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Researchers took a group of teenagers who had never smoked

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Updated on: 16 Jun 2018, 00:13
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Researchers took a group of teenagers who had never smoked and for one year tracked whether they took up smoking and how their mental health changed. Those who began smoking within a month of the study's start were four times as likely to be depressed at the study's end than those who did not begin smoking. Since nicotine in cigarettes changes brain chemistry, perhaps thereby affecting mood, it is likely that smoking contributes to depression in teenagers.

Which of the following, if true, most strengthens the argument?

(A) Participants who were depressed at the study's start were no more likely to be smokers at the study's end than those who were not depressed.

(B) Participants who began smoking within a month of the study's start were no more likely than those who began midway through to have quit smoking by the study's end.

(C) Few, if any, of the participants in the study were friends or relatives of other participants.

(D) Some participants entered and emerged from a period of depression within the year of the study.

(E) The researchers did not track use of alcohol by the teenagers.

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Originally posted by saurya_s on 08 Apr 2005, 14:01.
Last edited by hazelnut on 16 Jun 2018, 00:13, edited 2 times in total.
Reformatted question
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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26 May 2012, 05:12
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Chembeti wrote:
I still don;t understand how A is the answer.
All it says is - depression is not the reason for smoking.

And as per the argument, we have to prove that smoking contributes to depression. This can not be proved on the basis of A.

But, except A, nothing comes close and hence I select A.

What i feel is -> Conclusion is: smoking (in teenagers) causes depression. X causes Y.

Option A -> Depression (in teenagers) does not causes Smoking. Y doesn't causes X. i.e It strengthens the conclusion by implying that The reverse causation is not possible. This is also one way to support/strengthen the conclusion.

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Mahtab Md.
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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08 Apr 2005, 15:05
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definitely (A).

(A) says that the people who started smoking are mentall/biologically same as those who did not smoke.
Infact (A) is an assumption.
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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09 Apr 2005, 07:41
I may be way off on this but I will go with 'B'

Conclusion: Smoking contributes to depression in teenagers.

A. Participants who were depressed at the studyâ€™s start were no more likely to be smokers at the studyâ€™s end than those who were not depressed.
This does not attack the conlcusion.

B. Participants who began smoking within a month of the studyâ€™s start were no more likely than those who began midway through to have quit smoking by the studyâ€™s end.
This is it, this fixes a potential flaw in the conclusion - which is - Smoking did not contribute to depression in teenagers but Quitting contributed to depression.
If people who started to smoke at the beginning were to quit at the end of it, quitting could be the reason why they are depressed.

C. Few, if any, of the participants in the study were friends or relatives of other participants.
Irrelevant.

D. Some participants entered and emerged from a period of depression within the year of the study.
Same as A

E. The researchers did not track use of alcohol by the teenagers.
Irrelevant
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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26 Mar 2010, 15:39
I may be way off on this but I will go with 'B'

Conclusion: Smoking contributes to depression in teenagers.

A. Participants who were depressed at the studyâ€™s start were no more likely to be smokers at the studyâ€™s end than those who were not depressed.
This does not attack the conlcusion.

B. Participants who began smoking within a month of the studyâ€™s start were no more likely than those who began midway through to have quit smoking by the studyâ€™s end.
This is it, this fixes a potential flaw in the conclusion - which is - Smoking did not contribute to depression in teenagers but Quitting contributed to depression.
If people who started to smoke at the beginning were to quit at the end of it, quitting could be the reason why they are depressed.

C. Few, if any, of the participants in the study were friends or relatives of other participants.
Irrelevant.

D. Some participants entered and emerged from a period of depression within the year of the study.
Same as A

E. The researchers did not track use of alcohol by the teenagers.
Irrelevant

i think the answer is A and here's my reason

A. if the smokers are those who were already depressed at the start of the experiment, then we could assume that those depressed people's own characters are more likely to cause the smoking tendency rather than nicotine does. so if we could eliminate the this possibility and make sure that depressed people were no more likely to become smokers than those who were not depressed, then it most strengthens the argument.

B. the argument is not relevant to the midway quitters. also, we couldnt see this kind of flaw in the argument that quitting contributes to smoking. its very clearly written in the argument that Smoking itself contributes to smoking bcuz nicotine changes brain chemistry.
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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18 Jan 2012, 05:30
I still don;t understand how A is the answer.
All it says is - depression is not the reason for smoking.

And as per the argument, we have to prove that smoking contributes to depression. This can not be proved on the basis of A.

But, except A, nothing comes close and hence I select A.
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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27 Jul 2013, 12:23
thank you mahtabmd ... got this wrong on GMATPrep your explanation hits the spot!
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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29 Dec 2014, 12:58
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Cause (Smoking for 11 months) ---> Effect (Depression at the end of 11 months)
Now, we need to strengthen this causal relation; So, any wened to eliminate reverse causation or alternate causation.
A. This option says: teenagers already depressed (effect) ---->NOT started smoking during the study (cause)
This option shows "effect" doesn't cause the "cause" . So the causality is srengthened.
Always remember whenever a causality is ecountered we check 3 basic causality rules.
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03 Oct 2015, 07:06
I selected A by POE ; there was solid reason behind choosing A .
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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04 Oct 2015, 22:27
Choice A makes it a better argument, by ruling out the possibility that the causation runs in the opposite direction (i.e., that depression leads kids to start smoking).
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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16 Oct 2015, 22:46
saurya_s wrote:
Researchers took a group of teenagers who had never smoked and for one year tracked whether they took up smoking and how their mental health changed. Those who began smoking within a month of the studyâ€™s start were four times as likely to be depressed at the studyâ€™s end than those who did not begin smoking. Since nicotine in cigarettes changes brain chemistry, perhaps thereby affecting mood, it is likely that smoking contributes to depression in teenagers.
Which of the following, if true, most strengthens the argument?
A. Participants who were depressed at the studyâ€™s start were no more likely to be smokers at the studyâ€™s end than those who were not depressed.
B. Participants who began smoking within a month of the studyâ€™s start were no more likely than those who began midway through to have quit smoking by the studyâ€™s end.
C. Few, if any, of the participants in the study were friends or relatives of other participants.
D. Some participants entered and emerged from a period of depression within the year of the study.
E. The researchers did not track use of alcohol by the teenagers.

I know there are previous answers to this question. I am just writing it for my benefit. I seem to not think clearly during the exam. But when I practice, I dont hesitate since I guess I know that this isn't the real exam. Probably explaining my answers will help me improve.

Premises:
A study was commenced ---> Teenagers were selected. ---> The officials of the study saw two things happening: teenagers who took up smoking, within four month were more likely to be depressed than teenagers who did not pick up smoking.

Conclusion: nicotine in cigarettes changes brain chemistry ---> this brain chemical change likely induces depression.

A. Participants who were depressed at the study's start were no more likely to be smokers at the study's end than those who were not depressed. participants who were depressed at the start of the study (G1) and participants who were not depressed at the start of the study (G2). G1 was not MORE likely to start smoking as G2 ---> They have equal inclinations to NOT Smoke. So that means the reverse cause of depression ---> take up smokingis negated If this is true, then maybe our study's officials reasoning is true

B. Participants who began smoking within a month of the study's start were no more likely than those who began midway through to have quit smoking by the study's end. people began smoking within a month (G1). People who left smoking midway (G2) G1 and G2 are equally likely to take up smoking and quit respectively. Does it tell us how nicotine affects brain chemistry to take up or give up smoking? No, we are confused with the relationship. So no clear answer, if true or false.

C. Few, if any, of the participants in the study were friends or relatives of other participants. not important.

D. Some participants entered and emerged from a period of depression within the year of the study. emerging from depression doesnt tell us how nicotine affects brain chemistry

E. The researchers did not track use of alcohol by the teenagers. out of scope.

Ans: A
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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18 Aug 2016, 09:31
Feels like medium difficulty or it is just me.
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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17 May 2017, 20:50
Researchers took a group of teenagers who had never smoked and for one year tracked whether they took up smoking and how their mental health changed. Those who began smoking within a month of the studyâ€™s start were four times as likely to be depressed at the studyâ€™s end than those who did not begin smoking. Since nicotine in cigarettes changes brain chemistry, perhaps thereby affecting mood, it is likely that smoking contributes to depression in teenagers.
Which of the following, if true, most strengthens the argument?

A. Participants who were depressed at the studyâ€™s start were no more likely to be smokers at the studyâ€™s end than those who were not depressed.
B. Participants who began smoking within a month of the studyâ€™s start were no more likely than those who began midway through to have quit smoking by the studyâ€™s end.
C. Few, if any, of the participants in the study were friends or relatives of other participants.
D. Some participants entered and emerged from a period of depression within the year of the study.
E. The researchers did not track use of alcohol by the teenagers.

My 2 cents.

Conclusion : smoking causes depression

A. So this is saying that at the start of the depression, there were some participants who were depressed. And these depressed participants were no more likely to be smokers than those who were not depressed. So this is trying to establish that depression does not cause smoking. So, by shooting down alternative explanation, the argument is strengthened.

Not an easy question but if you are aiming high on gmat, you need to see why A is correct answer.
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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17 May 2017, 22:29
It Says that both Depressed and Non-depressed people are equally predisposed to smoke in the defined period. Only then is the result of the study accurate and can be considered true. It defies the circular reasoning that X causes Y as well as Y causes X.
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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25 Nov 2017, 17:27
GMATNinja VeritasPrepKarishma

Smoking (which contains nicotine) -> Depression in Teenagers

To strengthen: we need to prove reverse causation in not possible

Depression in Teenagers -> Smoking (which contains nicotine) in not feasible

This is what (A) does on negation

But correct strengthener can also be: Eliminating any alternate causes for stated effect.

Why (E) incorrect?
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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01 Dec 2017, 01:17
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GMATNinja VeritasPrepKarishma

Smoking (which contains nicotine) -> Depression in Teenagers

To strengthen: we need to prove reverse causation in not possible

Depression in Teenagers -> Smoking (which contains nicotine) in not feasible

This is what (A) does on negation

But correct strengthener can also be: Eliminating any alternate causes for stated effect.

Why (E) incorrect?

If at all, (E) weakens the argument. It says that the study was limited in its scope and did not track drinking. Perhaps the teens who started smoking started drinking too and actually that caused depression, not the smoking. It doesn't make our argument stronger i.e. it doesn't make the conclusion of our study more likely to be true.

Knowing that A and B are linked and by saying that B is not the cause of A, we make it more likely that A is the cause of B. So option (A) is correct.
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Re: Researchers took a group of teenagers who had never smoked  [#permalink]

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19 Jan 2018, 05:39
WaterFlowsUp wrote:
Cause (Smoking for 11 months) ---> Effect (Depression at the end of 11 months)
Now, we need to strengthen this causal relation; So, any wened to eliminate reverse causation or alternate causation.
A. This option says: teenagers already depressed (effect) ---->NOT started smoking during the study (cause)
This option shows "effect" doesn't cause the "cause" . So the causality is srengthened.
Always remember whenever a causality is ecountered we check 3 basic causality rules.

Can you or any guys tell me about 3 basis causality rules?

Many thanks.

Do you mean this:

Temporal sequencing — Independent variable must come before dependent variable

Non-spurious relationship — Relationship between independent variable and dependent variable cannot occur by chance alone

Eliminate alternate causes — There is no other intervening or unaccounted cause for the relationship
Re: Researchers took a group of teenagers who had never smoked &nbs [#permalink] 19 Jan 2018, 05:39
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