一道比较奇怪的题目,大家一起讨论讨论

jane1109

Choi: All other factors being equal, children whose parents earned doctorates are more likely to earn a doctorate than children whose parents did not earn doctorates.

Hart: But consider this: Over 70 percent of all doctorate holders do not have a parent that also holds a doctorate

Which one of the following is the most accurate evaluation of Hart's reply?

A) It estalishes that Choi's claim is an exaggeration

B) If true, it eddectively demonstrates that Choi's claim cannot be accurate

C) It is consistent with Choi's claim

D) It provides alternative reasons for accepting Choi's claim

E) It mistakes what is necessary for an event with what is sufficient to determine that the event will occur

正确答案是C, 大家讨论下为什么

nidm

这道题是有点怪.怪的原因是: CHOI和HART谈的不是一回事. 换个说法:
CHOI: 现役球星的孩子更可能成为球星
HART: 但是,球星的孩子中只有10%选择了踢球.

两个人自说自话,既不否认对方,也不支持对方. 比较五个答案,只有C可以吧.
C不是个好答案,但是比其他四个好些

对了,下次能不能把题目的来源也贴出来?比如说,那年那月的题

fredshen

以下是引用nidm在2006-8-25 23:41:00的发言：

两个人自说自话,既不否认对方,也不支持对方. 比较五个答案,只有C可以吧.
C不是个好答案,但是比其他四个好些

You are right about the conclusion, but not right on your analogy to explain.

Choi is saying if a child has doctorated parents it's more likely to have doctor's degree than the same child if it doesnt have such parents.(All other things being equal). Hart counters that there are more doctors without doctrated parents than those who have. Hart is confusing two different percentages.(why? ) This kind of percentage error  question appeared many times in LSAT, and most of them are flawed question, and some are weaken If I remember correctly.

For example, Woman over 40 tend to have much higher risk than woman under 40 to have premature baby, therefore a premature is more likely born to a woman over 40. 

  

[此贴子已经被作者于2006-8-26 2:36:07编辑过]

fredshen

By the way, I think biology, econ, psyc majors will have much less hard time dealing with this kind of questions than the rest of us. Because they deal with this kind of study with simliar data all the time.  When there is cororlation between two variables (parent's doctor degree, and their kid's chance to have doctor's degree),  we cannot simply look at the data that might introduce other variables to confirm it. So in this case, even if Hart says "You are right, there are 70% doctors that have doctor parents in this field". It still wont confirm Choi's claim.

[此贴子已经被作者于2006-8-26 2:41:39编辑过]

damnyou

It's consistent because they can co-exist. meaning the both statements are valid and not against one and the other.

philipfang

Suppose there are 100,000 non-doctor parents and 10% of them (10,000) have doctor children.

Suppose again there are 10,000 doctor paretns and 15% (2000) have doctor children.

Then both Choi and Hart's statements are true.

fredshen

以下是引用philipfang在2006-9-10 18:35:00的发言：

Suppose there are 100,000 non-doctor parents and 10% of them (10,000) have doctor children.

Suppose again there are 10,000 doctor paretns and 15% (2000) have doctor children.

Then both Choi and Hart's statements are true.

This line of thinking can be dangerous.

Suppose there is a similar question

Instead of two people aguing. It's one person's argument goes like this

"Clearly, all other factors being equal, children whose parents earned doctorates are more likely to earn a doctorate than children whose parents did not earn doctorates. This is because  over 70 percent of all doctorate holders have a parent that also holds a doctorate."

or vice versa

"Recent study  shows, all other factors being equal, children whose parents earned doctorates are more likely to earn a doctorate than children whose parents did not earn doctorates. Therefore, this study explains why over 70 percent of all doctorate holders in my university have a parent that also holds a doctorate."

Now what's the flaw of this logic? Or harder, it can ask you to evaluate whether it is valid logic and why.

Again the key here is not come up with a number, rather you have to see the statement about likely hood of a effect to a subject with  a variable on and off is irrelevant to the statement about the sheer percentage of that effect in a population.

Once one graps this. LSAT percent and number question will become easy.

There are questions like

80% of  percent airplane crash had one common thing assoicated with it, therefore that thing should be avoided to remdey potential crash.

More premature babies are born to women under 40, therefore to the contray of common belief, woman under 40 are more like to have premature baby than over 40.

on and on, same thing

 

[此贴子已经被作者于2006-9-13 11:17:15编辑过]