use observation
sort observeid
save observation, replace
use household_head
keep individid socialgpid hhd_sdate
gen refdate = $refdate 
drop if refdate < hhd_sdate
gen period = qofd(refdate )-qofd(hhd_sdate ) +1
expand period
sort individid hhd_sdate
by individid hhd_sdate: gen p= _n-1
gen quarterdate = qofd(hhd_sdate) + p
gen refquarter = qofd(refdate )
sort individid quarterdate
egen maxhhd_sdate = max(hhd_sdate), by(individid quarterdate)
keep if hhd_sdate == maxhhd_sdate 
sort individid
tostring quarterdate, generate(key)
replace key = socialgpid + individid + key
duplicates drop key, force
sort key
save crossehousehodlheadtemp, replace
keep if refquarter == quarterdate 
format refdate %td
sort individid
duplicates drop individid, force
save cross\crosshouseholdhead, replace