为什么线性性是良好性质?

回归方程的系数可由y1，...，yn线形表示，则各系数也服从正态分布，这应该是一个良好的性质吧，否则我们对于回归系数的显著性检验将更加棘手

我觉得说得通俗一些就是线性比较简单，易于处理

如果是个神秘的隐函数。。。那你想想连函数形式都不知道，更谈不上研究或者操作了

this easy to understand in the concept about projection, we can approximate a cuve as a line by project it to column space. and this need lieaner property!! so we need!! in fact we do not have the ratioal reason to require the lieaner property.

if yoy want to complete the economics you should master the linear algebra!! otherwise you can not understood it!!