Question from GMAC GMAT Review 11th Edition

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Question from GMAC GMAT Review 11th Edition

by pranavc » Sat May 31, 2008 11:45 am
Hi All,
I am really stuck on the following question below:

In tests for pironoma, a serious disease, a false positive result indicates that people have pironoma when, in fact, they do not; a false negative result indicates that people do not have pironoma when, in fact, they do. To detect pironoma most accurately, physicians should use the laboratory test that has the lowest proportion of false positive results.

Which of the following, if true, gives the most support to the recommendation above?

(A) The accepted treatment for pironoma does not have damaging side effects.

(B) The laboratory test that has the lowest proportion of false positive results causes the same minor side effects as do the other laboratory tests used to detect pironoma.

(C) In treating pironoma patients, it is essential to begin treatment as early as possible, since even a week of delay can result in loss of life.

(D) The proportion of inconclusive test results is equal for all laboratory tests used to detect pironoma.

(E) All laboratory tests to detect pironoma have the same proportion of false negative results.

At first glance, this looked like an easy question but based on the answer and its rather convoluted explanation, I am not too sure anymore. Any input would be appreciated. Thanks in advance,

Regards,

Pranav
Source: — Critical Reasoning |

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by chidcguy » Sat May 31, 2008 12:06 pm
Look at the conclusion. physicians should use the laboratory test that has the lowest proportion of false positive results.

So what happened to the false negative results. In other words the conclusion is ignoring the impact of false negative results. When will this happen? Some instances are

(1) these days the tests do not have any false negatives at all. So pick the one with lowest false positives.

(2) all the tests have same/similar number of false negatives but some have low & high false positives. Then also pick the one with lowest false positives makes sense.

E mirrors the (2) thought and hence my answer is E.

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by pranavc » Sat May 31, 2008 12:56 pm
Breaking it down into two parts like you did clarifies things. I guess the focus is on "lowest false positives" and not just false positives. That puts things in perspective. Thanks a lot.

Regards,

Pranav

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by wawatan » Sat May 31, 2008 1:09 pm
i know e is a better answer but can someone explain why d is incorrect?

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by chidcguy » Sat May 31, 2008 4:32 pm
(D) The proportion of inconclusive test results is equal for all laboratory tests used to detect pironoma.

The key word trap D uses is proportion. inconclusive test result?? Wait a sec. There is nothing like inconclusive test result in the stimulus. That makes it out of scope. Not only it is out of scope, but also it does not add any more information to strengthen the conclusion that only tests false positives should be used to determine P.

We can strengthen an argument

by adding more evidence or by substantiating an underlying assumption.

(E) adds more evidence

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by airan » Tue Jun 03, 2008 6:49 am
Why cant it be B ? B states it clearly.
Thanks
Airan

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by khanshainur » Tue May 10, 2016 4:20 am
i would go with option E