2004-12-A-24

In criminal proceedings, defense attorneys occasionally attempt to establish that a suspect was not present at the commission of a crime by comparing the suspect's DNA to the DNA of blood or hair samples taken from the scene of the crime. Although every person's DNA is unique, DNA tests often fail to distinguish among DNA samples taken from distinct individuals. Hence, it is a mistake to exonerate a suspect simply by because that person's DNA did not match the DNA samples taken from the scene of the crime.

Which one of the following is a error in the reasoning above?

Answer: (B) It confuses a test that incorrectly identifies DNA samples as coming from the same person with a test that incorrectly shows as coming from different persons that come from a single person.

其他几个选择明显不对. 但不明白为什么(B)对, 请NN翻译一下.

个人认为:文章论据提到"DNA检测有误把不同人DNA识别为同一人的DNA的可能性",我个人理解为:该检测有误抓好人的可能性.结论是说DNA会有宽大坏人的可能性.这个就与论据相反了.(B)提到:文章混淆了"把不同人的DNA错误地识别为同一人的DNA"和"本属于同一人的DNA错误地识别为是属于不同人的DNA".前者才是文章的论据.

不知道有没有道理.大牛进来评论一下.

以下是引用zindan在2006-9-1 0:20:00的发言：

个人认为:文章论据提到"DNA检测有误把不同人DNA识别为同一人的DNA的可能性",我个人理解为:该检测有误抓好人的可能性.结论是说DNA会有宽大坏人的可能性.这个就与论据相反了.(B)提到:文章混淆了"把不同人的DNA错误地识别为同一人的DNA"和"本属于同一人的DNA错误地识别为是属于不同人的DNA".前者才是文章的论据.

不知道有没有道理.大牛进来评论一下.

Close, but not exactly.

This one reminds me of an older lsat question. It was something like "Airport metal detector only mistakenly catches a bag without a bomb 1% of the time, therefore it catches bags with bomb 99% of the time."

Also another one "A computer security program never give access to unauthorized users, so it is reliable to grant access to autorized users."

All of these same error, a satistics of a group mistakenly applied to another group.