在计量模型中添加解释变量，如何解释之后其他解释变量系数变化的现象？

比如原先解释变量有x1,x2,对应的系数分别是0.1和0.2。现在方程加入一个解释变量x3之后，x1的系数变为0.05。这样，能否从现实的角度解释为，x3削弱了x1对Y的影响。

不能
因为本来就有很多因素影响Y

Hello chuan1985,

Based on my knowledge, you don't have solid evidence to do so.
You may use P value or t value to evaluate independent variables influence on dependent variable.
We normally don't reply on constants to illustrate such influence.

Theoretically speaking, original equation will changed after inputting another variable.
This won't guarantee your conclusion.
You'd better use statistic terminology to illustrate your conclusion.

To make your conclusion reliable,
use adjusted R square not R square, please.
I hope this helps.