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For a university study on exercise habits, three equal groups were eac

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For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 30 Apr 2017, 06:58
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A
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For a university study on exercise habits, three equal groups were each led in one type of exercise for 45 minutes each day for a month: rowing, jogging, and dancing. When surveyed three months later, about half of those in the jogging and rowing groups were still participating in that activity at least twice per week, but for the dance group that figure was closer to 80%. It can be concluded, then, that of the three types of exercise dance is the activity that people are most likely to continue pursuing once they’ve started.

Which of the following is an assumption upon which the argument relies?

(A) Of the survey participants who changed to a different type of exercise after the survey ended, fewer changed from dance to another activity than changed from either jogging or rowing to dance.

(B) Joggers and rowers are no more likely than dancers to become injured while pursuing their chosen activity.

(C) Dance is an activity for which participants are less dependent on favorable weather than jogging and rowing are.

(D) The ratio of study participants who chose their activity to those who were randomly assigned their activity was no lower for jogging and rowing than it was for dancing.

(E) The number of participants in the dance group was no lower than the number of participants in the jogging and rowing groups.

Spoiler: :: OE

OFFICIAL EXPLANATION


A common logical flaw with regard to statistics is that of correlation vs. causation: here the argument wants us to be impressed by the comparison between 80% and "about half," but do we know that 80% retention rate for dance reflects improvement from before the study, or was the group of dancers always more likely to stick with dancing?

With assumption questions, you can often get a better feel for the flaw in logic, and necessity of the right answer to plug that flaw, if you use the Assumption Negation Technique, essentially turning the Assumption question into a Weaken question by taking the opposite of each answer and determining whether that rephrased choice directly weakens the argument.

With choice D, you should see that if the opposite were true - if the ratio of people who picked their activity to people who were assigned it was higher for dancers than for the other groups - then you don't know whether that rate of retention (a higher percentage kept dancing) was because dancing is inherently an easier activity for anyone to stick with, or because this particular group was already predisposed to want to keep dancing. Essentially, without answer choice D, you don't know whether you have a valid control group to effectively compare activity to activity.

Of the incorrect answer choices, choice B is often the most tempting for people. But keep in mind that the conclusion is only concerned with whether people continue to pursue the activity, not with why they might not be able to pursue it. If joggers and rowers were more likely to become injured (the negated choice B), that only supports the conclusion that people are more likely to continue with dance - not necessarily because they prefer it, but because they cannot keep up with the other activities. Since B and C, each negated, go on to support the conclusion, they are incorrect.

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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 30 Apr 2017, 07:38
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What is wrong with E... Help me to get to the best answer

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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 30 Apr 2017, 18:52
yogesh610 wrote:
What is wrong with E... Help me to get to the best answer

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Whenever the problem states percentages/likelihood generally avoid using numbers. As it does nothing. Please correct me if am wrong.

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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 07 May 2017, 07:45
yogesh610 wrote:
What is wrong with E... Help me to get to the best answer

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Yogesh,

E cannot me an assumption coz its already stated in the argument that the Groups were divided into equal.

Hope this helps !!
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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 07 May 2017, 09:00
[quote="yogesh610"]What is wrong with E... Help me to get to the best answer

If you read the question, the group were divided equally. thus no group can have lower number of participants
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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 08 May 2017, 03:18
aj1703 wrote:
ziyuen wrote:
For a university study on exercise habits, three equal groups were each led in one type of exercise for 45 minutes each day for a month: rowing, jogging, and dancing. When surveyed three months later, about half of those in the jogging and rowing groups were still participating in that activity at least twice per week, but for the dance group that figure was closer to 80%. It can be concluded, then, that of the three types of exercise dance is the activity that people are most likely to continue pursuing once they’ve started.

Which of the following is an assumption upon which the argument relies?

(A) Of the survey participants who changed to a different type of exercise after the survey ended, fewer changed from dance to another activity than changed from either jogging or rowing to dance.

(B) Joggers and rowers are no more likely than dancers to become injured while pursuing their chosen activity.

(C) Dance is an activity for which participants are less dependent on favorable weather than jogging and rowing are.

(D) The ratio of study participants who chose their activity to those who were randomly assigned their activity was no lower for jogging and rowing than it was for dancing.

(E) The number of participants in the dance group was no lower than the number of participants in the jogging and rowing groups.

OFFICIAL EXPLANATION


A common logical flaw with regard to statistics is that of correlation vs. causation: here the argument wants us to be impressed by the comparison between 80% and "about half," but do we know that 80% retention rate for dance reflects improvement from before the study, or was the group of dancers always more likely to stick with dancing?

With assumption questions, you can often get a better feel for the flaw in logic, and necessity of the right answer to plug that flaw, if you use the Assumption Negation Technique, essentially turning the Assumption question into a Weaken question by taking the opposite of each answer and determining whether that rephrased choice directly weakens the argument.

With choice D, you should see that if the opposite were true - if the ratio of people who picked their activity to people who were assigned it was higher for dancers than for the other groups - then you don't know whether that rate of retention (a higher percentage kept dancing) was because dancing is inherently an easier activity for anyone to stick with, or because this particular group was already predisposed to want to keep dancing. Essentially, without answer choice D, you don't know whether you have a valid control group to effectively compare activity to activity.

Of the incorrect answer choices, choice B is often the most tempting for people. But keep in mind that the conclusion is only concerned with whether people continue to pursue the activity, not with why they might not be able to pursue it. If joggers and rowers were more likely to become injured (the negated choice B), that only supports the conclusion that people are more likely to continue with dance - not necessarily because they prefer it, but because they cannot keep up with the other activities. Since B and C, each negated, go on to support the conclusion, they are incorrect.



Why not "C" ?


Even when me negate C, it doesn't affect the conclusion. Hence, C is wrong. Moreover, I don't think weather has to do anything to it. Please correct me if am wrong.
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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 08 May 2017, 06:48
Hi can somebody please explain how to negate B I was really confused between B and D

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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 18 Jun 2017, 21:08
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I got confused between B and D as they both eliminate the possibility of alternate reason rather than the love for dancing.Why B is not the right choice.B states that it was not injury that have decreased the number of participant for jogging and rowing.
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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 18 Jun 2017, 21:24
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techiesam wrote:
I got confused between B and D as they both eliminate the possibility of alternate reason rather than the love for dancing.Why B is not the right choice.B states that it was not injury that have decreased the number of participant for jogging and rowing.


For me B states that the likelihood to get injured while dancing is the same as the other 2 activities. This would not help me reach the conclusion that people will continue to pursue dancing as a form of exercise.

D - If I assume that the groups were assigned randomly without paying heed to personal interests for all 3 exercises, then it potentially leads me to conclude that a participant who picks up dancing as a form of exercise is more likely to continue dancing Vs. the other exercises.
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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 18 Jun 2017, 22:04
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For a university study on exercise habits, three equal groups were each led in one type of exercise for 45 minutes each day for a month: rowing, jogging, and dancing. When surveyed three months later, about half of those in the jogging and rowing groups were still participating in that activity at least twice per week, but for the dance group that figure was closer to 80%. It can be concluded, then, that of the three types of exercise dance is the activity that people are most likely to continue pursuing once they’ve started.

Type- Assumption
Boil it down- more participation in dance --> dance is activity people are most likely to continue once started
Per-thinking - All the three groups were equally motivated to pursue the respective exercise

(A) Of the survey participants who changed to a different type of exercise after the survey ended, fewer changed from dance to another activity than changed from either jogging or rowing to dance. - Irrelevant

(B) Joggers and rowers are no more likely than dancers to become injured while pursuing their chosen activity. - Negation test - if Joggers and rowers are more likely to become injured as dancers do, then this supports the conclusion that people continue to pursue dance not because of preference but because they are less likely to be injured

(C) Dance is an activity for which participants are less dependent on favorable weather than jogging and rowing are. - Negation test - If dance as an activity for which participants are equally or more dependent on weather, then it supports the conclusion

(D) The ratio of study participants who chose their activity to those who were randomly assigned their activity was no lower for jogging and rowing than it was for dancing. - Correct - the folks who took dancing were inclined before the survey even began . Thus , this option on negation breaks the conclusion .

(E) The number of participants in the dance group was no lower than the number of participants in the jogging and rowing groups. - Irrelevant - the absolute number of participants in a group does not matter

Answer D
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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 02 Feb 2018, 00:23
Skywalker18 wrote:
For a university study on exercise habits, three equal groups were each led in one type of exercise for 45 minutes each day for a month: rowing, jogging, and dancing. When surveyed three months later, about half of those in the jogging and rowing groups were still participating in that activity at least twice per week, but for the dance group that figure was closer to 80%. It can be concluded, then, that of the three types of exercise dance is the activity that people are most likely to continue pursuing once they’ve started.

Type- Assumption
Boil it down- more participation in dance --> dance is activity people are most likely to continue once started
Per-thinking - All the three groups were equally motivated to pursue the respective exercise

(A) Of the survey participants who changed to a different type of exercise after the survey ended, fewer changed from dance to another activity than changed from either jogging or rowing to dance. - Irrelevant

(B) Joggers and rowers are no more likely than dancers to become injured while pursuing their chosen activity. - Negation test - if Joggers and rowers are more likely to become injured as dancers do, then this supports the conclusion that people continue to pursue dance not because of preference but because they are less likely to be injured

(C) Dance is an activity for which participants are less dependent on favorable weather than jogging and rowing are. - Negation test - If dance as an activity for which participants are equally or more dependent on weather, then it supports the conclusion

(D) The ratio of study participants who chose their activity to those who were randomly assigned their activity was no lower for jogging and rowing than it was for dancing. - Correct - the folks who took dancing were inclined before the survey even began . Thus , this option on negation breaks the conclusion .

(E) The number of participants in the dance group was no lower than the number of participants in the jogging and rowing groups. - Irrelevant - the absolute number of participants in a group does not matter

Answer D

Skywalker18, VeritasPrepKarishma,
Option D says that the ratio of participants who chose activity to those who were randomly assigned was equally likely for all the 3 modes of exercise. So, we can conclude that there is no biased case involved. But the conclusion is based on the study that of the three types of exercise dance is the activity that people are most likely to continue pursuing once they’ve started. How can we say that participants will continue to do so. We have a report of 3 months only. So, I feel that d is not the complete assumption. Also, what is wrong with A? A mentioned that fewer changed from dance to another activity than changed from either jogging or rowing to dance. So, we know that they did not stop the activity ie. continued. Please help me to understand further.
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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 03 Feb 2018, 05:47
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sunny91 wrote:
Skywalker18 wrote:
For a university study on exercise habits, three equal groups were each led in one type of exercise for 45 minutes each day for a month: rowing, jogging, and dancing. When surveyed three months later, about half of those in the jogging and rowing groups were still participating in that activity at least twice per week, but for the dance group that figure was closer to 80%. It can be concluded, then, that of the three types of exercise dance is the activity that people are most likely to continue pursuing once they’ve started.

Type- Assumption
Boil it down- more participation in dance --> dance is activity people are most likely to continue once started
Per-thinking - All the three groups were equally motivated to pursue the respective exercise

(A) Of the survey participants who changed to a different type of exercise after the survey ended, fewer changed from dance to another activity than changed from either jogging or rowing to dance. - Irrelevant

(B) Joggers and rowers are no more likely than dancers to become injured while pursuing their chosen activity. - Negation test - if Joggers and rowers are more likely to become injured as dancers do, then this supports the conclusion that people continue to pursue dance not because of preference but because they are less likely to be injured

(C) Dance is an activity for which participants are less dependent on favorable weather than jogging and rowing are. - Negation test - If dance as an activity for which participants are equally or more dependent on weather, then it supports the conclusion

(D) The ratio of study participants who chose their activity to those who were randomly assigned their activity was no lower for jogging and rowing than it was for dancing. - Correct - the folks who took dancing were inclined before the survey even began . Thus , this option on negation breaks the conclusion .

(E) The number of participants in the dance group was no lower than the number of participants in the jogging and rowing groups. - Irrelevant - the absolute number of participants in a group does not matter

Answer D

Skywalker18, VeritasPrepKarishma,
Option D says that the ratio of participants who chose activity to those who were randomly assigned was equally likely for all the 3 modes of exercise. So, we can conclude that there is no biased case involved. But the conclusion is based on the study that of the three types of exercise dance is the activity that people are most likely to continue pursuing once they’ve started. How can we say that participants will continue to do so. We have a report of 3 months only. So, I feel that d is not the complete assumption. Also, what is wrong with A? A mentioned that fewer changed from dance to another activity than changed from either jogging or rowing to dance. So, we know that they did not stop the activity ie. continued. Please help me to understand further.


What is the meaning of "assumption"? An assumption is a "missing necessary premise". A assumption may not be and is usually not sufficient.
There is nothing called a "complete assumption". You could need a 100 assumptions to establish a conclusion without doubt. All we are looking for is one of those assumptions.
Option (D) says that the sample did not have bias A. This is required to arrive at the conclusion.
Note that "how many changed to what" has nothing to do with our argument. All we care about is how many stopped the chosen activity. We don't care what they switched into. This is outside our scope.
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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 13 Feb 2018, 00:50
VeritasPrepKarishma

Can you explain answer choice D with an example. It seems confusing!

Thanks,

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Re: For a university study on exercise habits, three equal groups were eac  [#permalink]

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New post 14 Feb 2018, 03:25
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ucb2k7 wrote:
VeritasPrepKarishma

Can you explain answer choice D with an example. It seems confusing!

Thanks,

ucb2k7


Let' say the rowing, jogging and dancing groups had 100 participants each.
See what happens if (D) doesn't hold.
Say 40 people each of the rowing and jogging groups had selected these activities on their own and 60 each were randomly assigned. Whereas 80 had selected dancing and 20 were randomly assigned to it.
Now is it a surprise that 80 people continued dancing while only 50 each continued rowing and jogging? No. The sample was biased. Out of the 100 that picked dancing, 80 actually wanted to pick it. So there is a higher probability that from this group, more people will continue to be interested in it.
Hence we cannot conclude that dancing is more likely to be continued than jogging and rowing.

Hence (D) is an assumption.
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Re: For a university study on exercise habits, three equal groups were eac &nbs [#permalink] 14 Feb 2018, 03:25
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