clear all
cd e:\chililabdata\data
use individual
sort individid
save, replace
use observation
sort observeid
save, replace
use indmarstatus
rename mar_sobserveid observeid
sort observeid
merge m:1 observeid using observation, keepusing(obs_entry_date)
keep if _merge ==3
gen visitdate = obs_entry_date/86400000
gen year = year( obs_entry_date/86400000)
drop if year < 2004
gen h = halfyear(obs_entry_date/86400000)
gen round = yh(year,h)
sort individid round
gen period = round[_n+1]-round
replace period = 109-round if individid!=individid[_n+1]
expand period
replace round = round-89
sort individid round
by individid round: gen p= _n-1
replace round = round + p
drop if round > 19
drop  period p _merge  
tostring round, generate(rounds)
replace rounds = "0" + rounds if strlen(rounds) == 1
gen individkey = individid +  rounds
sort individkey
duplicates drop individkey, force

sort individid
merge m:1 individid using individual, keepusing(gender ethnicid  bod)
gen firstdate = mdy(7,1,2004)
gen roundtime = firstdate+ 180*round
gen age = (roundtime-bod)/365.25
drop  mar_episodeid observeid mar_eobserveid obs_entry_date year h _merge
save rMarstatus, replace