GWD21-Q4 求解

luting0616

Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal;consequently, patients with symptoms strongly suggesting appendicitis almostalways have their appendix removed.  Theappropriate surgery is low-risk but performed unnecessarily in about 20 percentof all cases.  A newly developed internalscan for appendicitis is highly accurate, producing two misdiagnoses for every98 correct diagnoses.  Clearly, usingthis test, doctors can largely avoid unnecessary removals of the appendixwithout, however, performing any fewer necessary ones than before, since______.

A.   the patients who are correctly diagnosedwith this test as not having appendicitis invariably have medical conditionsthat are much less serious than appendicitis

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

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

D.   every patient who is diagnosedwith this test as having appendicitis has more than one of the symptomsgenerally associated with appendicitis

E.    the only patients who are misdiagnosedusing this test are patients who lack one or more of the symptoms that aregenerally associated with appendicitis

看到讨论的有B也有C的 到底答案应该是哪个

我的答案里显示的是B 但是想不明白为什么，求详解啊

alzn2765

每天限答两题，恭喜中奖。

这题就是一个数学题。

因果推理找加强
前提（因）：新的检测方法误诊率是2%
结论（果）：使用新方法可以在不减少应该做手术的情况的前提下，减少不必要的阑尾切除手术的数量。

以前是100%的病人医生都建议割了算了（不管是有必要割还是没有必要割），这样应该做手术而没有做的病例是0（完全没有漏网之鱼，都TM割了）。
现在的方法会有2%的误诊，同时还要满足“不减少应该做手术而没有做的情况”，这个情况以前是0。所以，为了让结论成立，我们必须保证那2%的误诊病人必须是“没得阑尾炎，但是做了手术的”。这就是B选项的内容。也就是新方法会让2%没得阑尾炎的病人“不幸的”被割阑尾，但是更之前20%相比，还是有巨大进步的，同时这个新方法保证所有得了阑尾炎的病人都会进行阑尾切除术（这个才是最重要的）。不管医院用哪个方法，这个方法必须是可以把不应该割的割掉（割健康阑尾对病人不会有大影响），但一定不能把应该割的没割，这是会出大事情的医疗事故啊！

C等于就是一句废话，完全起不到加强结论的作用

luting0616

alzn2765 发表于 2015-11-1 20:01
每天限答两题，恭喜中奖。

这题就是一个数学题。

明白了 谢谢