Derivation
variable: wife (table[s]: all_spouse_pairs_clean_summarised [derived table])
variable: husband (table[s]: all_spouse_pairs_clean_summarised [derived table])
variable: ident (table[s]: all_marstatus_reports [derived table])
<on all_spouse_pairs_clean_summarised:>
expand 2, gen(exp)
gen ident=wife if exp1==0
replace ident=husband if exp1==1
drop if ident==""