use houseres
sort socialgpid
egen counter = count(episodeid), by(socialgpid)
drop if (res_edate != . & res_edate < $refdate )
drop if (res_sdate != . & res_sdate > $refdate )
gen refdate = $refdate
keep socialgpid locationid
sort socialgpid

duplicates drop socialgpid, force
sort socialgpid
save cross\crosshouseresidency, replace