NO.PZ2015120204000018
问题如下：
If an omitted variable is correlated with variables already included in the model, coefficient estimates will be biased and inconsistent and standard errors will also be inconsistent. Is this Statement correct?
选项：
A.Yes.
B.No, because the model’s coefficient estimates will be unbiased.
C.No, because the model’s coefficient estimates will be consistent.
解释：
A is correct.
Chang is correct because a correlated omitted variable will result in biased and inconsistent parameter estimates and inconsistent standard errors.
就这道题目衍生有两个问题：
- 什么是一致性？
- 什么情况下会影响一致性（违反那些假设？或模型设定中有哪些错误？）及其原因
