谨请注意！！去年5月的CR-JJ, 今年好像也已出现，但还没好好讨论...

xinfaxian

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 having 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

晕！ 我选A, 各位呢？

[此贴子已经被作者于2005-5-17 9:42:49编辑过]

dashasha

选B啊。B的意思就是那两个误诊不碍事啊。

questionmark

支持B

xinfaxian

如果B 对，那C 呢？意思不是基本一样吗？

xinfaxian

是不是我钻牛角尖啊？

我是这样理解A的，

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

被正确诊断为没有阑尾炎的人是那些根本不严重的病人→这不就是在说，被诊断为有阑尾炎的人是那些真正严重的人，也就是说是需要手术的人。

所以，A 解释了2者，即减少了不必要切除手术病例，但又没有减少由必要的病例。（Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before）

而，B, C都只是解释了一个方面，without performing any fewer necessary ones than before。没有解释doctors can largely avoid unnecessary removals of the appendix 呀？

我是转弯转的太多吗？有没有那位N 人帮忙疏通一下？

真的有点郁闷......

xinfaxian

怎么没有人回帖呢？？？

wwwhahchn

B说被误诊的都是没得病的被诊断为得病，再加上题目给出的条件，其他98%（高于原来的80%）都是正确诊断，这样就可以推出“unnecessary removals的几率下降，同时necessary ones的几率又没有变少”

举个例子，100个人去看病，实际情况是50个人得病，50个人没得病。

原来的情况：80个人是正确诊断，20个人是unnecessarily performed surgery，也就是得病的50个人都被诊断为得病，没得病的50个人有30个被诊断为没得病，还有20个被诊断为得病了。

现在的情况：98个人是正确诊断，2个人是错误诊断，如果按照B说的，2个人是没得病的却被诊断为得病，那就是说得病的50个人都被诊断为得病，没得病的50个有48个被诊断为没得病，还有2个被诊断为得病了。

这样不就是

(1)largely avoid unnecessary removals of the appendix（从20到2）

(2)without performing any fewer necessary ones than before（从50到50，没有变少）

A只说了正确诊断的情况

C说被诊断为得病的人确实得病，但是没说被诊断为没得病的人是否得了病，所以不能判断necessary ones的几率是否变少

xinfaxian

哦.........原来是这样理解的。

我一直以为unecessary removals 指得范围是你所举例的那80个被确诊的人里面，而不是100个人里。

也就是说如果是80个人里出现unecessary removals 的话，就一定要考虑病的严重不严重的问题了对不对呀？有如A的回答，对吗？我也觉得奇怪，怎么会这么想的，题干里从来没有这么说过呀。。。看来还是我钻牛角尖了

谢谢wwwhahchn mm  

xinfaxian

不好意思，再问一个非常菜鸟的问题：

现在的情况：98个人是正确诊断，2个人是错误诊断，如果按照B说的，2个人是没得病的却被诊断为得病，那就是说得病的50个人都被诊断为得病，没得病的50个有48个被诊断为没得病，还有2个被诊断为得病了。→→→这样，如果这两个也会被手术的话，还是有2个unnecessary removals?   原来是20个，只不过现在是2个。不过题目说largely avoid...所以这是所允许的范围吗？可以这样理解吗？

wwwhahchn

就是这样滴