bwhbwh 发表于 2012-7-27 14:04
sort sirmid year
gen exit=0
replace exits=1 if firmid[_n]!=firmid[_n+1]&year!=你的报后年份2009 ...
试运行OPREG时出现以下错误:
tsset code year
panel variable: code (unbalanced)
time variable: year, 1999 to 2007, but with gaps
delta: 1 unit
. opreg salerevenue, exit(exit) state( fixasset) proxy(investment) free( profit l)
Note: ignoring 608993 observations with missing value for proxy variable
(running opreg on estimation sample)
_investment_investment_investment invalid name
an error occurred when bootstrap executed opreg
求教这是什么错误啊?我的数据感觉没有问题了啊.....