您可以在回归中使用## 运算符来获得具有固定效应的饱和模型:
首先,输入数据,使您有一个二元结果(bought)、一个因变量(saidhi)和一个固定效应变量(sign)。 saidhi 应该与您的结果相关(因此 saidhi 的一部分与 bought 不相关,而一部分与您的结果相关),并且您的FE 变量应该与 bought 和 saidhi 相关(否则,如果您只对 saidhi 的影响感兴趣,则在回归中没有任何意义em>)。
clear
set obs 100
set seed 45
gen bought = runiform() > 0.5 // Binary y, 50/50 probability
gen saidhi = runiform() + runiform()^2*bought
gen sign = runiform() + runiform()*saidhi + runiform()*bought > 0.66666 // Binary FE, correlated with both x and y
replace saidhi = saidhi > 0.5
现在,运行你的回归:
* y = x + FE + x*FE + cons
reg bought saidhi##sign, r
exit
你的输出应该是:
Linear regression Number of obs = 100
F(3, 96) = 13.34
Prob > F = 0.0000
R-squared = 0.1703
Root MSE = .46447
------------------------------------------------------------------------------
| Robust
bought | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
1.saidhi | .3571429 .2034162 1.76 0.082 -.0466351 .7609209
1.sign | .3869048 .1253409 3.09 0.003 .138105 .6357046
|
saidhi#sign |
1 1 | -.1427489 .2373253 -0.60 0.549 -.6138359 .3283381
|
_cons | .0714286 .0702496 1.02 0.312 -.0680158 .210873
------------------------------------------------------------------------------
1.saidhi是sign == 0时saidhi的效果。 1.sign 是符号的效果,单独,即saidhi == 0时。 saidhi#sign 下的部分描述了这两个变量之间的相互作用(即它们同时为 1 的边际效应......请记住,它们都为 1 的总效应包括前两项)。您的常数代表 bought 当两者都为 0 时的平均值(例如,这与您从 sum bought if saidhi == 0 & sign == 0 获得的值相同)。