讲义说：
- 多重共线性不会影响到consistency of regression coefficient estimate,
- regression coefficient estimate又会变得unreliable
=> 这不就说明其实 regression estimate是有被effect到的吗，否则怎么会变得unreliable呢？
- estimated regression coefficients and coefficient estimates 是同一个东西吗？ 怎么理解not affect the consistency of estimated regression coefficients and coefficient estimates 呢？
Heter中也谈到：not affect the consistency of parameter estimators, coefficient estimates are not affected - 怎么理解呢？
