filter_pers.do

// import individual socio-economic data
use ../BATS96/compPER, clear
sort sampno
// if with_dist == 1, then 
// calculate the eocnomic distance based on working time span
local with_dist 0

******** merge work activity
if `with_dist' == 1 {
	merge 1:1 sampno persno using filtered_work
	tab _merge
	keep if _merge == 3
	drop _merge
}
******** filter household heads
// replace missing variables
// replace age = . if age == 999
// replace income = . if income == 98 | income == 99

// remove missing observations
drop if age == 999
drop if income == 98 | income == 99
drop if employ == 3 | gender == 3 | student == 3
drop if license == 3

// only consider the household heads
keep if relate < 2
by sampno: gen numpers = _N
keep if numpers == 2
by sampno: gen has_spouse = sum(relate==1)
by sampno: replace has_spouse = has_spouse[_N]
keep if has_spouse == 1

******** calculate economic distance
// number of persons in each household
qui tab relate
global N = r(r)

// generate household working time span
sort sampno persno
by sampno: gen persid = _n
if `with_dist' == 1 {
	forvalues j = 1/$N {
		by sampno: gen dist_`j' = max(ending[_n], ending[`j']) - ///
								  min(begin[_n], begin[`j'])
	}
}
else {
	forvalues j = 1/$N {
		by sampno: gen dist_`j' = 0
	}
}

// save refined data
save dat/filtered_pers, replace