模型类似如下：y=x1_big4+x1_n_big4+controls bysort year Indcd_mid :  egen sumbig4=sum(big4)
bysort year Indcd_mid big4: egen totalbig4=sum(x1) if big4==1

gen x1_big4=(totalbig4-x1)/(sumbig4-1)

bysort year Indcd_mid :  egen sumn_big4=sum(n_big4)
bysort year Indcd_mid n_big4: egen totaln_big4=sum(x1) if n_big4==1

gen x1_n_big4=(totaln_big4-x1)/(sumn_big4-1)

回归如下：
xi：reg y x1  x1_big4  x1_n_big4 controls  i.year if big4==1
xi：reg y x1  x1_big4  x1_n_big4 controls  i.year if n_big4==1


结果一开始出来的是no observations
然后我调整完数据之后，就由于多重共线性把 x1_n_big4剔除了，求教啊！！真的不知道怎么办了~