Half of the subjects in an experiment—the experimental group—consumed

Question

Half of the subjects in an experiment—the experimental group—consumed large quantities of a popular artificial sweetener. Afterward, this group showed lower cognitive abilities than did the other half of the subjects—the control group—who did not consume the sweetener. The detrimental effects were attributed to an amino acid that is one of the sweetener's principal constituents.

Which of the following, if true, would best support the conclusion that some ingredient of the sweetener was responsible for the experimental results?

Which of the following, if true, would best support the conclusion that some ingredient of the sweetener was responsible for the experimental results?

A. Most consumers of the sweetener do not consume as much of it as the experimental group members did.

B. The amino acid referred to in the conclusion is a component of all proteins, some of which must be consumed for adequate nutrition.

C. The quantity of the sweetener consumed by individuals in the experimental group is considered safe by federal food regulators.

D. The two groups of subjects were evenly matched with regard to cognitive abilities prior to the experiment.

E. A second experiment in which subjects consumed large quantities of the sweetener lacked a control group of subjects who were not given the sweetener.

"Half of the subjects in an experiment" Resolve Paradox Question

Salsanousi · Answer

Here we have two different groups, experimental and control group. In general we want the two groups to be comparable in order to test for a certain hypothesis.

How can we make them comparable? by making sure they are evenly matched.

Answer choice D.

dabaobao · Answer

Solution:

Type: Cause (Consuming sweetener with amino acids) & Effect (lower cognitive abilities)

A. Most consumers of the sweetener do not consume as much of it as the experimental group members did.  Irrelevant

B. The amino acid referred to in the conclusion is a component of all proteins, some of which must be consumed for adequate nutrition.  Irrelevant

C. The quantity of the sweetener consumed by individuals in the experimental group is considered safe by federal food regulators.  Irrelevant

D. The two groups of subjects were evenly matched with regard to cognitive abilities prior to the experiment.  Correct: No alternate cause

E. A second experiment in which subjects consumed large quantities of the sweetener lacked a control group of subjects who were not given the sweetener.  Irrelevant

haithamnimer · Answer

Conclusion:

The detrimental effects were attributed to an amino acid that is one of the sweetener's principal constituents.
Why? Because people who consume the sweetener, their cognitive abilities are lower than people who did not consume any sweetener.

However, in order to strengthen the argument, one point should indicate that before eating the sweetener, both groups have the same abilities, in order to conclude that the sweetener is the reason for lower the abilities!

Thus, below is the correct answer:

D. The two groups of subjects were evenly matched with regard to cognitive abilities prior to the experiment.

mohitwadhwa28 · Answer

Hi Experts,

I am getting confused with question asked and the explanation given for the right answer choice.

The question is: " Which of the following, if true, would best support the conclusion that some ingredient of the sweetener was responsible for the experimental results?"

So it is ideally asking to find a reason that some ingredient was responsible for the results.

However, the answer choice D says,  "The two groups of subjects were evenly matched with regard to cognitive abilities prior to the experiment. " : that shows there wasn't any biasing with respect to the experiment. But how can it prove that some ingredient was responsible for the results?

Could you please correct me if I am wrong in my understanding?

AlexTheTrainer · Answer

You are correct in your assertion that D does not prove the conclusion to be true. But the question is not asking for something that proves the conclusion to be true - it merely asks for something that strengthens the conclusion. That is, something that makes the conclusion more likely to be true.

D eliminates an alternative explanation for the evidence/premises. If the study had been poorly constructed, this would explain the resulting evidence, thus weakening the original conclusion (explanation).

Since D indicates that the study was properly constructed, the possibility of a poorly constructed study explaining the resulting evidence is eliminated.

Again, this does not prove the conclusion to be true. D does however create a stronger argument.

Posted from my mobile device

mohitwadhwa28 · Answer

Hi Alex,

Thanks for your detailed response.

Yes, I got that the question is not asking for something that proves the conclusion to be true - it merely asks for something that strengthens the conclusion. However, option D just strengthen our belief on that the study was correct. Not sure how it increases our belief on that that some ingredient of the sweetener was responsible for the experimental results?

I do agree that remaining options are invalid in all sense.

AlexTheTrainer · Answer

Hello

Eliminating four wrong answers, without buying into the correct answer, is undoubtedly an essential skill for the GMAT. But that’s not your question.

You’re probably aware that evidence/premises are assumed to be true. But what exactly does this mean? In this case, we assume that the study produced the results claimed. Our belief isn’t a consideration. Of course, nothing is said about how the study was constructed.

What if previous to the study, those in the experimental group had much lower cognitive abilities than those in the control group? If that were the case, the study would be irrelevant to the conclusion.

Put another way, if those in the experimental group started with much lower cognitive abilities, this would be a legitimate (alternative) explanation for the results from the study, thus weakening the original conclusion.

Demonstrating that evidence is irrelevant and/or providing an alternative explanation weakens an argument.

Thus, demonstrating that evidence is more relevant and/or eliminating an alternative explanation strengthens an argument. D does both.

................

On a final note: strengthen and weaken questions engage in a strange form of logic with which a lot of folks aren’t familiar - Inductive Reasoning.

Inductive Reasoning is an evaluation process that labels arguments only as Strong or Weak and Cogent or Uncogent.

Cogency goes to the truth of the evidence, which is irrelevant for GMAT purposes.

A Strong argument is defined merely as evidence that leads to a conclusion that is probably true.

A Weak argument is defined merely as evidence that does not lead to a conclusion that is probably true.

These are all real academic definitions, by the way.

What exactly is meant by “Strong” and “Weak?” Good question...

brains · Answer

Half of the subjects in an experiment—the experimental group—consumed large quantities of a popular artificial sweetener. Afterward, this group showed lower cognitive abilities than did the other half of the subjects—the control group—who did not consume the sweetener. The detrimental effects were attributed to an amino acid that is one of the sweetener's principal constituents.

Which of the following, if true, would best support the conclusion that some ingredient of the sweetener was responsible for the experimental results?

Which of the following, if true, would best support the conclusion that some ingredient of the sweetener was responsible for the experimental results?

A. Most consumers of the sweetener do not consume as much of it as the experimental group members did.

B. The amino acid referred to in the conclusion is a component of all proteins, some of which must be consumed for adequate nutrition.

C. The quantity of the sweetener consumed by individuals in the experimental group is considered safe by federal food regulators.

D. The two groups of subjects were evenly matched with regard to cognitive abilities prior to the experiment.

E. A second experiment in which subjects consumed large quantities of the sweetener lacked a control group of subjects who were not given the sweetener.

MartyTargetTestPrep ,  VeritasKarishma

What is the impact of C on the argument? C says that the quantity consumed is considered safe by regulators. Earlier i thought that if the quantity consumed is safe then why are the amino acids affecting cognitive ability.? It could be the fact that quantity consumed is safe but amount of amino acids consumed in the same quantity is too high to consume . Am i wrong here.? When they say that quantity consumed is safe, does it mean that amino acid proportion consumed is also safe for them?

Can you tell specifically how it impact my conclusion. Does it weaken or does it have no impact at all? If weakens then how it weakens.

Sorry for bothering with too many posts lately

MartyTargetTestPrep · Answer

Here, highlighted in blue, is what you are saying (C) says:

Earlier i thought that if  the quantity consumed is safe  then why are the amino acids affecting cognitive ability.? It could be  the fact that quantity consumed is safe  but amount of amino acids consumed in the same quantity is too high to consume . Am i wrong here.? When they say that  quantity consumed is safe , does it mean that amino acid proportion consumed is also safe for them?

Here's what (C) actually says:

C.  The quantity  of the sweetener  consumed  by individuals in the experimental group  is considered safe by federal food regulators .

Do you see the key difference between what you are saying and what the answer choice says?

A key aspect of getting CR questions correct is being sure to be exact in our reading and thinking about what the passages and answer choices say.

The implications of  "the quantity consumed is safe"  and  "the quantity ... consumed ... is considered safe by federal food regulators"  are quite different.

In the context of this argument, the fact that regulators consider the quantity safe has very little impact. After all, the opinion of the regulators could be incorrect. So, the fact that they consider the quantity safe does not mean that the quantity is in fact safe, and the fact remains that the people who consumed that quantity of the sweetener showed lower cognitive abilities than were shown by the other half of the subjects.

At the same time, the fact that regulators consider the quantity safe is not 100 percent worthless. After all, in the real world, we might think, "If regulators consider that quantity safe, then maybe something else is going on." So, the fact that regulators consider that quantity safe is an extremely weak weakener, one that makes us wonder just the tiniest bit whether maybe there is another reason for the difference in cognitive abilities.

KarishmaB · Answer

Experiment had two groups:
One consumed large quantities of a popular artificial sweetener.
Other, the control group, did not consume the sweetener. 
The group that consumed showed lower cognitive abilities than did the other half of the subjects.

Conclusion: An amino acid that is one of the sweetener's principal constituents is responsible for the ill effects.

We need to strengthen the argument. We can do that by proving that the study was genuine. We can also do that by showing that amino acids are the ones that impact cognitive abilities etc.

A. Most consumers of the sweetener do not consume as much of it as the experimental group members did.
Consumers are irrelevant. The study is focussed on what happens when people consume a certain amount of the sweetener. How much actual consumers consume is irrelevant.

B. The amino acid referred to in the conclusion is a component of all proteins, some of which must be consumed for adequate nutrition.
Doesn't strengthen our argument for sure. Doesn't weaken it much either. The amino acid consumed naturally could be harmless due to the low amounts but could be harmful in the sweetener.

C. The quantity of the sweetener consumed by individuals in the experimental group is considered safe by federal food regulators.

brains  -
Couple of things here - "considered safe by federal food regulators" does not mean that it is safe. 
Also, what does safe mean? Perhaps it is considered safe if it doesn't kill you or doesn't have any long term detrimental impact but it could still cause some short term cognitive issues. 
In any case, even if these points were ignored, the option, if at all, would weaken the conclusion but we want to strengthen it. We want to say that the sweetener is not safe because of the amino acid. Hence, this option should be ignored.

D. The two groups of subjects were evenly matched with regard to cognitive abilities prior to the experiment.
Correct. This tells us that the two groups had similar cognitive abilities before the experiment. So ideally, they should have performed similarly in the test. But if one group performed worse in the cognitive test after consuming the sweetener, it does seem that the sweetener is responsible for the bad performance.

E. A second experiment in which subjects consumed large quantities of the sweetener lacked a control group of subjects who were not given the sweetener.
Doesn't impact our experiment and its conclusion.

Answer (D)

VerbalBot · Answer

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Half of the subjects in an experiment—the experimental group—consumed

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Half of the subjects in an experiment—the experimental group—consumed

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