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tracyyahoo: Master | Next Rank: 500 Posts; Posts: 147; Joined: Tue Jun 14, 2011 7:03 am; Thanked: 3 times

by tracyyahoo » Tue Sep 27, 2011 9:15 pm

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.

I know C,D,E are irrelevant, why A not B??? Pls explain me????

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Source: Beat The GMAT — Critical Reasoning | Tue Sep 27, 2011 9:15 pm

ratan_2009: Junior | Next Rank: 30 Posts; Posts: 12; Joined: Fri Jul 17, 2009 2:32 pm

by ratan_2009 » Tue Sep 27, 2011 10:25 pm

i think its A

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mundasingh123: Legendary Member; Posts: 2330; Joined: Fri Jan 15, 2010 5:14 amFollowed by: 26 members; Thanked: 56 times

by mundasingh123 » Tue Sep 27, 2011 10:51 pm

tracyyahoo 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 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.

I know C,D,E are irrelevant, why A not B??? Pls explain me????

Hi Tracy ,
I suggest that you go through the causation chapter in the Powerscore Cr . According to it
a causation relationship X->Y could be weakened by showing
1)an alternate reason for Y
2)Y lead to X and not X lead to Y.The reverse is true .
3)
4)
5)
There 5 ways in which the causation could be weakened
Option A here follows Technique No. 2 .It strengthen the argument by precluding the chance of technique 2 happening . It says Y did not lead to X .It strengthens the conclusion by defending the conclusion .

I Seek Explanations Not Answers

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navami: Legendary Member; Posts: 540; Joined: Sat Dec 20, 2008 7:24 pmFollowed by: 6 members; Thanked: 37 times

by navami » Wed Sep 28, 2011 4:42 am

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.

-------------

We have to strengthen the conclusion ...
CONCLUSION : it is likely that smoking contributes to depression in teenagers

now how can we negate the colclusion ?
we can do it if we prove that the depressed people pick up the habit of smoking... ---(1)
and Option A says that the face (1) that 'that the depressed people pick up the habit of smoking' is not true.

This time no looking back!!!
Navami

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theforrestgump: Senior | Next Rank: 100 Posts; Posts: 54; Joined: Tue Aug 30, 2011 12:29 pm; Thanked: 4 times

by theforrestgump » Wed Sep 28, 2011 1:55 pm

navami 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 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.

-------------

We have to strengthen the conclusion ...
CONCLUSION : it is likely that smoking contributes to depression in teenagers

now how can we negate the colclusion ?
we can do it if we prove that the depressed people pick up the habit of smoking... ---(1)
and Option A says that the face (1) that 'that the depressed people pick up the habit of smoking' is not true.

Once again DO NOT apply the Negation Test for questions apart from Assumption questions....if you do not believe me, the following should help explain

https://gmatclub.com/forum/negate-test-96785.html

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Bigred2008: Junior | Next Rank: 30 Posts; Posts: 18; Joined: Sun Jul 18, 2010 3:09 pm

by Bigred2008 » Wed Sep 28, 2011 6:20 pm

It should be A

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.

If you take a look at an argument you need to figure out what the weakness is, in this case what if "Since nicotine in cigarettes changes brain chemistry, perhaps thereby affecting mood, it is likely that smoking contributes to depression in teenagers." Anything that can strengthen the bolded portion. In this case, it eliminates the idea that people who are already depressed start smoking, rather then smoking causes depression.

"No Pressure, No Diamonds. "

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sl750: Master | Next Rank: 500 Posts; Posts: 496; Joined: Tue Jun 07, 2011 5:34 amFollowed by: 1 member; Thanked: 38 times

by sl750 » Thu Sep 29, 2011 6:46 am

In choice B, it is talking about one group that is as likely as the other group to quit smoking. We are not interested in whether the group has an addiction problem or not. So, this does not strengthen the argument

Only A, which is a convoluted response is the correct answer. Choice C,D,E can be easily eliminated

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