Scientists have created double-blind studies so that neither the subje

Question

Scientists have created double-blind studies so that neither the subjects of the experiment nor scientists know whether the subject is receiving an actual drug or a placebo, which is nothing more than a sugar pill. Essentially, if one knows whether one is receiving actual medicine or a placebo, such knowledge can affect the outcome of a study. A recent double-blind study on the effectiveness of the Selective Serotonin Reuptake Inhibitor (SSRI) Freloxamine on depression found that those subjects administered the drug were 15% more likely to have a decrease in symptoms than the control group, which was comprised of those who received a placebo. Since neither group knew which they were receiving, the placebo or the SSRI, the observed drop in depression can only be attributed to Freloxamine.

Which of the following, if true, best calls into question the conclusion of the argument?

(A) Neither the subjects nor the doctors in either group (the control group or the Freloxamine group) knew which drug they were receiving.

(B) Since subjects in both groups were debriefed on the potential side effects of SSRI, which can often be pronounced, many in the Freloxamine group, upon exhibiting side effects, concluded that they were being administered the SSRI.

(C) Freloxamine does not exhibit a uniform effect in all subjects, with many reporting little improvement in symptoms of depression, even after several months of taking the drug.

(D) At dosages two-fold of those employed in the trial, Freloxamine has been shown to cause brief episodes of psychosis.

(E) One subject from the Freloxamine group experienced debilitating side effects and was forced to drop out of the trial before its completion.

Bunuel · Accepted Answer

Official Explanation:

The credited response is choice (B).  The argument states: if one knows whether one has received the actual drug or the sugar pill, that can influence the outcome of the study. The assumption of the experimental design is that no one knows this. But, if folks who get the real drug get side-effects, it won't be hard for them to figure out that they got the real drug, and folks who don't get any side-effects will deduce that they only got a sugar pill. Thus, subjects will know which kind of pill they received, and this knowledge will skew the results of the study.

Choice (A) reiterates the conditions of the design. This conforms to the assumptions of the experiment, so it doesn't call the experiment into question at all. Choice (A) is incorrect.

Choice (C) would account for why some people in the group that received the drug did not see a decrease in symptoms, but the argument does not depend on any kind of claim of universal effectiveness. It merely says that the folks who receive the drug were 15% more likely to show improvement than folks who receive the sugar pill. It is assumed that some people in each group were not helped. Choice (C) does not weaken the argument, so it is incorrect.

What might happen at dosage levels not employed in the experiment is irrelevant to the interpretation of the experiment. Choice (D) is irrelevant, so it is incorrect.

The results of the experiment concerns overall probabilities over a group of people. Scientist don't run studies like this on only, say, six people: this study likely has dozens, if not hundreds, of subjects --- such numbers would be far more typical. If one person had to drop out, that's unfortunate for that person, but that person simply would not be counted: this wouldn’t significantly change the probabilities of the group. Choice (E) is irrelevant and incorrect.

PyjamaScientist · Answer

As per the stimulus, the  secrecy of being administered  the drug or the placebo is  paramount . If the subjects  knew   what  they were being  administered , then the results would  not be attributed  solely to the  drug .

Hence,  option (B  )  is the correct option, as, it brings in a way through which the subjects were able to  "come to know"  that they were being " administered " the drug via the route of " side effects ", hence the drug  can not be  attributed to being the sole reason behind the observed results in the study.

Boho · Answer

Option (B) suggests that because of knowledge of side effects the results may have been biased.

(B) is my answer

vishalsinghvs08 · Answer

Can we discuss option C once?

Freloxamine does not exhibit a uniform effect in all subjects, with many reporting little improvement in symptoms of depression, even after several months of taking the drug.
--> This can mean that their are other aspects or factors thats working to make it 15% more likely for the patients to have reduced symptoms. The conclusion "observed drop in depression can  only  be attributed to Freloxamine" is not valid anymore.

Bunuel   GMATNinja   KarishmaB  - Can you please help?

KarishmaB · Answer

The argument already says that 15% were more likely to have a decrease in symptoms than the control group (which means that 85% were not).

Option (C) Freloxamine does not exhibit a uniform effect in all subjects, with many reporting little improvement in symptoms of depression, even after several months of taking the drug.

But we already know that. We are not given that all had a uniform reduction in symptoms. We know that the effect was not uniform with many not reporting much improvement. 
There could be other factors affecting the depression but those are common to all. Between the drug and the placebo groups, the only difference is Freloxamine and if there is a definite 15% reduction in the drug group, then it stands to reason that the decrease can be attributed to the drug.

Now if people getting the drug were to find out that they were getting the drug, then we cannot compare results and then the entire premise of double blind studies is lost. If people know that they are getting the drug, not just sugar, they may automatically start feeling better. Then the drug may not be responsible for the improvement.

Hence option (B) works.

VerbalBot · Answer

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Scientists have created double-blind studies so that neither the subje

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