我是把year和rank_year改成字母型变量（tostring）
gen 新变量=year+rank_year [这样加起来就会变成20001 20012.。。]
然后保留所需，以2007年上市公司为例
keep if standard == "20071" | standard == "20082" | standard == "20093" | standard == "20104" | standard == "20115" | standard == "20126" | standard == "20137" | standard == "20148" | standard == "20159" | standard == "201610"
再然后
collapse (mean)leverage, by(rank_year1 leverage4q) [求平均]
.......
扫码加好友，拉您进群
全部版块
我的主页
收藏
