

Let's say
P = periodontal disease
Q = cardiovascular problems
The dentists' argument is, essentially, P & Q are correlated, so P cause Q. The dentists' argument is abysmally bad, a classic flawed argument pattern.

To strengthen such an argument, we would have to demonstrate there was some mechanism of connection ---- e.g. bacteria or viruses in the mouth that become blood-borne and infect the heart, something like that.

One of the best ways to weaken a correlation/causality argument is to show that both terms arise from something else. This is in essence what (B) does. (B) says: there are a category of people --- call them "health all over" people --- and these folks take care of themselves from head to foot --- they brush and floss, which prevents periodontal disease, and separately, they eat healthy and exercise, so they don't get heart disease. That implies there would be other people, the "don't take care of self" people, who don't brush, don't floss, don't eat health, don't exercise, don't laugh, don't sing, don't do much of anything to take care of themselves. These latter people would be prime candidates to get periodontal disease (from not brushing & flossing) as well as heart disease (from poor diet and no exercise), but the periodontal disease and the heart disease do not have relationship of causality with one another --- rather, they are both products of an overall unhealthy lifestyle. This decisively weakens the argument, which is all about the leap from correlation to causality.

By contrast, (E) simply provides more evidence for the correlation. We already know P & Q are correlated. That was the first sentence. That's the evidence in this argument. That's beyond doubt. The crux of the argument is this vast logical leap from correlation to causality. Choice (E) simply gives more evidence that P & Q are correlated. In a strange way, it is a kind of strengthener, insofar as it reinforces evidence. It doesn't address the issue of causality and it doesn't clearly weaken the argument.
Another way to weaken the argument "P causes Q" would be to show that, actually, Q causes P --- something along those lines would be a good weakener, but (E) doesn't clearly support this.

Does all this make sense?

Mike :-)
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 15 Feb 2014, 04:26
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Hey MSJ,

I agree, this is a tricky one. It's deffo a 700+ level question. And at this level they love to play tricks, and a key trick is with messing with lots of negatives.

In this question. You need to flip the logic a couple of times.

B says: Teeth brushers are excersisers. Therefore people who have healthy hearts have healthy teeth

So think about the opposite

non teeth brushers are not excersisers. This gives a 'nurture' argument for the link in the two diseases. Therefore it weakens the 'nature' argument in the passage.

So B is correct.

Tricky :)

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Citing the frequency with which gum disease and heart [#permalink]

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New post 30 Jan 2012, 09:36
B for me. It indicates that there is no relation between coronary artery disease and gum disease. It's a person's habit that leads to the occurrence of both the diseases.

As far as D goes, I think it strengthens the argument, since it would explain one way that periodontal disease indirectly causes consumption of unhealthy foods, which would increase the occurrence of negative health effects.
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 16 Jul 2012, 11:56
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With this kind of the argument:

A and B happen in the same patient, then A => B.

How to weaken this conclusion. choice (D) states that, due to A ( periodontal disease), the eating habits of patients change, making the cause to the disease B ( cardiovascular disease).

Choice (E) is the reverse choice, strengthen the argument by assert that B not cause A. The 3 remain first answers are easy to spot, so I did not mention in my reasoning.
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 28 Nov 2012, 20:30
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Citing the frequency with which gum disease and heart disease occur in the same patients, many dentists believe that periodontal disease is a cause of a variety of cardiovascular problems, including Coronary Artery Disease.

Which of the following, if true, would most weaken the claim that periodontal disease is a cause of Coronary Artery disease?
this is a scenario which means if A, B occur simultaneously means A causes B;
to weaken we will tell
i)When A occurs, B does not happen
ii)B happens even whenA is not there
iii)C causes B not A

To strengthen we need to do the following
i) Say C is not the cause
ii)give an example when A occurs B occurs
iii)when Not A -> Not B
iv)possible problems with the data

A) Bacteria present in infected gums can become mobile and enter the bloodstream, causing arterial plaque to accumulate.
strengthens the argument telling missing link
B) People who brush and floss their teeth regularly are also more likely to exercise and eat a healthy diet.
giving a alternative cause execise and healthy habits that can lead to , also here it is not that A causes B , it tells b is likely also..
C) Infected gums are more prone to bleeding, which allows bacteria to escape the mouth and irritate arteries.
strengthens the argument telling missing link
D) People who experience loss of teeth due to periodontal disease usually cut back on many foods that are harder to chew, such as lean meats and vegetables, and increase their consumption of processed foods like pudding and ice cream.
it has no effect , to think this strengthens is out of scope..we don't know hthe effects of processed food
E) Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.
strengthens as it tells ; no periodental low heart disease but cardiac transplant history more chances Periodontal disease not A -> not B

Please correct me if i m wrong somewhere...
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 21 Mar 2013, 20:11
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Hi Mike,
If the option E states
Patients with no history of heart disease do not suffer from periodontal disease. - Would this weaken the argument. As per me it should weaken.

Original option E
E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.

Waiting for reply
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 22 Mar 2013, 10:39
fameatop wrote:
Hi Mike,
If the option E states
Patients with no history of heart disease do not suffer from periodontal disease. - Would this weaken the argument. As per me it should weaken.

Original option E
E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.

Both versions, the original (E) and your modified (E), are strengtheners, insofar as they reinforce the evidence. They don't really provide additional support, but they are entirely consistent with a scenario in which the argument is true.

Pretend for a moment, that the dentists are 100% correct. Let's make it even more extreme -- pretend that periodontal disease is the only cause of heart disease. This is a hyper-strengthened version of the argument. In this version, it would most certain be the case that "Patients with no history of heart disease do not suffer from periodontal disease", because as soon as someone got the least little plaque on their teeth, they would go down with a coronary. Periodontal disease and heart disease would go together 100% of the time, so you would never find one without the other. That is what would be true in an over-the-top strengthened version of the argument. Anything consistent with this scenario is most certainly not a weakener.

Does that make sense?

Mike :-)
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 22 Mar 2013, 20:26
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agdimple333 wrote:
Citing the frequency with which gum disease and heart disease occur in the same patients, many dentists believe that periodontal disease is a cause of a variety of cardiovascular problems, including Coronary Artery Disease.

Which of the following, if true, would most weaken the claim that periodontal disease is a cause of Coronary Artery disease?

A. Bacteria present in infected gums can become mobile and enter the bloodstream, causing arterial plaque to accumulate.
B. People who brush and floss their teeth regularly are also more likely to exercise and eat a healthy diet.
C. Infected gums are more prone to bleeding, which allows bacteria to escape the mouth and irritate arteries.
D. People who experience loss of teeth due to periodontal disease usually cut back on many foods that are harder to chew, such as lean meats and vegetables, and increase their consumption of processed foods like pudding and ice cream.
E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.

Another strange question... Is it just me or do you guys also think these questions are not true representation of actual GMAT style questions..


Responding to a pm:

Two issues, gum problems and heart problems, often appear together - but it doesn't imply a causal relation between them. There could be a common underlying cause which makes them appear together.
Option B gives you that common cause - lifestyle.

People with unhealthy lifestyles tend to suffer from both the problems since they don't brush and they don't exercise and eat healthy.
People who ignored B because 'A implies B' doesn't mean 'Not A implies Not B' - very good. But, there is a catch here. It is not the simple logical relation 'A implies B' in option (B). Option (B) says that 'people who brush are also more likely to exercise' Notice the words 'more likely'. It gives you a comparison. So logically, people who brush are more likely to exercise as compared to people who don't brush. So people who don't brush are less likely to exercise and hence the lifestyle issue we talked about.

Answer (B)

Let me discuss (C), (D) and (E)

C. Infected gums are more prone to bleeding, which allows bacteria to escape the mouth and irritate arteries.
If this is true, gum problems might actually cause heart problems. Infected gums lead to irritated arteries. This is a strengthener.

D. People who experience loss of teeth due to periodontal disease usually cut back on many foods that are harder to chew, such as lean meats and vegetables, and increase their consumption of processed foods like pudding and ice cream.
I am actually in two minds about this option. The way it is worded, it makes you feel that people have a choice - they choose to cut back on harder (but healthier) foods and consume more processed foods. It that is the case, then gum problems do not cause heart problems; instead, it's people's choices (read processed food) that cause that cause heart problems.
This option should have been worded a little differently e.g.
'People who experience loss of teeth due to periodontal disease NEED to cut back on many foods that are harder to chew, such as lean meats and vegetables, and increase their consumption of processed foods, which have a softer texture.'
Basically, something that tells us that it is not a choice they make. They are forced to do it due to gum problems which means gum problems indirectly cause heart problems. Just like in option (A), people cannot help it if bacteria from their gums enter the bloodstream and cause heart problems, similarly, if they are forced to change their eating pattern due to problems, then we can say that gum problems cause heart problems.

E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.
What does this option tell you? Basically, it just tells you that gum diseases and heart diseases often appear together. It doesn't say anything about heart disease being the cause of gum disease. Our premises in the argument are from the perspective of a gum disease patient (say, if we studied people with gum diseases). This option is from the perspective of heart disease patients (if instead we surveyed the heart disease patients). The conclusion drawn is the same in both - gum diseases and heart diseases are often found together. So actually, it adds no new info.
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 23 Mar 2013, 03:34
agdimple333 wrote:
Citing the frequency with which gum disease and heart disease occur in the same patients, many dentists believe that periodontal disease is a cause of a variety of cardiovascular problems, including Coronary Artery Disease.

Which of the following, if true, would most weaken the claim that periodontal disease is a cause of Coronary Artery disease?

A. Bacteria present in infected gums can become mobile and enter the bloodstream, causing arterial plaque to accumulate.
B. People who brush and floss their teeth regularly are also more likely to exercise and eat a healthy diet.
C. Infected gums are more prone to bleeding, which allows bacteria to escape the mouth and irritate arteries.
D. People who experience loss of teeth due to periodontal disease usually cut back on many foods that are harder to chew, such as lean meats and vegetables, and increase their consumption of processed foods like pudding and ice cream.
E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.

Another strange question... Is it just me or do you guys also think these questions are not true representation of actual GMAT style questions..


Premise: Erequency with which gum disease and heart disease occur in the same patients is high

Conclusion: Gum disease is a cause of a variety of cardiovascular problems, including Coronary Artery Disease.

Since this is a weaken question, we need to find the choice that,

(i) weakens the premise or,
(ii) weakens the conclusion

To do (i) the choice needs to show that the frequency of gum disease and heart disease occurring in the same patients is not high. If for some reason a choice shows that this is really the case, then the premise will be weakened.

To do (ii) the choice has to show that gum disease may not be the cause of heart problems. That is how the conclusion is weakened.

Choice B does (ii) because it suggests that those who do not take care of their teeth are those who are likely to have unhealthy food habits and that indeed is the cause of their heart problems .

Other choices do neither (i) nor (ii).

Hence the answer is choice B.
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 09 Sep 2013, 03:51
mikemcgarry wrote:
agdimple333 wrote:
Citing the frequency with which gum disease and heart disease occur in the same patients, many dentists believe that periodontal disease is a cause of a variety of cardiovascular problems, including Coronary Artery Disease.

Which of the following, if true, would most weaken the claim that periodontal disease is a cause of Coronary Artery disease?
A. Bacteria present in infected gums can become mobile and enter the bloodstream, causing arterial plaque to accumulate.
B. People who brush and floss their teeth regularly are also more likely to exercise and eat a healthy diet.
C. Infected gums are more prone to bleeding, which allows bacteria to escape the mouth and irritate arteries.
D. People who experience loss of teeth due to periodontal disease usually cut back on many foods that are harder to chew, such as lean meats and vegetables, and increase their consumption of processed foods like pudding and ice cream.
E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.


Another strange question... Is it just me or do you guys also think these questions are not true representation of actual GMAT style questions..

fameatop wrote:
I am not able to understand why option B is correct & E is incorrect. Can you kindly throw some light on the same. Waiting eagerly for your detailed explanation.

So far as I can tell, this is a Knewton question, and the OA is (B). First, as to agdimple333's point, while this prompt is perhaps a little on the short side, I would say the logic of the question very much captures the kind of logic you will see on GMAT CR questions. This is, in essence, a very good question --- not least because it has a very clear and well-defined OA, and yet, many folks on this page have fallen for one of the trap answers, most notably, (E).

The big underlying idea of this question is ---- correlation does not imply causality. This blog
http://magoosh.com/gmat/2012/gmat-integ ... tterplots/
is primarily about regression and correlation, but it does touch on this issue.

Let's say
P = periodontal disease
Q = cardiovascular problems
The dentists' argument is, essentially, P & Q are correlated, so P cause Q. The dentists' argument is abysmally bad, a classic flawed argument pattern.

To strengthen such an argument, we would have to demonstrate there was some mechanism of connection ---- e.g. bacteria or viruses in the mouth that become blood-borne and infect the heart, something like that.

One of the best ways to weaken a correlation/causality argument is to show that both terms arise from something else. This is in essence what (B) does. (B) says: there are a category of people --- call them "health all over" people --- and these folks take care of themselves from head to foot --- they brush and floss, which prevents periodontal disease, and separately, they eat healthy and exercise, so they don't get heart disease. That implies there would be other people, the "don't take care of self" people, who don't brush, don't floss, don't eat health, don't exercise, don't laugh, don't sing, don't do much of anything to take care of themselves. These latter people would be prime candidates to get periodontal disease (from not brushing & flossing) as well as heart disease (from poor diet and no exercise), but the periodontal disease and the heart disease do not have relationship of causality with one another --- rather, they are both products of an overall unhealthy lifestyle. This decisively weakens the argument, which is all about the leap from correlation to causality.

By contrast, (E) simply provides more evidence for the correlation. We already know P & Q are correlated. That was the first sentence. That's the evidence in this argument. That's beyond doubt. The crux of the argument is this vast logical leap from correlation to causality. Choice (E) simply gives more evidence that P & Q are correlated. In a strange way, it is a kind of strengthener, insofar as it reinforces evidence. It doesn't address the issue of causality and it doesn't clearly weaken the argument.
Another way to weaken the argument "P causes Q" would be to show that, actually, Q causes P --- something along those lines would be a good weakener, but (E) doesn't clearly support this.

Does all this make sense?

Mike :-)



Dear Mike
If option E were to be a weakener then, what would that option be?
As you said, (P causes Q) weakener would be (Q causes P). is this the classic weakener to use on these question types?
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 09 Sep 2013, 21:51
akijuneja wrote:
If option E were to be a weakener then, what would that option be?



A note on option (E): It adds no new information.
E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.
What does this option tell you? Basically, it just tells you that gum diseases and heart diseases often appear together. It doesn't say anything about heart disease being the cause of gum disease. Our premises in the argument are from the perspective of a gum disease patient (say, if we studied people with gum diseases). This option is from the perspective of heart disease patients (if instead we surveyed the heart disease patients). The conclusion drawn is the same in both - gum diseases and heart diseases are often found together. So actually, it adds no new info.

If it were to be a weakener it would need to say that Heart diseases cause gum problems, not just that they appear together.

akijuneja wrote:
As you said, (P causes Q) weakener would be (Q causes P). is this the classic weakener to use on these question types?


Our conclusion 'P causes Q because they appear together' can be weakened by reasoning in various different ways. e.g.
1. Instead Q causes P
2. P and Q are both caused simultaneously by an element R

Option (B) uses the second line of reasoning to weaken the conclusion.
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 10 Sep 2013, 01:31
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VERITASPREPKARISHMA

Thank you for your analysis,
I chose D because of the reasons you mentioned. This answer choice made me think that gum disease and cardiac problems are not causal
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 07 Oct 2013, 21:37
E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.
For weakening a causal relationship say A====>B we have to prove
1. B=====>A or
2. some evidence which states that A DOES not lead to B or
3. some other thing say C=====>B
E states Patients with no history of heart disease are much less likely to have periodontal disease
which means Patients "with" history of heart disease are much "more" likely to have periodontal disease i.e, it falls in category 1 as stated above.It affirms causal relationship in reverse thus weakening the conclusion that A=====>B.
Had option E been "Patients with history of heart disease are much less likely to have periodontal disease," then it means B=/=/=/=>A
which in fact strengthens the argument.
based on this text book approach I chose E.
What is wrong with my explanation?
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 07 Oct 2013, 21:52
madn800 wrote:
E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.
For weakening a causal relationship say A====>B we have to prove
1. B=====>A or
2. some evidence which states that A DOES not lead to B or
3. some other thing say C=====>B
E states Patients with no history of heart disease are much less likely to have periodontal disease
which means Patients "with" history of heart disease are much "more" likely to have periodontal disease i.e, it falls in category 1 as stated above.It affirms causal relationship in reverse thus weakening the conclusion that A=====>B.
Had option E been "Patients with history of heart disease are much less likely to have periodontal disease," then it means B=/=/=/=>A
which in fact strengthens the argument.
based on this text book approach I chose E.
What is wrong with my explanation?


E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.

Note that E does not give you a causal relationship. It just tells you that many people with heart diseases have gum problems i.e. it just tells you that the two problems appear together. It adds no new information. It doesn't say anything about heart disease being the cause of gum disease. Our premises in the argument are from the perspective of a gum disease patient (say, if we studied people with gum diseases). This option is from the perspective of heart disease patients (if instead we surveyed the heart disease patients). The conclusion drawn is the same in both - gum diseases and heart diseases are often found together. So actually, it adds no new info.

If it were to be a weakener it would need to say that Heart diseases cause gum problems, not just that they appear together.
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 08 Oct 2013, 05:44
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mikemcgarry wrote:
agdimple333 wrote:
Citing the frequency with which gum disease and heart disease occur in the same patients, many dentists believe that periodontal disease is a cause of a variety of cardiovascular problems, including Coronary Artery Disease.

Which of the following, if true, would most weaken the claim that periodontal disease is a cause of Coronary Artery disease?
A. Bacteria present in infected gums can become mobile and enter the bloodstream, causing arterial plaque to accumulate.
B. People who brush and floss their teeth regularly are also more likely to exercise and eat a healthy diet.
C. Infected gums are more prone to bleeding, which allows bacteria to escape the mouth and irritate arteries.
D. People who experience loss of teeth due to periodontal disease usually cut back on many foods that are harder to chew, such as lean meats and vegetables, and increase their consumption of processed foods like pudding and ice cream.
E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.


Another strange question... Is it just me or do you guys also think these questions are not true representation of actual GMAT style questions..

fameatop wrote:
I am not able to understand why option B is correct & E is incorrect. Can you kindly throw some light on the same. Waiting eagerly for your detailed explanation.

So far as I can tell, this is a Knewton question, and the OA is (B). First, as to agdimple333's point, while this prompt is perhaps a little on the short side, I would say the logic of the question very much captures the kind of logic you will see on GMAT CR questions. This is, in essence, a very good question --- not least because it has a very clear and well-defined OA, and yet, many folks on this page have fallen for one of the trap answers, most notably, (E).

The big underlying idea of this question is ---- correlation does not imply causality. This blog
is primarily about regression and correlation, but it does touch on this issue.

Let's say
P = periodontal disease
Q = cardiovascular problems
The dentists' argument is, essentially, P & Q are correlated, so P cause Q. The dentists' argument is abysmally bad, a classic flawed argument pattern.

To strengthen such an argument, we would have to demonstrate there was some mechanism of connection ---- e.g. bacteria or viruses in the mouth that become blood-borne and infect the heart, something like that.

One of the best ways to weaken a correlation/causality argument is to show that both terms arise from something else. This is in essence what (B) does. (B) says: there are a category of people --- call them "health all over" people --- and these folks take care of themselves from head to foot --- they brush and floss, which prevents periodontal disease, and separately, they eat healthy and exercise, so they don't get heart disease. That implies there would be other people, the "don't take care of self" people, who don't brush, don't floss, don't eat health, don't exercise, don't laugh, don't sing, don't do much of anything to take care of themselves. These latter people would be prime candidates to get periodontal disease (from not brushing & flossing) as well as heart disease (from poor diet and no exercise), but the periodontal disease and the heart disease do not have relationship of causality with one another --- rather, they are both products of an overall unhealthy lifestyle. This decisively weakens the argument, which is all about the leap from correlation to causality.

By contrast, (E) simply provides more evidence for the correlation. We already know P & Q are correlated. That was the first sentence. That's the evidence in this argument. That's beyond doubt. The crux of the argument is this vast logical leap from correlation to causality. Choice (E) simply gives more evidence that P & Q are correlated. In a strange way, it is a kind of strengthener, insofar as it reinforces evidence. It doesn't address the issue of causality and it doesn't clearly weaken the argument.
Another way to weaken the argument "P causes Q" would be to show that, actually, Q causes P --- something along those lines would be a good weakener, but (E) doesn't clearly support this.

Does all this make sense?

Mike :-)



Thanks Mike, this explanation was clear. But reading it gave me the impression that the question is not representative of what Official GMAT would look like. GMAT answers wouldn't require any sort of "over" inference, but answering B was necessary to infer something beyond, as you've pointed out:

"they eat healthy and exercise, so they don't get heart disease."

In other words, to choose answer B is necessary to assume that healthy habits and exercise prevent someone from getting the heart disease (real world true, but the question really implied that?). This is what refrained me from picking B.
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 09 Oct 2013, 06:08
agdimple333 wrote:
Citing the frequency with which gum disease and heart disease occur in the same patients, many dentists believe that periodontal disease is a cause of a variety of cardiovascular problems, including Coronary Artery Disease.

Which of the following, if true, would most weaken the claim that periodontal disease is a cause of Coronary Artery disease?

A. Bacteria present in infected gums can become mobile and enter the bloodstream, causing arterial plaque to accumulate.
B. People who brush and floss their teeth regularly are also more likely to exercise and eat a healthy diet.
C. Infected gums are more prone to bleeding, which allows bacteria to escape the mouth and irritate arteries.
D. People who experience loss of teeth due to periodontal disease usually cut back on many foods that are harder to chew, such as lean meats and vegetables, and increase their consumption of processed foods like pudding and ice cream.
E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.

Another strange question... Is it just me or do you guys also think these questions are not true representation of actual GMAT style questions..



I've seen a lot of different OAs on this one but the answer has to be D.

Argument core: gum problems and cardiovascular problems are correlated THEREFORE gum problems causes cardiovascular problems.

Assumptions: gum problems are THE ONLY possible cause of CV problems, and gum problems always produce CV problems.

Task: To weaken this argument; let's undermine these assumptions.

A. Bacteria present in infected gums can become mobile and enter the bloodstream, causing arterial plaque to accumulate.

gum problems can cause heart problems --> strengthener --> wrong

B. People who brush and floss their teeth regularly are also more likely to exercise and eat a healthy diet.

If you have...
Cause but no effect --> drives wedge between premise/conclusion
The effect but no cause --> drives wedge between premise/conclusion
No cause and no effect --> ...hmmm, how does this matter? --> wrong


C. Infected gums are more prone to bleeding, which allows bacteria to escape the mouth and irritate arteries.

GP cause CVPs --> strengthener --> wrong

D. People who experience loss of teeth due to periodontal disease usually cut back on many foods that are harder to chew, such as lean meats and vegetables, and increase their consumption of processed foods like pudding and ice cream.

This must be the correct answer, whether its the "OA" or not. This choice states that people with serious gum problems radically CHANGE THEIR DIET from from healthy foods to junk. In other words, this directly undermines the assumption that gum problems are the ONLY cause of CV problems, ie, that they are not caused by radical changes in diet, a change which may or may not have been precipitated by GPs ("usually"). --> correct

E. Patients with no history of heart disease are much less likely to have periodontal disease than patients who have had a cardiac transplant.

--> if this is not an irrelevant comparison (issue with "no HISTORY"), then we have another case of "no cause and no effect"; people without CV problems are much less likely to have GPs (a zero percent chance works just fine) --> unclear impact --> wrong.

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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 09 Oct 2013, 12:08
Reinfrank2011 wrote:
I've seen a lot of different OAs on this one but the answer has to be D.

Everywhere I have looked, I have seen users claim all kinds of things are answers, but I have only seen experts and OA posting indicate (B) is the answer.

Reinfrank2011 wrote:
B. People who brush and floss their teeth regularly are also more likely to exercise and eat a healthy diet.

If you have...
Cause but no effect --> drives wedge between premise/conclusion
The effect but no cause --> drives wedge between premise/conclusion
No cause and no effect --> ...hmmm, how does this matter? --> wrong

D. People who experience loss of teeth due to periodontal disease usually cut back on many foods that are harder to chew, such as lean meats and vegetables, and increase their consumption of processed foods like pudding and ice cream.

This must be the correct answer, whether its the "OA" or not. This choice states that people with serious gum problems radically CHANGE THEIR DIET from from healthy foods to junk. In other words, this directly undermines the assumption that gum problems are the ONLY cause of CV problems, ie, that they are not caused by radical changes in diet, a change which may or may not have been precipitated by GPs ("usually"). --> correct

The conclusion of the prompt argument posits a causal relationship ----- "periodontal disease is a cause of a variety of cardiovascular problems" and we are asked to weaken the argument. Demonstrating "no cause" is precisely what we have to do, in order to weaken this argument. As I explained above, the logic of the argument is the classic correlation-implies-causality mistake. If P & Q are correlated, a very effective weakener for this the causation argument is to show that something else accounts for the correlation of P & Q. This is precisely what (B) does. It tells us (brushing & flossing regularly) are correlated with (exercise & healthy diet) --- one could say, they are both "caused" by a person's overall health-awareness & quality of self-care. Brushing & flossing cause the absences of periodontal disease: that's common knowledge. Regular exercise and a health diet cause the low frequency of heart disease: that's also common knowledge. Therefore, lack of brushing and flossing would lead to a higher frequency of periodontal disease, and lack of exercise & a poor diet would lead to a higher frequency of heart disease. That's precisely how these two could be correlated without having a causal relationship.

One could say that (D) strengthens the argument --- periodontal disease "cause" people to stop eating lean meat & veggies (both good for the heart), and "cause" people to eat unhealthy foods, which, in turn, cause heart disease. Thus, periodontal disease would stand at the head of a causal change that leads to heart disease. This is consistent with the causal claim of the argument, so it is not a weakener.

For some reason, you believe that an assumption or conclusion of the argument is that periodontal disease is the ONLY cause of heart disease. This is 100% not supported by anything in the argument. That would be a 10-times stronger argument than that one presented here. There's a HUGE difference between saying "P causes Q" (which leaves open the possibility that many other factors could also cause Q) and "P is the only cause of Q" (which creates a unique link between P & Q). Nothing in the prompt justifies the "ONLY" reading, and in fact, if you think about it, it's patently illogical for anyone to make that claim, because it's common knowledge that all sorts of things in everyday life (lack of exercise, high-fat diets, smoking, etc) cause heart disease. Be very careful of making arguments & assumptions more rigorous or more exclusive than the text justifies.

Does all this make sense?
Mike :-)
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 09 Oct 2013, 15:06
mikemcgarry wrote:
[

For some reason, you believe that an assumption or conclusion of the argument is that periodontal disease is the ONLY cause of heart disease. This is 100% not supported by anything in the argument. That would be a 10-times stronger argument than that one presented here. There's a HUGE difference between saying "P causes Q" (which leaves open the possibility that many other factors could also cause Q) and "P is the only cause of Q" (which creates a unique link between P & Q). Nothing in the prompt justifies the "ONLY" reading, and in fact, if you think about it, it's patently illogical for anyone to make that claim, because it's common knowledge that all sorts of things in everyday life (lack of exercise, high-fat diets, smoking, etc) cause heart disease. Be very careful of making arguments & assumptions more rigorous or more exclusive than the text justifies.


Thank you for your reply, Mike.

Here is why I believe that an assumption of the argument is periodontal disease is the only cause of cardiovascular problems:

The argument is:
Premise = these two things appear to happen together
Conclusion = one of these things causes the other / one of these things is "a cause" of the other

The only way the author can conclude that a casual relationship is at work is by having considered every other possible explanation and ruled every single one of them out--otherwise, how could the author possibly conclude that causality is at work? Without that assumption, that same evidence could just as well be used to support a very different conclusion, namely that those two things are both caused by some third factor, or perhaps that they are just correlated. The reason my assumption is so extreme is that making a casual claim from one data point about the frequency with which two things to happen together is incredibly extreme--it's also why casual conclusions on the gmat/lsat, or in everyday life, are all inherently flawed. I am not the one being extreme here--the author is.

As for the "the cause" versus "a cause"; when the author concludes that one of them is "a cause", that author is STILL assuming that it's the only cause--if there were other potential causes, the author could not CONCLUDE that one causes the other (why and how could he conclude that, in this case, the cause is what he claims it to be, not the other potential causes that he acknowledges exist?). Therefore the author MUST be assuming it's the only cause, whether he means to or not. That assumption is the only way for the argument to be valid. However much the author may want to hedge his claim by including that it is "a" cause, or for however frequent this type of argument occurs in everyday life, the fact of the matter is that author reached that conclusion from evidence that merely shows that the two things seem to happen together. There is a massive gap between the premise and the conclusion, and the only way that can be bridged is by an equally massive assumption.

mikemcgarry wrote:
[
The conclusion of the prompt argument posits a causal relationship ----- "periodontal disease is a cause of a variety of cardiovascular problems" and we are asked to weaken the argument. Demonstrating "no cause" is precisely what we have to do, in order to weaken this argument. As I explained above, the logic of the argument is the classic correlation-implies-causality mistake. If P & Q are correlated, a very effective weakener for this the causation argument is to show that something else accounts for the correlation of P & Q. This is precisely what (B) does. It tells us (brushing & flossing regularly) are correlated with (exercise & healthy diet) --- one could say, they are both "caused" by a person's overall health-awareness & quality of self-care. Brushing & flossing cause the absences of periodontal disease: that's common knowledge. Regular exercise and a health diet cause the low frequency of heart disease: that's also common knowledge. Therefore, lack of brushing and flossing would lead to a higher frequency of periodontal disease, and lack of exercise & a poor diet would lead to a higher frequency of heart disease. That's precisely how these two could be correlated without having a causal relationship.


How does the logic used to justify the answer choice NOT commit the same error of judgement that the author or the original argument did, that correlation implies causation? All this says it that people do not have gum problems are more likely to not have cardiovascular problems. Even if you take it imply correlation, how does proof of correlation deny causation? EX: "Not being shot in the head is correlated with not dying, THEREFORE that fact weakens the argument that being shot in the head causes death?". Please explain.
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Re: Citing the frequency with which gum disease and heart disease occur in [#permalink]

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New post 09 Oct 2013, 15:54
Reinfrank2011 wrote:
mikemcgarry wrote:
[

For some reason, you believe that an assumption or conclusion of the argument is that periodontal disease is the ONLY cause of heart disease. This is 100% not supported by anything in the argument. That would be a 10-times stronger argument than that one presented here. There's a HUGE difference between saying "P causes Q" (which leaves open the possibility that many other factors could also cause Q) and "P is the only cause of Q" (which creates a unique link between P & Q). Nothing in the prompt justifies the "ONLY" reading, and in fact, if you think about it, it's patently illogical for anyone to make that claim, because it's common knowledge that all sorts of things in everyday life (lack of exercise, high-fat diets, smoking, etc) cause heart disease. Be very careful of making arguments & assumptions more rigorous or more exclusive than the text justifies.


Thank you for your reply, Mike.

Here is why I believe that an assumption of the argument is periodontal disease is the only cause of cardiovascular problems:

The argument is:
Premise = these two things appear to happen together
Conclusion = one of these things causes the other / one of these things is "a cause" of the other

The only way the author can conclude that a casual relationship is at work is by having considered every other possible explanation and ruled every single one of them out--otherwise, how could the author possibly conclude that causality is at work? Without that assumption, that same evidence could just as well be used to support a very different conclusion, namely that those two things are both caused by some third factor, or perhaps that they are just correlated. The reason my assumption is so extreme is that making a casual claim from one data point about the frequency with which two things to happen together is incredibly extreme--it's also why casual conclusions on the gmat/lsat, or in everyday life, are all inherently flawed. I am not the one being extreme here--the author is.

As for the "the cause" versus "a cause"; when the author concludes that one of them is "a cause", that author is STILL assuming that it's the only cause--if there were other potential causes, the author could not CONCLUDE that one causes the other (why and how could he conclude that, in this case, the cause is what he claims it to be, not the other potential causes that he acknowledges exist?). Therefore the author MUST be assuming it's the only cause, whether he means to or not. That assumption is the only way for the argument to be valid. However much the author may want to hedge his claim by including that it is "a" cause, or for however frequent this type of argument occurs in everyday life, the fact of the matter is that author reached that conclusion from evidence that merely shows that the two things seem to happen together. There is a massive gap between the premise and the conclusion, and the only way that can be bridged is by an equally massive assumption.

OK, two different issues. I will respond in two different posts, just to keep things organized.
It's perfectly true that the prompt argument is a lousy argument, with an untenable jump from premise to conclusion.

We have the scenario:
Premise: P and Q appear together (i.e. P is correlated with Q)
Conclusion: P causes Q
The classic "correlation does not imply causality" error. What's the assumption here?

You claim the assumption is, and must be "P is the only cause of Q". As you may know, one of the classic tests for the assumption of an argument is the Negation Test --- if you can negate a statement and still imagine the argument surviving, then what you have is not a principal assumption of the argument. If, when you negate the statement, this creates a devastating objection from which the argument cannot recover ---- then, that's an assumption. This is described in more depth in:
http://magoosh.com/gmat/2013/assumption ... -the-gmat/
I will apply the Negation Test to your assumption: "P is not the only cause of Q." Well, in the scenario in which (P = smoking, Q = cancer) or (P = lack of exercise, Q = susceptibility to heart disease), then it would be perfectly possible for the negation of your assumption to be true and the argument would still work. That tells us, in general, this is not a universal assumption for this scenario.

You seem to be trying to establish an airtight path from the premise to the conclusion, but this is inherently a faulty argument. The question is simply saying --- we have a faulty argument, so how do we knock it down? That's it. That's all the question is asking. By contrast, what you are doing is --- first, let's take this faulty argument, and make it as solid as concrete, reinforce it with stainless steel girders, and then we'll take the most sophisticated industrial equipment and demolish it. That's a wonderful exercise in its own right, but that is most certainly not the task at hand. You are way over-analyzing this scenario, and thereby overlooking the very simple task the question asks. When one is very gifted with logical analysis, as you clearly are, it's very simple to overthink and completely miss the very straightforward tasks of GMAT CR.

Does all this make sense?
Mike :-)
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Re: Citing the frequency with which gum disease and heart disease occur in   [#permalink] 09 Oct 2013, 15:54

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