删了pre1依旧是这种结果

gen Dyear= year-2012
gen pre6= (Dyear==-6&did==0)
gen pre5= (Dyear==-5&did==0)
gen pre4= (Dyear==-4&did==0)
gen pre3= (Dyear==-3&did==0)
gen pre2= (Dyear==-2&did==0)
gen pre1= (Dyear==-1&did==0)
gen current=(Dyear==0&did==1)
gen post1= (Dyear==1&did==1)
gen post2= (Dyear==2&did==1)
gen post3= (Dyear==3&did==1)
gen post4= (Dyear==4&did==1)
gen post5= (Dyear==5&did==1)
gen post6= (Dyear==6&did==1)
gen post7= (Dyear==7&did==1)
gen post8= (Dyear==8&did==1)
drop pre1
reg tfp_lp pre* current post* growth lev cash Top1 labor capinten size age,vce(cluster id)
这是我的代码，请问有什么问题吗，由于是多期did，我是用gen did = (year>IPPyear)对did进行赋值的

你可以参考一下https://zhuanlan.zhihu.com/p/137617052这篇帖子看看

楼主你好，我也正在进行多期did，我想请问下，对于一个公司来说，它只有政策实施前的数据或者只有政策实施后的数据，是不是应该删掉这个公司。

不吧，我没删哎