请问这个问题解决了吗？我就是搞不定退出这个变量，所以决定用LP法了

计算exit
sort  id year
by id: gen exit=1 if year[_n+1]-year!=1
egen mis = rowmiss(exit)   
replace exit=0 if mis  
drop mis
replace exit=0 if year==2016  //是否使用需进一步思考
label define exit 1 "exit" 0 "survive"

计算exit
sort  id year
by id: gen exit=1 if year[_n+1]-year!=1
egen mis = rowmiss(exit)   
replace exit=0 if mis  
drop mis
replace exit=0 if year==2016  //是否使用需进一步思考
label define exit 1 "exit" 0 "survive"

或计算exit
sort  firmid year
by firmid: gen has_gaps = 1 if year[_n-1] != year-1 & _n != 1
. sort firmid has_gaps
. by firmid: replace has_gaps = 1 if has_gaps[_n-1] == 1
. replace has_gaps = 0 if has_gaps == .
. by firmid: generate exit = survivor == 0 & has95 == 0 & has_gaps != 1
> & _n == _N
. replace exit = 0 if exit == 1 & year == 2002

gen firmid = gvkey
. sort firmid year
. by firmid: gen count = _N
. gen survivor = count == 8
. gen has95 = 1 if year == 2002
. sort firmid has95
. by firmid: replace has95 = 1 if has95[_n-1] == 1
. replace has95 = 0 if has95 == .

您好？固定资产投资怎么计算？跪求代码。就是变量I_Dd