Adding flag for imputed missing value

[Pratap Pundir]

In ILO data on unemployment, I am imputing missing values

* Impute unemployment  
sort countrycode year  
replace unemployment_wb = (unemployment_wb[_n-1] + unemployment_wb[_n+1])/2 if unemployment_wb == . & countrycode == countrycode[_n-1] & countrycode == countrycode[_n+1]  
replace unemployment_wb = (unemployment_wb[_n-2] + unemployment_wb[_n+2])/2 if unemployment_wb == . & countrycode == countrycode[_n-2] & countrycode == countrycode[_n+2]  
replace unemployment_wb = (unemployment_wb[_n-1] + unemployment_wb[_n+1])/2 if unemployment_wb == . & countrycode == countrycode[_n-1] & countrycode == countrycode[_n+1]  
replace unemployment = (unemployment[_n-1] + unemployment[_n+1])/2 if unemployment == . & countrycode == countrycode[_n-1] & countrycode == countrycode[_n+1]  
replace unemployment = unemployment_wb if unemployment == . & unemployment_wb != .  
replace unemployment = (unemployment[_n-1] + unemployment[_n+1])/2 if unemployment == . & countrycode == countrycode[_n-1] & countrycode == countrycode[_n+1]   
replace unemployment = (unemployment[_n-2] + unemployment[_n+2])/2 if unemployment == . & countrycode == countrycode[_n-2] & countrycode == countrycode[_n+2]  
replace unemployment = (unemployment[_n-1] + unemployment[_n+1])/2 if unemployment == . & countrycode == countrycode[_n-1] & countrycode == countrycode[_n+1]

Whenever I impute a missing value, I want to add a flag...let's say I have a flag column (boolean), which should be TRUE for every imputed missing value. How could I go about achieving that?

[Maarten Buis]

In the code below I cleaned up your imputation code by using the bysort : and by: prefixes and created the flags (in Stata 1 is true and 0 is false)

 gen byte imp_wb = (unemployment_wb == .)
* Impute unemployment  
bysort countrycode (year): replace unemployment_wb = (unemployment_wb[_n-1] + unemployment_wb[_n+1])/2 if unemployment_wb == .  
by     countrycode       : replace unemployment_wb = (unemployment_wb[_n-2] + unemployment_wb[_n+2])/2 if unemployment_wb == .  
by     countrycode       : replace unemployment_wb = (unemployment_wb[_n-1] + unemployment_wb[_n+1])/2 if unemployment_wb == .  
replace imp_wb = 0 if unemployment_wb == .
gen byte imp = (unemployment == .)  
by     countrycode       : replace unemployment    = (unemployment[_n-1] + unemployment[_n+1])/2 if unemployment == .  
by     countrycode       : replace unemployment    = unemployment_wb if unemployment == . & unemployment_wb != .  
by     countrycode       : replace unemployment    = (unemployment[_n-1] + unemployment[_n+1])/2 if unemployment == .  
by     countrycode       : replace unemployment    = (unemployment[_n-2] + unemployment[_n+2])/2 if unemployment == .  
by     countrycode       : replace unemployment    = (unemployment[_n-1] + unemployment[_n+1])/2 if unemployment == .  
replace imp = 0 if unemployment == .