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# A recent study of college students shows that, contrary to

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A recent study of college students shows that, contrary to  [#permalink]

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06 Jul 2008, 18:16
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A recent study of college students shows that, contrary to predicted results, special nutritional planning does not positively affect students’ grades. Sixty students, half of whom were given a nutritionally balanced diet, had grades no higher than did those students who were not placed on the diet plan.

Which of the following, if true, is most useful in determining the accuracy of the study described above?

(A) Performance of business executives was shown to improve drastically after major alterations were made in their diets.
(B) Honors students, after altering their diets, maintained that they did not change their study habits.
(C) Students who participated in various fitness regimens found that their grades improved appreciably after they altered their exercise habits.
(D) High school students who previously had low grades found that after they altered their diets, their grades improved dramatically.
(E) All of the college students who volunteered for the study were either in their first or second year of college.

I marked the answer at ii), because if no changes were made to the study habits then we can conclude that there was no effect of study habits on the study, hence effect of diet can be correctly determined (Whether it had some effect or not). But this answer is wrong . Can anybody explain the correct answer).
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06 Jul 2008, 18:25
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contrary to predicted results, special nutritional planning does not positively affect students’ grades

Predicted results would have been special nutritional planning positively affect students’ grades

C & E are out of scope

Among A, B and D

A is using business executive performance improvement. We don't know whether we can relate real time performance improvement to grades (ironically like GMAT and real time) Still I would hold it for now

I agree with your reasoning on B but we simply don't know whether it had any effect or not. But it sounds as if diet did not had any effect Also, we are talking about a subset of students

D is saying low grade HS students with the new diet improved their grades

Look at the Q again.

Which of the following, if true, is most useful in determining the accuracy of the study described above?

D stands on the expected side of results. Probably study is wrong or this case of college students is an anomaly

##### General Discussion
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A recent study of college students shows that, contrary to  [#permalink]

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07 Jul 2008, 09:54
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Conclusion: special nutritional planning does not positively affect students’ grades.
Evidence:Sixty students, half of whom were given a nutritionally balanced diet, had grades no higher than did those students who were not placed on the diet plan.

The evidence here is weak becuase it provides no details about the student's grade before and after the intake of special diet.Only D brings in information to say students with previously lower grades performed well after they started takin in special diet and refute the conclusion that special diet donot affect student's growth. This answer choice can used to measure the accuracy of this conclusion made in the argument.

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Updated on: 07 Jul 2008, 09:59
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Interesting question.

bhatiasanjay01 wrote:
A recent study of college students shows that, contrary to predicted results, special nutritional planning does not positively affect students’ grades. Sixty students, half of whom were given a nutritionally balanced diet, had grades no higher than did those students who were not placed on the diet plan.

In blue, I've highlighted the conclusion that is drawn. Is this conclusion part of the study? We don't know. In any case, it's a strange conclusion: from a study of only college students, the writer concludes that nutrition "does not positively affect students’ grades" in general. If you wanted to weaken the conclusion, answer D is a clear choice:

bhatiasanjay01 wrote:
iv) High school students who previously had low grades found that after they altered their diets, their grades improved dramatically.

But weakening the conclusion is not what we're asked to do. The question is:

bhatiasanjay01 wrote:
Which of the following, if true, is most useful in determining the accuracy of the study described above?

I highlighted the part of the stem that refers to the study in red. We're asked to assess the accuracy of the study itself, not the conclusion. We can ignore what I've highlighted in blue. The only answer that refers to the methodology of the study (research methods, population that was studied, etc), is E:

bhatiasanjay01 wrote:
v) All of the college students who volunteered for the study were either in their first or second year of college.

Those studied were volunteers- the sample isn't random- and they were from a particular subset of the overall population. This could affect the vailidity of the study; a properly conducted study might reveal different results. So I agree with gixxer here; the correct answer should be E.
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Originally posted by IanStewart on 07 Jul 2008, 09:58.
Last edited by IanStewart on 07 Jul 2008, 09:59, edited 1 time in total.
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01 Aug 2011, 09:58
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Wait... So the fight is so hot b/w D and E. Let us analyze the weak points and strength points of each choice in "determining the accuracy of the study described above":

E: What makes this choice suitable is the fact that it points at some weaknesses in the methodology. Right. So let's put this choice aside for now since it may be the best choice. So, this choice helps us evaluate the accuracy of the study by evaluating the methodology. The methodology in part determines the accuracy of a study.

D:
The problem with E is that since it talks about a test result that was drawn about HIGHSCHOOLS students, it may be considered IRRELEVANT. BUT, on it's good side, choice E states a result from another study-no matter with what kind of subject/sample, that directly stands AGAINST that of the main study. Right? IanStewart, you are right that choice E is an obvious weakener to the conclusion, but what's wrong with it? This fact can not prevent this choice from "determining the accuracy of the study described above"? Not only it's not prevented but also weakening the results, and determining the accuracy of the results of a study are two concepts so close to each other. If we can weaken a conclusion, the perceived accuracy will be decreased.

The golden point is this: Look at the stem again; it says: A recent study of college students shows that, contrary to predicted results, special nutritional planning does not positively affect STUDENT'S grades. The counterargument (what we are to determine the accuracy of the results of a study against it) is about students' performance in general, NOT just performance of COLLEGE students. So a hypothesis about any kind of STUDENTS' performance can be tested by studying ANY KIND of students.

In sum, my choice is D. Though both D and E aim at accuracy of the conclusion, while E focuses on the defects of methodology, D focuses on the DIRECT opposite results found from another VALID study. Do not forget the point: we are talking about a conclusion about ALL students.

What is the source of this question?
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A recent study of college students shows that, contrary to  [#permalink]

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05 Aug 2012, 21:30
Actually, there is no ambiguity in the question.

What was the study? 60 students were put on nutritious diet. 60 were not.
What was the result? The 60 students who were put on nutritious diet did not have higher grades than other 60.
What did they conclude? Special nutritional planning does not positively affect students’ grades.

Now, we need to evaluate the accuracy of the study. What will help us figure out whether what we concluded from the study is valid or not?
Because 60 students with diet plans did not get better grades, can we say nutrition does not have any positive affect on grades? Perhaps not. What if nutrition can improve low grades (by giving students more energy and making them more active) and bring them up to average (but not improve average to take them to above average since they need to work hard too)? If this were true, the conclusion of the study would not be valid. Special nutritional planning WOULD have a positive affect on students’ grades. "If grades were low, they could become better by nutritional planning"
Hence option (D) is useful in determining the accuracy of the study.

As for other options, focus on what was concluded from the study. Are they relevant to the conclusion "Special nutritional planning does not positively affect students’ grades."?

(A) Performance of business executives was shown to improve drastically after major alterations were made in their diets.

(B) Honors students, after altering their diets, maintained that they did not change their study habits.
Students saying that they did not alter their diet doesn't mean anything. It is true that they said it but did they actually maintain their study habit or not, we don't know. So not relevant. No need to think further.

(C) Students who participated in various fitness regimens found that their grades improved appreciably after they altered their exercise habits.
Nothing to do with fitness regime and grades. Only food and grades connection is our concern.

(E) All of the college students who volunteered for the study were either in their first or second year of college.
Again, not relevant.
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Re: A recent study of college students shows that, contrary to  [#permalink]

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06 Jul 2014, 22:15
HarishLearner wrote:
Wouldn't the fact that Honors' students did not change their study habits remove any bias that might occur? For example if you took the diet and studied well, then the results could have been due to study habits rather than diet. So we need to know this.

We need to find the option that is MOST helpful in determining the accuracy of the study.

The study says "special nutritional planning does not positively affect students’ grades"

(D) says "High school students who previously had low grades found that after they altered their diets, their grades improved dramatically."

This is directly against the result of the study. It implies that the study is not accurate.

Option (B) talks about honors students. We do not know how many students in the study were honors students. So we don't know how relevant this information is to our study.

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Re: A recent study of college students shows that, contrary to  [#permalink]

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21 Jul 2014, 23:38
dennis14 wrote:
I dont know why everybody is discussing B and D.

I think we should discuss D and E here.

I think D is useful to determine accuracy however E as well is needed to udnerstand that the sample of students are similar. They are not highest rankers in the class. Top of the top.

So im torn between D and E.

Or the question is incorrect.

(E) only tells you that they are 1st or 2nd year students, not 3rd or 4th year. How does that affect your study? Half of them are getting balanced diet and half are not. Even if they were 3rd and 4th year students, why would we challenge the results of the study?
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Re: A recent study of college students shows that, contrary to  [#permalink]

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22 Aug 2016, 09:44
A recent study of college students shows that, contrary to predicted results, special nutritional planning does not positively affect students’ grades. Sixty students, half of whom were given a nutritionally balanced diet, had grades no higher than did those students who were not placed on the diet plan.

X = special nutritional planning

X not related positively to students’ grades.

60 students => 30 on diet plan + 30 not on diet plan
Grades were similar after the experiment. so does that mean there is no increase on grades at all.What if grades were lower for "before the experiment" for diet plan group.

Which of the following, if true, is most useful in determining the accuracy of the study described above?

(B) Honors students, after altering their diets, maintained that they did not change their study habits.

(D) High school students who previously had low grades found that after they altered their diets, their grades improved dramatically.

Both seems sketchy to me. But D can't be OA for sure.

(D) High school students who previously had low grades found that after they altered their diets, their grades improved dramatically. :- Altered diet doesn't mean they started taking "Nutritional diet". Whatever doesn't concern Nutritional diet is out of the question. Second, High school student? we are only concentrating on "students in experiment". That's it.

We have to provide certain information that shows whether Nutritional diet has any effect on the grades or not.

B is saying they donot change their study habits. So?? How does that matter? Does that tell us Nutritional diet have any effect? Hence, Incorrect.

D is somehow weakening the conclusion by providing some information on change in diet plan and its effect on grades. hence, D is the correct answer.
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Re: A recent study of college students shows that, contrary to  [#permalink]

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22 Aug 2016, 15:08
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Part of what makes this an unfair question is the phrasing of the sentence "Sixty students, half of whom were given a nutritionally balanced diet, had grades no higher than did those students who were not placed on the diet plan." Is it saying that there was a group of 60 students who all volunteered for the study, half of the volunteers received a nutritious diet, but all 60 (regardless of diet) had higher grades than students who weren't involved in the study? Or is it saying that of the 60 students who volunteered for the study, the half who were given a nutritious diet had the same grades as the half who didn't?

Even though the first reading seems illogical, it's what the sentence is saying, grammatically! But if the second reading is what's intended, I can understand why (E) isn't correct. If every student who volunteered for the study was in the first or second year, including both the students who were given a nutritious diet and the students who weren't, then the result could still be valid. It's not extensible to the entire college population (maybe, for some weird reason, nutrition only affects older students and not younger ones?) but it's still valid, because it's comparing two comparable groups.

(D) is certainly wrong by GMAT standards too, though. The GMAT doesn't accept answers that require that you assume that one group of people is the same as another group of people, without proving it. The argument would have to show that high school students are physiologically the same as college students, for (D) to stand a chance.
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23 Aug 2016, 11:25
Study habits is related to grades. The red alert here is "Honor students" that is out of our scope, which is limited to students in Experiment. If this option is properly phrased as : Sixty students, half of whom were given a nutritionally balanced diet, had changed their study habits. They are spending less amount of time. This is still not providing information if they got better or worse. But still it provides some information that their is some differentiation other than nutrition factor that can explain why half of whom were given a nutritionally balanced diet, had grades no higher than did those students who were not placed on the diet plan.

Remember, we don't have to break the argument here or find another reason.

We just to find out something that proves that the argument is inaccurate or something that proves that the argument is accurate.

So, D here clearly tells that this happened somewhere else and that proves the argument accurate.
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