比如:ivreghdfe y x2 x3 x4 (x1=IV) i.id#i.year, cluster(id) first
会出现:Warning - endogenous variable(s) collinear with instrumentsVars now exogenous: Dig
Warning - collinearities detected
Vars dropped: 30.province#2017.year 30.province#2018.year
30.province#2019.year 30.province#2020.year
30.province#2021.year 30.province#2022.year gong
有没有大牛说下应该怎么解决呢,谢谢~