V2

　　Medical diagnostic Screen Test 医学界有一部分学者一直强调Medical diagnostic screen test 的重要性。这种screen test就是定期对一大群并没有任何症状的人进行检查。通过这样普遍性的screen test，如果有发现问题可以尽早得出解决办法(pre-exempt treatment)。然而也有人说这种方法的是一种浪费。首先，这样大规模的检查是很昂贵的。再说了，早期诊断出病症和能够治疗病症是两回事，因为医学上的一些限制，很多情况下，就算诊断出病症，也是无法根治。而且，这种screen test还经常有错误errors。它只要有两种错误。第一种叫做false positive errors，就是当被检查的人没有病的时候，检查结果却说他有病。第二种叫做false negative errors，就是当被检查人有病的时候，却说他没有病。第一种错误是非常costly的，因为一旦检查结果是positive，医生们就需要 followup treatment，还有再研究，如果最后发现其实结果的错误的话，就浪费了很多人力物力。所以医学界大部分人宁可检查结果多一点false negative errors.因为如果有人第一次被漏掉了，很有可能会在下一次的检查中被发现。

　　考了一道主题题，一个关于false positive and false negative errors 的细节题，一个关于pre-exempt的细节题。

　　考题:

　　1.考了一道主题题，我选了比较了两种方法

　　2.一个关于false positive and false negative errors 的细节题

　　3.一个关于pre-exempt的细节题

　　4. 如果要使screening test更加specific，应该怎么样。

　　5.细节题：作者做了下列事情Except，我选得E(这个比较确定)

　　A define false positive

　　B define false negative

　　C 说明了运用se..tive的好处

　　D 说明了运用re..tive的好处

　　E说哪种病可以更好的被采用这种screen strategies

　　6. 细节题：以下哪个是re..tive的(即针对false positive)：选E，定位到re..tive的定义处说fewer false positive即可解决。E选项是：replacing 10%的false positive with 5%的false positive。

　　54.**medical screening 对于health的intervention的作用

　　好像是2段。先说screening呢可以稍微prevent disease一下 但是呢prevent disease不比treat来的简单哪 screening会产生误诊什么的。没什么考题。第二段说screening report很多时侯会产生sensitive specific这个会括号定义这两个现象 有题。sensitive=false negative specific=false positive如果对于一个人群 hardly have this disease screening interval的次数过多 (还不考虑screening的成本) 那么就会更多产生specific . 有一道题问 下列哪里是作者解释的时候没有define的 我选了false negative 和false positive。这个确定。还问了个下列哪个example会产生specific的例子 选了那个interval的选项

　　背景资料：

　　wikipedia有注解：

　　http://en.wikipedia.org/wiki/False_positive#Type_I_error

　　其实这个false positive和false negative的最好举例就是伊索寓言里“狼来了”的故事，小孩子说狼来了，结果其实狼没有来，那就是一个false positive，最后一次狼真得来了，没有人相信小孩，那就是一个false negative。

　　我摘取了一些可以帮助的内容：

　　Consequences of type I and type II errors

　　Both types of errors are problems for individuals, corporations, and data analysis. A false positive (with null hypothesis of health) in medicine causes unnecessary worry or treatment, while a false negative gives the patient the dangerous illusion of good health and the patient might not get an available treatment. A false positive in manufacturing quality control (with a null hypothesis of a product being well-made), discards a product, which is actually well-made, while a false negative stamps a broken product as operational. A false positive (with null hypothesis of no effect) in scientific research suggest an effect, which is not actually there, while a false negative fails to detect an effect that is there.

　　Based on the real-life consequences of an error, one type may be more serious than the other. For example, NASA engineers would prefer to throw out an electronic circuit that is really fine (null hypothesis H0: not broken; reality: not broken; action: thrown out; error: type I, false positive) than to use one on a spacecraft that is actually broken (null hypothesis H0: not broken; reality: broken; action: use it; error: type II, false negative). In that situation a type I error raises the budget, but a type II error would risk the entire mission.

　　Alternatively, criminal courts set high bar for proof and procedure and sometimes release someone who is guilty (null hypothesis: innocent; reality: guilty; test find: not guilty; action: release; error: type II, false negative) rather than convict someone who is innocent (null hypothesis: innocent; reality: not guilty; test find: guilty; action: convict; error: type I, false positive). While in totalitarian states, the opposite may be true, with the preference to jail someone innocent, rather than allow an actual dissident to roam free. Each system makes its own choice regarding where to draw the line.

　　Minimizing errors of decision is not a simple issue; for any given sample size the effort to reduce one type of error generally results in increasing the other type of error. The only way to minimize both types of error, without just improving the test, is to increase the sample size, and this may or may not be feasible.

　　以上就是关于Medical Diagnostic Screen Test这篇GMAT阅读机经的全部内容，考生可以有选择的看看，机经虽好，但是也要适度哟。最后祝大家都能考出好成绩。