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Appendicitis (inflammation of the appendix) is potentially fatal; cons

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Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post Updated on: 27 Aug 2018, 04:20
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Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since .


A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis

B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis

D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis

E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that are generally associated with appendicitis

Can someone also explain what does the last line mean?

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Originally posted by GMBA85 on 30 Sep 2008, 06:48.
Last edited by Bunuel on 27 Aug 2018, 04:20, edited 3 times in total.
Edited the question.
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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 13 Nov 2014, 02:49
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I read this in other forum and it help me understand better the solution. See if helps anyone:

"Complete the passage questions are like inference questions. You will most likely have to put in the correct conclusion or else (as here) a correct piece of evidence that would logically support the conclusion. As with other inference questions, the best approach is to follow the gist of the passage, make a deduction and scan for a match.

Here, the author is arguing that the scan will obviate the need for surgeons to perform unnecessary appendectomies. Really? Let's examine what we have learned about the scan: the misdiagnosis rate is 2%. But are the misdiagnoses false positives or false negatives? A false positive is where the scan says you have appendictis when you don't while a false negative is when the scan fails to pick up that a patient has appendictis when in fact they do. False positives are not risky here b/c if a person who doesn't have appendictis gets his/her appendix removed, its no big deal. On the other hand, false negatives are very risky b/c if a person who has appendicitis doesn't get his/her appendix removed, then they may die. So, in order for the author's conclusion to be correct, the kind of misdiagnoses the scan makes must be false positives and not false negatives. That would be the piece of evidence that would support the conclusion (we know we want to put in some evidence here b/c the passage ends with "since'). That is our deduction, and now we scan for a match....choice B."

-> I think the statement we need to fill is a piece of information that will guarantee that they will perform "ALL THE NECESSARY" operations, in this case even when is a misdiagnoses. I think C does not clear that as well as B. C lives room to ask "what about the misdiagnoses?"

Hope it helps!
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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 30 Sep 2008, 18:17
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B for meIf you overdiagnose cases, you will end up doing more than required surgeries but you will not miss any necessary ones. This is a case of false-positives. False-positives are always better than false-negatives. This way you will not miss any true-positive cases.
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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 03 Oct 2008, 15:02
1
GMBA85 wrote:
Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with
symptoms strongly suggesting appendicitis almost have their appendix removed. The
appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A
newly developed internal scan for appendicitis is highly accurate, producing two
misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid
unnecessary removals of the appendix without, however, performing any fewer necessary
ones than before, since .

A. the patients who are correctly diagnosed with this test as not having appendicitis
invariably have medical conditions that are much less serious than appendicitis

B. the misdiagnoses produced by this test are always instances of attributing appendicitis
to someone who does not, in fact, have it

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact,
have appendicitis

D. every patient who is diagnosed with this test as having appendicitis has more than one
of the symptoms generally associated with appendicitis

E. the only patients who are misdiagnosed using this test are patients who lack one or
more of the symptoms that are generally associated with appendicitis

Can someone also explain what does the last line mean?

Should be (B)

Say 80 out of 100 cases were correctly diagnosed per the previous surgery. Using the new scan, how would you ensure that the 80 surgeries that were previously diagnosed correctly will continue to be accurately detected? This is possible only when the new scan detects 98 surgeries that are correct (AND INCLUDES the 80 correct ones from the earlier surgery) and perhaps misdiagnoses 2 (that are essentially false positives). It is essential that these 2 be false positives, as the new scan should not leave out any real cases that were correctly identified before.
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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 11 May 2010, 10:06
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B.

The answer seems obvious when you rephrase the last sentence of the question as: new tech lowers instances of false positive but does not lower those of real positive since____

Answer: the misdiagnosis is always false positive instead of false negative.
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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 02 Apr 2012, 00:23
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Basically the info that fills the blank is the one that suggests why in spite of using the internal scan the number of surgery performed will not decrease. We need some information regarding the misdiagnosed case. B fills the gap saying the misdiagnosed cases are infact not the misdiagnosed ones; they actually dont have appendicitis. hence the number actually infected is not reduced and hence the necessary removals will not decrease.

Hence B.

Hope this helps..!!
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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 11 May 2012, 14:00
2
It is a really tough question.

I initially picked C but after reading other people's opinions, realized that the correct answer must be B.
My understanding is like this. Feel free to point out any flaws.

Before a newly developed internal scan, the surgery was performed unneccessarily in about 20 percent.
(We can say from this statement that of the patients who underwent this surgery, 20 percents didn't actually have Appendictis. I can assume that those unneccessary surgery were caused by misdiagnoses.)

The newly developed internal scan lowered the chance of misdiagnoses.

This newly developed internal scan enables doctors to avoid unnecessary surgery but doesn't lower the number od incidents that patients who need the surgery don't get the surgery.

As people say, misdisgnoses have two cases. 1. actually have one but diagnoed as not having
2. actually don't have one but diagnosed as having.

In the case 1, patients need the surgery but don't get it.
In the case 2, patients don't need the surgery but get it.

If misdiagnoses with the newly developed internal scan is only case 2, unneccessary surgery can be reduced because the number of misdiagonoses is decreased while neccessary sugery is not decreased.
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Re: Which is the right ansvver for this one  [#permalink]

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New post 26 Jul 2012, 04:01
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B. the misdiagnoses produced by this test are always instances of attributing appendicitis to
someone who does not, in fact, have it

The new machine diagnoses that someone doesn't have appendicitis with appendicitis and so ,it's doesn't causes any risk (removal is easy and eventually harmless for people)

(B) WINS


The following link can be useful- explanation by testluv is exemplary.
http://www.beatthegmat.com/logically-co ... 49564.html
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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 09 Sep 2014, 09:43
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Just to be sure - The OA is B) and the question is part of GMATPrep Exam Pack 1 - Mock 3

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since _____ .

Basically, the doctors can reduce the unnecessary operations but cannot avoid the necessary operations, using the new test. So, misdiagnosis is always shows Positive for negative cases or false negative cases. If it is the other way around, the false positive cases, the doctors will be performing more necessary removals.

A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis
- OFS as we are not talking about other medical conditions

B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it
Correct as mentioned above

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact,have appendicitis
It doesn't say about the misdiagnosis. If the misdiagnosis is false positive, that will increase the necessary removals

D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis
We are not talking about the symptoms associated with appendicities

E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that are generally associated with appendicitis
It doesn't explain why unnecessary removals can be done by the doctors
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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 15 Sep 2015, 23:27
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1) Appendicitis is potentially fatal
2) 20% surgeries are unnecessary
3) New scan detects 98% cases correctly
4) => It leaves out 2% cases
5) Argument says that it is still OK to use and will still ensure that doctors won't skip surgery where it is needed.

This has to be based on the fact that 2% are always false positives (don't have appendicitis, but are detected as having it) rather than false negatives (have appendicitis, but not detected). This is because, if 2% are false negatives, these will potentially cause deaths. However if these are false positives, maybe 2% patients will have it removed when they didn't need to, but this is still better than 20% unnecessary surgeries, and as the surgery is safe, there is no hazard to these 2%.

So, (B) is correct.

Prajat wrote:
Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since .......

Which of the following logically completes the passage?

A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis
B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it
C. all of the patients who are diagnosed with this test as having appendicitis do, in fact,have appendicitis
D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis
E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that are generally associated with appendicitis

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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 15 Jan 2016, 00:49
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Imagine there were 100 patients earlier out of whom 80 had appendicitis and 20 didn’t. But all 100 were given surgery (although only 80 were necessary and 20 were not necessary).

With the test that is 98% accurate, there are 2 extreme possibilities:

Case 1:

80 people have appendicitis; the test says all 80 have it.
20 people don’t have appendicitis; the test says 18 don’t have it and 2 have it. In this case 18 out of 20 unnecessary will be avoided and the doctors will still perform 82 surgeries (more than the necessary number 80). So this satisfies all the conditions. This case will be obtained when someone who doesn’t have appendicitis is diagnosed to have it. Option B says the same.

Case 2:

20 people don’t have appendicitis; the test says all 20 don’t have it.
80 people have appendicitis; the test says 78 have it and 2 don’t have it. In this case 2 necessary ones will also be avoided. The doctors will perform 78 surgeries (fewer than the necessary number 80). So this doesn’t satisfy any condition.

In a test, a false positive refers to a diagnosis that mistakenly indicates that a condition, disease or infection is present. A false negative refers to a diagnosis that mistakenly indicates that a disease, infection or condition is absent. A false positive result from a doping test could ruin the career of an honest cyclist. A false negative result on a paternity test could prevent a father and son from reuniting.

Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix (eliminate false positives) without, however, performing any fewer necessary ones than before (i.e. without producing more false negatives), since .....

It seems clear that before this test was developed, doctors removed the appendix of everybody who either had appendicitis or seemed to have it (false positives).

This test has an accuracy rate of 98%, but in order for the conclusion to be true, these few mistakes must involve cases in which people without appendicitis are deemed to have it (false positives) , not the other way around. In other words, these mistakes cannot involve genuine cases of appendicitis that are classified as having nothing to do with appendicitis (false negatives), or else doctors would be performing newer necessary operations (i.e. operations on appendicitis patients) than before.

The part in bold basically means that, with the test, they'll still perform the same number of necessary operations (as they used to). In other words, they'll catch people who have appendicitis just as much as they used to.

To complete this argument we need to find some evidence that supports the conclusion (notice the keyword "since").

How can we support the conclusion that they'll catch just as many people who have appendicitis as they used to?
Well, if the 2% error rate is exclusively due to the test saying you have appendicitis when you don't (rather than not catching your appendicitis), then the author's argument is supported (since the error rate without the test is 20%)...that's essentially what choice B says.

If the 2% error rate were due to the test not catching your appendicitis, then the author's conclusion that the test would decrease the number of unnecessary operations is clearly weakened: the test would be decreasing the number of NECESSARY operations--clearly a bad outcome. Because the denial of choice B hurts the argument, choice B must be evidence that supports the argument.

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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 20 Jul 2016, 04:12
eybrj2 wrote:
Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with
symptoms strongly suggesting appendicitis almost have their appendix removed. The
appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A
newly developed internal scan for appendicitis is highly accurate, producing two
misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid
unnecessary removals of the appendix without, however, performing any fewer necessary
ones than before, since .

A. the patients who are correctly diagnosed with this test as not having appendicitis
invariably have medical conditions that are much less serious than appendicitis

B. the misdiagnoses produced by this test are always instances of attributing appendicitis
to someone who does not, in fact, have it

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact,
have appendicitis

D. every patient who is diagnosed with this test as having appendicitis has more than one
of the symptoms generally associated with appendicitis

E. the only patients who are misdiagnosed using this test are patients who lack one or
more of the symptoms that are generally associated with appendicitis


Can someone explain why 'C' is wrong
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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 20 Jul 2016, 12:59
1
smartguy595 wrote:
eybrj2 wrote:
Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with
symptoms strongly suggesting appendicitis almost have their appendix removed. The
appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A
newly developed internal scan for appendicitis is highly accurate, producing two
misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid
unnecessary removals of the appendix without, however, performing any fewer necessary
ones than before, since .

A. the patients who are correctly diagnosed with this test as not having appendicitis
invariably have medical conditions that are much less serious than appendicitis

B. the misdiagnoses produced by this test are always instances of attributing appendicitis
to someone who does not, in fact, have it

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact,
have appendicitis

D. every patient who is diagnosed with this test as having appendicitis has more than one
of the symptoms generally associated with appendicitis

E. the only patients who are misdiagnosed using this test are patients who lack one or
more of the symptoms that are generally associated with appendicitis


Can someone explain why 'C' is wrong


The passage ends with "since". Therefore a reason is required why the number of surgeries will go down (while the number of necessary surgeries will NOT go down).

Option C states that at present the diagnosed patients do all have appendicitis, that is there no wrong diagnosis for those who are actually positive. In future also there will be no wrong diagnosis for these actually positive patients. Therefore this is not the reason that the number of surgeries will go down.

If in future there are wrong diagnoses for these actually positive patients, (the positive patients will then be diagnosed as negative, i.e. not having appendicitis), then the number of surgeries will go down, but there is no indication that the new test will be carrying out such misdiagnoses. Hence C cannot be the answer.
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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 17 Sep 2016, 08:33
Hi,
I know this CR question from prep has been discussed.

"Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost always have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since ____________. "

"A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis

B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis

D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms
generally associated with appendicitis

E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that
are generally associated with appendicitis "


However, I am quite confused b/w B and E.
Kindly note that I new to this forum,So pretty unsure about the posting rules.

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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 17 Sep 2016, 09:26
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abhishek03050 wrote:
Hi,
I know this CR question from prep has been discussed.

"Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost always have their appendix removed. The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases. A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses. Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since ____________. "

"A. the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis

B. the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it

C. all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis

D. every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms
generally associated with appendicitis

E. the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that
are generally associated with appendicitis "


However, I am quite confused b/w B and E.
Kindly note that I new to this forum,So pretty unsure about the posting rules.

Reagrds,
Abhishek Sinha


There is no need to open a new topic - just add your comment in the previous thread. For this one, I have merged your new topic with the previous one.

Coming to your query:

Misdiagnosis can be of two types:
False positive: A person who does not have appendicitis is identified as having appendicitis.... this leads to unnecessary operation.
False negative: A person who has appendicitis is identified as not having appendicitis.... this leads to faulty release of the patient without operation.

Option B implies that the misdiagnoses are always "false positive" type. There is no chance of getting a "false negative", i.e. there are 2% false positive misdiagnoses and 0% false negative misdiagnosis.

The latter implies that there is no way that that a person who has appendicitis is identified as not having appendicitis. Hence necessary operations are not going to be reduced, since the test does not produce a single case of "false negative".

On the other hand because the test is 98% accurate (only 2% "false positive" misdiagnosis), there will be drastic reduction of unnecessary operations (though they cannot be eliminated altogether).
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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 07 Apr 2018, 19:56
Hi Experts / sayantanc2k / VeritasPrepKarishma

Though I understand the solution, I am not too sure about choice C.

In my opinion choice C weakens the conclusion. If all the patients with append. do have app., then that would mean there are no patients who don't have append. but are diagnosed with append. But we are also told that 2% misdiagnosis is there. So this would mean that 2% cases would be of the patients who have append. but the tool misdiagnosed them. This would result in fewer surgeries than the necessary ones, and hence would not support the conclusion. Is my reasoning correct? Thanks very much!

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Re: Appendicitis (inflammation of the appendix) is potentially fatal; cons  [#permalink]

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New post 08 Apr 2018, 18:32
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sdlife wrote:
Hi Experts / sayantanc2k / VeritasPrepKarishma

Though I understand the solution, I am not too sure about choice C.

In my opinion choice C weakens the conclusion. If all the patients with append. do have app., then that would mean there are no patients who don't have append. but are diagnosed with append. But we are also told that 2% misdiagnosis is there. So this would mean that 2% cases would be of the patients who have append. but the tool misdiagnosed them. This would result in fewer surgeries than the necessary ones, and hence would not support the conclusion. Is my reasoning correct? Thanks very much!

SD

Quote:
C. all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis

Choice (C) tells us that everyone who tests positive actually does have appendicitis. That means that the 2% comes from people who test negative. Most of those people probably do not have appendicitis, but there will be some people who test negative even though they have appendicitis.

Yes, this would result in fewer surgeries, but it would also mean that NECESSARY surgeries would not be performed. Say that five people test negative even though they have appendicitis. Obviously those people need the surgery to avoid potentially fatal consequences. But they won't get the surgery because they tested negative.

So the number of NECESSARY surgeries is likely to decrease... very bad news for the people in that 2% and, more importantly, it goes against the portion in bold:

Quote:
Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before

I hope that helps!
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Re: Which of the following most logically completes the passage?  [#permalink]

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New post 06 Sep 2018, 09:21
Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
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April 2018: New Forum dedicated to Verbal Strategies, Guides, and Resources

GMAT Club Bot
Re: Which of the following most logically completes the passage? &nbs [#permalink] 06 Sep 2018, 09:21
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