OG 2017 CR 627 难题，求讲解！

熊先生

The difference in average annual income in favor of employees who have college degrees, compared with those who do not have such degrees, doubled between 1980 and 1990. Some analysts have hypothesized that increased competition between employers for employees with college degrees drove up income for such employees.

Which of the following, if true, most seriously undermines the explanation described above?

A) During the 1980s a growing percentage of college graduates, unable to find jobs requiring a college degree, took unskilled jobs.

B) The average age of all employees increased slightly during the 1980s.

C) The unemployment rate changed very little throughout the 1980s.

D) From 1980 to 1990 the difference in average income between employees with advanced degrees and those with bachelor’s degrees also increased.

E) During the 1980s there were some employees with no college degree who earned incomes comparable to the top incomes earned by employees with a college degree.

麻烦主要讲解A和E，感谢！

看了国外的论坛有讨论该题目的，对A的解释是：

1. ANSWER IS A
In 1980 salary per month
No degree employee:- 100 $
Degree employee:- 110 $
Difference = 10 $

In 1990 salary per month
No degree employee = 200 $
Degree employee= 516 $
Difference=316 $

Main reason for the growing difference in salary of degree and no degree workers; the degree holders of 1980 who sold themselves short and started working at the same pay as the non degree holders.
Result:- Very little salary difference between degree and no degree employee

Fast Forward to 1990
Degree holder took only high paying jobs whereas no degree took the same worker level low paying jobs.
Result :- The salary difference between degree and non degree worker increased.

http://gmatclub.com/forum/the-difference-in-average-annual-income-in-favor-of-employees-who-have-220521.html
如果是这个解释，那么E也符合这个意思啊，为什么不能选？

2. A) During the 1980s a growing percentage of college graduates, unable to find jobs requiring a college degree, took unskilled jobs.
taking unskilled jobs means less pay
example in 1980 suppose there are 100 employees 50% worked for unskilled jobs
and in 1990 suppose 20%
Skilled pay : 100
unskilled pay: 50

1980 avg income : (100)(50)/50 = 100
1990 abg income : (100)(80)/50 = 160

so its not the competition but the higher percentage of people working for skilled jobs.

http://www.beatthegmat.com/og-cr-the-difference-in-average-annual-t292542.html
这个解释没看懂……

我还是觉得稀里糊涂的，希望有大神慷慨帮助！

Bradz

我说说我的想法。原题是说80-90年，有大学学历的（C）和没有大学学历的（NC）工资差翻番了；有人推测是雇主对C的争夺激烈，推高了C的薪水。问怎么weaken推测。

E说有的NC拿了和最高的C一样的薪水，这和推测没关系，无关选项。

A说越来越多的C找不到合适的工作。如果雇主对C的争夺很激烈，C怎么会越来越难找工作呢？这里就是demand and supply的问题，如果是demand高（像推测说的那样）推高了price，那么supply怎么会找不到相对应的demand呢？

ccp92

Bradz 发表于 2016-11-14 18:12
我说说我的想法。原题是说80-90年，有大学学历的（C）和没有大学学历的（NC）工资差翻番了；有人推测是雇主 ...

同意！               

熊先生

Bradz 发表于 2016-11-14 18:12
我说说我的想法。原题是说80-90年，有大学学历的（C）和没有大学学历的（NC）工资差翻番了；有人推测是雇主 ...

感觉是我看的那几个帖子把问题复杂化了，谢谢！！

windowshade

你说：蓝翔的哥们赚钱多， 因为老板抢。我说：扯淡，蓝翔的哥们好多都找不到挖掘机的工作，都失业了，没人抢

熊先生

windowshade 发表于 2016-11-21 06:35
你说：蓝翔的哥们赚钱多， 因为老板抢。我说：扯淡，蓝翔的哥们好多都找不到挖掘机的工作，都失业了，没人 ...

猪小王

A的重点是, 越来越多的college students找不到需要大学学位的工作，所以并不存在employers争抢大学毕业生的现象。否定了employers争抢大学生（因）导致（果）有大学学位的雇员平均工资高这个因果关系。
如果真有employers争抢大学生，那么文中果-》因推理成立；如果没有，说明还有别的原因。

KellyLu961031

我觉得提问是问的哪个undermine了explanation. 而E选项是undermine了premise - 你说有很大的工资差，可事实证明很多不是Cdegree的也拿了差不多的工资。 （没有工资差）

而explanation：increased competition between employers for employees with college degrees drove up income for such employees.才是需要你去攻击的东西。你应该说要么没有increased competition; 要么increased competition 没有 drove up income,或者increased competition between employers for employees without college degrees is even higher.

Hope this helps. 我自己也选成了E.

可聪明了

这道题，答案要多一层假设：雇主竞争激烈=好工作特别好找

找论证中的因果关系
因：雇主对有学历的人竞争激烈
果：有学历的人工资比无学历的高

A 很多有学历的人，找不到好工作 （隐晦的切断了因果间的联系，俗称无因有果，干扰原文的因果关系）
B 年龄增长（年龄增长，无法与有无学历建立直接联系，不干扰原文因果）
C 失业率没变（同样失业率包含有学历与无学历两块，有多种排列组合情况使总失业率不变的，不能永恒同方向的干扰因果）
D增加了新信息：说学历越高、工资更高（如果因果正确，反而有加强效果；如果是他因，也不会干扰原文因果）
E无学历的也有高收入人群（这是一种经典的逻辑错误：不能因为没有加强，就认为它是削弱理由，属于证据不充分型的无效论证）

YunZoo

分享一下我的觀點，我猜測這題主要是在考閱讀的陷阱，或許native speaker在時間壓力下也會看錯

The difference in average annual income in favor of employees who have college degrees, compared with those who do not have such degrees, doubled between 1980 and 1990. Some analysts have hypothesized that increased competition between employers for employees with college degrees drove up income for such employees.

比較的對象是“有大學學歷的average annual income在1980-1990年間的差距”，比起沒有此學歷的這十年中的差距，有大學學歷的差距在1980-1990年間翻了兩倍。
假設大學學歷：1980 $1000，1990 $800 difference: $200
   非大學學歷：1980   $500，1990 $600 difference: $100    --> differece:200是100的兩倍

這樣才符合答案，不是拔尖的拉高，而是拖油瓶拉低，才導致1980-1990年間，大學學歷平均收入差距擴大兩倍
A) During the 1980s a growing percentage of college graduates, unable to find jobs requiring a college degree, took unskilled jobs.

如果只寫difference in ...between A and B 我想大家都不會想錯，但偏偏中間插入跟另一個東西比，就容易搞混了