clear
cd e:\chililabdata\data
use outmigration
replace out_date=out_date/86400000
format out_date %td
gen year = year( out_date)
gen h = halfyear(out_date)
gen round = yh(year,h)-89
tostring round, generate(rounds)
replace rounds = "0" + rounds if strlen(rounds) ==1
gen socialkey = socialgpid+  rounds
gen individkey = individid+  rounds
drop  EID h socialgpidGuid   eventid observeid year
duplicates drop individkey, force
drop if round < 0
save rOutmigration, replace